Here is a collection of notes, reviews, and my personal and somewhat subjective recommendations on telescopes, binoculars, eyepieces, and various other equipment for amateur astronomy. Prices are more of a ballpark figure, approximately as of 2013-15.
Every amateur astronomer needs a binocular. Many find that they do not need a telescope. That is why is start the list with binoculars. They provide not just a handy tool helping in finding objects for the telescope, but a completely valid and enjoyable viewing experience by themselves.
The Nikon Action EX 8x40 costs about 160 dollars. That price is about mid-market. You can spend much more money on a binocular, but will you get as much more quality? I don't think so. This instrument is a joy to use. It is a wide-angle design, and about 60% of the field are tack sharp. Towards the edge things quickly get blurry, but the wide field of view is still very nice to have. The weight is a comfortable 750g. The size is small but the instrument feels very solid, and the surface provides good grip. The focuser is bit stiff, but not excessively so; you won't change the focus by accident. I also own an Olympus DPS I 10x50, and comparing them side by side you can immediately see that the Nikon is a different class.
The eye relief is very generous. However, the eyecups twist out and do not provide complete cover against stray light from the side. I would prefer cups that extend towards the sides.
This 8x40 is advertised as having 8.2° angle of view, but when I compare the views with my star charts it looks more like about 7.5°. Still good, and it's definitely easier to hold steady than the 10x50. Of course this binoc is also great for daytime viewing. If you are into birding or general nature viewing as well as astronomy then this instrument will serve very well; the coatings must be very good, since the image is brighter and colors come out more lively than with cheaper binocs.
Compared to the Nikon the DPS-1 is undoubtedly inferior, but it only costs about 60 dollars, so if you are looking for a cheap yet decent binocular then this is an option. In this price range you get a lot of junk that is pretty much unusable. This 10x50 is a perfectly acceptable instrument for amateur astronomy. Sharpness extends to about 60% of the field of view, just like in the Nikon, but you can't get the the image as tack sharp as in the Nikon, and there is a bit more false color around very bright objects. However, the faint deep sky objects look much the same as in the Nikon, aside from the higher magnification, which of course shows a little more detail (if you can hold it steady).
The differences to the Nikon are most apparent when you compare them side-by-side in daytime use; you just don't get the wonderfully vivid images of the Nikon Action EX. Still, this binoc is much better than my vintage 1960s 'Empire Made' (probably in Hongkong) which I inherited from my father and keep just for nostalgic reasons. Much progress has been made with optics and coatings since then.
Mechanically the binocular is decent, and the focuser works well. Unfortunately I had to return my first delivery, it was not just completely out of collimation, you could see the wrong angle of one of the front tubes without looking through the glass. I cannot imagine how this one got through quality control. Maybe quality control was outsourced to the customer. Anyway, as always Amazon replaced it speedily and without a fuzz. There are individual caps for each front lens and each eyepiece, so the chance of losing one of those four little plastic things is quite high.
Another option for the low-price Olympus DPS I is this ultra-wide binoc featuring a huge 9.3° angle of view (and 65° apparent field of view). The image quality is similar to the 10x50, stars just don't focus to perfect tiny circles, and about halfway from the center the image becomes increasingly blurry, but for the price this is still a very good deal. The eye relief is smaller than with the Nikon AE, but still acceptable, at least for people not wearing glasses. The magnification of 7x is much easier to hold steady than the 10x50, which means that I see about as much detail in this binoc since the image is more stable. The small size and weight (650g) are of course another bonus. This instrument also works well for birding. It is so small it fits in the outer pocket of my duffle coat. The only disappointment are the four individual plastic caps again, which are tedious to handle, and easily lost.
This binoc costs about 150 dollars and received good reviews in various birding forums. Birders tend to prefer the roof prism design because of smaller size and weight. I am so happy with the Celestron that I use them for all my birding and star gazing since I bought them. The optics are of course not perfect which should not be surprising at the price range. However, the view is surprisingly sharp across most of the field, and colors come out lively. There is a little purple fringing, but it is so faint that it does not bother me. I particularly like the smart design of the caps for lenses and eyepieces: they can be attached to the body and the strap so they can't get lost, yet they can be taken on and off quickly and easily. Of course this doesn't affect optical performance, but it improves the overall user experience quite a bit if you don't have to worry about losing a lens cap. Eye relief is good, and the construction feels very solid. They serve very well for both birding and astronomical viewing.
This Newton reflector on a Dobson mount was my first telescope, and it is still the one that I like best. For about 200 dollars you get a good parabolic diffraction-limited mirror, a solid mount, and two eyepieces, one of them of good quality, the other at least decent. The whole scope weighs about 7kg which makes it almost perfect for grab and go. It's maybe a somewhat bulky grab, but you can carry it with one arm, leaving the other free for the rest of your equipment.
