What idiotic mistake did I make?

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mikehughesc

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Mike
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It was a clear night last night, and the moon was due to rise just after 2 am, with the azimuth (i.e. where it would rise) right opposite my spare bedroom window. Perfect opportunity for a shot of the moon coming over the horizon.

So I had the EOS 20D and 70-200 f4 L lens (with 2x extender) all set up on the tripod before going to bed. I woke up on schedule, crept out to the spare room so as not to wake the wife, snapped a series of shots, and came back to bed.

This morning I downloaded the shots in great anticipation, and found the whole lot were pitch black. Not just under-exposed - there was no detectable variation from black in any of 'em.

And yet, a few weeks ago I took some great shots of the moon using exactly the same (mroe or less "sunny 11") settings - i.e.

- focal length 400 (200 with the extender)
- full manual
- f/11
- range of speeds from 1/100 to 1/250, just to be sure
- ISO 100
- mirror lockup
- cable release

So what on earth could I have done wrong in my bleary-eyed semi-asleep state?

No, it wasn't the lens cap - thought of that, and removed it the night before - and anyway, I was focussing manually because the 2x extender kills the AF.

I've checked the EXIF on the JPGs, and the above settings are correct. But for some reason they're all completely black.

This has been bugging me all day. Can anyone suggest what stupid thing I might have done to give me totally black pics?!

Mike
 
ChrisGilbert said:
Waaaay too short a shutter speed at that ISO/aperture

f5.6/ 1/50 sec ISO 400 would have produced something
Click to expand...

Oooo - I dunno..... :thinking:
I just checked the settings on this shot.
ISO 100, f5.6, 1/160s and it was over exposed, so reduced the exposure by nearly a stop in LR3.
i-gFcHrtJ-M.jpg


Did you take the lens cap off?
MLU requires two shutter presses; did you forget the second one?
No live view; the moon moves very fast at long focal lengths, it was definitely in the shot, yes?
erm.. Struggling to think of reasons after that.
 
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No, the settings were fine. Here's a 100% crop of one I took a few weeks earlier - exactly the same lens, + extender, f/11, 1/125, ISO 100. Check the EXIF if you don't believe me! Focus could have been better but that was user error!

IMG_1746-002.jpg


I'm beginning to think it was a camera fault - except that it was working fine the following morning. But I've opened the JPG in Photoshop and zoomed in to pixel level, and every single pixel is totally black. If it was just under-exposure, surely there'd be something there?
 
ChrisGilbert said:
Big, big difference between f5.6 and f11(+extender)
Click to expand...

Depends on the extender.
I have the same lens as the OP and my f5.6 shot is wide open with a 1.4xTC.
With a 2xTC f8 is the widest it will go, f11 is only stopped down a tiny bit.

Back of a fag packet EV calculations....
The OP's aperture is just over a stop darker, but his shutter speed is a bit longer making the total difference in our exposures roughly a stop.
And Mine was a nearly a stop over exposed.
So I think the OP's exposure was bang on.

Also - the OP said "And yet, a few weeks ago I took some great shots of the moon using exactly the same (mroe or less "sunny 11") settings".
 
mikehughesc said:
No, the settings were fine. Here's a 100% crop of one I took a few weeks earlier - exactly the same lens, + extender, f/11, 1/125, ISO 100. Check the EXIF if you don't believe me! Focus could have been better but that was user error!

I'm beginning to think it was a camera fault - except that it was working fine the following morning. But I've opened the JPG in Photoshop and zoomed in to pixel level, and every single pixel is totally black. If it was just under-exposure, surely there'd be something there?
Click to expand...

Ah Ha!
Mike posted while I was writing (and doing the maths).

I'm liking KIPAX's suggestion :thumbs:
 
Yeah, I like the curtains suggestion too, or the wrong window. But ... I know I was a bit bleary-eyed, but I do distinctly remember trying to focus on the moon!

It was an amazing sight, too - don't think I've ever seen a half-moon rising before - it was like an illuminated shark's fin appearing over the hill.

It's clear again tonight ... if it stays that way for another few hours I might get a second chance. Stay tuned...
 
mikehughesc said:
Yeah, I like the curtains suggestion too, or the wrong window. But ... I know I was a bit bleary-eyed, but I do distinctly remember trying to focus on the moon!

It was an amazing sight, too - don't think I've ever seen a half-moon rising before - it was like an illuminated shark's fin appearing over the hill.

It's clear again tonight ... if it stays that way for another few hours I might get a second chance. Stay tuned...
Click to expand...

Whilst there's a suggestion that 1/125 or greater *should* have been OK based on the other settings, maybe the fact the moon was rising and perhaps not as bright as it'd normally be means a slower shutter/higher ISO was needed in this scenario?

Half moon and just over the horizon could mean it was less than half as bright as a full moon high up in the sky?

Seeing as the moon is only reflecting sunlight, surely a half moon would only reflect half as much light as a full moon? (OK I know it's not quite as simple as that)
 
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OK, mea culpa. Russ is spot on. Of course, a crescent moon low in the sky is going to be nowhere near as bright as a full moon up high. I tried it again last night with various settings, but (for example) at ISO200 and f/9 it needed 1.3 seconds to get a half-decent exposure.

You live and learn. At least now I know it was the brain at fault, rather than the camera!

Thanks for all the suggestions (especially the curtains).

Mike
 
mikehughesc said:
OK, mea culpa. Russ is spot on. Of course, a crescent moon low in the sky is going to be nowhere near as bright as a full moon up high. I tried it again last night with various settings, but (for example) at ISO200 and f/9 it needed 1.3 seconds to get a half-decent exposure.

You live and learn. At least now I know it was the brain at fault, rather than the camera!

Thanks for all the suggestions (especially the curtains).

Mike
Click to expand...

Good comeback from leaving the lens cap on/curtains closed ;) :lol:

Glad you sussed it in the end, all set for next time!
 
Ah yes, I realise that - that was really just for comparison with the rest of the discussion - "sunny 11" and all that.

But with the extender on, my max aperture was f/8, so the only other way out was a higher ISO, and at 3:20 this morning I wasn't thinking clearly enough to find the ISO control in the dark...
 
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