Lens to Film Distance for 180mm?

[Garry Madlung]

I have a question for anyone with a 180mm lens. I'm considering a 180mm for my Ebony SW45. It's a wide angle camera but is supposed to take up to a 180mm. My question is this: With a 180mm how much draw do I need to focus at a relatively close distance - perhaps around 10 feet?

I'd rather not have to attach a bellows extension. If the camera doesn't have enough draw to focus at 10', I'll look at the 150.

[Drew Wiley]

You need to look at the mfg spec for the actual focal length of the specific lens. But
the SW45 only has 190mm bellows draw. You won't need too much to focus at 10ft.
But if it was me I'd mount the lens on a slightly extended lensboard (avail from Ebony,
Linhof, or Bromwell). Too much board extension risks vignetting with strong tilt or rise.
But generally a 180 with give better coverage and more even illumination than a 150.

[Bob Salomon]

It is the flange focal length that you need to know not the actual focal length. As an example a 180mm Apo Sironar S has a flange focal length of 177mm at infinity with a Copal 1 shutter. The 180mm Apo Sironar N has a flange focal length of 173mm with a Copal 1 at infinity.

[Bob Salomon]

"slightly extended lensboard (avail from Ebony,
Linhof, or Bromwell)"

Wista makes extension boards, Linhof does not.

[Drew Wiley]

Sorry Bob, I should have stated "Linhof-style" board. You can also get them custom
made from SK Grimes.

[Bob Salomon]

Sorry Bob, I should have stated "Linhof-style" board. You can also get them custom
made from SK Grimes.

Since Wista makes screw together extension boards that accept additional extensions and come with screw-in 0, 1 and 3 rings it would be hard to see how one would need a "custom" version. The Wista can be as short as 1" and as long as you need.

They also make fixed length extended boards with a 0, 1 or 3 thread.

[venchka]

I have a Nikon 180mm lens. Shall I set up the camera and measure tonight?

[drew.saunders]

Ebony lists this information: http://www.ebonycamera.com/articles/lenses.html
From that list, the 180 with the shortest flange to focal distance is the Fuji CMW at 170.7mm. Most of the rest are 177mm or so.

With 190mm of bellows, rounding the CMW to 171mm, you get (1/171) - (1/190) = (1/distance to subject) and that comes out to 1615mm minimum focusing distance. With 178mm, the minimum focusing distance works out to 2819mm.

Drew

[Henry Ambrose]

You'll be very close. I have an SW45 and had a 180 that I seldom used, so sold it. I find the 150 to be more useful for me. You can add an extension board to get closer focusing but the front movements will get a little goofy since you will be moving the lens's nodal point away from the camera's movement pivots. This is not a huge problem.

[Garry Madlung]

Thank you everyone. (I've been occupied with some prep work this evening.) Wayne, if you have a chance, please test it out.

The extended lens board is an excellent option. I won't have to attach a back extension.

Out of curiosity, a number of months ago I tried to focus a 210. Nowhere close to focusing. The 180 might be more useful to me than the 150, and I might have a use for it on some more detailed work than my usual wide angle pursuits.

Garry