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Thread: Lens problem after all? Flare?

  1. #1

    Lens problem after all? Flare?

    HiI posted a question about possible lens flare some time ago. The problem seemed to be solved: there was a problem with the lens board / front standard giving a light leak. I didn't shoot much film with the suspect objective then, apart from the light leak tests, which came out ok. No image was formed with the camera facing the sun for many minutes with both objectives in place. Now that I've had the chance to try making more pictures, it seems like it was a lens problem from the start after all. Or that at least the lens board light leak wasn't so significant in the first place.Here's the url to the images, if you wouldn't mind viewing them. They're in a single table, so about 400kb to load.http://www.anttiaalto.com/lensproblem/index.html
    The left three are the earlier images with the lens board light leak still there. The middle three are with the light leak, but using another objective, as to say, maybe the leak effect was just that little extra at the corners. The three on the right all have the light leak fixed, or that I assume. I can't expose a test sheet every time, but the seal's still firmly in place. Of the three on the right, the topmost is taken with a 90mm objective which I think is working. The sun was somewhat close to the top right corner, so that would explain the intensity there. The two lower images are from this morning, taken with the suspect tele objective. Both were taken facing the sun, but the lens was in good shade. They seem to share the same pattern with the left three negatives.Now, my ideas really sum up to the lens being somehow faulty. Then again there is the possibility of patterns due to bad hanger development, but in the set of eleven negatives developed today there are those without the vertical mark going across the top. Neither of the 90mm objective negs has it. I've also had considerable difficulty printing negatives exposed with the tele objective under a favourable low side light, where all four corners, and maybe the top seem to have received illogical extra light not so obviously visible on the negative, the top left corner being the most difficult to print.I'd like to hear opinions on what may cause this. How big a part my own actions with the camera might play here? If I've got a narrowed down subject, as tends to be the case with a 270mm objective, should it be perfectly likely that I can make a negative that'll need no corrections in print for uneven density on the neg? I mean, if I have the sun in my back, are the corrections I'll make supposed to be solely based on aesthetical preferences? It's been quite a load of work getting into LF. I can't afford a high end objective that I'd think is guaranteed not to have this kind of problems, but should it still be quite possible to have a decent and dependable objective where I can actually see the light fall off errors I'm about to make on the ground glass and also judge by how it looks, if my shade is going to do it's job? I know these may sound just silly questions, but in the photographic equipment market I've got to know, it's never been about the print and usability. Who knows how much you're to pay to make a decent negative.Many thanks in advance!

  2. #2

    Join Date
    Jan 2001
    Posts
    4,585

    Lens problem after all? Flare?

    You've still got a light leak somewhere. Maybe the shutter doesn't close completely.
    Wilhelm (Sarasota)

  3. #3
    David Vickery
    Join Date
    Oct 1998
    Location
    Texas, USA
    Posts
    216

    Lens problem after all? Flare?

    Hello Antti,
    If you haven't done this already then you need to put a bright light inside your camera from the lens end and then from the film end and look for light leaks. Take your time with this and look all around the camera and especially near the film holders and rear bellows area.

    I am also wondering about your processing procedures???? What do you use to process your film?

    If the shutter were staying open then the image would be overexposed all over, since it would be image forming light.
    Sudek ambled across my mind one day and took his picture. Only he knows where it is.
    David Vickery

  4. #4

    Lens problem after all? Flare?

    I guess I'll give checking with a torch one more go tomorrow. The initial leak I could see pointing the camera to the sun. After filing the lens board level and installing a seal strip, I couldn't see the leak anymore. Also, would it be smart to flash the test sheets with an enlarger first? ~5 min without a darkslide showed no signs of leaks with both objectives. ...this was done with temporary tool boxes for trays though...buggerAs you've probably noticed (for me it hadn't sunk in), the biggest leaks (or whatever) are at the film end which is at the top during development, or the opposite end to the dark slide slits in a holder. I guess I'll check tomorrow if the camera back might give a leak there, but I guess the objective should be pretty much left out of the question. Very good news for me if true!As to my development, and the highest densities being at the top and bottom corners, could development using hangers in tanks cause that? I was instructed that it should be sufficient to rock the tanks from side to side once a minute to agitate, instead of lifting the hangers out. No streaks should develop. The hangers do have the sliding stopper on top, which has a part to it that resembles the wide U-shape on the negatives disturbingly lot. If the problem should be this, any tips would be very warmly welcomed. The tanks have space for twelve hangers, they've got a lid for some light seal (so supposed to use lid on I'd think). Japanese make, can't recall the brand. So far I haven't been able to figure a solid routine to agitate all twelve equally except for rocking the tank. For example rotating them around and lifting them all at once both seem likely to cause scratches and are difficult in other respects as well.

  5. #5

    Lens problem after all? Flare?

    You have almost every kind of defect on the negs.

    First eliminate the light leak and then work on the process which is not even.

    Put some black tape around the lens board and camera to seal it for sure. This is temporary. Don`t use a tape that will pull the finish off the camera.

    Are you using regular Kodak or other stainless hangars? From these type of hangars, you get two main defects. Marks from the perforations around the edges incorrectly called surge marks. And marks across the top where the U shapped clip hold the film onto the hangar. This is usually a low density area under the clip like the lower right sample. It is along the right edge.

    The lids are for storage, not for keeping light out. Work in total darkness.

    The mottling is from insufficient agitation. Insufficient agitation will also cause the marks around the edges near the hangar perforations. Here developer is forced thru the holes causing more replenishment in the small area, but less in the full neg. It is NOT over agitation or surge as there is no such thing, just lack of complete agitation elsewhere.

    You must remove the hangars from the developer, tilt one side 45 deg minimum, drain 4 sec. reimerse, and repeat tilting to the other side. This takes 15 sec. Rest 45 sec and repeat. Initial agitation is in and out four times with appropiate tilts taking 30 sec.

    A hangar rack that hold all the hangars is a big asset. Arkay will still make on special order. Just got one for 8 hangars, a bit steep at $100. BUT

    Every time you set the hangars to rest, bang them against the tank to dislodge any bubbles.

    It is possible you have a film holder or two that leak causing the exposure along the short end. Or the film may have been exposed to light before you loaded it.

    Test the holder by exposing it to light, but do not take a picture. The film should be blank. Check to see the the film was exposed at one end by reverse loading, ie notch code end in first.

    Keep notes so you know which pics were from which holder so you can isolate a bad holder.

    Also look at the orientation of each neg as you remove it from the hangar. Examine it carefully to note problem areas. These are clues as to the problem that needs solving.

    For a while, Do two negs of each subject. Only process one. This gives you a chance to correct a process error.

    Low density under the U clip is under agitation too. Developer is trapped the clip and not replenished. This is why you must remove and tilt, not just slosh around.

    The agitation plan you use may work sometimes, but it will not work all the time.

  6. #6

    Lens problem after all? Flare?

    Well, checked on the camera again and could see no leaks with a holder in. I guess I'd have to get the developing out of the picture first, as it seems certain that it plays the biggest part, if not the only part. It's remarkably funny that the manufacturer makes no hangar racks whatsoever. I'm told at least ten people have bought these tanks off the retailer and none has complained about unevenness. Simple calculation shows I'd be able to develop four sheets at a time with less certainty of good routine. Will not do. I did read the instructions on this site on appropriate development, but similar quality was supposed to be doable the other way as well. A friend might be able to make me the racks, as getting a surely working rack for other manufacturer's tanks and hangers might be a problem with Arkay. In every case it's bye bye to getting the darkroom going for quite some time. Anyway, many thanks for the suggestions! At least I've got something solid to fix now!

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