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

[d5heilman]

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?

[jrhoffman75]

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. 

[d5heilman]

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...

[jrhoffman75]

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.

[d5heilman]

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. 

[Waddizzle]

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@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. 

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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.

[kvbarkley]

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.

[CaliforniaDream]

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.

[Mitsubishiman]

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

[ebiggs1]

" 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.