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How to repair a Zenitar 16mm f2.8 Fisheye?
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PostPosted: Sat Aug 30, 2008 3:54 am    Post subject: How to repair a Zenitar 16mm f2.8 Fisheye? Reply with quote
Hi, i have a Zenitar 16mm f2.8 fisheye lens, that has oily blades and i suspected infinity focusing problem. The lens is mount to my minolta A100 cam with a m42 to minolta AF adapter. Is there any guide on the disassembling of the lens to fix the oily blades and the infinity focusing problem? Thanks alot.

Eric


PostPosted: Sat Aug 30, 2008 2:43 pm    Post subject: Re: How to repair a Zenitar 16mm f2.8 Fisheye? Reply with quote
Can't help you with the oily blades as I never disassembled mine, but here's two links explaining how to fix the infinity focus issue:

cpicture.net/zenitar/

etischer.com/zenitar/zenitar16mm.html


PostPosted: Sat Aug 30, 2008 2:49 pm    Post subject: Reply with quote
Great links, Fer! I don't know why they won't work properly in your message. Here they are again:

http://www.cpicture.net/zenitar/
http://www.etischer.com/zenitar/zenitar16mm.html

Eric, I don't have this lens myself so I can't help with dismantling, but I do know it has a non-automatic diaphragm. Oily blades on this type are fairly normal and don't cause the problem of sticking blades that affects auto-aperture lenses, the kind with a pin. Are you having any problems opening and closing the aperture? If not I think you should leave it alone.

As for infinity focus I can't help, except that focussing accurately at infinity with such a wide angle lens is almost impossible, and even worse when looking at the small viewfinder of a crop-sensor camera. Are you actually finding that the pictures are out of focus?


PostPosted: Sat Aug 30, 2008 3:15 pm    Post subject: Reply with quote
Good news, the Zenitar is one of the easiest lenses to fix. I did it myself and I am not good to such things.

Infinity problem
http://www.dyxum.com/dforum/forum_posts.asp?TID=6375

I removed the pin as well, before that it only could shoot f2.8. This is a normal problem using Sony/Minolta.

Hope it helps.


PostPosted: Sat Aug 30, 2008 3:18 pm    Post subject: Reply with quote
peterqd wrote:

As for infinity focus I can't help, except that focussing accurately at infinity with such a wide angle lens is almost impossible, and even worse when looking at the small viewfinder of a crop-sensor camera. Are you actually finding that the pictures are out of focus?


Independently of being able to focus accurately, it's a fact that many of this lenses don't reach infinity focus from factory, mine was one of them. Of course it's noticeable only at faster apertures, from f5.6 forward and the DOF is big enough to get infinity within DOF but at faster apertures forget it (at least on my lens, the sample on the second link I past before was much worst than mine), after tweaking it I can get decent sharp photos even at F2.8 and at F4 is as sharp as my Tokina 12-24 witch is a very good sample.
I see many people stating that this lens isn't sharp until F/8 or so, I suspect this is the problems with most of these lenses.

peterqd wrote:
Great links, Fer! I don't know why they won't work properly in your message. Here they are again:


Thanks, I took off the URL tags because it wasn't showing properly when I submited the post, really don't why.


PostPosted: Sat Aug 30, 2008 6:43 pm    Post subject: Reply with quote
FernandoBatista wrote:
peterqd wrote:

As for infinity focus I can't help, except that focussing accurately at infinity with such a wide angle lens is almost impossible, and even worse when looking at the small viewfinder of a crop-sensor camera. Are you actually finding that the pictures are out of focus?


Independently of being able to focus accurately, it's a fact that many of this lenses don't reach infinity focus from factory, mine was one of them. Of course it's noticeable only at faster apertures, from f5.6 forward and the DOF is big enough to get infinity within DOF but at faster apertures forget it (at least on my lens, the sample on the second link I past before was much worst than mine), after tweaking it I can get decent sharp photos even at F2.8 and at F4 is as sharp as my Tokina 12-24 witch is a very good sample.
I see many people stating that this lens isn't sharp until F/8 or so, I suspect this is the problems with most of these lenses.