The mount is a sort of half Dobson design. The tube is fixed to an arm which sits on a base similar to a lazy susan, but with teflon pads; friction and stiction in both alt and az is very good, and there is no perceptible wobbling. The only downside of the mount is its low height. You need some kind of support for the scope to put it on a higher level if you want to observe while sitting in a chair. A beer crate or a second chair work well. Of course, this puts the portability in perspective. On the other hand, if you are moderately flexible you may be fine with sitting on the ground while observing, as I have done many times.
Recently I purchased a Skywatcher AZ-4 for the Starblast, and with this sturdy alt-az mount the scope is much more comfortable to use. I can now sit on my favorite observing chair, a cheap plastic gardening product. Of course, the whole setup now comes close to 10kg, but this is still quite portable.
With its short focal length of 450 mm and 114 mm aperture the Starblast is king of the rich field. The kit 17 mm eyepiece provides a magnification of 26x, an exit pupil of 4.3 mm, and a angle of view of 2°. This is just about perfect for leasurely scanning the Milky Way, and for observing most of the larger deep sky objects. The image quality with the 17 mm is surprisingly good for this price range. There is some coma, but it is tolerable, and the sharpness across most of the field is fine. This eyepiece provides pleasing views, very suitable for going through most of the Messier catalog, especially in combination with a Barlow to double the magnification while retaining the nice eye relief.
The focuser is workable with the 17 mm, but difficult with the 6 mm. Use a 2x Barlow on the 6 mm and focusing becomes a Zen-like exercise in patience. I can see that Orion had to cut cost. This is a cheap rack-and-pinion affair, dunked in the infamous Chinese goo. The Starblast would be really great with a Crayford, or just a high-quality rack-and-pinion, but this is probably not possible within the 200 dollar budget.
When observing the moon at 150x there is a little less contrast compared to a refractor of similar aperture (such as the 4.7 inch Startravel 120), which is to be expected from the Newton design. The difference is not huge, and only apparent when you compare them side by side.
While the 17 mm is of good quality, the 6 mm is obviously supplied by Orion to sell the scope as an allrounder, suitable for the planets as well as deep sky. There is very little eye relief, and the apparent field of view is quite small. Barlowed 2x at 150x I can see the two major cloud bands on Jupiter with average seeing, but not much more. My first reaction was to chuck the 6 mm into the land of unloved eyepieces. After about a year I have come to accept the 6 mm. I guess it takes time to gain a little more experience before you can appreciate the pieces of equipment that are more diffcult to use. Speaking of EPs, there is also an eyepiece rack on the back side of the mount. It holds up to three eyepieces, which is very convenient in the field.
An f/4 Newton like the Starblast is rather unforgiving with bad collimation. However, collimating the Starblast is not rocket science and takes only a few minutes. Since the scope is so small the collimation screws can be reached easily while looking throught the eyepiece. A simple collimation cap is supplied and works well enough.
Even with the cheap focuser and the low mount, the Starblast is still just that - a blast. Simple to use, great views, and small and light for easy transport. It makes a great first scope, unless your interest is primarily the planets; then you would be disappointed.
Aperture fever hits everyone sooner of later, and when it got me I went for the biggest scope I thought I could handle. The Flex 10 obviously has 254 mm aperture, and 1200 mm focal length, making it a rather fast f/4.7 instrument. It costs about 650 dollars and comes with two good Plossls, a 25 mm and a 10 mm. The 25 mm gives you a 5.2 mm exit pupil at 48x magnification and a field of view of 1°4'. This means that even the smaller objects in the Messier catalog like the Owl nebula show reasonably bright and at a good size in the eyepiece. Reasonably bright here of course means not to much averted vision. I am still unable e.g. to see any spiral structure in M101 or even M51. I guess the moderate light pollution in the area is to blame (yellow zone), not the Flex.
The optical quality is sufficient for most deep sky targets, where aperture is much more important than perfect optics. However, it is a bit disappointing that moderately bright stars always show a bit of coma. Nevertheless, observing the moon is pleasant. I could also see several shadow transits of the Jupiter moons quite clearly.
The Dobson mount is stable and works well, having the right amount of friction and stiction; however, it keeps cracking a bit whenever I change alt or az. This can be annoying on those quiet summer nights when you would rather not make squeaking noises in your backyard all the time.
The one thing that I completely underestimated was the size and weight of the thing. This scope is really big. At 27 kg (about 60 pounds) it's just too much for me in one go. I disconnect the tube from the mount and carry them separately; this means two trips, and even so the pieces are bulky and not much fun to lug around. After having hauled the beast out of the shed and onto the observing spot I wonder whether I may not have bitten off more than I can chew.
Of course, once in place the scope is a joy to use. The crayford focuser is a delight, and in comparison with e.g. the Starblast the views of the smaller DSO are much improved. The Flex system works well, and there is no problem with collimation. The OTA consists of two parts: the upper section slides up from the lower one on three thick rods; three wing-type screws hold it in place. I once managed to drop it onto the lower section with a loud bang, fortunately nothing broke. You have to keep holding unto the upper section while lowering it down.
