Moon photography aperture opinions

Quote:

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Originally Posted by george013

Don't forget that lenses absorb light. Big lenses as the one being used might absorb 50%, that's 1 stop. Matthews setting are the "F11-rule" minus 1 stop.

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For the EF 500 F/4 L IS USM MkII, the T-Stop is closer to ½ Stop difference. I expect it would be about the same for the original version of the lens. (i.e. When set at F/4, the lens’s T-Stop is T/4.5)

(REF: DXO MARK Lens’s Transmission Testing)

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But:

Considering the Lens's T-Stop in the equation of this situation is academic/pedantic (and of course fun):

Remembering that these exposure "Rules of Thumb" (like the F/16 Rule, etc) were made long ago when Lenses for Still Photography where much less sophisticated than is the EF 500F/4 L IS USM.

Therefore arguably if any ‘correction’ for the T-Stop for this particular lens (EF 500/4L) were to be made, we might find that we would need to stop it down a bit or "plus" a bit (i.e. use slightly smaller aperture) when applying the “F/11 Rule” for photographing the moon.

WW

BTW - having never made one, it's really nice looking at all the excellent moon photos.

Quote:

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Originally Posted by William W

For the EF 500 F/4 L IS USM MkII, the T-Stop is closer to ½ Stop difference. I expect it would be about the same for the original version of the lens. (i.e. When set at F/4, the lens’s T-Stop is T/4.5)

(REF: DXO MARK Lens’s Transmission Testing)

*

But:

Considering the Lens's T-Stop in the equation of this situation is academic/pedantic (and of course fun):

Remembering that these exposure "Rules of Thumb" (like the F/16 Rule, etc) were made long ago when Lenses for Still Photography where much less sophisticated than is the EF 500F/4 L IS USM.

Therefore arguably if any ‘correction’ for the T-Stop for this particular lens (EF 500/4L) were to be made, we might find that we would need to stop it down a bit or "plus" a bit (i.e. use slightly smaller aperture) when applying the “F/11 Rule” for photographing the moon.

WW

BTW - having never made one, it's really nice looking at all the excellent moon photos.

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I just wanted to point out that those rules of thumb are referring to the exposure value, not to the f-number.

Big lenses with a lot of glass and coatings have a higher resistance for light. I remember a discussion several years ago about a Nikon, a very expensive one, where the loss of light was nearly 1 stop. But when metering thrue the lens this is not important anymore.

George

Yes, I understood your intent George, I wasn't disagreeing with you.

Best,

WW