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ZM 25mm and M9

Double Negative

Not Available
Interesting discovery! It all seems to make sense...

I'm thinking a bit of black silicone in the screw hole might be a good solution as well.
 

Stuart Richardson

Active member
Very interesting. I was going to come in here to say that mine did not do it, but that might be because mine is a very old one -- one of the first and it still has an original bayonet (though mine has been coded).
 

markowich

New member
i just tried my new 21mm Zeiss biogon f2.8 and log exposure shots with the hood on are uniformly black.
btw excellent lens.
peter
 

thrice

Active member
i just tried my new 21mm Zeiss biogon f2.8 and log exposure shots with the hood on are uniformly black.
btw excellent lens.
peter
So 8s+ with the lens cap on, in a reasonably bright light (like sunshine) is all black?

Can you see if the screw on the lens is aligning with the screw on the body?

I guess with some lenses the rear element/internal barrel will block any flare.
 

thrice

Active member
Ok, problem solved on my 50 C-Sonnar, just put a little black silicone over the offending screw and no more problems even in direct sunlight.

I also made an interesting discovery. Curious as to why my other two ZM's don't have this problem while my 25 and 50 do, I had a closer look at their flanges.

On my 18mm Distagon, it turns out I have the older bayonet which is not as easy to code, so that answers that one.
However, on my 35mm C-Biogon, which has the newer flange, it appears that the countersinking for the screws is MUCH more minimal than on the 50mm C-Sonnar. I think Zeiss know about the issue, or have a new QC issue they weren't aware of.
 

kuau

Workshop Member
I am about ready to buy a M9 and the zeiss 18, 25, and 35mm lenses from pop flash
I assume I am going to have this problem
Should I wait for a fix from zeiss?
Steven
 

thrice

Active member
Steven I'd just go for it. You're unlikely to encounter the problem very often, and the fix is simple and inexpensive. The 18mm and 35mm don't have this problem, and I doubt Zeiss will issue a fix.

Tony Rose at Popflash is my #1 guy to deal with in the camera industry, you can't go wrong buying from him.
 

kuau

Workshop Member
Thanks for the info Daniel.
I was for sure going to buy my zeiss lenses from Popflash.

Steven
 

Double Negative

Not Available
...Should I wait for a fix from zeiss?
I wouldn't worry about it, honestly. For one thing, it takes an eight second exposure with a bright light hanging literally over your lens. Unless you shoot like this regularly...

As for a fix from Zeiss... Heh. I wouldn't hold your breath. If they do fix it, it'll be a silent fix for future lens versions (witness the new flanges on some lenses).
 

trisberg

New member
I have three Biogons (25/2.8, 28/2.8 and 35/2) and they all show this leak. I think Daniel has a 35/2.8 Biogon C which has a different type of screw in the mount and this lens does not show the leak. So, depending on which 35 you are looking to get, it could show the problem.

Either way, the leak isn't noticeable for most types of shooting situations. If it becomes a problem the fix is simple, just put some tape or silicone over the screw in the mount on the lens.

-Thomas
 

thrice

Active member
Reposting my update here, in case anyone is following here but not on RFF.

No contact from the Zeiss factory, but that was expected, I assume they're hoping the discovery of this design flaw just goes away.

Tony Rose at Popflash.com replaced my lens (even though I let him know he didn't have to) which was very kind of him! I received the replacement lens today.

Unfortunately the problem is not resolved, in fact it is much worse on the new lens! This is still with an ND filter, but taken at f/16 at 0.7s! That's a very short exposure and a result that could easily occur in real world environments. The leak is so intense that it caused the camera to meter the scene as a lot brighter than the light coming through the lens. This is as shot, -2/3 exposure comp, no processing. Look at that flare!



Suffice to say I'm currently waiting for the Silicone to set on the lens and will re-post when that is finished.
 

Stuart Richardson

Active member
It sounds like your particular body is at the far end of the tolerance range. It may work fine with Leica's tolerances, but I guess not with Zeiss's. If you got two in a row that show this severe problem, and no one else is really getting the problem as badly as you (or even visibly in most cases), then it is the body/lens combo rather than just a faulty lens.
 

thrice

Active member
Plenty of people are getting the problem, did you read the thread? or the one at RFF? I have not seen a SINGLE post of someone testing a 25mm ZM with the method I described on an M9 and not seeing the issue. A desk lamp is not a quantifiable light source, the sun is.

Thomas right above me posted that he has the issue on 3 different ZM's, I've only had the issue on 25mm and 50mm, my 35/2.8 and 18/4 don't have the issue at all.

Do you not get the issue at all on any of your ZM's with your M9 using the prescribed testing methodology above?
 

Stuart Richardson

Active member
I have not read the thread at RFF. I tried using my 25mm and M9, and I saw the faintest evidence of it being a bit brighter at 8 seconds at iso 2500 while shining a flashlight on it. There is no evidence of it in a normal exposure like you are getting. At least here, you seem to be the only one getting it in normal photography. Doing a long exposure with a flashlight shining on the lens is not really a real-world test...
I am certainly not saying that you are not having a problem, I just think your problem is one of lens-body compatibility, not there being a fundamental problem with all 25mm biogons.
 

thrice

Active member
No problems. just FYI the sun's intensity is approximately 650 times brighter than a flashlight, I guess if you only shoot in flashlight-lit environments not a problem! :p

I'm testing with an ND filter at f/16 in direct sunlight. I'm planning to shoot waterfalls in New Zealand... I'd want much longer than 0.7s, hopefully I won't be in direct sunlight, but you know I'd expect a $1000 Zeiss lens to be fine on a body for which no incompatibilities are publicised.
 

Stuart Richardson

Active member
I stand corrected. I took my lens outside (today was sunny finally), and at 8s I did get obvious flare in the bottom corners. It still does not show up in normal photography for me (normal for me is f/5.6 or wider...I rarely stop down a lot or use neutral density filters). Looking carefully at the lens mount, I can see bits of the Leica screw holes peeping out from under the Zeiss lens mount. I do not see this with Leica lenses. I think the issue here is that the Leica mount is just a little larger in diameter, and it completely covers the screw holes in the mount...the Zeiss does not seem to.
 

trisberg

New member
Yes, you are right, the Zeiss mounts are just a tiny bit narrower than the mount on my Leica lens. Enough to expose a tiny bit of the screw on the camera mount and let a small amount of light through. All my Zeiss lenses also have the groove which makes it easier for the light to make its way past the mount.

-Thomas
 

Stuart Richardson

Active member
I will add, however, that my other ZM lens is an 18mm. It has a coded mount that John Milich machined. It completely covers the screw holes. I have not had a chance to test it with the 8s test, but I have never noticed any leaks in normal shooting.
 

thrice

Active member
My 18mm has a non-grooved mount, no leaking issues at all.

Here is the result of 0.7s again (I'm gonna need stronger nd's for waterfalls I think) with the freshly modified 25mm Biogon:

 
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