Need help understanding image blur with Cirkut
This is only my second Cirkut picture ever. Click on the scans for a higher res. study. I made the image in bright sunlight today with a #10 Cirkut. I had one building that was going to be an issue with focus. Most of the focus was at about 85 ft. I used an 18" Cooke Series IX process lens and a #42 gear. I stopped down to f64 and ran the camera at 1/2 second.
In the 1600 DPI capture, look at how the image is formed at the edge of the culvert, or at the crown of the gables in the old stone house. A smear of lines.
Is this because of the very slow speed I used. It's like image smear but not quite. The 1600 DPI capture is a 3/4 inch wide by 1.75 inch long area of the total neg.
about 2X2 at 600dpi
.75X1.75 at 1200dpi
Thanks for ideas. Maybe I should just try again at 1/10th sec. This 10 is a particularly good runner. A sweet old camera.
The world is vibrating at a different frequency than your camera.
Heavily sedated for your protection.
Is there a moving slit in the Cirkut?
If so, what you're seeing could be an unsharp picture that's made sharper in the direction parallell to the movement direction of the slit by the smaller effective aperture in that direction. Not that the slit is narrow, but that the edge is moving across the image of the aperture for a significant fraction of the total exposure time.
Just guessing here, but since the sharpness is clearly different across and along the long dimension of the image, it's my best guess.
Last edited by Ole; 08-17-2008 at 01:47 PM. Click to view previous post history.
Reason: Spellling - too early in the night shift for me...
-- Ole Tjugen, Luddite Elitist
In a nut shell:
Overall blurring is not caused by the shutter speed. Shutter speed variation will cause banding (light and dark) but since the system is a locked gear train, the film has to move at the rate set by the pinion gear.
You can get blurring like you have experienced by using the wrong gear or wrong lens focus/gear. The correct gear is the most important issue for sharp focus. As much as the original instructions allude to a range of focus for each gear, it really doesn't work that way. You will need to retest your lens and try different focus distances until you get it closer.
For a field test, try using paper plates with a big "+" drawn in the middle. Staple them on stakes and place them every 10 feet from the camera beginning at 20 feet but add one at 25 and 35 feet. Best to have them in a row that doesn't use much film to photograph all of them. Then start by shooting with the lens focused on the first plate and proceed to the last plate. The last couple of shots could also be made with the lens focused at hyper infinity, but know how much past your focus scale you went.
Anyhow, when the film is developed, the vertical lines on the plates will show you which gear is right, and the horizontal lines will determine if the lens is in focus.
Collin Bullard in Australia used to make a giant "+" on a perfectly square piece of plywood painted white then he could simply measure the width of the plywood verses the height and using some math, determine the right gear. Again, it is knowing the horizontal line is in focus and measure the stretch or compression of the HORIZONTAL sides of the square.
The original Turner Reich lens middle cell claimed to be 18 inches but is actually closer to 16.5 inches and the 42 tooth gear puts the focus at 50 feet (slightly different with each lens). It is possible your lens is a different focal length and should be measured on a nodal slide.
Another issue with cirkut film is not getting it perfect on the take up drum in the beginning, then it starts a wrinkle that will cause blurring as the film is jerked across the slit trying to correct itself. In that case the image is sharp, blurry, sharp etc.
Hope this helps,
Ron in Alaska
How was the lense set up? I've found it important to test each lense when setting it up an the camera. Setting up a target like ron said is important. Each lense needs to be done individually and you can only hope that the turner reich you have now might have the same placement as the same lens type with a different serial #
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Hmmm. I guess I just got lucky a couple of years ago when I made my other picture. I used an 18" Artar that time. It had some banding but the image itself was surprisingly sharp. In the meantime I've sold that Artar. I like the 18 or 450 length for this camera. This time I used a Cooke 18" process lens. I was hoping for a second case of dumb luck. I guess if testing is involved I should nail down a lens that I'll use every time without fail. I have a Voigtlaender APO Skopar 450mm that I think might be the one. 450 might be a little closer to the TR nodal than the Cooke was. If you know where the nodal point is, isn't there some math that would get you very close without all the messing around?
the T-R triples were popular on the cirkuts because you could set it up for three different focal lengths. Once set up, you are good to go. BUT cirkuts aren't a good platform for trying different lenses. Even with the computer program and the measuring of the nodal point it takes a bit of time to get everything fine tuned. You were very lucky the first time. The advantage of having a camera with a factory lense is that they did all the work.
