@abirkill Lots of night shooting, but the shots I'm thinking about are like the one I just posted of the Milky Way. I find it hard to get enough exposure under 20 sec. I am getting star trails. I hate using such a high ISO.
It's a pretty good lens for star photography, but if you want a lens *just* for star photography you can do better.
Here are some star photos I took with the 16-35:
The two biggest problems with the 16-35mm are sharpness and coma. The lens simply isn't sharp wide open at the corners of the frame (it's arguably not all that sharp even when stopped down). Coma is a lens aberration which results in point light sources become stretched and misshapen, and this also occurs wide open in the corners.
As a general-purpose wide-angle lens it's an OK good choice -- it has beautiful starbursts, can be handheld in low light, can throw backgrounds out of focus slightly if you try hard, and is superb build quality. It does an excellent job at the purpose it was designed for -- wedding photography. It is hard to recommend for most people over the 17-40mm you already have though -- another lens that's not exactly sharp in the corners, but at least doesn't cost quite such a ridiculous amount.
If you want a lens just for star photography, then you have around four choices, in no particular order:
1. Nikon 14-24mm f/2.8 with Canon adapter. This is probably the best general purpose lens, and can work well for star photography as well. Stunningly sharp across the entire range even wide open, this is the lens Canon should be making. A very common purchase for Canon landscape photographers.
2. Rokinon/Samyang/Bower 14mm f/2.8. A 14mm f/2.8 prime lens without autofocus, but that is a match for the Nikon wide open, and way better than any super-wide lens that Canon produces (including their own 14mm f/2.8L) for star photography. Much better corner sharpness and much less coma than the 16-35L or 14L. And the best part? You can pick one up for between $299-$349.
3. Canon 24mm f/1.4L II. The ultimate Canon star photography lens, with a hefty price tag. Having autofocus, it's an excellent general-purpose super-low-light lens that will work in all kinds of situations, but this combination of focal length and aperture is by far the best you can buy for star photography. You will need to take shorter exposures due to the longer focal length, but the f/1.4 aperture means you'll still capture way more light in that time than with any of the f/2.8 offerings. The downside, other than price? Once again, too much coma and insufficient sharpness wide open.
4. Rokinon/Samyang/Bower 24mm f/1.4. Once again, Rokinon have produced an optically superior lens for a fraction of the price. Again, no autofocus on this lens, which is a slightly bigger concern, given the wider aperture and longer focal length, which is why you might pay more than twice as much for the optically inferior Canon. However, if you just want a star photography lens, this is pretty much the best lens you can pick, and will set you back a fairly reasonable $600-$650.
Bear in mind that with all these lenses, you will want to stop them down from wide open to gain sharpness -- so with the f/2.8 lenses you will be at f/3.5 or so anyway, similar to what you were shooting at before. Unfortunately by far the best thing you can do is find a darker location to shoot -- but these lenses can help when that isn't possible.
@abirkill Wow, thank you so much for all the info. I'm intrigued buy #2 and #4. I manually focus any way at night, so this may be a good option! I really appreciate your help!
Yes, I agree a darker spot would help too! The moon had just set and the sun was about an hour from rising. Plus there was a lot of light pollution coming in from Las Vegas.
My biggest issue with the 17-40 f4 is that I have to either shoot at a super high ISO, or have a longer exposure. If I go over about 20 sec's I start to get star trails
@catwhiskers That's definitely too close to sunrise, astronomical dusk generally ends a couple of hours before the sun rises. Unfortunately as we get closer and closer to the solstice, the amount of astronomical dusk gets less and less (here in Vancouver, for 15 days either side of the solstice it *never* gets dark enough!)
Remember that it doesn't make any difference if you increase your shutter speed once the stars start to trail -- once that's happening, the light has moved on from one sensor site to another and you are not increasing the light captured, just smearing it. (The only way around this is to use an astronomical mount to track the apparent motion of the stars).
There is a basic rule for working out how long your shutter speed can be, which is called the Rule of 600, and states that you can't use a shutter speed longer than 600/focal length before you get trails. In the case of your 17mm lens that gives you a maximum length of 35 seconds, but as you've noticed, with high-resolution cameras now, the rule is somewhat outdated, so many pros use a rule of 500 or 400. You must, of course, have a very steady tripod as well.