Thanks for the information. I didn't know about this until I read your links. Is it a quality control problem do you think, or do they maybe set it for a camera with slightly larger register distance?

Quote:
peterqd wrote:
Great links, Fer! I don't know why they won't work properly in your message. Here they are again:


Thanks, I took off the URL tags because it wasn't showing properly when I submited the post, really don't why.

I guessed you had! Smile I thought I'd try and be "clever" and add the tags but I got the same problem - weird. Rino in Argentina has the same problem, where are you?


PostPosted: Sat Aug 30, 2008 8:45 pm    Post subject: Reply with quote
Nice to see you guys here!


PostPosted: Sun Aug 31, 2008 4:38 am    Post subject: Reply with quote
hi guys,

thanks for the information. Now i can finally do some tweaking to the lens.

Eric


PostPosted: Sun Aug 31, 2008 11:11 am    Post subject: Reply with quote
peterqd wrote:

Thanks for the information. I didn't know about this until I read your links. Is it a quality control problem do you think, or do they maybe set it for a camera with slightly larger register distance?


I think it has more to do with quality control, I'm using nikon as in one of those links, still the adjustment needed for my lens was no where near what that guy had, his lens focused at about 1m, mine focused a good bit farther. If it was an error based on the register it should be the same for both.

BTW while we're discussing this, I also call attention for this post:
http://www.chassimages.com/forum/index.php?topic=13145.msg270244#msg270244 , I don't understand french but from the very little I got from the posts, this guy is using a M42 to Canon mount and had to remove the rear filter system to get infinity focus, anyone who understands french can explain it better. Nevertheless I think it's worth knowing to anyone on a M42/canon mount.

peterqd wrote:

I guessed you had! Smile I thought I'd try and be "clever" and add the tags but I got the same problem - weird. Rino in Argentina has the same problem, where are you?


I'm in Portugal.
I guess the key is not to use the tags, on the link above I just pasted the link and it worked. On the first post I saw the URL button while posting and thought I had to put them, after all guess not Smile


PostPosted: Sun Aug 31, 2008 12:07 pm    Post subject: Reply with quote
hey, i just opened up my zenitar and cleaned the oily blades problem. now at least the aperture is working. After that i did a few test shot, found out tat at f2.8, image is soft, thus have to stop down to at least f5.6 or f8 to get a decent picture. Well i think i dun have the focus to infinity problem after all. Maybe i will try to remove the filter just to make sure the image quality.


PostPosted: Sun Aug 31, 2008 12:14 pm    Post subject: Reply with quote
Sounds like you might have the infinity problem. After reading this interesting post I went out and took a few shots with my Zenitar at f2.8 and it seems fine, in fact quite sharp, looks like I was lucky and got a good one Very Happy I've only used it at about f8 and above before now. I'm sure I read somewhere that the filter can have an effect on the image clarity too but cant remember where, Embarassed


PostPosted: Sun Aug 31, 2008 2:20 pm    Post subject: Reply with quote
hi, poolhall,

thanks for your info.


PostPosted: Sun Aug 31, 2008 2:45 pm    Post subject: Reply with quote
No prob good to see you here its a great place to learn dont be afraid to ask! Very Happy Very Happy Very Happy


PostPosted: Mon Sep 01, 2008 2:23 pm    Post subject: Reply with quote
funny, when i look thru the view finder, the picture seems sharp to me, but when i take the snap shot and look at the photo. its a bit soft. How come?


PostPosted: Sun Sep 21, 2008 11:44 pm    Post subject: Reply with quote
Adjusting focus is simple and I think the question has been answered.
As for your other request.
http://forum.manualfocus.org/viewtopic.php?id=11596


PostPosted: Sun Mar 25, 2012 1:17 pm    Post subject: Reply with quote
Using the info in this thread I just adjusted infinity focus on the zenitar I bought today at a used photography gear fair. It looked almost new, and i had to struggle a bit with the seller to pay it what I wanted to, so i was really disappointed when i noticed it didn't reach infinity.

So, thanks everybody.
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