I've set up my cameras with different lenses and it just takes time. I have a 24" artar on my 10 which I love.
Frustrating. I'm not blessed with limitless time plus I've got so many other photographic interests. I'll have to dedicate a block of time and re-read Ron's post several times. I'm not sure I understand what I would be doing and don't really want to waste a bunch of time. I focused several lenses on the camera this afternoon. One is an original Turner Reich #4 of the advertised focal lengths that would have come with the 10 Cirkut. 10 18 24. It didn't focus anywhere near the cheater marks on the camera in either it's 10 or 18" iterations. The one that I left on the 4X4 'C' board was a 450mm Nikon. It came closest to the marks on the camera body so maybe it would be the one to start with?
Originally Posted by jamie young
Oh well, fwiw, here's my picture, warts and all. I've got a lot of work to do, but at least the camera saw some daylight for the first time in maybe 65 years. Click the thumbnail for a bigger version. Bookmark it for a page to come back to show your students everything that can go wrong with one of these pics.
It's a wonderful composition. Darn shame about the banding. I can sympathize. BTDT; I know the feeling.
I'm especially impressed that it's only your second Cirkut shot. Wow!!!!!! I can't imagine having so much gap between attempts.... I'd forget everything I thought I learned each time if I waited that long.
I've done maybe 6 Cirkut shots now in 6 weeks on my new-to-me #10 Cirkut, and my learning curve has been very steep. Given all the variables that the photog has to get under control, I took the seller's advice, and did small pans first, to conserve film and really *learn*. I'll err, figure out what I did wrong, won't make that mistake again, but will go and find a new smaller mistake to make. I've had minor banding, made almost invisible by warming the camera up with a warmup lap before the real shot. Found the warmup lap cure accidentally when somebody in a group moved on the first try, and I had enough film for a reshoot, and the reshoot was silky smooth. I've had a single vertical dark strip toward the begining of several early negs, which at first I worked around by starting the camera well in advance of the subjects, but which now I think was the odometer detent spring causing drag before the Cirkut was really up to speed. Seems to be solved by my carefully tweaking the odometer counter detent spring, so it was just barely strong enough to do its job. I've had banding from having the drivegear-to-ringrear mesh too loose, and having it skip.... was just dumb luck that I happened to be watching the gears, and saw what I thought was 2-3 skips, and then found on the neg 3 dark bands where I thought the skipping had occurred. I'm confident that won't happen again, experience is a good teacher, but not necc. a fast teacher.
I'm fortunate in that the original lens came with my camera, so I didn't have to re-engineer anything, or re-calc gears ratios or anything else. And I've had good advice. The original seller told me what Ron said above, ie, that the horizontal focus is best at 25' and 50' and 100', and to work with those numbers for best results. So I avoided that pothole.... Being able to use the factory lens / factory focus & gear scales / factory gears has probably been a huge help for me. Something else I think was a big help, was having spent a couple years shooting with swing-lens cameras, sometimes splicing multiple swing-lens images together in Photoshop, to simulate a Cirkut pan long before I owned one.
I'm finally getting to the point where I feel confident that I can shoot a photo with the Cirkut, and capture what I expect to capture. But even so, for a shot where I absolutely must produce results, I keep the swept angle down to 120 degrees, and have my Kodak Panoram set up just behind the Cirkut, for a backup shot. The one group I've done so far, I didn't need the backup, but was sure glad to have it.
I'm shooting a large group this weekend at a motorcycle event, and will use the Panoram as a backup just a few feet behind the Cirkut (take the Cirkut shot, move the Cirkut away, and take 2 Panoram shots with the already set-up Panoram), but I also took a test shot with the Cirkut on Monday, to verify that all is well. Seems to be. Hopefully I won't learn any new mistakes this weekend.
Your eye for suitable subjects is excellent. And I'd be the last person in the world to say it's an easy thing to get up to speed on a Cirkut. Hang in there.