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Jena MC Sonnar 3.5/135 - Very wrong!
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PostPosted: Sun Oct 31, 2010 11:51 am    Post subject: Jena MC Sonnar 3.5/135 - Very wrong! Reply with quote
I decided recently to get a Sonnar 135 to see what all the fuss is about but there seems to be something quite wrong with my copy. It's not sharp and has a massive loss of contrast. I just have a few test shots as it doesn't seem dependable enough to take out. I am thinking of getting a lens spanner to see if it has been dismantled and an element put in backwards.

This is my usual first test shot with a lens, out of the window. The church is about 3.5 miles away. Loss of contrast isn't too bad in this.


It is with this though, the plant is lit from the window behind it.


From what I can see there doesn't appear to be any haze on the elements or a breakdown in coating. Does anyone have any ideas what the matter could be with this lens?


PostPosted: Sun Oct 31, 2010 11:53 am    Post subject: Reply with quote
Difficult to say from these two images, I am not able to give an answer.


PostPosted: Sun Oct 31, 2010 12:02 pm    Post subject: Reply with quote
Maybe low sharpness and low contrast aren't related and the lens has two independent problems. Hard to say without having the lens in my hand.

You can check if the rear element isn't twisted, you can check if some of the other elements isn't loose. Or if the rear part of the lens doesn't lack the black tube (I don't know how to call it - it's like a small hood located behind the rear optical element - it should prevent reflections - it's visible here)


PostPosted: Sun Oct 31, 2010 12:35 pm    Post subject: Reply with quote
no-X, I think you are referring to light baffling? The whole barrel looks dark internally so I don't think it's reflections from that. There's a slight rattle on one of the elements which suggests that something may be amiss.

I've ordered a lens spanner so I will be able to properly remove the elements and if the sun appears sometime before next June I will be able to get some highly contrasted images to test it further.


PostPosted: Mon Nov 01, 2010 7:22 am    Post subject: Reply with quote
Please take the photo of the same subject under the same conditions with this Sonnar and some other 135mm lens wide-open so we'll be able to compare.


PostPosted: Wed Nov 03, 2010 7:10 am    Post subject: Reply with quote
@ william: can you upload the sonnar's optics photo (through the glass)? Let's see the optics condition, first.
Smile
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