A thing to consider is the height of the eyepiece when viewing near the zenith. I am not a small guy, and yet I have to stretch quite a bit on my favorite seat, a cheap but light and comfortable gardening item. A proper height-adjustable observing chair would be better for a scope of this size.
Note that a scope of this focal length cannot go below 37x with a 1 1/4 (Plossl) eyepiece, which corresponds to about 1.3° of FOV. This scope is not suitable for wide-field views, it excels at going deep and studying the small faint fuzzies. Nevertheless, if you are planning on purchasing something of this magnitude I seriously urge you to reconsider. Quite often I find that I just don't want to do any heavy lifting tonight, and grab the Starblast instead.
The Skyscanner is similar to the Starblast in design. However, it is even more portable, since the mount is much smaller. The whole thing fits into a medium size backpack, with room to spare for accessories. Given the aperture you cannot get more portable than this. Yet the mount employs teflon pads like the Starblast's; it works really smoothly, and stability is very good. You definitely need some kind of support for this scope, as the eyepiece is otherwise very close to the ground. It works well on a table, or a convenient tree stump. Mounting on a sturdy camera tripod is also possible. Like everything else today the scope is made in China, but it's not easy to find out for sure: the packing box says China, a sticker on the OTA says Orion Telescopes/Division of Optronic Technologies, Watsonville CA; another sticker on the mount says Hua Lu Company. So there; my guess is that Hua Lu make the mount, and Synta make the OTA, on specs from Orion. The result is a cheap but nifty instrument that really delivers.
With 100 mm aperture and 400 mm focal length the kit 20 mm EP yields an exit pupil of 5 mm at 20x with a field of view of about 2.5°. This would be even better than the Starblast for rich field viewing, were it not for the slightly inferior optics. Everything looks just a little bit mushy compared to the Starblast. This only becomes apparent when you have them side by side on the same targets. It is not a huge difference, but it is there. Also, a certain amount of coma is always present, moderately bright stars just do not focus to perfect little dots like their fainter brothers.
Nevertheless, for about 120 dollars the Skyscanner is a very good deal. It comes with 20 mm and 10 mm eyepieces sporting rubber caps against stray light. They are basic but decent quality and work well with this scope. The eye relief is good even with the 10 mm, and they are also pretty much parfocal so you do not need to change focus after changing eyepieces; very convenient. Cost has again been cut most painfully with the focuser, but at this price range it is a miracle that Orion can sell scopes like this at all; a miracle of cheap Chinese manufacturing. Build quality is good, and the package is quite complete: you also get a red-dot finder which works nicely, a manual that is actually useful, and the planetarium software Starry Night which does a good job of integrating photographic images of deep sky objects into the night sky view, up to about 10x magnification, where the illusion is dispelled.
There are collimation screws for the secondary, but not for the primary; fortunately, mine arrived in almost perfect collimation and has not deviated since. The design is very simple and rugged. My guess is that it will not got out of collimation easily. The rear part is screwed on rather than glued, so one could improvise some method of collimating the primary if necessary.
One feature that strikes me as somewhat unfortunate is the angle of the eyepiece. It points straight up when the scope is level. The Dobson design has the eyepiece at an angle of about 30°, and the result is that the eyepiece is always in a convenient position for viewing. Obviously the Skyscanner was designed as a tabletop, to be leaned over. For me, the classic Dobson angle would have been better. But this is a minor issue. Another thing to note: the Skycanner lacks an eyepiece rack. Again, no big deal.
I think this is the perfect gift for kids with an interest in the stars. The Skyscanner is small, it weighs only about 3 kg, and the solid construction is designed to last. Planetary viewing is of course not its strong point, but even with the kit 10 mm eyepiece at 40x the Moon looks spectacular, the mystery and majesty of Saturn is revealed, and the Galileian moons and even the two main equatorial bands of Jupiter can be observed, conditions permitting. There is also a secondary smaller cap within the main OTA cover that allows for dimming the view when looking at the Moon, very much recommended, as the image is otherwise uncomfortably bright.
If you are an older kid with a bit more pocket money, and minimum size and weight are not your primary concern, then choose the Starblast instead. But if you want to get into the hobby while spending as little as possible, or if you are looking for a scope that is decent both optically and mechanically while at the same time the ultimate in portability then get this little gem.
Together with the EQ-1 mount (see below) this package costs about 150 dollars. The Startravel 80 is a very small and light f/5 short-tube refractor. It works well on very light astronomical mounts, but it can even be mounted on photo tripods. The focal length of 400 mm and aperture of 80 mm result in an exit pupil of 5 mm with the kit 25 mm eyepiece at 16x magnification and about 2.5° field of view. This frames large objects nicely, especially loose open clusters, which are difficult to identify and appreciate in narrow frames. On the other hand going to 40x with the supplied kit 10mm EP is also possible without the image getting too dark. The majority of the Messier objects and at least another fifty or so non-Messier deep sky objects can be observed reasonably well with this scope, in other words on any given night several dozens of objects wait to be explored. Not too bad for such a small and cheap instrument.
