Hi together,
perhaps this bit of information can help: The first generation of the Tamron 90mm 1:2,5 Macro lenses had a blue spot problem when used on a DSLR. Reason was the completely flat rear element that didn't work well together with the flat sensor. The problem became only visible when the aperture was closed beyond 8.
Bob
blue in center of FOV
Re: blue in center of FOV
That is a very good point.The first generation of the Tamron 90mm 1:2,5 Macro lenses had a blue spot problem when used on a DSLR. Reason was the completely flat rear element that didn't work well together with the flat sensor. The problem became only visible when the aperture was closed beyond 8.
With an afocal setup the lens should be focused at infinity (real infinity - not what the dial says*) and the aperture wide open.
*Place camera on a tripod - focus carefully on the farthest object you can see clearly on the horizon and then tape the lens so that it can't move.
Zeiss Standard WL (somewhat fashion challenged) & Wild M8
Olympus E-P2 (Micro Four Thirds Camera)
Olympus E-P2 (Micro Four Thirds Camera)
Re: blue in center of FOV
That's optically similar [albeit not identical] to the Pentax problem that I mentioned here:MicroBob wrote:Hi together,
perhaps this bit of information can help: The first generation of the Tamron 90mm 1:2,5 Macro lenses had a blue spot problem when used on a DSLR. Reason was the completely flat rear element ...
viewtopic.php?f=9&t=7027&hilit=pentax+filter
In the Pentax case, the reflection was bounced between the rear of a flat filter and the flat face of a lens element. ... so they produced a 'watchglass shaped' filter.
MichaelG.
Too many 'projects'