Exorcise my spirit catchergreenspun.com : LUSENET : Large format photography : One Thread
I need to tap into the knowledge base of you die-hard LF users. This is probably a no brainer, but I can't figure it out, guess we all know what that means!
A ghost image is appearing within the frame on the final film that is not discernable on the ground glass, but only under certain circumstances, usually involving direct light [sun]. The lighting angle is not into the camera position, usually 30 degrees or more out of frame. The ghost is usually the size of a dime, and is a non-mirrored, 50% intensity likeness of a bright object within the frame.
I would like to know why this happens, and how to eliminate it.
It appears to be related to any bright object [in direct light, or from direct light] that is within the composition, that is approximately +1 1/2 to +2 stops over the base exposure. It also seems to happen more often when this object/zone [has happened with potted flowers, as well as with a sun spot on the exterior of an adobe house] is located in the outside 1/3 of the frame, but not always. It has happened with all of my lenses, and both with and with out camera movements.
I have purposely re-shot several of the shots with different combinations of lenses, apertures, bed angle, movements, etc. all to no avail! The simple answer is to shoot in total shade, but that is not applicable for this assignment [architectural exteriors].
Arca-Swiss F-line 4x5, std. & bag bellows, Caltar II N 75/6.8, 90/6.8, 135/5.6, 210/5.6, Arca Bino hood, Canham modified lens shade, all of this stuff is new. The shots are proofed on Polaroid type 54 [NO GHOST VISIBLE!!] and final film shot on Fuji Q/L RVP [With Ghosts] with Fuji Q/L film holder, typical exposure is f22.5 @ 1/8 sec. though I've tried just about every other combination and bracketing.
I typically shoot medium format on location, and use the 4x5 for product shots and interiors. I have never encountered this before. Any help would be most welcome and appreciated.
-- Robert Anderson (firstname.lastname@example.org), April 23, 1999
Sounds like flare to me. Since it seems to be happening with all of your lenses I'd check inside of the camera - the bellows, the back of the lens board anything that might be reflecting light. I also wonder if there is a tiny light leak somewhere that is reflecting off something else. Stick a flashlight inside the bellows, in a darkened room to see if you can see any light.
If that doesn't produce the suspect start shading the lens with your hand or better yet with a good bellows lens shade. I've been using that "flare buster" gizmo with good results. Check View Camera Magazine for their ad.
Hope some of this works.
-- David Grandy (email@example.com), April 23, 1999.
I'm not sure I understand exactly what you are describing but are you maybe getting an image through a pinhole? Do you have a small hole in your bellows which is producing a pinhole image on your film? I think flare from a reflection would not result in a spot but in overall degradation (could be wrong on this) and you are using good coated lenses so I don't think that's the problem unless you are taking pictures of the sun.
I agree with the above advice with the flashlight. I bet you'll find a hole. Also - does this happen when you remove the darkslide, take the image instantly, and replace the darkslide, or are you removing the darkslide and then goofing around for awhile before replacing it (giving a pinhole image time to form.)
-- Erik Ryberg (firstname.lastname@example.org), April 23, 1999.
Since you don't see it on the Polaroid, I would look to your Fuji Q/L film holder.
-- Steve Pfaff (email@example.com), April 23, 1999.
Sounds like a bellows pinhole to me. Does it always show up in roughly the same place? And where is that top, bottom or left or right side of the frame?
-- Ellis Vener (firstname.lastname@example.org), April 23, 1999.
I like the pinhole theory too, since it doesnt matter which lens you are using. Am a little puzzled as to why it doesnt appear on the Polaroid, but does show up on the quickload. Have you tried using regular film holders too? Checking the bellows by racking them all the way out and placing a light inside the camera and then looking for holes in a darkened room is not a bad idea. You mention that you are using bag bellows so there are no sharp folds. Is there anything stuck on the inside like an inspection sticker or a bit of tinfoil or some such? Have you checked the locks or whatever arrangement is used to retain the bellows in place on the camera? Any sign of wear or abrasion in that area? Is the film holder seating properly?
-- tony brent (email@example.com), April 23, 1999.
I agree with Steve that the first thing to check is the QuickLoad holder/film combo. While the Fuji holder/Fuji film combination is reputed to be reliable, you might just have a lemon. Light leaks appear to be a common problem for Kodak Readyloads and either Kodak or Fuji film in a Polaroid holder (see the extensive discussion on holders at www.cs.berkeley.edu/~qtluong/photography/lf/holders.html). By the way, because you proof on Polaroid and therefore have the Polaroid 545 holder, have you tried the Fuji QL film in it? Although reported to be less reliable than the Fuji QL film, QL holder combo, if it comes out alright it is likely that you've found the Fuji QL holder was bad. I also agree with the suggestion to see what happens with a regular holder.
-- Greg Lawhon (firstname.lastname@example.org), April 24, 1999.
Bingo on the holder. Happened to me.
-- james (email@example.com), April 24, 1999.
Thank you all for the great, and prompt responses!
And the winner is... a pin-hole on the front lens board! I use the smaller Wista boards on all lenses, and mount them onto the Arca adapter board which stays on the body. This adapter board has a small pin to register the smaller boards, located at the 6 o'clock position. Evidently, when they drilled the hole to insert this pin in to, they slightly elongated the hole and viola, a pin-hole. This sucker was REALLY small. Approximately 1/5 the size of a straight pin's shaft diameter, and it was only found after placing a 4 D-cell flash light against every piece of the damn camera for an hour in a darkroom! I would have never guessed this could/would be the cause. As to the lack of evidence found on the polaroids, it would be my guess that they are too high in contrast to pick up this ghosting. It actually looked like a semi-focused portion of the main image, but only on the final chome's, and only of an item within the scene that was brighter than the rest.
Again, thank you all so much! It is a relief to be able to trust my camera again.
-- Robert Anderson (firstname.lastname@example.org), April 24, 1999.
Darn. I thought I had this one. Well, I didn't hit the lottery either. Ask me another one. Go ahead. James
-- james (email@example.com), April 25, 1999.