Shutter question

[Deniz]

hi all.

I am looking for a shutter with a front opening of 46.5mm or about 1 13/16" .

I will use this shutter to mount my barrel lens from the front which has a 46.5mm barrel diameter.

If you guys know any shutter with this size of opening or slightly larger, please let me know..

thank you very much

Deniz

[Dan Fromm]

Deniz, depending on what you have in mind to do, you may be able to use a smaller shutter. Here's a simple geometric model that may help you:

Call exit pupil-to-shutter distance d1, shutter-to-film distance d2. Call the shutter's radius r1, the circle to be covered's radius r2. Then for the shutter not to vignette, we need r1/d1 >= r2/(d1 + d2), i.e., r1 >= r2 d1/(d1 + d2).

The practical implication is that if the shutter is much closer to the lens than to the film, it won't vignette even if smaller than the rear of the lens. And it won't reduce illumination on the circle that the lens illuminates through it.

For example, I shoot a 210/9 Konica Hexanon GRII front mounted on a #1. It does what I need, cover 2x3.

Cheers,

Dan

[Deniz]

Dan actually the lens i am going to adapt to a shutter is a eskofot-ultragon 210/9 which i beleive the same lens as the konica hexanon. But i need this to cover an image area of 8x10 with movements.

maybe i should front mount the shutter to the lens.. so that the shutter hangs from the front element. i just want to jam the lens barrel into the shutter threads.

can you tell me how did you mount it on the shutter?

[Dan Fromm]

Deniz, its funny that you have that in mind.

I bought a $20 210/9 Ultragon in case the GRII didn't work out. They are NOT the same lens. The GRII is much, much bigger. The Ultragon is a 6-element plasmat, the 210/9 GRII seems to have six elements in six groups. The GRII is just fine, so I sold the Ultragon.

I had Steve Grimes make a cup-shaped adapter for the GRII. The lens screws into the adapter, the adapter screws into the shutter. Cute, works well. If you're interested, I can send you some digital photos from the office on Monday.

If the Ultragon will actually cover 8x10, I don't think it will quite cover if in front of a #1.

Take a look at the shutter dimensions published on www.skgrimes.com . You might be able to get by with an Alphax or Betax 4 or 5, and they're not that expensive. Mounting the lens on front of one of them will require a bushing threaded externally, to engage the shutter, and internally, to grab the lens.

Cheers,

Dan