I think, I need help.
Not long ago I have bought from Taiwan via eBay Contax N 50/1.4 converted by Conurus.
The lens looks very good, AF works, but it is sharp only from f/2.8.
At f/1.4 picture is unacceptable, few better at f/2.
It seems there is not front- nor back-focus.
I saw many pictures with N50 opened here on fredmiranda forums, which are sharp at f/1.4!
So, I need an advice - what can I do with my lens?
Try to send it to Conurus for forwarding to Contax for repair?
Or simply accept the situation and put the lens to shelf?
Thanks.
A.Erekhinski wrote:
If so, this lens is the worst of all N lens i have. 24-85, 17-35 and 85 all are sharp opened.
If you search a bit on this forum about the Zeiss 50/1.4 planar design in all its reincarnations, you will see that this lens has many qualities, but unfortunately wide open shooting at MFD is not one of them. As for the other N lenses mentioned, don't forget that the 24-85 has a very small max aperture, and the 17-35 is f/2.8. The 85 is a portrait lens and does have veiling haze wide open, but perhaps less than the 50, and its design has been optimized for closer portrait distances while the 50 is optimized for infinity.
By the way, can you post some real world photos taken with the 50 at f/1.4? They will be more telling than the lensalign shots, and if the lens is bad, it would be easier to assess it.
The 100% crop you're showing is certainly blurred, this can be seen even in the resized full images. I do have the impression that the lamp post, fence and tree on the right are sharper. Could the lens be front focusing at this distance? This can be easily adjusted as Conrus provides AF adjustment at 3 distance ranges. Also focus shift should be taken in consideration with this lens, though not at this distance.
edwardkaraa
I know about conurus` microadjustment, and i am planning to do this procedure, but it seems strange for me if the prime lens does not have frontfocus at one distance and has it at another. Afaik N50 is not susceptive to shiftfocus as 50L is.
Focus shift is evident in your lensalign shots, though I am not sure if the 50L is better or worse in this regard. AF is a weird animal, it can be spot on at one distance range and completely off at another. With zooms, it's even worse, it can be accurate at one FL and off at another. That is why cameras/lenses are factory adjustable to several ranges, eventhough they usually give the user the possibility of only a global adjustment. Evidently, Contax N AF is factory adjustable at 3 ranges, and Conurus took advantage of the feature and made it available to the owner.
A couple of suggestions. Check that you have not assigned a focus adjustment to a 50mm in the 1ds3. Then revisit the images shown, if it is front focussing then attempt the Conurus procedure. If it takes an inordinate amount of adjustment then prepare to send it to Conurus.
I had a similar problem with my N50 on my 1ds3 and was able to fix it with a combination of in camera micro adjustment along with programming the lens micro adjustment.
It works well now at both close and far distances.
