Moon focus

I tried shooting a bunch of the moon last night, and had no real trouble with exposures (just ran a bunch of combinations of settings to bracket), but discovered today when I pulled them out of the camera, that they were almost all moderately OOF. I was using my Canon T1i, Tamron 75-300 set at 300mm with manual focus, and just set the focus at infinity. The camera was on a tripod with a remote release, so I know I didn't have motion blur. The exposures were all short enough that the moon's apparent motion across the sky shouldn't be an issue either.

What should I look for, or try, to get the moon sharp? It didn't appear to matter what I used for aperture, though most of them were with a medium (f8 or so), with some wide ranges for bracketing. Do I need to adjust the focus a bit short of infinity? Or what?

There's your problem. I don't know why, but lenses focus "past" infinity, (if that makes sense). Focusing it right out isn't going to work and objects will be slightly OOF.

Does the T1i have "Live View"? If so, use that, zoomed in to 5x or 10x, and focus using that...much much easier.

Live view or mirror lock-up. But my guess is not camera shake. Maybe focus. Try some shots with autofocus and some with infinity focus.

Thanks, people. I didn't think of the "past infinity" focus, even though I've seen it before with other lenses. The T1i does have live view, though I don't know if I can zoom in it; I'll have to look for that. I tried to use live view, but without zooming, it didn't seem to have a big enough image to help much with focusing. And the protective cover I have over the lcd doesn't help its sharpness either.

I shot some more last night, trying careful manual focus through the viewfinder. I'll see how they come out and post back.

The infinity mark is never 100% acurate. Focus using live-view at 10x magnification (yes you can on the T1i). Furthermore don't dismiss motion blur / shake so quickly. The moon is very fast at 300mm x 1.6 crop. It's very important to let the tripod get rid of any vibrations produced by touching the camera while focusing, adjusting controls. Shield if from the wind and if you are not faster than 1/320 increase the ISO!

Not all tripods are the same, attach a laser pointer to your lens using masking tape, give the camera/lens a touch with your hand and see how the laser dances on a wall, that will give you an idea about how stable your setup is and how long do you have to wait to make sure vibrations are absorbed.

Luis

Thanks, Luigi. I was shooting mostly 1/125 or 1/250, IIRC. Good idea about the laser pointer. I did have the tripod center post jacked up all the way to the top so I didn't have to bend over so much, which made it shake more than I liked. I think I had its shaking stopped before I triggered, but anything is possible at this point.

The center column of the tripod must remain low, it's incredible how you add shake if you extend the center column.

archer1960 wrote in post #10605309
Thanks, people. I didn't think of the "past infinity" focus, even though I've seen it before with other lenses. The T1i does have live view, though I don't know if I can zoom in it; I'll have to look for that. I tried to use live view, but without zooming, it didn't seem to have a big enough image to help much with focusing. And the protective cover I have over the lcd doesn't help its sharpness either.

With my T1i, I switch on AF, let the lens focus on the moon using the center AF point. Then turn off AF before shooting so it doesn't try to refocus again. Also, while on a tripod I turn off IS on the lens, and use a wireless remote or the 2 sec self-timer as to reduce camera shake.

About your LCD screen protective, are you using a glass or plastic? The glass ones are way better. This is the one I bought on Amazon...

GGS DSLR LCD Optical Glass Screen Protector for Canon 450D / 500D / XSi / T1i

http://www.amazon.com …ics&qid=1280293​826&sr=8-1

spotz04 wrote in post #10616191
With my T1i, I switch on AF, let the lens focus on the moon using the center AF point. Then turn off AF before shooting so it doesn't try to refocus again. Also, while on a tripod I turn off IS on the lens, and use a wireless remote or the 2 sec self-timer as to reduce camera shake.

The 500mm lens I want to use is only manual focus, but as I did a bit more research, I may need to speed up my shutter a bit from what I've been doing.

spotz04 wrote in post #10616191
About your LCD screen protective, are you using a glass or plastic? The glass ones are way better. This is the one I bought on Amazon...

GGS DSLR LCD Optical Glass Screen Protector for Canon 450D / 500D / XSi / T1i

http://www.amazon.com …ics&qid=1280293​826&sr=8-1

Thanks for that link; I didn't know they had glass ones. The one I've got is the adhesive plastic one that came with the camera. I just ordered that one from Amazon; should be here next week.

archer1960 wrote in post #10618602
The 500mm lens I want to use is only manual focus, but as I did a bit more research, I may need to speed up my shutter a bit from what I've been doing.

Shouldn't need any more than 1/50s. Just make sure you have a stable platform and use mirror lockup with a remote release.

Manual focus through the viewfinder shouldn't be too hard, liveview probably makes it easier though (I've not got liveview ) It will come down to how nice the manual focus ring and action is on your particular lens though, I personally don't like the Canon USM lenses for it as they seem less precise.

This is 1120mm @ F/16 manually focused through a 20D viewfinder: http://www.clubpoint.n​et ….misc/IMG_0344_​800w_2.JPG

phreeky wrote in post #10621982
Shouldn't need any more than 1/50s. Just make sure you have a stable platform and use mirror lockup with a remote release.

...

This is 1120mm @ F/16 manually focused through a 20D viewfinder: http://www.clubpoint.n​et ….misc/IMG_0344_​800w_2.JPG

Do you recall what your shutter speed was for this?

archer1960 wrote in post #10623800
Do you recall what your shutter speed was for this?

That one was 1/100s