Q about manual focus for star photos

I am newish to star photos, and have two lenses that I'd like to use. Either a 28mm Zeiss or a 21mm Oly. I prefer to use my 5Dc, so no good liveview facility. That said, I will try a set with my T3i next time, just to be able to see more of what is going on in liveview as I learn.

Anyway, I am confused about how to setup focus and what works best. I would like to know how those of you with more experience set up to shoot night landscapes that have starry backgrounds.

For ex, the Zeiss stops at infinity, and stars look sharp. Near foreground objects are not in perfect focus at wide apertures. I read up on the hyperfocal scale on the camera (which obviously I never useops - should I use it to focus or should I just stick with using it at infinity? I think on my last shot, I messed up the foreground exposure by not setting the f-stop to f/8 and making a longer exposure - I shot the longer exposure but at wide aperture - so that's def. an improvement for next time.

As an aside, if I am shooting two photos to blend, do I need to shoot it more like a focus stack, with one image set for the stars and one image focused nearer for the landscape subject?

Same question for the OM21, which is one step more confusing for me because it seems to focus past infinity. It is VERY hard to see that through the viewfinder with the 5D on such a wide angle lens, so I am not sure how to use it for star photos. Should I just use the hyperfocal focusing scale? Or do I need to figure out where 'infinity' is and use that to focus?

Thanks & advance apologies if I screwed up the terminology!

Michelle

mco_970 wrote in post #12693887
...

For ex, the Zeiss stops at infinity, and stars look sharp. Near foreground objects are not in perfect focus at wide apertures. I read up on the hyperfocal scale on the camera (which obviously I never useops - should I use it to focus or should I just stick with using it at infinity? I think on my last shot, I messed up the foreground exposure by not
setting the f-stop to f/8 and making a longer exposure - I shot the longer exposure but at wide aperture - so that's def. an improvement for next time.

As an aside, if I am shooting two photos to blend, do I need to shoot it more like a focus stack, with one image set for the stars and one image focused nearer for the landscape subject?

Same question for the OM21, which is one step more confusing for me because it seems to focus past infinity. It is VERY hard to see that through the viewfinder with the 5D on such a wide angle lens, so I am not sure how to use it for star photos. Should I just use the hyperfocal focusing scale? Or do I need to figure out where 'infinity' is and use that to focus?

Thanks & advance apologies if I screwed up the terminology!

Michelle

Personally, I don't really care if the foreground stuff is sharp, as long as it looks halfway decent. I always focus for the stars, which are the primary subject.

As for the other question, one of my lenses also goes past the point of best infinity focus, but I learned from trying it where the best infinity focus is. The other thing you could do is find something (the moon or a bright star) bright enough to see in the viewfinder, and use that to focus, then move over to your intended victim.

One of the advantages of such wide angle lenses (especially on the FF 5D where wysiwyg) is that they normally actually focus on infinity when against the stop

I am currently experimenting with a Hartmann mask on a 500mm mirror on my 5D. This little lens is a b*tch to focus at the best of times, let alone in the dark, but I have had good results with a twin aperture Hartmann mask in daytime, so have great hopes for this evening, if the clouds go away

Well to follow up...

I tried the OM21 on the T3i -
1st issue is that with only stars to focus on, liveview was useless for me to focus. W/ the new moon, I couldn't find anything bright enough that I could see it in the viewfinder or LV, even with the ISO at 1600 and the lens at f/2. I also could not see the rock arch *at all* in liveview or the VF, so framing the image was a PITA. I have been shooting on a daily basis for 2-3 years now and can sort of intuitively frame the photo, but still - tough to do without being able to see ANYTHING. I gave up and tried with my 5D & Zeiss 28 instead, and the optical VF worked better for me - I can at least see the outlines of the rock for framing the subject.

2nd issue is the few test images that I took showed a fair bit of coma w/ the 21. Not sure if it's from misfocus, though, so I can't blame the lens for it. I may just need to stop down a bit more, so that will be the next order of operation. I am starting to miss my ZE 21, even if it's like carrying a friggin' brick.

Next try with T3i will be OM21 > f/4 > using hyperfocal scale, fuggetabout Liveview!

3rd issue is that I REALLY should have brought two tripods and should have been shooting two cameras at once. It was really slow going with one camera between shooting the exposure and then dark frame subtraction, and I didn't do as much as I hoped to... Next time I'll at least be shooting two, if not three bodies at the same time (if I can sucker my husband into shlepping some gear for me).

The other OTHER interesting issue at this shoot is during scouting at dusk we found a freshly killed owl carcass on the route to the rock arch. Almost certainly had to have been a cat - bobcat or mtn. lion, I'm not sure. It did make venturing back into the rocks after dark *Very Interesting*! I was glad for once to have someone with me, even though I think it does botch my concentration! I don't think I would have tried this shoot solo after finding the animal tracks and the carcass!

I'll try to remember to followup after the next outing. I'd like to think I'll go back out tonight, we shall see if my motivation level matches the dream.