Zenitar MC 16mm Fisheye (Lens Vignetting Problem)

BobClack · Jun 30, 2016

The attached photos are from my first test with the Zenitar MC 16mm Fisheye lens on my Minolta SRT-201 (M42 screw mount using a Minolta adapter and a yellow filter).

First shot at f/16 and at 0.6 meters focusing.

Second shot at f/16 and at 1.2 meters focusing.

Would anyone know why the lens is giving these serious vignettes in the 2 corners? These vignettes appear in each shot on 2 rolls of film no matter the aperture or focus.

Thanks in advance.

ic-racer · Jun 30, 2016

You don't notice anything odd, like the lens is on crooked? The focus mark should line up with the top of the pentaprism.

Ricardo Miranda · Jun 30, 2016

BobClack said:
M42 screw mount using a Minolta adapter and a yellow filter

I think you got your answer.
It is a Fisheye, any misalignment will be shown.
Why don't you use a nice M42 body with it and see if you still have the same problem?

onre · Jul 1, 2016

ic-racer said:
You don't notice anything odd, like the lens is on crooked? The focus mark should line up with the top of the pentaprism.

This. If the lens is not in 100% correct position, the ends of the two-part lens-shade thing will show on the frame.

AgX · Jul 1, 2016

How can a M42 lens/Minolta bayonet adapter be off by 45° ?

The Zenitar's mount itself is held by three srews. Misaligning here would produce a dífferent angular fault and likely the automatic aperture pin would not fit.

rubbernglue · Jul 1, 2016

I have noted several times that my nikon-mount zenitar fisheye does not lock on all my cameras and therefore is prone to move like this.

AgX · Jul 1, 2016

To my understanding the lens in question has a screw mount.

cuthbert · Jul 1, 2016

I agree with the above comments, the best thing is to try the lens with a M42 body to see if the problem is the adapter or the lens.

Jesper · Jul 1, 2016

This may seem like (and it probably is) a very stupid question but it looks like the lens hood is 45 degrees off. 16mm fisheye lenses usually have a lens hood to protect the protruding front lens. Sometimes it is fixed and sometimes not. Maybe the adapter turns the lens. This is however very obvious so it is most likely a very stupid question, but have you checked the lens hood?

rubbernglue · Jul 1, 2016

Jesper said:
This may seem like (and it probably is) a very stupid question but it looks like the lens hood is 45 degrees off. 16mm fisheye lenses usually have a lens hood to protect the protruding front lens. Sometimes it is fixed and sometimes not. Maybe the adapter turns the lens. This is however very obvious so it is most likely a very stupid question, but have you checked the lens hood?

Pretty much what everyone is saying

BobClack · Jul 1, 2016

`Thank you for your responses.

Everyone nailed it. The lens was on off-center and apparently this is the culprit.

Just put the lens on a Mamiya MSX 1000 (no adapter needed) and took some test shots. Will post results this evening.

Thanks once again.

AgX · Jul 1, 2016

BobClack said:
The lens was on off-center and apparently this is the culprit.

As indicatd above it is already hard to imagine the lens being rotated.
But the lens being off center?
This is not even revealed in your images.

neilt3 · Jul 1, 2016

FSU quality control at work !
My Zenitar 16mm fisheye mounted on a Zenit TTL left the aperture and focus alignment line within about 3 degrees of being at the top .
Same lens mounted on a Pentax Spotmatic left it about 10 degrees out .

Looking from above you can see how far out the hood is from centre .

Your picture's clearly show the ribs of the hood in the picture , with this lens the hood is not in the frame .
This lens was used quite a bit via an adapter on Canon EOS and Minolta/Sony A mount cameras , in both cases the lens aligned in the adapters good enough that it was almost perfectly centred .

If the hood still needs a bit of adjusting to get it square on , it's easy to adjust .

Four little screws . Slacken off a touch , twist hood and tighten . Job done . Enjoy .

Edit ; just had a better look at my lens , and the mount can not be fitted wrong to the barrel due to the aperture controls , not can it be adjusted .

BobClack · Jul 1, 2016

AgX said:
As indicatd above it is already hard to imagine the lens being rotated.
But the lens being off center?
This is not even revealed in your images.

Roger that. What I mean by "off center" is that the aperture scale was not at top-dead-center when I took the shots. Basically, the adapter was on, I'm convinced, correctly. And it only went on 1 way. When I screwed the lens into the adapter, it's tightest fit was off of "dead-top-center" by quite a bit.

Will send a snap of this this evening with the results of the lens tested on the Mamiya MSX 1000.

BobClack · Jul 1, 2016

neilt3 said:
FSU quality control at work !
My Zenitar 16mm fisheye mounted on a Zenit TTL left the aperture and focus alignment line within about 3 degrees of being at the top .
Same lens mounted on a Pentax Spotmatic left it about 10 degrees out .
View attachment 159980
Looking from above you can see how far out the hood is from centre .
View attachment 159981
Your picture's clearly show the ribs of the hood in the picture , with this lens the hood is not in the frame .
This lens was used quite a bit via an adapter on Canon EOS and Minolta/Sony A mount cameras , in both cases the lens aligned in the adapters good enough that it was almost perfectly centred .

Check the lens mount is screwed in the correct holes , as it could be out .
If it's 45 degrees out when screwed in , that will be the culprit .
If the hood still needs a bit of adjusting to get it square on , it's easy to adjust .
View attachment 159982
Four little screws . Slacken off a touch , twist hood and tighten . Job done . Enjoy .

Neil, once again you've hit it. As before, back tonight with some images.

AgX · Jul 1, 2016

neilt3 said:
FSU quality control at work !
My Zenitar 16mm fisheye mounted on a Zenit TTL left the aperture and focus alignment line within about 3 degrees of being at the top .
Same lens mounted on a Pentax Spotmatic left it about 10 degrees out .

