topic Re: Having trouble focusing on Moon Is there a way to adjust the manual focus sensitivity on a lens? in EF & RF Lenses

Having trouble focusing on Moon Is there a way to adjust the manual focus sensitivity on a lens?

d5heilman — Tue, 19 Feb 2019 19:14:16 GMT

I am using a 5D Mark 4 with a 70-200mm f/2.8L ii and a 2x iii teleconverter to take Moon photos. The problem I am facing is Autofocus is not accurate enough at that range, and when trying to focus manually it is way too sensitive. I turn the manual focus ring the absolute smallest amount I can and the focus point overshoots my target by miles (literally miles). Is there anyway I can adjust how sensitive the manual focus ring is? Or any other ideas I could try?

Re: Having trouble focusing on Moon Is there a way to adjust the manual focus sensitivity on a lens?

jrhoffman75 — Tue, 19 Feb 2019 20:30:16 GMT

The AF system needs a target with contrast. The moon disk doesn't have the required contrast. Try setting the focus point on the edge of the moon disk. That might give sufficient contrast to allow AF to work.

Re: Having trouble focusing on Moon Is there a way to adjust the manual focus sensitivity on a lens?

d5heilman — Tue, 19 Feb 2019 20:41:11 GMT

OK I will try this tonight, only problem with that idea is now the focus point will be on the edge of the moon, and the face will be out of focus. I was shooting at f5.6. Maybe I just need to up my fstop a little so more is in focus. I was able to shoot at 100 ISO using 1/350 and f5.6 so i have some room...

Re: Having trouble focusing on Moon Is there a way to adjust the manual focus sensitivity on a lens?

jrhoffman75 — Tue, 19 Feb 2019 21:07:22 GMT

The moon is basically flat at that distance, so I don't think the face will be out of focus. At least it works for me.

Re: Having trouble focusing on Moon Is there a way to adjust the manual focus sensitivity on a lens?

d5heilman — Tue, 19 Feb 2019 21:14:07 GMT

Yea I will give it a try tonight. I was suprised at how touchy the manual focus was at that range. I figured at that range it would be super easy to focus. Maybe its just the teleconverter that is making the focus more touchy.

Re: Having trouble focusing on Moon Is there a way to adjust the manual focus sensitivity on a lens?

kvbarkley — Tue, 19 Feb 2019 21:54:13 GMT

I think you can safely assume that the entire moon is at infinity. 8^)

Assuming that the teleconverter does not mess up the focus distance, you should be able to set a hyperfocal distance on the distance scale.

Once you get an acceptable focus with AF, set the lens to Manual to keep it there.

Re: Having trouble focusing on Moon Is there a way to adjust the manual focus sensitivity on a lens?

CaliforniaDream — Tue, 19 Feb 2019 21:57:20 GMT

I try manual focusing on a star and make it as small a point as possable. This is my inifity focus, easier than trying to manual focus on the moon.

Re: Having trouble focusing on Moon Is there a way to adjust the manual focus sensitivity on a lens?

Mitsubishiman — Wed, 20 Feb 2019 03:42:39 GMT

I learned a tip that I use often, manual focus, live view, use the magnification at maximum, adjust the camera so you can see the edge of the moon, focus then exit the magnification and take the shot. Start with ISO 100, speed 100, f11 (Looney Rule) and adjust to your liking, I find it better to increase shutter speed and deal with exposure in post processing.

Canon 5DsR + Canon EF 100-400mm F4.5-5.6L IS II USM + Canon 2x III Teleconverter

f11, ISO 100, 1/20 1/6 Crop Factor

Re: Having trouble focusing on Moon Is there a way to adjust the manual focus sensitivity on a lens?

Waddizzle — Wed, 20 Feb 2019 03:41:02 GMT

@d5heilman wrote:
Yea I will give it a try tonight. I was suprised at how touchy the manual focus was at that range. I figured at that range it would be super easy to focus. Maybe its just the teleconverter that is making the focus more touchy.