With a 32 mm Plossl the magnification goes down to 12.5x, and 4.1° angle of view, which provides nice views of very large objects such as the Pleiades and the Andromeda Galaxy; with this eyepiece the generous 6.4 mm exit pupil makes viewing even more comfortable. In other words, this scope can provide almost the same field of view as a 10x50 binocular, but without the wobble! This very wide field of view is very beneficial to beginners, since it makes it much easier to find deep sky objects.
In terms of image quality the ST80 does not disappoint; for a product in this very low price range it performs surprisingly well. Comparing it side by side with a very cheap reflector like the Orion Skyscanner it becomes apparent that the ST80 does not suffer so much from coma. The Skyscanner has the edge on faint DSO because of its 100mm aperture, but stars tend to be more perfect little pinpoints in the ST80 and just look really neat. Of course this is an achromat, so there is some chromatic aberration, but purple fringes only show on the planets and the brightest stars; for most deep sky objects they are completely unnoticeable.
An aperture of 80 mm cannot gather enough light for deep sky observing at higher magnification. This scope is best used at very low magnification on large deep sky objects. However, it does a surprisingly decent job on the planets; with the kit 10mm EP and 2x Barlow nice views of the moon at 80x can be obtained. I use a medium yellow filter for pleasant brightness and contrast. The two major cloud bands on Jupiter and its Galileian moons can be observed without difficulty. Of course, focusing becomes a challenge.
The focuser is a basic rack and pinion, and the whole section contains ample amounts of the Chinese mystery goo, which tends to get onto your hands, as the rack is exposed and easily touched. The focuser works well enough at low magnifications. At higher magnifications focusing gets quite frustrating. Note that there are two tiny holes with grub screws on the opposite side of the focuser. Select your smallest hex wrench and adjust those screws to provide just the right amount of friction on the focuser action. Mine arrived a little loose, which resulted in some wobble, but after adjusting the grub screws things are much better. I got this tip from a very helpful video on youtube by a guy under the nick astronomyshed, titled Skywatcher ST80 Mods & Tweaks which describes a lot more improvements for this scope.
With a 45 degree prism the ST80 can be used as a spotting scope e.g. for birding. The image is crisp and pleasant, surprising for an instrument at this price level. Similar quality in dedicated spotting scopes demands much higher prices. Attach your DSLR via the T2 connector of the ST80 and you have a decent 400 mm telephoto lens, again at a fraction of the cost of similar equipment from the camera shop. You may need an additional extension tube to reach focus; I bought a 40mm tube for about 20 bucks to reach focus on my Nikon D5100.
The ST80 works best on large targets like big open clusters. For general deep sky observing more aperture is desirable, and in this respect there are better choices in this price range (considering the ST80 plus mount), such as the Orion Starblast. However, for beautiful refractor looks at very low magnification the ST80 is hard to beat: decent optics, small and light, and very low price. If you use it with the EQ-1 in alt-az mode (see below) then you have a truly ultra-portable setup.
Another f/5 short-tube refractor, this time with a focal length of 600 mm. Compared to the ST80 this version can go to a little higher magnification on the faint fuzzies while still providing maximum brightness: the supplied 25 mm results in 24x and 5 mm exit pupil, compared to 16x for the ST80. Perhaps more importantly, it also offers a better focuser that works more smoothly and is still decent to use at 200x. Even a rack and pinion focuser can work just fine if it is good quality.
Compared to the ST80 this scope does not really provide that much more magnification at 5 mm exit pupil (24x instead of 16x), yet it is already significantly bigger and heavier than the ST80, and unlike that scope this one is not easily carried about in a backpack. The dew shield looks like it could be detached easily, but it can't, it's part of the objective assembly. The OTA weighs in at about 4 kg which is still relatively lightweight. However, it really needs a sturdy mount, at least something like the AZ-4, so the whole package comes to about 10 kg.
The same goo is used here as in the ST80. Do not touch anywhere near the underside of the focuser, that stuff is incredibly sticky and very hard to get rid of. You could probably replace it with better grease, but I don't want to do any serious disassembly, might mess up things for worse. If you want to give it a shot then check the aforementioned video. It's probably not rocket science.
Optically the scope is a pleasant surprise, given its price tag of about 250 dollars. The planets are not the strong point of a short-tube refractor, but when observing the moon at 200x the image is crisp and very satisfying. There is noticeably more contrast here than in the Starblast, which has a very similar aperture (4.5 for the SB, and 4.7 for the ST120). This is to be expected from the design (refractor vs Newton). Chromatic aberration is of course present but easily taken care of with a filter. Aside from not being particularly suitable for travel, as the name would imply, this refractor is a very decent and reasonably priced instrument.
