Help me diagnose a shutter (I think) Issue. SRT 101

Cholentpot · Mar 11, 2019

I got an SRT 101 that is in very good condition. I just ran a roll through it and noticed something on a few of the photos.

Is this a shutter issue or lens? It's appeared on photos using a Rokkor 50 1.7 and it seems only to show up at lower speeds, say 1/30 and lower. Honestly it's something I can live with I'm just curious what's causing it. Any ideas?

Minolta SRT 101, Rokkor 50 1.7, Lucky SHD 400 HC-110 DilH 11 min.

I'm looking at that gradient at the bottom of the photo. It's more apparent in other scans. On the positive side the meter is pretty much spot on.

And yes, this is the first frame off the roll. I'm aware.

BAC1967 · Mar 11, 2019

Maybe a developing issue?

Cholentpot · Mar 12, 2019

BAC1967 said:
Maybe a developing issue?

I thought so but it's only on a few frames. This roll was also on the bottom reel so it's not a surge mark. I'll try to upload the other shots when I finish scanning. As of now I only notice it on 3 frames and they were all taken with the 50 and lower shutter speeds.

Kino · Mar 12, 2019

Your mirror might be sticking a bit on it's upward travel at slower shutter speeds, giving more exposure to the bottom of the frame. Check your aperture interface lever on the 50mm lens; it might be bent or sticky, causing it to pause the upward motion of the mirror. Compare the lever position and shape to your other lenses to see if there is something obvious.

The shutter curtains are horizontal, so that would not explain the issue...

Kino · Mar 12, 2019

You need to clarify if the partially blank image is in consideration at all here. I thought you were only speaking of the extra density at the bottom of the frame and that the partial image was due to it being the first image on the roll.

Correct?

Mainecoonmaniac · Mar 12, 2019

If the shutter slows down or gets stuck, this would explain the over exposed area.

Theo Sulphate · Mar 12, 2019

The dark band at the bottom of the image (which will appear at the top of the negative frame) is the issue in question, correct? I'm also assuming this artifact actually appears on the negative and isn't a scanning issue.

Does the band appear just in the image frame or does it extend outside the frame? If outside, it's a development issue.

If inside the frame...

This dark band can't be the shutter because the curtains in an SRT-101 are travelling horizontally. However, I don't think it is possible that this problem is caused by a retardation of the mirror's upward travel. This is because, typically, SLR's don't release the first curtain of the shutter until after the mirror has completed its upward travel (*).

What may be possible is that the mirror is not staying at the top. At slower speeds, the mirror is sagging down long enough to reduce exposure at the top of the frame. That is: the top of the negative as it sits in the camera has a lighter band of exposure. Since the lens' image is upside down, when you print the negative normally this becomes a dark band at the bottom.

One thing to try is to take the lens off and operate the shutter at various speeds as you look at the mirror from the front. At 1/30 and longer, you may see if the mirror is sagging.

(*)
That is, when you press the shutter release, what happens first is the mirror travels up to the top of the mirror box and only when that operation is complete does the first curtain of the shutter get released (the gear timing releases the second curtain).

Kino · Mar 12, 2019

That is true, Theo. I should have caught that the band is inverted in the aperture!

I still wonder though if a bent/warped/sticky aperture linkage on that particular lens could be causing the uneven movement of the mirror.

Cholentpot · Mar 12, 2019

Theo Sulphate said:
The dark band at the bottom of the image (which will appear at the top of the negative frame) is the issue in question, correct? I'm also assuming this artifact actually appears on the negative and isn't a scanning issue.

Does the band appear just in the image frame or does it extend outside the frame? If outside, it's a development issue.

If inside the frame...

This dark band can't be the shutter because the curtains in an SRT-101 are travelling horizontally. However, I don't think it is possible that this problem is caused by a retardation of the mirror's upward travel. This is because, typically, SLR's don't release the first curtain of the shutter until after the mirror has completed its upward travel (*).

