View Full Version : Checking coverage, Sinar 4x5 non-metering back

31-Mar-2013, 08:07
Does anyone else have the same issues I do, checking lens coverage using your Sinar 4x5? I have an F2 with a "non-metering" style back, but the problem seems to be the same (and likely worse) with the metering back. Even though I remove the fresnel, the ground glass is recessed too far into the back to be able to see through the clipped corners of the GG for a coverage check.

Obviously, this problem is compounded with shorter lenses, 125mm being my most used lens. It's even worse when using very much front rise, which is when I most need to check for vignetting! With the 250mm and longer and standard (not WA) bellows, I can sometimes get a peek at the aperture if I'm not using much movement.

How do you visually check lens coverage on your Sinar 4x5? Rick? Leigh?

Ken Lee
31-Mar-2013, 08:35
One solution is to simply replace the ground glass with one that is not clipped in the corners.

31-Mar-2013, 10:04
How does doing away with clipped corners facilitate checking coverage? On other cameras with clipped corner GGs, I can usually see the lens aperture through the clipped corners from all four corners as long as I'm within the IC/Coverage of the lens when applying movements.

Maybe there's just no way to do this effectively with Sinar GG backs? I've had a few problems lately exceeding the IC of my lens with movements and I guess without actually measuring rise, shift, etc., in mm, there's no way to avoid vignetting?

Tin Can
31-Mar-2013, 10:13
Ken, I don't think Cletus understood your joke...

or I don't

31-Mar-2013, 10:14
Oh that was a joke. oops! :o

Jason Greenberg Motamedi
31-Mar-2013, 10:20
I have the same issue with my Norma with some but not all lenses. One imperfect solution is to look the other way; look through the lens and see if you can see the corners of your ground glass. If so, your lens is covering. However, this method does not help you figure out what aperture is required.

Tin Can
31-Mar-2013, 10:55
Cletus, I am new to LF, long time film addict, and I replaced several GG on different cameras with un-cut corner new GG. I was ignorant and thought the corner cutting was only to release bellows air pressure when moving the frames. I thought it would help keep dust out of lenses by not pressurizing them. I do think there is something to that. More than a few LF cameras has vent holes and don't need cut corners for pressure release, BUT...

LATER, I learned my error and realized those cut corners are handy for checking coverage and seeing if I am stopped down, and even if I closed the aperture, BEFORE pulling the DS.

We do need a WIKI.

and now I am checking my herd for easy to view cut corners...

31-Mar-2013, 12:03
Look through the lens with the GG open to sunlight or whatever.

If you see four square corners, you're good.

- Leigh

31-Mar-2013, 13:50
Thank Leigh - Somebody else suggested that too. I guess I never thought to try it backwards! I think I'll set up a light and do some tests with a couple lenses, then mark my scales so I'll have a reference in the field when I'm about to run out of coverage. My Nikkor 75/4.5 only allows a little movement, so it's even more important to know how much rise/shift I have to not chop off the top of the image!

BTW - How is that Sironar W210 working out? I've had a few pangs of regret for selling it, but I do have a nice Shen Hao FCL810A to show for it. (Which is in the shop for repairs right now. :o:o:o)

31-Mar-2013, 14:10
BTW - How is that Sironar W210 working out? I've had a few pangs of regret for selling it
Very nice lens. Love it.

I always regret selling things. That's why there's no room to move in my office. :eek:

- Leigh