n0b0 wrote:
So to stack 10sec exposures to get 10mins worth, you're gonna need 60 shots. Not to mention the stars would've "moved" which means you'll need to align the frames.
Correct, and it still won't be the equivalent exposure of a single ten-minute exposure, it'll just be (if properly processed/combined) a cleaner (less noise) 10-second exposure.
Thanks for the wealth of information to everyone who contributed to this thread (and most importantly what the AstroTrac is). I'm not very handy at all, so making one myself is completely out of the question. I could kick myself for selling my 35L this past week since that would have been good to use wide open, but I think I'll settle for renting a lens. The one thing I now have to justify is whether dropping $600 on the AstroTrac would be a good investment or not. Since I'm just getting into this aspect of photography, I don't want to spend the money, then I find it's not for me, and it just sits in my apartment.
In addition to the AstroTrac you'd also want a geared head as well as another head for mounting the camera on the AT. And of course a good tripod. So it isn't just the AT. Also, the 35L (as any lens really) would be much better at f/2-2.8 than 1.4. Just not all that sharp and lots of coma. (another artifact that wasn't touched upon here). Most fast lenses have that problem though. Good luck. It is fun though mine sits in its case a lot.
Astrophotography can be a remarkably satisfying hobby, but it certainly isn't for everyone.
You have to wait for it to get fully dark (late in the northern latitudes in the summer; cold in the winter). Without a tracking mount (or a fairly large-aperture scope), you're going the severely challenged (to say the least) to get much of anything worth keeping.
In your shoes, I wouldn't buy the AstroTrac (or any other tracking mount) before I had some pretty good idea that I was going to do this a lot (I've acquired a good bit of my astronomy equipment used, in perfect condition, from those who bought it and found this nocturnal activity wasn't for them). Take your best shot, with a fast lens, camera with fairly good high-ISO performance, and solid tripod, and take varying exposures, to see what you get.
You may like the challenge; you may like taking photos of things few other can/do; you may think it's for the geeks.
Try looking on Craigslist for used telescope mounts. I've seen some really nice equatorial ones going in the $100-$150 range. It's not that hard to get them to work with a camera plate/adapter.
You could also try a FE lens where the image is so wide and compressed you don't really notice trailing that much. You have to like that FE "look" though.
In addition to the AstroTrac you'd also want a geared head as well as another head for mounting the camera on the AT. And of course a good tripod. So it isn't just the AT. Also, the 35L (as any lens really) would be much better at f/2-2.8 than 1.4. Just not all that sharp and lots of coma. (another artifact that wasn't touched upon here). Most fast lenses have that problem though. Good luck. It is fun though mine sits in its case a lot.
Benson
+1
I've tried astrophotography a bit and the learning curve is very high.
You can't just go out and point the camera up and shoot.
Fast lenses are good for reducing the exposure time, but most have poor sharpness at wide open apertures, especially on the edges.
Getting a fast lens and shooting 10 sec exposures may not get very good results.
I've taken a serious look at the AstroTrac at a local telescope/photo store at that looks like a good piece of gear for relatively light equipment. The key component to getting good results is the precision in which the gear tracks. The longer the exposure and the longer the focal length, the more precision is needed.
I would suggest that you go to your local telescope store, they have a ton of experience and are usually very willing to offer their advice.
Astrophotography can be a remarkably satisfying hobby, but it certainly isn't for everyone.
You have to wait for it to get fully dark (late in the northern latitudes in the summer; cold in the winter). Without a tracking mount (or a fairly large-aperture scope), you're going the severely challenged (to say the least) to get much of anything worth keeping.
In your shoes, I wouldn't buy the AstroTrac (or any other tracking mount) before I had some pretty good idea that I was going to do this a lot (I've acquired a good bit of my astronomy equipment used, in perfect condition, from those who bought it and found this nocturnal activity wasn't for them). Take your best shot, with a fast lens, camera with fairly good high-ISO performance, and solid tripod, and take varying exposures, to see what you get.
You may like the challenge; you may like taking photos of things few other can/do; you may think it's for the geeks....Show more →
Very sound advice. I appreciate your honesty.
For starters, I am just going to use my 17-40 and 5DII mounted on my tripod, scout out a dark place far from the city (I live extremely close to Philadelphia, so this is very much a challenge). And see what I can capture with star trails. As much as I would like to purchase the AstroTrac, I'll experiment with the equipment I have now, and see if I want to dive deeper into astrophotography. $6-700 is a decent chunk of change. If they were around $100, it would be a completely different story.
I know I'm not going to get images that are going to blow me or anyone else away for that matter. But it is something I'm interested in and would like to pursue.
I truly appreciate your contribution and everyone else who chimed it. Your responses certainly gave me a more realistic expectation on what I could and should expect when I start photographing the night sky.
ggreene wrote:
Try looking on Craigslist for used telescope mounts. I've seen some really nice equatorial ones going in the $100-$150 range. It's not that hard to get them to work with a camera plate/adapter.
You could also try a FE lens where the image is so wide and compressed you don't really notice trailing that much. You have to like that FE "look" though.
I'm guessing I would need a ballhead such as the RRS? I had one on my current Manfrotto tripod, but sold a few years ago.
For astrophotography, depending on what you're wanting to do, you'll most likely want to stop down a stop or two for sharper star images. I've shot some using a 50/1.4 and a 135/2.8 and stopped both down.
If you're OK with trails, you'll probably be stopping down quite a bit anyway due to sky fog.
You could boost up the ISO if your camera will allow it and shoot wide open with a fast lens and use a short enough shutter speed to prevent trails, but you won't record very deeply into the Milky Way. You can search the i'net for a formula that will tell you how long you can expose to prevent trails based on focal length, image size, etc.
dobro wrote:
For astrophotography, depending on what you're wanting to do, you'll most likely want to stop down a stop or two for sharper star images. I've shot some using a 50/1.4 and a 135/2.8 and stopped both down.
If you're OK with trails, you'll probably be stopping down quite a bit anyway due to sky fog.
You could boost up the ISO if your camera will allow it and shoot wide open with a fast lens and use a short enough shutter speed to prevent trails, but you won't record very deeply into the Milky Way. You can search the i'net for a formula that will tell you how long you can expose to prevent trails based on focal length, image size, etc....Show more →
Regardless of whether or not you didn't look at the first page, I still appreciate your input. Unfortunately, the DIY barn-door mount would most likely be a no-go since I'm not very handy to begin with. But I appreciate your response. I'm actually thinking of purchasing a 50/1.4 for lowlight stuff, so I may utilize this lens as well for my attempts at astrophotography.
n0b0 wrote:
So to stack 10sec exposures to get 10mins worth, you're gonna need 60 shots. Not to mention the stars would've "moved" which means you'll need to align the frames.
Good stacking software does a reasonable job of automatically aligning the frames, so that's not something to worry too much about. Astrophotography-specific post processing tools are helpful for getting the best results with the least hair pulling.