It really helps to have a tripod rig that is as solid as a tree trunk, when manually focusing a super telephoto lens. It also helps to manually focus in Live View mode, at 10x magnification.

Make sure the lens is switched to MF mode, and turn off IS in the lens, too. If you are not using a remote shutter release, then use the built-in shutter delay timer. Some people like to use Mirror Lockup mode.

You will need to manually set exposure, too. I suggest 1/100, f/11, ISO 100 as a starting point.

Re: Having trouble focusing on Moon Is there a way to adjust the manual focus sensitivity on a lens?

ebiggs1 — Wed, 20 Feb 2019 15:24:32 GMT

" Is there anyway I can adjust how sensitive the manual focus ring is?"

Whenever you have a problem it is mandatory you identify the cause. I believe you are looking at the wrong solution. I am going to suggest it is not focus that is the problem but movement of the camera and/or tripod. The best most critical focus is ruined if the camera is allowed to move.

Added to that, one more problem, 400mm isn't really enough FL. That means you are going to crop heavily to get a big Moon in the image. This will magnify the movement issues. But wait there is more! Having a less than good 'seeing' condition will appear like poor focus. You need a clear night, no haze, no fog or clouds and no city for best results.

Things are so far away in the sky that once something is in focus everything is in focus.

If Tim Campbell sees this post he ca give you exact numbers and procedures for great sky photography.

Re: Having trouble focusing on Moon Is there a way to adjust the manual focus sensitivity on a lens?

d5heilman — Wed, 27 Feb 2019 15:38:35 GMT

I don't think it is the tripod, yes it shakes a little while I am manually adjusting focus. I was using the 10x zoom to do the adjustments, but the tiniest adjustment would move the focus plane so quickly, even at f11. I am beginning to think it might just be some Haze between me and the moon that may just be the problem, but I still don't understand why the focus plane is so narrow and moves so quickly at f11, I thought it should be pretty deep focus at that distance. Here is my final result.

Re: Having trouble focusing on Moon Is there a way to adjust the manual focus sensitivity on a lens?

ebiggs1 — Wed, 27 Feb 2019 16:23:24 GMT

Seeing conditions are the number 1 priority. There is even a scale to rate it.

"...yes it shakes a little..."

Not good. Even a tiny shake will show up most of the time. Even a slight breeze on the tripod can effect sharpness.

Your Moon shot is pretty nice so I think you are getting the idea OK.

Re: Having trouble focusing on Moon Is there a way to adjust the manual focus sensitivity on a lens?

Waddizzle — Wed, 27 Feb 2019 22:02:44 GMT

“I don't think it is the tripod, yes it shakes a little while I am manually adjusting focus. I was using the 10x zoom to do the adjustments, but the tiniest adjustment would move the focus plane so quickly, even at f11. I am beginning to think it might just be some Haze between me and the moon that may just be the problem, but I still don't understand why the focus plane is so narrow and moves so quickly at f11, I thought it should be pretty deep focus at that distance. Here is my final result. “

Yes, the tripod cannot be ruled out. If you have not already done so, lower the center column all the way down.

As for how sensitive it is to focus, I would suspect it could be a consequence of the extender. Try focusing on a bright star. It might be better.

Re: Having trouble focusing on Moon Is there a way to adjust the manual focus sensitivity on a lens?

RobertTheFat — Thu, 28 Feb 2019 05:52:10 GMT

Forgive me if this point has already been raised, but I wonder if it could be part of your problem. A lens designed for autofocus is usually capable of focusing beyond infinity. (This keeps it from banging on the stop if it temporarily overshoots the target.) But as others have pointed out, autofocus doesn't work very well on the Moon because of its lack of contrast. But if you switch to manual focus and then accidentally overshoot the infinity point, the picture will be OOF at any aperture. A common way to deal with that is to focus on an object (a tree or building, for example) that is far enough away to be within the hyperfocal range of infinity at the chosen aperture, then leave it there as you switch to manual focus and point the camera at the Moon.