What may be possible is that the mirror is not staying at the top. At slower speeds, the mirror is sagging down long enough to reduce exposure at the top of the frame. That is: the top of the negative as it sits in the camera has a lighter band of exposure. Since the lens' image is upside down, when you print the negative normally this becomes a dark band at the bottom.

One thing to try is to take the lens off and operate the shutter at various speeds as you look at the mirror from the front. At 1/30 and longer, you may see if the mirror is sagging.

(*)
That is, when you press the shutter release, what happens first is the mirror travels up to the top of the mirror box and only when that operation is complete does the first curtain of the shutter get released (the gear timing releases the second curtain).

Correct, the band is only within the frame and is on the negative. I DSLR scan so any issues with scanning are in full control. I'll take a look and see if the mirror is sagging. It appears that this is only happening with the 50mm on slower speeds. That being said, the camera might just need some exercise, I have no clue how long it was sitting around for.

Cholentpot · Mar 12, 2019

Kino said:
That is true, Theo. I should have caught that the band is inverted in the aperture!

I still wonder though if a bent/warped/sticky aperture linkage on that particular lens could be causing the uneven movement of the mirror.

I used this same lens on a X-700 with no issues. I don't seem to be having this problem with the 135 2.8.

Kino · Mar 12, 2019

Have you tried putting the camera on "B", firing the shutter and examining the mirror linkages to see if there is excessive wear or warping?

Cholentpot · Mar 12, 2019

Just fired at low speeds and in B. All seems well. I'm going to run another roll and see if the problem sorted itself out.

Cholentpot · Mar 16, 2019

Here's another shot showing the issue

I can't seem to replicate by eyeball and the 135mm shots don't seem to have this problem. I did not encounter it either with the 50mm and X-700.

Theo Sulphate · Mar 16, 2019

It can't be a light leak, otherwise the band would appear on all frames and between frames.

It can't be the shutter, otherwise the band would appear with other lenses at that speed.

It can't be the aperture blades, otherwise you'd see a progressive dark-to-light progression across the entire frame from left to right - not just a small band at the bottom.

Note that the darker part of the band on the print is at the lower left and the band disappears at lower right. When viewed inverted (by the lens) and as a negative, that corresponds to less light striking the upper right of the negative and more light striking the upper left, respectively ( trust me on this). That is exactly what I'd expect of a mirror that has not quite risen all the way when the first curtain has uncovered the film gate.

I think you have a mirror issue that will appear as uneven exposure only at slower speeds due to perhaps the first curtain being released too early (just a guess on my part). Also (again guessing), it doesn't appear with the longer focal length lenses because the cone of light with such lenses misses the edge of the not-fully-up mirror. I'll bet you'd see the problem with wider angle lenses as well.

I suspect perhaps the mirror lever has been slightly bent inside the body.

Cholentpot · Mar 17, 2019

Theo Sulphate said:
It can't be a light leak, otherwise the band would appear on all frames and between frames.

It can't be the shutter, otherwise the band would appear with other lenses at that speed.

It can't be the aperture blades, otherwise you'd see a progressive dark-to-light progression across the entire frame from left to right - not just a small band at the bottom.

Note that the darker part of the band on the print is at the lower left and the band disappears at lower right. When viewed inverted (by the lens) and as a negative, that corresponds to less light striking the upper right of the negative and more light striking the upper left, respectively ( trust me on this). That is exactly what I'd expect of a mirror that has not quite risen all the way when the first curtain has uncovered the film gate.

I think you have a mirror issue that will appear as uneven exposure only at slower speeds due to perhaps the first curtain being released too early (just a guess on my part). Also (again guessing), it doesn't appear with the longer focal length lenses because the cone of light with such lenses misses the edge of the not-fully-up mirror. I'll bet you'd see the problem with wider angle lenses as well.

I suspect perhaps the mirror lever has been slightly bent inside the body.

It's only on a few frames. This is the fun of shooting these old cameras. I'll live with it. Thanks!

