90mm f8 vs 5.6

can someone who has used a good dark cloth comment if there's a significant brightness difference between them when focusing on GG?

without a dark cloth, the difference I find is significant especially under dim lighting conditions.

the issue is not focusing, but composing the image.

I’ve only used a 5.6 and it’s bright. Quite a bit brighter than when it is stopped down to f/8. The downside is that it’s big and heavy.

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Originally Posted by BrianShaw

I’ve only used a 5.6 and it’s bright. Quite a bit brighter than when it is stopped down to f/8. The downside is that it’s big and heavy.

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And you were under a dark cloth? I know the brightness difference without a dark cloth, I have several f8's and f5.6's.

I've always used WOOD HOODS that have elastic bands around the camera and my head. Even in bright SUNLIGHT, I've found my f8.0, f9.0, and even f12.0 lens bright enough. Without a dark cloth, of some sort, even my f4.5 lens is impossible to use.

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Originally Posted by Ben

And you were under a dark cloth? I know the brightness difference without a dark cloth, I have several f8's and f5.6's.

I mean a real dark cloth, not one of those terrible one's made by harrison.

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Yes, I always use a dark cloth to focus on ground glass. Not sure what you mean by a “real” dark cloth though. Mine make it dark so they should be considered real.

And going back to the first post… I think most folks would say that brightness is more important for focusing than composing. What are you finding difficult when composing?

This is a trick question. If you’re trying to compose near sunrise for example then 5.6 makes a big difference even under a good dark cloth, particularly to see the full screen. At f8 it’s hard to see near the corners in particular. I’ve found myself for example seeing the composition doesn’t quite work after more light is available because I didn’t see everything well enough with an f8 lens. So for those occasions I bring my 5.6 90mm. Also helps focusing. For normal bright conditions, I bring the f8 which is lighter and more compact.

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Originally Posted by BrianShaw

Yes, I always use a dark cloth to focus on ground glass. Not sure what you mean by a “real” dark cloth though. Mine make it dark so they should be considered real.

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I mean a hooded dark cloth that blocks out stray to create a true darkened environment, so that your eyes adjusts accordingly to the level on the GG. One could speculate that once your eyes adjusts properly, the light hitting the GG becomes less of a factor.

There are other dark cloths, such as the one made by harrison. The harrison goes over the entire camera using velcro, so it does not create a true darkened envoriment.

I've used both in Super Angulon form and yeah, the ƒ5.6 is brighter, but the ƒ8 is plenty bright for focusing (in the environments I use.) And this is with a Black Jacket or Harrison dark cloth.

Ben, you might want to start a separate thread on dark cloths. Many use a trade flat cloth very effectively.