The EQ-1 is a cheap and very basic equatorial mount for very small and light telescopes. I bought this mount in a package with the Startravel 80. Separately it costs about 80 dollars. The tripod and head are quite light, but you really need a counterweight for proper equatorial tracking. Unfortunately, the one supplied is too hefty for a featherweight like the ST80. It adds a lot of weight to the whole package while riding only about halfway out for balance. Substituting a lighter counterweight that can ride on the end of the bar would improve the situation.
For changing RA and DEC the corresponding wing screws have to be loosened and then re-tightened. Fine adjustment can be done via hand wheels within a small angle only, then the gears run out of space. The whole operation is pretty frustrating. The DEC and RA scales on the EQ-1 mount are more for show than real use, they are too small and too imprecise for more than a ballpark figure. In this price range you really get what you pay for.
In equatorial mode the EQ-1 is barely workable with large tolerances,
certainly no fun to use. If you want a decent
equatorial mount you have to look elsewhere.
However, note that you can always put an equatorial mount into alt-az mode by
pointing the RA axis at the zenith. Depending on the weight of your scope
you can even remove the counterweight (as in the image above).
When used in this way the EQ-1 is
decent enough, at least with a very light scope like the ST80.
This setup works for birding as well.
The AZ-3 is a cheap and very basic alt-az mount; mine cost about 80 dollars. It works on the
same simple principle as the AZ-4, using a friction or slipping clutch.
Unfortunately, the design is flawed; there is a lot of slipping with anything heavier than the ST80. Even with that
very lightweight scope the clutch has to be tightened quite a lot to prevent the scope
from slowly dipping. You need a wrench for that, and it means that tilting the scope takes
much more effort than with the AZ-4.
The reason why this mount doesn't work
is basic physics: if you want equilibrium in the altitude axis then the center of
mass of the telescope must be on that axis. On the AZ-3 the center of mass of the telescope is about
15 cm above the altitude axis; this means that there is nearly always a nasty lever working on the
slipping clutch. If you look at alt-az mounts that actually work (such as the AZ-4, or
any Dobson mount) you will see that
they allow the telescope to be mounted and balanced in such a way that its center of mass is
precisely on the altitude axis, since only this arrangement removes all force from the clutch,
regardless of where you point the scope.
Stay away from this mount unless you are looking for something that is both very cheap
and very light, which are about the only strong points of this device.
This alt-az mount cost about 180 dollars. I bought it primarily for the Starblast, as its
own small Dobson mount puts the scope too close to the ground for using a chair. The AZ-4 is very sturdy and weighs about
6 kg. It could probably support much more than the weight of the Starblast OTA. I got the aluminum
version; they also make the tripod with steel legs. The alu tripod feels very solid already.
The design uses a simple slipping clutch, but it works fine.
The movements in altitude
and azimuth are very smooth, and the friction on both axes can be adjusted easily without any tools.
The Starblast and the much heavier Startravel 120 can be pointed straight up at the zenith,
there are no problems with balance.
The upper part of the mount can be detached very easily for transport.
100% satisfaction with this product.
The first accessory to buy after the Starblast was of course a Barlow,
to double the magnification of the 17 mm while retaining the nice eye relief.
I chose a 40 dollar TS Barlow which also sports a T2 mount, and it did not
disappoint. There is of course some
loss in transmission because of the additional glass surfaces, but the effect
is small compared to the loss of brightness from the increased magnification.
For me the retained eye relief is certainly worth a small loss in brightness.
With the Starblast 17 mm kit EP a 2x Barlow yields 52x in addition to 26x;
this covers most deep sky objects I like to observe.
For my first additional eyepiece I chose not to spend a fortune, so I went
for the low budget Baader Classic line. Those are mostly Ortho designs, except for the 32 mm,
which is a Plossl. At 50 dollars it did not break the bank, but it works well.
The rubber cap shields from stray light, and the swivel design means
you can adjust the cap angle even with the eyepiece screwed in, which is nice.
32 mm provides the largest field of view possible with 1.25 inch eyepieces,
and the views with the Starblast are really worth trying. You get a whopping
3 deg 42 ' FOV! Just great as a finder EP, and for sweeping across the Milky Way.
For my next eyepiece I wanted something more up-market, so I went for
the 120 dollar Hyperion wide-angle. It gives about the same FOV as the 32 mm but
with higher magnification, so that sounded like the best of both worlds. Unfortunately,
the lack of focus off-axis was somewhat surprising. About 50% of the way everything
becomes so mushy that it's hardly worth having at all. Maybe my fast scopes are
the reason for this rather disappointing performance. Eye relief and
transmission are good, but I find that I use the 32 mm more often.
This is an allround filter for improving contrast on various types of nebulosity.
Of course it also darkens the view of background stars, but for emission nebulae the effect is striking.
