Astrophotography and Ronikon: I recently purchased a Ronikon autofocus 14mm 2.8 for my Canon R6 to be utilized for landscape Astrophotography. I am struggling on how to focus the...

Michael Butler

I recently purchased a Ronikon autofocus 14mm 2.8 for my Canon R6 to be utilized for landscape Astrophotography. I am struggling on how to focus the Ronikon. Should I keep it in autofocus or manual focus? And if I am in manual focus, how do I determine when I am best focused? Still very much in a long learning curve. Thanks. mike

jerryc41 Loc: Catskill Mts of NY

Do you want landscape in the foreground with the night sky in the background? In that case, I think focusing on the landscape would be best. Using a smaller f/stop would allow for a greater depth of field. A wide angle lens is more forgiving of imperfect focus.

I bet more exact answers will follow.

repleo Loc: Boston

Do you mean Rokinon?
Best use manual focus. You may be able to focus on a star with the blinkies on. Alternatively, focus on a distant object while you still have enough light and mark the focus ring or tape the ring in position. Keep the exposure to less than 500 divided by the apparent focal length to minimize star trails. Boost the ISO as needed. Make sure any foreground objects are within your depth of field.

Michael Butler

Thank you! And I did mean Rokinon.

Michael Butler

Yes, I meant Rokinon. Thank you! That helps.

wmurnahan Loc: Bloomington IN

Michael Butler wrote:

I recently purchased a Ronikon autofocus 14mm 2.8 for my Canon R6 to be utilized for landscape Astrophotography. I am struggling on how to focus the Ronikon. Should I keep it in autofocus or manual focus? And if I am in manual focus, how do I determine when I am best focused? Still very much in a long learning curve. Thanks. mike

Don't know Canon, but with Sony there are a couple of manual focus aids, one magnifies and there is a color contrast that will highlight the in focus area, and you don't want to trust that infinity. For astro you do want to manually find your infinity by focusing on a bright star. Some people will mark their lens with paint or tape for this focus point. With a wide angle, as has been pointed out, depth of field means, you focus from 10 ft to infinity.

bleirer

I know astro is its own special thing and I believe there is a forum here for it. I don't think you want to rely on depth of field for something that is a point source like stars. To my understanding infinity is the point where the light rays are parallel, so you want to nail it without going past it. A distant object is far enough away for the rays to be parallel.

I found this interesting, stars start around 30 minutes in https://youtu.be/1ah8EEqfFsM

Michael Butler

Thank you for taking the time to respond! Any bit of information helps and sometimes the trends and patterns of answers can be very telling.

RWR Loc: La Mesa, CA

Michael Butler wrote:

I recently purchased a Ronikon autofocus 14mm 2.8 for my Canon R6 to be utilized for landscape Astrophotography. I am struggling on how to focus the Ronikon. Should I keep it in autofocus or manual focus? And if I am in manual focus, how do I determine when I am best focused? Still very much in a long learning curve. Thanks. mike

You might want to check out the Astronomical Photography Forum:
https://www.uglyhedgehog.com/s-109-1.html

mflowe Loc: Port Deposit, MD

Michael Butler wrote:

I recently purchased a Ronikon autofocus 14mm 2.8 for my Canon R6 to be utilized for landscape Astrophotography. I am struggling on how to focus the Ronikon. Should I keep it in autofocus or manual focus? And if I am in manual focus, how do I determine when I am best focused? Still very much in a long learning curve. Thanks. mike

I have the Rokinon and it's extremely easy to use. For astrophotography manual focus is a must. Just focus on something at infinity during the daytime and notice where it is. Everything from infinity to a couple feet in front of the lens will be acceptably sharp. Every individual lens is probably different, but luckily the infinity mark on mine was accurate and I didn't have to put a mark on the lens.

ORpilot Loc: Prineville, Or

mflowe wrote:

I have the Rokinon and it's extremely easy to use. For astrophotography manual focus is a must. Just focus on something at infinity during the daytime and notice where it is. Everything from infinity to a couple feet in front of the lens will be acceptably sharp. Every individual lens is probably different, but luckily the infinity mark on mine was accurate and I didn't have to put a mark on the lens.

I also have the Manual focus Rokinon. Stay away from autofocus with night shots. Another thing to note is that focus can change with temperature. If you focus at infinity when it's 90' out and then go out when it's a crisp 25' the focus will have changed. This is because of thermal expansion and contraction. It is more noticable with metal lenses vs composite lenses. Granted it may not be much but it could be the difference between a WOW photo and Thats Nice photo.

knutte

In the past you had to MF on stars, using Live View and magnify 10X but now on my new R5 with my EF16-35/2.8 it was able to AF on stars. Actually I think it was either saturn or Jupiter when I was out a few weeks ago. Lonely Speck has a focusing tool when using MF

rsworden

If you can get or make a Bahtinov mask for your particular lens, that makes it easier to accurately focus at infinity for the stars.