I'm on a quest to shoot the Milky Way. Need help.

[Wildewinds]

After watching this video a dozen times ( http://www.vimeo.com/4505537 ) I've decided to view the Milky Way galaxy in person. My idea is to make my way out to the northern part of Death Valley (the closest truly dark area to me), hopefully around August 19th (no moon), with my camera and tripod and take some good photos of it. I understand that the best time to view the Milky Way is right around this time of year. It seems like a solid plan. The only thing that can mess me up is cloudy skies, right?

What I want to know from you guys is what techniques I should use and/or what equipment I should take with me, in order to get some good photos. Right now I have a 20D, a Tamron 28-75 2.8, a Tokina 11-16 2.8, and a Canon 50mm 1.4. I don't plan on buying a new lens for this, so I have to use what I got.

Are there any inexpensive must-have astro-photography gadgets I should get?

Are there any techniques that need to be used for the best results? Or do I just pick the sharpest aperture and work from there?

Thanks for any help.

[wickerprints]

Mirror lockup and a remote release are probably two things you must make sure you use.

What kind of photos do you want to take? There are all kinds of ways to take images of the night sky. If you want star trails, then you're talking about exposure times ranging from minutes to hours. If you want pictures of the Milky Way, you want relatively short exposure times with as wide an angle as you can manage. That's why the video is so successful--it is taken with a 15/2.8 fisheye with a 180 diagonal field of view, 20 second exposures, and ISO is probably quite high.

There are conflicting issues with getting a sharp picture of the Milky Way. You need a short exposure, because long ones will show the Earth's rotation relative to the galaxy, blurring the image. However, the Milky Way is quite dim. Absolute darkness will allow its light to come through with contrast, but only the clearest possible sky will maximize its brightness. Therefore you want to shoot as wide open as you possibly can. Sadly, the widest aperture you have is on the 50/1.4, which is too long for the 20D to get a wide-angle view, so you'll have to settle for the 11-16/2.8 (though I don't know about optical quality). The bonus is that the wider you go, the less apparent the motion of the stars across the field of view, so you can expose for longer. Another bonus is that you will have plenty of time to adjust your camera settings, and try and retry again.

So say you choose 11/2.8. Fix that, then set ISO to as high as you can tolerate, probably around 1600, then try a 30" exposure. Then review and revise accordingly. Longer shutter speed = more blur; shorter shutter speed = requires higher ISO and more resultant noise.

If your lenses are not centrally sharp wide open and focused at infinity, you need a better lens. You must shoot wide open because stopping down gets you nothing--you don't need DOF--and costs you shutter speed and/or noise. For most lenses, any modest increase in sharpness will not be outweighed by the doubling (or worse) of exposure time or increase in noise. If your lens is soft at f/2.8 and only gets sharp starting at f/4 or f/5.6, you've lost a whole stop or two of usable brightness. And besides, the Milky Way is not a very contrasty object anyway.

Star trails are different...you just pop open the shutter and let it go for half an hour or so. You can calculate a ballpark correct exposure by cranking up the ISO and then using reciprocity to compute the appropriate shutter speed when you dial it back down to around 100-400, remembering that each full stop is a doubling of exposure time. Or you can do exposure stacking, which is less guesswork but more post-processing.

[jmx]

I say set that tokina at 11mm, and take 10-15 exposures of 20-30 seconds (I usually use ISO 800, f/2.8 or f/4). Then take some dark frames (with the lens cap on). Average the dark frames together, then subtract that from each of your normal exposures you took. Then stack the exposures together (using software to align the shots, they'll drift a pixel or two as the sky appears to move), apply some curves, and you're going to have a sharp contrasty shot with low noise, and no star trails. I use nebulosity ($60 program) to average my darkframes and subtract them from my light frames, as well as do the stacking, but im sure it can be replicated in photoshop.

Keep in mind your shots will look fairly dark, or black, but the stretching/processing later will bring the details out. I usually take 1 test shot at ISO 6400 just to see a real grainy version of what the final product might be, and help me center on a part of the sky I like.

Unfortunately I have no wide field stuff to show for it yet, but the above procedure is what i used for this one at 100mm. http://jmx.ls1howto.com/pics/antares.jpg

Just got my 10-22mm EF-S today, so next time I'm out (indeed, August 19th) I'll give it a shot.

PS, I use the canon timer thingie to take all the exposures, but a regular remote release cable will work since you're gonna stick to 30second or less exposures. You could do it just by pressing the button and I don't think its going to affect things much if you're careful.

[Adrena1in]

Lovely video you linked there, it amazes me how much Milky Way detail can be captured on a single, relatively short exposure at a really dark site. If I were you I would attempt to roughly recreate what you saw in the video. 11mm, f/2.8, 20 or 30 second exposures, ISO 800 or preferably 1600, burst mode on, mirror lockup off*, lock the remote shutter down and leave the camera to do it's thing.

* I put mirror-lockup off only when I'm locking my remote shutter down and leaving the camera to take dozens and dozens of photos. If you're only intending to take a few photos, and want to do it manually, then put mirror lockup on.

Otherwise, what others have said is the way to go. Basically, as long as clouds don't ruin your evening, you're extremely likely to capture some pretty nice Milky Way shots. It's not that dim really...you can see it clearly with the naked eye at a dark site after all.

[Wildewinds]

Thanks for the tips.

I'm not familiar with stacking, but I assume I'm just overlaying underexposed photos on top of each other? Or are they fully exposed?

[jmx]

Thanks for the tips.

I'm not familiar with stacking, but I assume I'm just overlaying underexposed photos on top of each other? Or are they fully exposed?

It doesn't matter if they are underexposed or not, stacking kinda averages them all together to average out noise and give you a more resolved signal. If you're underexposed, then you simply need to apply more curves passes in photoshop.

Many of my shots appear nearly black straight out of the camera, but once fully processed look just as good as everybody elses.

In case it hasn't been mentioned yet, shoot raw for all these shots. JPG is not an option.

[hollis_f]

Mirror lockup and a remote release are probably two things you must make sure you use.

I wouldn't bother with mirror lockup. Even a semi-decent tripod will not vibrate for more than a second or so due to mirror slap. On a 30 second to 30 minute exposure that won't affect the image to any real extent.