This filter cost about 50 bucks and is worth every single one of them. E.g. the
Veil nebula is completely invisible from my yellow zone backyard, but becomes immediately
apparent and very distinct with the UHC filter.
Very effective on some types of gas nebulae that emit strongly in the O3 part
of the spectrum, like M27; however, the rest of the view
is darkened so much that I prefer to use the UHC filter on M27, even though the contrast
in the nebula itself is not as pronounced, but the view as a whole (including the background
stars) seems more pleasing to me; of course, a highly subjective decision.
I have to admit that I am a little disappointed by the performance of this
filter so far. May be I just haven't found the right applications yet, but
for me the views so far have been better in the UHC filter. E.g. the Veil is hardly
visible at all in this filter, while the UHC brings it out very clearly.
This 400 dollar DLSR has the same low-noise 16 MP sensor as the more expensive D7000.
The articulating display is
very useful when the camera points up at the sky and you want to do live view
focusing without twisting your neck into unhealthy angles. The interval timer
can be set for up to 999 frames. This means you can let the camera do the
shooting all by itself while you continue observing; very convenient.
The camera can save images in NEF raw format, but I do not use it anymore,
as I cannot see any difference to basic JPEG which means much smaller file size.
I realize that most people use Canon cameras for astrophotography, if they
use DSLR at all, but I am a Nikon guy.
The Canon vs Nikon flame war has been going on for decades between fans of either
side. I have owned a number of Canon and Nikon cameras over the years, and
I find that the colors just come out a little more lively on the Nikon, while the
Canon tend to look a little flat in comparison. There, I drew first blood,
but this is not a discussion forum, otherwise it would be on now.
There is another, less subjective aspect to the Canon vs Nikon discussion
in astrophotography. Older Nikon cameras used an algorithm to get rid of noise
that resulted in small isolated bright dots to be deleted: the infamous star eater
effect. With the newer cameras (maybe starting with about 2010 or so) this
algorithm has been improved, and the star eater effect is generally agreed to be
a thing of the past.
This lens is manual focus only on the D5100. Contrary
to most current lenses it still has the distance scale on the focus ring
with the hard
stop at infinity which alone makes it very useful for astrophotography.
No more tedious fiddling with live view focusing!
This Nikkor is small and light and also incredibly sharp even wide open;
quite a feat for a 100 dollar lense.
Of course there is a lot of coma off center at f/1.8, but it
becomes much more subdued at f/2.8. The angle of view is 46°
in the diagonal, just about perfect for constellation shots without tracking. For daytime
use the lens excels at portrait and of course low light.
This lens has a distance scale with a hard stop at infinity, but it is not completely
accurate. At the hard stop the focus is a little 'beyond' infinity, so you have to back up
a tiny bit, maybe about 0.5 mm or so. This is normal for high-quality lenses, as there are always
some tolerances; this buffer makes sure the lens can actually reach infinity, rather than
stop just a tiny bit too early.
Large deep sky objects can be imaged nicely with this lens:
mount the camera to a standard photo tripod, set exposure to 4 seconds, f/2.8 and ISO 1600.
Stopping down to f/4 and increasing ISO to 3200 or even 6400 with 2 seconds is another option, with more noise, but
less optical distortion. Use 2 seconds for objects close to the celestial equator, otherwise a small amount
of star trailing in the form of slightly eliptical stars will show.
4 seconds are fine for objects close to the poles.
Set the timer for something from 20 to 50 frames; note that the interval needs to be longer than
the exposure, 5 seconds is minimum
when you use 4 seconds exposure. Later use DeepSkyStacker
on your PC for automatically stacking the frames.
Of course you should not expect
Hubble quality from the result; as a very rough estimate I would venture that
the stacked image shows about as much detail as you can observe with a 10x50; maybe a little more.
This makes the method very
interesting for the binocular observer, as the images provide a sort of photographic star map that
shows the objects in their larger context and
corresponds quite closely to what you can expect to see.
Faint nebulae and some amount of light pollution are managed much better by the camera (in conjunction with image
stacking)
than the human eye and the binocular; e.g. the North America Nebula NGC 7000 is a tough challenge for my somewhat light-polluted
small town backyard, 20 miles from the capital, but the Nikon has no problem at all showing the nebula
very distinctly.
Sooner or later you want a comprehensive sky atlas.
I own the Cambridge Sky Atlas and the Pocket Sky Atlas, and I prefer
the later. I like to study them during leisure hours on the couch,
but I never take them out in the field. The one I always take with me is a little
book called
The Observer's Sky Atlas, by Erich Karkoschka
It has everything I need, in just the right format and presentation,
ideally suited for visual hobby astronomy (the German title is Atlas für Himmelsbeobachter).
