Wednesday, January 12, 2011

[UV, IR] A surprising lens without UV + IR focus shift III

Well, my orchids started to blossom again, so why not take a chance and try one of those lenses out I published about a while ago here.

The sequence is: UV (through Baader-U), VIS (through UV/IR Cut filter), IR (through B+W 092)

[click on image to see a larger one]

and here the same sequence but showing left and right differentials (VIS-UV, VIS, VIS-IR):

No focus correction was done during the shots using a single 400Ws adjustable power Xenon flash and ND filters to balance out the exposure differences, so as to ensure an identical light direction.

And here a multispectral composite image by assigning UV->blue, VIS->green, IR->red and combining into one image without further ado.

I find that result quite interesting due to the very small focus shift this lens shows for UV and IR as compared to the visible shot. To prove that, I made a shot under the same conditions of above of my calipher (this is a differential center cut out shown UV-VIS, VIS, IR-VIS):

Which shows, that for UV there was only a 0.2mm and for IR a 0.4mm focus shift (but in opposite direction).

Stay tuned, more will follow on that fascinating subject...

More info on this very interesting field may be found on my site