Into the rebate.
What's gone wrong?
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- Thread starter Paul Manuell
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Into the rebate.
MattKing
Moderator
That means it is a light leak, not a shutter problem. It probably is dependent on the direction and intensity of the light source.
How are the seals on the camera?
How do I check the seals? I haven't got the camera back yet, but what do I look for to check the seals?
MattKing
Moderator
It is probably best to ask the Pentax 645 owners here.
But generally speaking, the foam (or yarn) material that is embedded in the channels around the back and (sometimes) around the opening that the mirror rests on starts to deteriorate and needs to be scraped out and replaced.
I would contact the people who checked your camera and ask them if they checked the seals.
When you sent the camera to them, did you include an example of the problem negatives themselves? If not, tell them now that the line extends into the rebate.
But generally speaking, the foam (or yarn) material that is embedded in the channels around the back and (sometimes) around the opening that the mirror rests on starts to deteriorate and needs to be scraped out and replaced.
I would contact the people who checked your camera and ask them if they checked the seals.
When you sent the camera to them, did you include an example of the problem negatives themselves? If not, tell them now that the line extends into the rebate.
Yeah, I sent them a negative with the camera, as well as emailing them the same 2 photos as at the start of this thread. Might be a bit late to contact them now to ask if they checked the seals cos I've paid the return postage now and they're sending it back to me tomorrow to arrive on Tuesday. I'll send them an email now though, see if they can hold off on its return and get the seals checked if they haven't already done so.
Looking at the samples from the OP, those sure are very defined straight lines. I don't think I've seen seal leaks that are so crisp.
It is possible for a 'leak' or exposure problem due to a shutter to extend beyond the film gate due to overexposure and the antihalation coating being overwhelmed. For example, changing the lens on a Leica M3 in bright light can overwhelm the light seals around the curtains. Without seeing the full negative it's hard to be certain what the OP means by 'yes, it extends into the rebate.'
This is the first thing when looking into a possible leak or shutter problem- look at the full negative. Posters should do this, and responders should insist on this if the poster doesn't provide it.
It is possible for a 'leak' or exposure problem due to a shutter to extend beyond the film gate due to overexposure and the antihalation coating being overwhelmed. For example, changing the lens on a Leica M3 in bright light can overwhelm the light seals around the curtains. Without seeing the full negative it's hard to be certain what the OP means by 'yes, it extends into the rebate.'
This is the first thing when looking into a possible leak or shutter problem- look at the full negative. Posters should do this, and responders should insist on this if the poster doesn't provide it.
The line on the photograph continues into and extends to both edges of the rebate on the negative.
Without an actual image (photograph) it's not possible to know what that means.
There are 2 of the photos in my opening post of this thread
The photos do not show the full negatives. Meaning the whole piece of film, the edges, numbers, space between frames, etc.
Well, best of luck. Erratic problems are the worst. Makes me simply not trust a camera, but it's not like I can sell it on in good faith either.
Ah, ok, didn't realise you meant photos of the negative. Well to described it even more simply, photos on the negative strips are in portrait orientation. The line runs vertically through the photo when viewed holding the strip of negatives horizontally. That line also continues out of the photo and into the rebate all the way to the top and bottom edges of the negative. Imagine a framed photo, with the photo containing a white border within the frame. Compare that border to the rebate on a negative. Now draw a straight line from one edge of the border, all the way through the photo and continuing right through the border at the other edge of the photo. Can't think of any other way to describe it.
Another way to describe/communicate what the negative looks like is to provide a digital image file taken with a camera of some sort.
The Pentax 645 doesn’t have a swinging back like 35mm cameras or the Pentax 67, instead it has film inserts, and, while I don’t know the camera from experience, looking at pictures it’s clear that the light seals are on the film insert. If you want to test without investing money or time, load a few rolls and before you shoot them, wrap some black electrical tape around the seam between the insert and the body. Shoot the entire roll like that before removing the tape. The light seals probably don’t cost much though and would be an better fix.
One other thing to mention about the artifact extending into the rebate. When we look at your posted images, one side of the artifact has a clear sharp line and the other side tapers to nothing. If the problem came from the shutter you either wouldn’t see anything in the rebate or the nature of the artifact would change once it passed the frame edge into the rebate. It would likely look like a flare outside the rebate, and would not have the clean line that you see in the photos you posted.
One other thing to mention about the artifact extending into the rebate. When we look at your posted images, one side of the artifact has a clear sharp line and the other side tapers to nothing. If the problem came from the shutter you either wouldn’t see anything in the rebate or the nature of the artifact would change once it passed the frame edge into the rebate. It would likely look like a flare outside the rebate, and would not have the clean line that you see in the photos you posted.
Yeah, unfortunately I haven't got a way of taking a photo of the negative then posting it, or at least not a way I know.
Do you have a cell phone? You could hold the negative up to a window and take a snapshot.
Yeah, but not one with internet ability
MattKing
Moderator
Anyone nearby who can take one for you? Can you send a cel phone photo attached to A text to someone who can then email the attachment back to you?
Do you have your own scanner? If so you might be able to scan the negatives as a positive when they are only half in the holder. in order to show the edges.
Do you have your own scanner? If so you might be able to scan the negatives as a positive when they are only half in the holder. in order to show the edges.
I've got my tablet (my only form of internet as it happens), I could take a photo of the negative with that I supose, then try to work out how to attach it to this thread. Will try tomorrow when it's daylight.
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Ok, they replied to my email, saying they checked the seals already.
That's a certified, guaranteed light leak. Most likely the seal is just barely too short and at some angle the sun can get in. Or it's always leaking just very very little. That's why you only see it on some pictures. I would be willing to bet that the longer the film spends in the gate, the more likely it is to have a visible leak on it.
But how do you explain why the other 3 photos on the strip of negatives of exactly the same subject, all taken within seconds of each other under exactly the same lighting conditions and exactly the same camera settings, never got the light leak? The one with the line was the 3rd of the 4 photos btw.
Whatever the reason though, all this uncertainty and the fact it's seemingly irreparable is doing my head in, frustrating as fuck!
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Was it the first picture in the group that was affected? If so the leak occurred before the picture was taken, while you were walking around and focusing. The other ones did not spend enough time in the film gate to be leaked on.
Sorry, edited my post to say it was the 3rd of the group of 4.
Hmm, then it's a bit trickier. Could the leak have occurred before or after the film was in the gate? I'm not super familiar with the geometry of the inserts. The fact that it's onto median of the film rules out the shutter. So light leaking is just about all we've got left.
Edit: leak in the median also rules out leak on film gate actually I think.
Edit: leak in the median also rules out leak on film gate actually I think.
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