So, likely the issue with the fisheye is due to (the orientation of) the threading itself.
Now it is to find out whether the male or female thread is off.

That in above example there is a difference in orientation between both cameras indicates that there is an issue on camera-side too.
The question is what camera to blame.

Interesting would be to learn the tolerance in angular deviation at the M42 mount.

neilt3 · Jul 1, 2016

Forget about the mount being put on 45 degrees out .
Rotation is impossible .
The mechanism for aperture control is split between the lens and the mount .

Have you tried it on a native M42 body yet ?
It can only be out by a short distance before the aperture pin miss's the lever in the camera .
It sounds like it's your adapters that has the thread started in the wrong place . Have you tried other M42 lenses on them to rule that out ?
If it's just the adapters at fault they can still be used by altering the position of the hood , but if you then want to use the lens on an M42 body you would need to re adjust it again .
If that's the case sending the adapters back and hoping the replacements are better might be the best option .

neilt3 · Jul 1, 2016

AgX said:
So, likely the issue with the fisheye is due to (the orientation of) the threading itself.
Now it is to find out whether the male are female thread is off.

That in above example is a difference in orientation between both cameras indicates that there is an issue on camera-side too.
The question is what camera to blame.

Interesting would be to learn the tolerance in angular deviation at the M42 mount.

In the case of my lens on a couple of my bodies , with the Zenitar on the Pentax it's clearly at the very end of it's limit . Any further rotation out and the aperture pin will miss the aperture lever on the body and the lens won't stop down correctly/at all .

Something to note is that several of my FSU lenses mounted on the Zenit are all consistently about 3 degrees from being at top dead centre with the mark on the lens barrel . They are all about 10 degrees out on the Pentax .
With Japanese lenses on the Zenit being the opposite .

It seems like the official start point for the thread on FSU cameras and lenses are about 5 degrees further anti-clockwise ( viewed from the front) than the Pentax .

As all the different lenses I have seem to be consistent , this seems correct and all lenses work as expected regardless of which body they are mounted on .

This doesn't explain the issue Bobs having , though it's seems it's the adapters that are the issue as I don't think he's mounted the lens on an M42 body yet .

AgX · Jul 1, 2016

Interesting to learn that there seems to be a standard-deviation at threads between manufacturers.

neilt3 · Jul 1, 2016

My made in the G.D.R (German Democratic Republic / East Germany , FSU ) Practica's are also consistent with the Zenit's .
Most of my gear is boxed as I am in the process of rearranging my study as part of it will be partitioned off as I am in the process of building a permanent darkroom ( at last !) , but it seems strange that my Spotmatic is off compared to the others .
When I get things sorted I will have to have another look at how the Takumar's fit on the FSU cameras .
I'm wondering if the Spotmatic might be a bit off , but just never noticed .
I will update as and when ....

AgX · Jul 1, 2016

GDR is not FSU. They are complete different countries

The FSU did not even yet exist when the GDR ceased to exist.

neilt3 · Jul 1, 2016

AgX said:
GDR is not FSU. They are complete different countries

The FSU did not even yet exist when the GDR ceased to exist.

Pardon my ignorance , I was always under the impression that whilst East Germany was effectively under Soviet rule that it was part of the USSR .
And since they wrapped up the Soviet Union , thus becoming a "Former" Soviet Union state .

Having just read a page on Wikipedia I have become much more enlightened . Complex , isn't it ?

It was a good few years ago that I went to school , and as it was in the 80's and the teachers tended to be on strike supporting various reasons for industrial action , I am at least no more ignorant than those who taught me what I know today .
But at least I am still willing and able to learn , which is more than can be said for them !

BobClack · Jul 1, 2016

OP here.

This shot shows how the Zenitar fit onto the Minolta SRT-201. Again, I believe the adapter is correctly placed and that it can only go on one way. When I mounted the adapter to the camera, it gave it's usual "click" sound, and locked in, identical as when mounting a Minolta lens. After that, I screwed in the lens and it's stopping point was as you see in the attached photo.

Shots by the Zenitar on a Mamiya MSX 1000 to follow shortly.

BobClack · Jul 1, 2016

Results from test today. Better, but a tweak is needed.

Zenitar 16mm Fisheye with rear-mounted yellow filter on a Mamiya MSX 1000. No adapter needed.

To my eye, the aperture scale landed at dead-top-center once fully screwed in. However, there is still a very small vignette in one of the corners on all shots. I think taking Neil's suggestion and loosening the screws to slightly turn the lens hood is the answer here. At that point, I'd probably dedicate the Zenitar to the Mamiya and call it a day instead of re-turning the hood for use on different cameras. Good to know that it can be done though if needed.

It would still be nice to know why the Zenitar overshoots things on the Minolta SRT-201! If the threads are wrong, I'm probably out of luck as the Minolta adapter was an ebay buy.

AgX · Jul 1, 2016

In case of changing that lens often between bodies of different manufacture the best solution should be to take off those set screws from the shade, grind off their points (if there are), making round tips and srew them in again and fasten them (and lock with varnish) to a degree that the hood can be rotated by small force. Thus enabling to adjust the shade position to the body.

The alternative would be to grind off those hampering parts of the shade. The use of such stub shade is limited anyway, thus reducing it a bit would not do that much harm.

Zenitar MC 16mm Fisheye (Lens Vignetting Problem)

BobClack

ic-racer

Ricardo Miranda

onre

AgX

rubbernglue

AgX

cuthbert

Jesper

rubbernglue

BobClack

AgX

neilt3

BobClack

BobClack

AgX

neilt3

neilt3

AgX

neilt3

AgX

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BobClack

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