Optical conundrum for advanced puzzlersgreenspun.com : LUSENET : Large format photography : One Thread
It's driving me crazy! 95% of vertical shots that I make with my Wisner 12X20 show a secondary "ghost image" about 1 inch down and to the left of bright objects towards the top of the image. These are virtually all shot with a Fuji 600 F11.5C lens. Never see the problem in horizontal orientation. Happens ALMOST every time shooting vertically, but then I will expose 6 negs of the same scene (portrait), all shot at same F stop, lighting, composition, etc, and one of them won't have it! It is quite pronounced. I get it even when shooting with the sun/softbox directly behind the camera. Only other time I have seen it, tho' less pronounced, was shooting a very wide horizontal shot with a Super Symmar XL 210. The "secondary" image is out of focus and lighter than the original, always in the same orientation relative to the real image. The camera is fairly new, so I suppose this has been present since the beginning, tho' I couldn't absolutely swear. BTW, I do the verticals by turning the head of my Reis tripod on its side, if that matters. No vignetting, focus problems, flare or other issues with my shots.
I need your brainy and insightful answers quickly, as I depart with 12X20 in hand for a shoot at Ayer's Rock in Australia in 5 days!
Thanks in advance for your help.
Signed, Bewildered in Baltimore
-- Nathan Congdon (firstname.lastname@example.org), April 08, 2002
I don't have any suggestions with the ghosting, but I just wanted to tell you to enjoy the trip to Uluru. I was there two years ago, almost to the day. Absolutely spectacular. I just read that the climb up it is currently closed out of respect to an Aboriginal elder who recently died (the Aboriginals ask you not to climb it anyhow -- and I did not). Not that I see you trekking your 12x20 up there anyhow.
It is supposed to be quite warm in the Outback this time of year (well into the 80s if not 90s); however, when we were there it was unusually cold so we spent quite a bit of time in long sleeves and pants and froze at night (we were camping). As long as you've gone that far, the Olgas, Kings Canyon, and Rainbow Valley (this being my favorite) are well with the stop.
Sorry to digress. Good luck finding your answer and have a great trip!
-- Jennifer Waak (email@example.com), April 08, 2002.
Ghost images like this are almost always due to a pinhole somewhere in the camera -- so you have two images forming, one from the lens, and one from the inadvertant pinhole camera. I suspect that it's due to something flexing just a little, and only occasionally when you rotate the camera to its side for the vertical photo. JDClark
-- John D. Clark (firstname.lastname@example.org), April 08, 2002.
Nathan, I understand the Rock is once again open to climbers -so don't miss it. It was only closed for a short time. Jennifer is right , it will be very cold at night despite the hot days (desert climate) If you get the opportunity the Flinders Ranges in the north of South Australia are excellent. Enjoy. John Quinn
-- John Quinn (email@example.com), April 08, 2002.
Sounds like a bellows pinhole to me. But it's possible there's a screw loose or something. Turning a wooden camera sideways (especially one that big) may place mechanical stress on it that it was never designed for. Have you spoken to Ron Wisner about it? I'm sure he'd want to help.
-- Mark Sampson (MSampson45@aol.com), April 08, 2002.
Pinhole was my first thought too. Worth a sheet of film to tilt on side, pop the strobes maybe several times with shutter closed, develop and see what you get. The orientation should be a clue as to where to look first. Best of luck.
-- Jim Galli (firstname.lastname@example.org), April 08, 2002.
Ayer's Rock? Don't we grow 'em just as big in Arizona and Utah?
-- H (email@example.com), April 08, 2002.
You have all of the information that you need to determine the approximate location of the pinhole. The relative size of the two images will give you an idea as to the differences in distance from the film between the lens and the pinhole (unless you're using a telephoto lens which you obviously are not), if the images are almost the same size it's probably right next to the front standard. The orientation you already know. Let us know what you find.
-- Wayne DeWitt (firstname.lastname@example.org), April 08, 2002.
A quick way to locate pinhole (or other leak) is to put a small light inside the camera and bellows and look at the whole thing in the dark. Any light leaks are immediately obvious.
I recall reading once that one user got a 2nd image because a pin holding a diaphragm leaf had popped out of the lens' shutter assembly.
-- Duane K (email@example.com), April 08, 2002.
H, you might grow them just as big in Arizona and Utah but the beers better in Australia!
-- Pete Watkins (firstname.lastname@example.org), April 09, 2002.