 Posted: Tue Nov 25, 2014 10:37 pm Post subject: Weird Coating/Cleaning mark Phenomenon?? |
 |
|
Rus wrote:
Hi guys, I've noticed an issue with the Canon LTM 50mm F1.2 lens that I have, and I'd be grateful if anyone could shed some light on it.
The Lens is fine when I look through it. But when I put a strong light through it at certain angles..I can see this bluish patch shown in the first photo below. Sometimes you can also faintly make out the edge of it when there is a strong light source, as shown in the 3rd photo below.
The lens works fine in daylight situations...nothing weird whatsoever...the "bokeh" of backgrounds without bright spot light sources is quite smooth...
However...
at night with bright spots.... the bokeh ball shows a weird shape inside them....
Here is the 100% crop:
And more similar shots:
100% Crop:
I have attempted a partial disassembly of the lens..(separating the front groups of elements and the rear groups, it's pretty easy with this lens)..and I know the defect is in the rear groups. What's more it does not seem to be on the rearmost element, nor the surface of the lens element immediately behind the aperture blades. I'm suspecting its on a surface somewhere in between.
Can anyone identify this bluish patch perhaps? Is it some dried up fluid? or is it a coating problem? (Since it leaves this distinct edges in the bokeh ball I'm wondering if it is in fact a coating problem...)
I hope it is not some problem occurring to the glue that holds the two lens elements together in the rear groups..coz that will be a huge pain to clean....
Anyway..all opinions and suggestions welcome!!
Thanks!!
-Ed |
Search
Memberlist
Register
Profile
Log in to check your private messages
Log in
