View Full Version : Exposure problems with the moon

29th January 2013, 12:11 PM
Winter is a time of cold clear nights, perfect for pictures of the stars and the moon. Well not this winter. It seems to have been overcast every night since November. It finally cleared up and I thought I would take some pictures of the nice full moon.

Problem No. 1
Well, half my shots were way overexposed even when the viewfinder looked perfect. The good ones were around 1/320s, ISO 200, F6.7 and the bad ones 1/8s, ISO 3200, F6.7 with no changes to the settings (I use auto ISO capped at 3200). It didn't seem to matter whether I was using spot metering, centre weighted, or ESP metering. How the end result can be a plain white overexposed disc when the viewfinder shows a perfect image is beyond me.

Problem No.2
Focussing was not perfect. Auto focus was quick to lock (after all the moon fills a fair proportion of the frame at 300mm) but often out by a tiny amount. Manual focus was not easy as even with the stabilisation on the moon jumps around a bit when you are twisting the lens ring. On a tripod its even worse as the stabilisation should be off. Does the moon just not have the necessary contrast? I even tried with my old vivitar 100-500 zoom but could not do any better than with the much lighter 75-300mm M.ZD.

So out of more than a dozen pictures there were only 2 that I was happy with and 6 that were a complete mess. Here is the best but I have no idea what I did differently to all the other shots.


29th January 2013, 01:49 PM
For this sort of shot I would always use manual control of exposure and not allow the camera to try to make a guess, The problem you saw was the camera struggling to decide if it was exposing for the brightness of the moon or for the averagely dark exposure of the overall scene

I usualyl stick it on a tripod, set to manual focus and manual control of shutter speed ISO200 with f8 - f11 and start for full moon at around 1/400th sec then go up / down depending on the appearance of my trial shots

This (quite old) article has a nice little table in it showing ISO vs shutter speed at f16 for the various phases of the moon http://home.hiwaay.net/~krcool/Astro/moon/howtophoto/index.htm

29th January 2013, 02:53 PM

When taking pictures of the moon you need to think about exposure conditions as if you were taking pictures on earth in sunlight, and furthermore considering the angle of the moon over the horizon.

For a high standing moon, say 45 degrees over horizon, clear sky, the recommendation is to expose at EV15. (Lower standing moon calls for lower EV).

You also need to consider eliminating motion blur. To freeze the moon and reduce motion blur to be in the order of a pixel on the camera sensor you would need to go down to around 1/250 s. (I did the maths and posted on the forum quite some time ago).

At ISO 100 this transforms into 1/250s, F/11.
Or 1/500s, F/8.

With a 500mm focal length lens you could probably shoot without tripod. Shorter times are better so you may want to increase ISO to e.g. 200.

Best exposure mode is manual. And focusing should be at infinity.


29th January 2013, 02:55 PM
I forgot to mention that, to achieve the most dramatic pictures of the moon you should try to capture the half moon, that is when the features in the terrain are illuminated with sunlight from the side and the shadows are most pronounced.

29th January 2013, 05:51 PM
If you set everything up and then use shutter delay, it works well. takes all the shake out of the shot.

Bluegrass Jim
29th January 2013, 06:25 PM
Hello OM user,
The moon is tricky at the best of times because of the huge variation in light from the dark of space to the highly reflective surface. I would agree with Tordan about shooting the phases rather than the full moon as the contrast on a full moon is very low. Having said that however the moon is interesting in all phases as the ray systems are usually more visible on the full moon whereas the mountains and craters are better seen on partial phases.

29th January 2013, 07:12 PM
I also prefer shooting phases in preference to the rather indistinct full Moon.
My current Tokina setup is tripod mounted, IS off, manual focus, antishock with delay or remote shutter release, spot metering, shutter speeds between 1/160 to 1/250, ISO200, aperture f/5.6 to 8.
If you shoot phases you will find it easier to pick out features to nail the focus. You can use zoom view to help with this, either through the EVF or rear screen.
Hope that helps :)

29th January 2013, 07:32 PM
I did find that on the tripod and with IS off I needed the 12s timer to eliminate the shutter press wobble, 2s just was not enough. I'll try the remote release next time. I didn't think of adding anything for shuttershock so thanks for the reminder. It seems like whenever I try a new subject I need a new set of settings.

I also found a problem with flare, moving the moon slightly off centre produced a hazy second image.

David M
29th January 2013, 08:37 PM
Try taking your protective filter off.

Stewart G
29th January 2013, 09:14 PM
The moon is tricky, esp with evf or live view, and though I see reasonably good sharpness in your image (compared to what I can do here at three feet above sea level), the other oddities might be due to atmospheric layering or high winds aloft. Keep trying!