Born2Late · Mar 17, 2019

Sort of looks like the fluid level (developer) was slightly low when you processed it. Just my opinion though.

shutterfinger · Mar 17, 2019

With the 50mm mounted on the 101 open the camera back and fire the shutter on slow sspeeds, say 1 second or 1/2 second, and observe the mirror. It should be full up when the first shutter curtain starts to move. Its likely the mirror is hanging/slightly touching the the rear of the lens barrel.

Cholentpot · Mar 17, 2019

Born2Late said:
Sort of looks like the fluid level (developer) was slightly low when you processed it. Just my opinion though.

This was on the bottom reel. More than enough chems to cover

shutterfinger said:
With the 50mm mounted on the 101 open the camera back and fire the shutter on slow sspeeds, say 1 second or 1/2 second, and observe the mirror. It should be full up when the first shutter curtain starts to move. Its likely the mirror is hanging/slightly touching the the rear of the lens barrel.

Everything is engaging fine. No hangups or catches.

shutterfinger · Mar 17, 2019

Cholentpot said:
Everything is engaging fine. No hangups or catches.

I assume that means the mirror goes up as far with the lens on as it does with the lens off.

Do/did you fill the tank with developer or use "just enough" to cover the reel? Do you pour in the developer at a consistent rate?

Theo Sulphate · Mar 17, 2019

Since the problem occurs within the boundaries of a frame and only on certain frames when a specific lens and shutter speed range is used, I don't see it as a development or scanning issue.

Having exhausted all rational possibilities, then, as with the Pentacon Six problem last year, it may be time to call an exorcist.

Cholentpot · Mar 17, 2019

shutterfinger said:
I assume that means the mirror goes up as far with the lens on as it does with the lens off.

Do/did you fill the tank with developer or use "just enough" to cover the reel? Do you pour in the developer at a consistent rate?

I always pour a bit more then needed. And consistent. Yes, the mirror is functioning fine. One question though. With the 101 the piece of metal that the piece of damper foam is attached to moves up and down and feels like it's spring loaded. Is this normal for a 101? I've not seen it in other SLRs.

Theo Sulphate said:
Since the problem occurs within the boundaries of a frame and only on certain frames when a specific lens and shutter speed range is used, I don't see it as a development or scanning issue.

Having exhausted all rational possibilities, then, as with the Pentacon Six problem last year, it may be time to call an exorcist.

I'm Jewish, maybe I should call the mohel.

Born2Late · Mar 17, 2019

Cholentpot said:
I always pour a bit more then needed. And consistent. Yes, the mirror is functioning fine. One question though. With the 101 the piece of metal that the piece of damper foam is attached to moves up and down and feels like it's spring loaded. Is this normal for a 101? I've not seen it in other SLRs.

I'm Jewish, maybe I should call the mohel.

I have a bunch of SRT's and all of my have the mirror damper and they are spring loaded. The spring is very small and weak. I did have one that popped off of one end and the damper would hang up occassionally. The spring is behind the damper if you care to look.

Theo Sulphate · Mar 17, 2019

Cholentpot said:
... With the 101 the piece of metal that the piece of damper foam is attached to moves up and down and feels like it's spring loaded. Is this normal for a 101? I've not seen it in other SLRs.

Perfectly normal.

I'm Jewish, maybe I should call the mohel.

shutterfinger · Mar 17, 2019

If the film is never out of the developer during inversion then its an inmitten mechanical problem in the camera. Intermitten problems are a major PITA as you have to the find the failing part at the time it happens to fail.

Cholentpot · Mar 17, 2019

Born2Late said:
I have a bunch of SRT's and all of my have the mirror damper and they are spring loaded. The spring is very small and weak. I did have one that popped off of one end and the damper would hang up occassionally. The spring is behind the damper if you care to look.

Theo Sulphate said:
Perfectly normal.

Thanks.

shutterfinger said:
If the film is never out of the developer during inversion then its an inmitten mechanical problem in the camera. Intermitten problems are a major PITA as you have to the find the failing part at the time it happens to fail.

Guess I'm not bringing this camera on any gigs. Good thing I have about 10 other ones that I can count on, and another 15 that'll do in a pinch.

Help me diagnose a shutter (I think) Issue. SRT 101

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