Over-coverage?

[AgentX]

Can a lens with significant excess coverage degrade image quality through internal reflections? Obviously, the particular camera's internal construction will play a part for better or worse, but is this something to be concerned about?

Would like to use a 10" Commercial Ektar on 4x5, possibly on a brand-new camera.

Thanks,

Mike

[Ron Marshall]

Excess light can be controlled by using a compendium lens shade.

Your 10" will work fine.

[AgentX]

cool...thanks!

[EdWorkman]

One can't be too rich, too thin, or have too much coverage

[Robert Hughes]

One can't be too rich, too thin, or have too much coverage
... unless you're at the beach. Then the less coverage, the better... if you're rich and thin enough.

[E. von Hoegh]

St. Ansel covered this in "The Camera".

[Drew Wiley]

The answer is unequivocally YES, unless you deliberately want flare. That's why a lens
shade, preferably bellows-style, is so important. But this is also a function of lens
design, coatings, etc.

[AgentX]

St. Ansel covered this in "The Camera".

Which I can't say any of the local bookstores here in Bujumbura are likely to be carrying at the moment...and going out at night this week is a bit dicey with all the grenade attacks.

So I guess I'll ask on the forum as I sit here on my couch.

[E. von Hoegh]

Which I can't say any of the local bookstores here in Bujumbura are likely to be carrying at the moment...and going out at night this week is a bit dicey with all the grenade attacks.

So I guess I'll ask on the forum as I sit here on my couch.



Sorry - I forget that we're not all in a position to read whatever we like whenever we like.
Say you are using a 300mm lens, with a 500mm image circle, on 4x5. You only need around a 160 mm image circle for the 4x5, so all this excess illumination will fall on areas other than the film causing loss of contrast, etc. It's known as "bellows flare" and can often be seen as an increase in density along the edges of the negative.
The cure is a properly adjusted compendium shade, excluding all light except that coming from the scene you wish to record.

[AgentX]

That's exactly what seemed logical to me...looks like there might be a compendium hood in the classifieds I could use. Thanks for clarifying.

Or I could just get a cheap 203 7.7 Ektar to use with the 4x5 instead of my big one.

[JRFrench]

Which I can't say any of the local bookstores here in Bujumbura are likely to be carrying at the moment...and going out at night this week is a bit dicey with all the grenade attacks.

So I guess I'll ask on the forum as I sit here on my couch.

I have PDFs of Adams' series if you would like a copy, I'm sure the Adams' estate would not mind helping a photographer in such a situation ;)

[Kirk Gittings]

Can a lens with significant excess coverage degrade image quality through internal reflections? Obviously, the particular camera's internal construction will play a part for better or worse, but is this something to be concerned about?

Would like to use a 10" Commercial Ektar on 4x5, possibly on a brand-new camera.

Thanks,

Mike

The answer is theoretically yes, but.....in the real world.....I made my living for almost 30 years using a 4x5 with lenses of extreme excess coverage for perspective correction of architecture subjects and never owned a lens shade other than my dark slide. Many of my lenses would cover 8x10 (like a Nikkor 120 SW). This is shooting transparencies for high end books and national magazines where I had no ability to correct anything in post. I am pretty picky and if I had detected an issue i would have gone to any lengths to correct it. It was never an issue then or now for me.

[AgentX]

Thanks to all for your replies!