I’m having back-focusing, around 6 cm at distance of 1 m when I put A16 back.
Any thoughts about this?
Thank you for prompt response, I should of mention that I have A12 which is not backfocusing.
Apology for not mentioning this.
Maybe rotted foam behind the mirror causing inaccurate focusing. But this would affect all film backs, not just your A16.
Hi all.
I’m having back-focusing, around 6 cm at distance of 1 m when I put A16 back.
Any thoughts about this?
Cheers.
@Philippe-Georges:
There are 3 foam pads between the mirror and the plate that holds the mirror in the mirror frame. (see the attached picture from the service manual found all over the internet. #4 = pads, #6 = mirror frame, #5 = mirror)
It seems that almost no one knows about them and they are frequently confused with the well known mirror damping foam strip at the focusing screen, but they are
equally important. When they deteriorate, the mirror is not held against its 3 bearing points anymore. This points can be seen as two little nubs in the front of the mirror and
one in the back. The frame #6 has the nubs on it and the mirror rests against them. If there is a gap, the pads are bad. It is best checked when cranking the camera
and the mirror comes down. It moves a bit skewed until it locks in the mirror-down position.
Remarks: This is probably not the cause for phass' problem, but important to mention with the older cameras, since they will be going bad with time, no matter what.
It can drive the users crazy. I bet that a lot of hasselblad owners have this problem but do not know that this pads even exist.
I had a lot of misfocused slides and then i remembered that there are those pads, had them replaced and now my focusing is razor sharp again.
The two photographs show the position of the nubs. If the mirror is in tight contact with them, you are fine. If there is a gap, you are in for service.
Mine has been serviced recently, but before, i could fit a strip of a business card between the mirror and the nub....
edit: typo
This is probably a stupid question, but when you loaded the film insert, did you ensure that the film sat beneath the silver metal tab "C"?
View attachment 321785
This is probably a stupid question, but when you loaded the film insert, did you ensure that the film sat beneath the silver metal tab "C"?
How old is the A16 back?
I keep this film back as back up one. I accidentally found its problem.correction/shimming withouth being able to measure the flange distance of the whole system is dangerous.
i do not know exactly, but as far as i can see, the magazine has no means to adjust the distance except for pressing the film ledges of the inner frame. if someone knows better, i would like to know how it is done.
the manual says nothing about shimming.
for information: i used a caliper with its depth probe to measure the whole camera from the flange lugs (where the front bayonet plane is defined) down to the corners of the pressure plate of the magazine, which should be in the film plane.
the total distance is 74.9mm. but this requires great care to get the angle of the probe right and it is very easy to displace the pressure plate with the measuring force. (or to scratch something!!)
but it was the only way for me to check things because i did not have any measurement fixture at that time.
@phass: have you checked the issue with the mirror foam pads and the gap between the nubs? (the one where i postet the photographs)
check it anyway, in my case it was intermittent and it could look as if one magazine is the culprit while it was just coincidence.
Just take it to an authorized Hasselblad repair place where they can put the body on a jig and put the body back into the shape of the factory specifications. Why are you making things hard on yourself?
Sorry, I missed you question. This back is from 1991.
I keep this film back as back up one. I accidentally found its problem.
I was able to check the mirror path by comparing the distance from the object - the film plane with the lens scales (I have 80 mm CF and 50 mm CF) which eliminates the mirror/the focusing screen error.
My original setting - body+back is fine, so I'm very hesitant to mess with them. I also know that all shops are for several moths back logged. Perhaps in the future I'll do something about it, unless I was lucky to got a frankenstine.
I am from Ohio.Where are you located? If we knew we could suggest less backlogged places. US is much to vage.
I would agree with you that if your other back and body are working fine, there is no issue there. Especially if you were able to check and measure focal flange distance.Thank you all for helpful info.
The distance between front plate of the back and internal rails is in 3.55 +- 0.05 mm.
And back paper was loaded correctly.
Is any way to calculate the thickness of shims to move front plate of the back. Though, I do not see the way to move the front plate without creating a light leaks.
Cheers.
I am from Ohio.
Cheers.
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