Effect of shutter type on image sharpness.

[IanG]

A serious question, I'm doing tests for a forth coming shoot. Initially I've been using a 17" (430mm) f5.6 ex military Telephoto (very late coated Dallmeyer) on a Speed Graphic as the lens has no shutter. My problem is I think the combination of a long focus lens and the vibration of the Graflex shutter rules out good results below 1/500 or maybe 1/200 if I'm very lucky, and initial tests lead me to think 1/100 would be better but there's not enough light.

I'd be happier with slower speeds and stopping right down but I'm shooting moving subjects so really what I'm asking is would a lens with a between the lens leaf shutter be a better option. That's my gut feeling so I have one on the way bu I'd like to hear others experiences.

Ian

[jp]

The shutter vibration on a speed graphic is basically as the shutter travel is done and is slowing down/stopping. I use a 19" lens on 8x10 with a speed graphic for a shutter no problem.

[Jim Jones]

Tests on a very small distant point light source at various speeds under conditions similar to your forthcoming shoot should settle the question. By moving the camera slightly between shots, it takes only one sheet of film.

[Jac@stafford.net]

A focal plane shutter has a much longer total exposure duration than a leaf shutter.
What Jim Jones said.

[IanG]

Thanks, I'll run some more tests later today and will also check how smoothly the shutter's running there may be room for some slight improvements. Part of the problem is I'm used to working with more sophisticated large focal plane shutters that run far smoother but my telephoto won't fit the cameras.

Ian

[LabRat]

A funny thing happened after I mounted a Dally 400mm f4.5 true tele on my 2X3 pre-anv SG... I did some test shots in bright sunlight, and noticed vertical blur on the negs, that varied speed to speed (and the blur followed the orientation of the camera)... Strangely, the higher speeds had more of this "effect", and at the slowest speed, the "effect" was less... The camera was on a sturdy (old metal Tiltall) tripod, cable release, and no wind... I had made some long exposure night shots that same evening, and they were sharp as a tack... I had also shot some images through a 161mm Tessar Ic, and looking at the neg at medium magnification, there was a hint of the blur, but much less...

The short of it was that a long lens on this Graflex FP revealed that there is some initial recoil when the shutter is fired, that seemed to increase with the higher tensions (like the camera was "hit" when the shutter released)...

I love this lens on this camera, so I went to work to reduce the problem... I made a oak mounting block that covered the bottom of the camera, and went along past the middle of the bed with different tripod screw mounting points, so I could change the balance point of the camera, and there was a larger seating area so more vibration could be transfered away to the tripod, switched to a more solid head that was more supported at the base, and used a MUCH bigger wooden tripod... But also added a ND filter to the lens so I could shoot SLOWER, not faster shutter speeds (where there was less recoil when the shutter was tripped)... All of this helped!!! (I wanted to add a leaf shutter to the 400mm, but the lens is too big for front mounting, and MUCH too big to fit on the tiny lensboard!!!)

I used to test shutter vibration on 35mm/telescope mounted astrocams by reflecting a stationary laser beam off the telescope's front element and watch how much the beam spot (on a distant wall) would deflect when the shutter was released, and find the "sweet spots" of balance. speeds, etc... (And I agree with the others that testing is in order... I would put a rollfilm back on your camera rig, and shoot frames at your common speeds, and see which one's are better/worse...)

But my 4X5 SG's and RB seem to be a little gentler when the shutter is released... (But the RB has that mirror...) If it's any comfort, the same day I was shooting, I had gone to an image show/sale, and was holding in my hands, an original print of Strand's "Bowls" that had the same vertical blur/multi highlight on an edge, as what I ended up with, so not only my problem!!!!! (I still would have bought the print if I had 2 grand to spare...)

Steve K

[Tobias Key]

My only experience of this is phenomenon is with Pentax 6x7's, but the principles should be the same. With these cameras 1/250th and faster would be my 'safe zone' for good results. 1/125th good on a tripod but 1/60th 1/30th 1/15th and 1/8th could be badly affected by vibration if you were not careful. It is useful to think in terms of what proportion of the exposure is affected by vibration, particularly when the shutter fully opens and closes again. 1/15th is always thought of as a the sour spot for 6x7's as the shutter opens fully, the exposure is quite long, and the whole camera is still shaking from the mirror slap! Slower speeds allow the vibration to subside and faster also make it less of an issue. The weight of the lens on your camera could also be an issue, making the front standard unstable, is there any way you could support the front standard more?

[IanG]

You raise an interesting point Steve, when I shot predominantly with my Mamiya 645's in the 1980's some shutter speeds were sharper hand held than on a tripod (unless you used the mirror lock). Working hand held dampens the vibrations unfortunately not a very practical option for this project.

I think you're right about the balance point, I know that's a huge issue if I try to use my 300mm f9 Nikon M on my Wista, it's why the press in the UK often used to use big Bertha cameras with telephoto lenses, the wooden bed as you describe. I'll look at other ways to dampen vibrations with the SG and make sure I've the brightest ground glass scree for optimum focusing.

JP's comments about using a SG shutter on a 10x8 camera effectively uses the central portion of the curtains travel.

Ian

[Jim Noel]

Your wooden block is approaching a solution. A good wooden tripod like an Otto which is not huge,but strong, should eliminate all vibrations. I have two different sizes,and a large Ries. The smallest Otto is as strong, and does a better job of dampening vibration than the large Ries. It is a matter of the type and shape of the wood used in the tripod.

[EdSawyer]

" I'm used to working with more sophisticated large focal plane shutters that run far smoother but my telephoto won't fit the cameras."

What type of cameras would these be? I am interested... (I have Graflex and Arca FP shutter LF cameras, so curious for others' experiences there.)