It's written to be used in the field
with the telescope or binocular,
and it does the job admirably. The small A6 size means that the sky maps are also
small, and much space is taken up with finder charts. Nevertheless,
locating deep sky objects works well enough, and the accompanying tables contain
the right amount of data and short descriptions. There are many observing lists compiled
by individuals and clubs, containing various largely intersecting collections of
recommended deep sky objects, but the collection of the 250 DSO in the Karkoschka
is simply the best of the bunch. It includes many southern targets.
There are some free printable star atlas projects as well; see
theonlineastronomer.com
for an overview. I particularly like
Andrew L. Johnson's fine Mag-7 Star Atlas, available e.g.
at cloudynights.
Custom maps showing only specific areas come in handy when you plan your next observing session.
The same maps can of course be used at the telescope
as well. Many astronomy software packages
can print more or less useful charts; however, the best ones imho are produced by
a package called PP3 written by Torsten Bronger. You can find it at
pp3.sourceforge.net.
This package creates very beautiful sky maps that need to be processed with the
LaTeX typesetting package. You can also use PP3 to create your
own customized star atlas covering the complete sky. Here are some that I have made for the Karkoschka
selection of 250 deep sky objects:
All the above contain the complete Messier catalog objects. However, due to the small A4 format
of the charts this results in clutter in some places. On the other hand, many of the Messier objects are
not particularly rewarding, and some are also difficult to observe.
Therefore I made another
6 page chart set containing
items from binocular and urban observing lists i.e. targets that are both
rewarding and easy, for a total of
180 deep sky objects. Coverage is whole celestial sphere but
with a slight shift (center of chart) towards the Northern hemisphere.
Comprehensive star charts like the Pocket Sky Atlas show a huge number of objects, but many of them
are too difficult to observe, and/or not very rewarding for the amateur observer; hence many astronomy clubs and authors
create their own observing lists.
Here are my favorites; check out the overview at
messier.seds.org
for many more.
Keeping an observing log seems like a nuisance, but it actually helps structuring
my sessions. I find that planning a session and writing short log
entries for every object observed leads to a more satisfying experience than casual,
random
viewing without any plan or note taking. I use abbreviations similar to Dreyer's in the NGC. This keeps the time
needed for an entry to a minimum. Small sketches are also a useful tool to keep track
of what has been seen.
The moment you use a white flashlight your night vision is gone. Fiddling with
equipment can be done in complete darkness with some practise, but for looking up
things in charts and for writing in your
log you need a flashlight that is both deeply red and very dim. I have used a
DIY version made with red foil glued onto a white flashlight, but it was a flimsy
affair, and I have
now switched to a proper dimmable red LED flashlight from TS Optics, which works very well.
My hooded duffle coat is an essential piece of equipment for most of the year. The hood makes all the
difference: it keeps the head warm, and it provides a nice
cover against stray light. The large pockets serve to carry
smaller items, and to occasionally warm your hands when they start
to refuse service during winter sessions.
I am a devoted Linux user and avoid Windows whenever I can, which is pretty
much all the time. For Linux there are several options; Sky Chart (Cartes du Ciel)
is the best, in my opinion. It concentrates on map functions and does not bother
to present a pseudo-realistic view of the night sky, like e.g. Stellarium. This never
works convincingly anyway, as the level of detail in the images is much higher
than in the surrounding star map, so it always looks like a picture glued onto a
background. Nevertheless, you can activate that function if you want, and
there are a lot of other features; you can use it for telescope control if you have
an interfaced motor drive.
This software is available via the package manager in Debian/Ubuntu/Mint as skychart.
You can find a Windows version at
sourceforge.net/projects/skychart/.
Chosing the right scope is a daunting task; many factors have to be taken into account,
such as
On the other hand, there are personal preferences (e.g., refractor look vs reflector look),
and areas of application
(e.g., planets vs deep sky, or both; portable vs stationary). Taken together it all results
in a multi-attribute
decision problem, and there are no easy answers. Yet it helps to clarify
the available options.
The primary task of an astronomical telescope is light gathering i.e. making very faint
objects look suffiently bright for observation. Aperture seems to be the most important
point, but it has to be considered in combination with the desired magnification,
which determines the field of view, which in turn
depends on the type of objects you wish to observe.
The concepts of exit and entry pupil are very helpful in this context: divide
the aperture by the magnification to get the exit pupil of an optical instrument
i.e. the diameter of the light bundle going out of the instrument and into your eye.
For most people over 40 the entry pupil of the fully dark-adapted eye is about 5 mm
(about 7 mm for teenagers).