The best thing to do is to make sure you are shooting at astronomical dusk (there are lots of calculators online and for smartphones that will show you when this is), and obviously without a moon. You also need very good atmospheric transparency -- the Clear Dark Sky site gives forecasts for most locations in North America showing transparency and 'seeing' values -- the closer both of these are to 5/5, the easier you will be able to shoot the stars: http://cleardarksky.com/csk/
@abirkill Once again, fantastic analysis Alexis! I couldn't agree more about loss of sharpness and coma, as I've seen it many times. I would say it's a pretty good landscape lens though, and my go-to when needed (though I will certainly look into the Nikon Alexis mentioned)! :)
@catwhiskers Here are some shots I've taken with the 16-35 L:
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Here are some star photos I took with the 16-35:
The two biggest problems with the 16-35mm are sharpness and coma. The lens simply isn't sharp wide open at the corners of the frame (it's arguably not all that sharp even when stopped down). Coma is a lens aberration which results in point light sources become stretched and misshapen, and this also occurs wide open in the corners.
As a general-purpose wide-angle lens it's an OK good choice -- it has beautiful starbursts, can be handheld in low light, can throw backgrounds out of focus slightly if you try hard, and is superb build quality. It does an excellent job at the purpose it was designed for -- wedding photography. It is hard to recommend for most people over the 17-40mm you already have though -- another lens that's not exactly sharp in the corners, but at least doesn't cost quite such a ridiculous amount.
If you want a lens just for star photography, then you have around four choices, in no particular order:
1. Nikon 14-24mm f/2.8 with Canon adapter. This is probably the best general purpose lens, and can work well for star photography as well. Stunningly sharp across the entire range even wide open, this is the lens Canon should be making. A very common purchase for Canon landscape photographers.
2. Rokinon/Samyang/Bower 14mm f/2.8. A 14mm f/2.8 prime lens without autofocus, but that is a match for the Nikon wide open, and way better than any super-wide lens that Canon produces (including their own 14mm f/2.8L) for star photography. Much better corner sharpness and much less coma than the 16-35L or 14L. And the best part? You can pick one up for between $299-$349.
3. Canon 24mm f/1.4L II. The ultimate Canon star photography lens, with a hefty price tag. Having autofocus, it's an excellent general-purpose super-low-light lens that will work in all kinds of situations, but this combination of focal length and aperture is by far the best you can buy for star photography. You will need to take shorter exposures due to the longer focal length, but the f/1.4 aperture means you'll still capture way more light in that time than with any of the f/2.8 offerings. The downside, other than price? Once again, too much coma and insufficient sharpness wide open.
4. Rokinon/Samyang/Bower 24mm f/1.4. Once again, Rokinon have produced an optically superior lens for a fraction of the price. Again, no autofocus on this lens, which is a slightly bigger concern, given the wider aperture and longer focal length, which is why you might pay more than twice as much for the optically inferior Canon. However, if you just want a star photography lens, this is pretty much the best lens you can pick, and will set you back a fairly reasonable $600-$650.
Bear in mind that with all these lenses, you will want to stop them down from wide open to gain sharpness -- so with the f/2.8 lenses you will be at f/3.5 or so anyway, similar to what you were shooting at before. Unfortunately by far the best thing you can do is find a darker location to shoot -- but these lenses can help when that isn't possible.
Yes, I agree a darker spot would help too! The moon had just set and the sun was about an hour from rising. Plus there was a lot of light pollution coming in from Las Vegas.
My biggest issue with the 17-40 f4 is that I have to either shoot at a super high ISO, or have a longer exposure. If I go over about 20 sec's I start to get star trails
Remember that it doesn't make any difference if you increase your shutter speed once the stars start to trail -- once that's happening, the light has moved on from one sensor site to another and you are not increasing the light captured, just smearing it. (The only way around this is to use an astronomical mount to track the apparent motion of the stars).
There is a basic rule for working out how long your shutter speed can be, which is called the Rule of 600, and states that you can't use a shutter speed longer than 600/focal length before you get trails. In the case of your 17mm lens that gives you a maximum length of 35 seconds, but as you've noticed, with high-resolution cameras now, the rule is somewhat outdated, so many pros use a rule of 500 or 400. You must, of course, have a very steady tripod as well.
The best thing to do is to make sure you are shooting at astronomical dusk (there are lots of calculators online and for smartphones that will show you when this is), and obviously without a moon. You also need very good atmospheric transparency -- the Clear Dark Sky site gives forecasts for most locations in North America showing transparency and 'seeing' values -- the closer both of these are to 5/5, the easier you will be able to shoot the stars: http://cleardarksky.com/csk/
@catwhiskers Here are some shots I've taken with the 16-35 L: