Fandyus Posted January 11 Share Posted January 11 Haven't posted in a while, but I have discovered an interesting method for emulating a polarizer in any wavelength by stacking several images, so I thought I'd share it. I'll demonstrate it on this banana cross section. All images were taken with a ZWB2+QB39 Tangsinuo stack, lit with 365nm LEDs. As you can see, the surface of the banana is extremely glossy, and that is very distraction when it comes to the texture and intricate details of the cross section. You could get around it a little bit by either using a diffused light or having a long exposure and moving the lightsource around when the camera is exposing. Neither technique helps this very much though. Another way, that I use in the visible, is to use a white LED spotlight with a polarizer mounted on it, and then using another polarizer on the camera itself. Turning the polarizers in opposite directions then causes all specular reflections to be eliminated. I have demonstrated this on a lemon cross section in visible. I however, do not own two UV polarizers, nor can I afford them. Even if I did, I am not sure how I would mount them. As a workaround, I have figured out that taking four pictures with the light positioned in a different spot each time, then aligning them and stacking them in Photoshop with stackmode set to "minimum" will successfully fake the effect. PIC 1 PIC 2 PIC 3 PIC 4 Stacked: You are then free to edit the image as you wish: For comparison, here's the same cross section in visible made with the analogue technique of using crossed polarizers. This obviously works for any wavelength, so long as it has specular reflecitons. Link to comment
Fandyus Posted January 12 Author Share Posted January 12 7 hours ago, colinbm said: Lots of good experiments here. Thanks! Link to comment
Andy Perrin Posted January 13 Share Posted January 13 Yep, I mean it’s not really simulating all the effects of a polarizer (no pretty colors for example) but it is a good way to get rid of specular reflections. Link to comment
Recommended Posts
Please sign in to comment
You will be able to leave a comment after signing in
Sign In Now