Here are some instruments that all provide a 5 mm exit pupil, together with their
magnification and approximate angle of view (assuming a Plossl eyepiece with 52° apparent
FOV for the telescopes, this is simply 52/magnification):
Skywatcher AZ-3
Skywatcher AZ-4
TS Barlow
Baader Classic 32 mm
Baader Hyperion 24 mm Wide Angle
Filters
Nikon D5100
Nikkor 50 mm f/1.8 D
Sky Atlas and Custom Maps
Observing Lists
Pencil and Paper
Red Flashlight
Hooded Coat
Planetarium Software
The Right Tool
| Instrument | Magnification | Angle |
|---|---|---|
| 7x35 binocular, wide-angle design | 7 | ~ 9 |
| 10x50 binocular | 10 | ~ 5 |
| 80 mm f/5 refractor with 25 mm eyepiece | 16 | 3.3 |
| 100 mm f/4 newton with 20 mm eyepiece | 20 | 2.6 |
| 120 mm f/5 refractor with 25 mm eyepiece | 24 | 2.2 |
| 250 mm f/5 newton with 25 mm eyepiece | 50 | 1.0 |
Any aperture resulting in a larger exit pupil than the entry pupil of your eye does not result in a brighter picture. It provides more comfortable viewing since the eye does not need to be exactly aligned with the optical axis of the instrument, but in terms of image brightness the additional aperture is wasted; the light simply cannot enter your pupil. In other words, e.g., if you are happy with viewing at 20x then you need no more than 4 inches of aperture.
A 10x50 or 8x40 binocular is perfect to scan the constellations, enjoy wide-field views of the milky way, and observe very large objects such as big open clusters; no setup, very easy to use. The small size and weight of a binocular means that it can easily be brought on a mountain hike or other ventures towards darker skies. It is also helpful for finding deep sky objects before you view them in more detail with a telescope. According to the Astronomical League's Binocular Messier Club at least 76 of the 110 Messier objects can be observed 'without much difficulties' with a 10x50 binocular under favorable conditions.
Assume a minimum size of 10 arcminutes for binocular observing (and ignore magnitude): 63 of the 110 Messier objects and another 85 non-Messier objects from the Karkoschka atlas are large enough.
Mes siz>=10 cnt ---------- ---------- ---------- 0 0 55 0 1 85 1 0 47 1 1 63
The main problem with binoculars is of course the wobbly image. It is impossible to hand-hold a binocular completely steady; many types of homemade mounts have been proposed, and some are commercially available (such as the Orion Paragon), but they all take away from the portability and the ease of use of the binoc. The most basic improvised mount is probably the upturned broomstick. If you are the DIY type, why not give the couch potato viewing chair a go.
Lying on the back and resting the eye cups on the face also works well. In addition, try this: use the right hand to hold the binoc, rest your head on the left hand, and extend the left elbow towards the sky; now you can press the binoc lightly against the elbow, which provides a surprising amount of support. In other words, you are holding the binocular with the right hand and the left elbow. I know it sounds weird, but give it a try. This works for everything close to the zenith, and down to the horizon on your left side. You can do a similar thing while reclining in a deck chair, although it is a little more tiring, as the elbow is not pointing straight up.
A telescope provides not just more magnification, but also a rock-solid mount. However, before considering any purchases it would be wise to identify the type of objects you wish to observe, as this largely determines the choice of instrument.
Optical quality: You can spend a lot of money on high-end optics, but will you actually benefit from it? For the Moon and the planets the answer is probably Yes, if conditions permit, but for deep sky objects the optical performance in terms of image quality is not the bottleneck, and any instrument above department store level will deliver nicely. The problem here is the extremely faint image, which can be improved by the proper combination of aperture and magnification; a bit of coma or purple fringing on some brighter stars doesn't really matter. Surplus money is better spent on good mechanical components, such as focuser and mount.
Conditions are much more important than aperture; a proper dark site makes a world of difference. And that big and heavy 10 inch is much more effort to haul across the countryside than a small and featherweight 4 inch. Try to get away from the lights as much and as often as possible. It's always worth the effort.
The lowest magnification an instrument can provide is related to the widest possible field of view; it is therefore actually more important than the highest magnification. Seeing usually does not allow to go much above 150x anyway, and pretty much every scope is able to deliver that. Dividing 52 by magnification gives a good estimate for the angle of view with Plossl eyepieces. It is much easier to locate objects with a scope that can go down to low magnification, and many deep sky objects are so large that they require a very low magnification to be enjoyed fully, with their context.
Consider a 150 mm f10 Schmidt-Cassegrain which only supports 1.25 inch eyepieces. From its aperture one should expect it to be a decent deep sky performer; however, the strengths of this type of scope are portability and planetary viewing. Sadly 1.25 inch eyepieces are only available up to 32 mm focal length which results in a magnification of 47x, an exit pupil of only 3.2 mm, and an angle of view of only 1 degree; none of that being ideal for observing most of the popular deep sky targets.
On the other hand, a humble 80 mm f/5 refractor like the Startravel 80 can go down to 12.5x and a whopping 4.16° with a 32 mm Plossl! This covers quite a lot of ground: there is not much in the Messier catalog or any of the other popular observing lists that you cannot conveniently spot, and in many cases even study in detail, with this little gem. It's small and light, and cheap to boot.
It all comes down to the right tool for the right job. Like many others (present author included) you may well end up with several scopes. Just don't let it get out of hand..