8x10 bellows -- At what point is extending them via a third standard a bad idea?

[Mark Carstens]

My Arca Swiss 8x10 Model C has 50mm bellow -- too short for at least one of my lenses (600mm) and more realistically two (450 as well) -- but my F-LIne 4x5 standard bellows fits into the frame of the older 8x10 and the front standard from my Discovery -- instant bellows extension!

My questions...

Am I kidding myself or have I stumbled on a poor-man's albeit clunky alternative to buying custom universal bellows?

At what point, in terms of focal length and angle of view am I asking for image compromise due to mechanical vignetting?

Any sage advice would be greatly appreciated!

~Mark

[Peter K]

Hi Mark,
why buy another gear, there is all you need! The middle standart needs only horizontal and vertical shift to avoid vignetting. This must always be controlled via groundglass, also with special gear. So the maximum extention / focal length is only limited by the lengt of the bench.
Peter K

[Ralph Barker]

I've considered the same thing for my Toyo 810G, Mark, as the 45C bellows will also fit into the front standard of the 810G. Aside from the "extra canvas in the wind" issues, the practicality, I think, depends on the size of the front opening on the 8x10 bellows and the size of the 4x5 bellows.

Knowing those dimensions, geometry could be employed to calculate the distance at which the bellows transition point would vignette the image area. t might be easier, however, to simply set it up and test it, being careful to center the middle standard.

[David Karp]

Hi Mark,

I have not tried it, but your idea seems like it should work. Think of the older Cambo SC 8x10. It had a standard bellows that pretty much does what you describe. It starts out at the 8x10 size and extends forward a bit, then converges rapidly to the size of the 4x5 front standard (as opposed to so many cameras that descend gently and continuously from the 8x10 sized bellows at the rear standard to mate with a smaller front standard.

Seems like it would be a matter of experimentation.

[Mark Carstens]

Peter, Ralph & Dave,

Thanks, guys, I think you're right.

That was my first impression -- shoot and find out, through a series of focal lengths and bellows extensions, where the limitations fall in. The standards/frames are easy to center in advance, so it's just a matter of finding a convenient way to pack the bellows along with the third standard/carrier on a focus rail.

I should be able to see any mechanical vignetting, on the ground glass, right?

[Ralph Barker]

Don't forget to pack a second tripod and a couple of support struts, as well.

I, too, would think the physical vignetting would be obvious on the GG.

As an aside, the same setup would also allow the use of long lenses on a 4x5 reducing back, but without the vignetting issue.

[Mark Carstens]

Don't forget to pack a second tripod and a couple of support struts, as well.

Oh, man...I think it's time to rent a mule! My son's barely five years old...pretty much worthless for grunt labor at this point.

As an aside, the same setup would also allow the use of long lenses on a 4x5 reducing back, but without the vignetting issue.

Good suggestion. Ironically, I'm on the verge of selling my 8x10 to 4x5 reducer board and GG holder for it. I have both standard and long bellows for my 4x5 Discovery, so I have the reach I need. At this point, I'm only limited by the focus rails and bench.

[Darryl Baird]

I have this setup with a studio Cambo Legend. I own two of these, a 4x5 and 8x10. The standards are interchangeable on the rail, so I was able to "borrow" a standard, an extension rail and a bellows from the 4x5. Super close-ups were the goal and it worked well. I did have to really check for vignetting when I had a dark background. I later purchased an extra standard so I could leave the big camera setup and still carry the 4x5 with me if needed.

[CG]

Mark,

An intermediate stand and second bellows works just fine. Preventing vignetting is easiest when you can get around to the front and view the ground glass through the lens - stopped down is best. You'll see any cut off even faster than through the ground glass the usual way, since you only really know if you're OK when you are fully stopped down to working aperture and the gg can be very dark.

Sinar sells intermediate stands and extra bellows for just such needs. I use Sinars, but I think the geometry is universal. I believe the geometry favors putting the intermediate stand relatively closer to the lens if you have a tapered bellows that's 8x10 sized at back and lensboard sized at front and if you are close to vignetting.

In other words, with a tapered bellows, tend towards fuller extension of your primary bellows, and fill the rest of the needed length by the supplemental bellows.

With all but heroic lens extensions, a second tripod can often be largely replaced by a monopod to support one end of a fairly long rail. Should you really crank it out with magnificent extension, maybe a second tripod is a good idea.

Then again, take a look at the ingenious camera support illustrated here: www.naturfotograf.com/sacht3.html

I haven't been able to justify such expense for myself but that's a real camera support.

Best,

C

[Mark Carstens]

Thanks again for the input, everybody.

I'll be moving forward with securing a spare function carrier to go with the frame.

~Mark