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UltravioletPhotography

Multispectral Chestnuts


Andy Perrin

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Chestnuts on a cutting board with salt and a square of Acktar Metal Velvet as white and black references. White balance was off the salt in the photo, in-camera. Lens was 80mm EL-Nikkor 5.6 except in the visible and SWIR cases.

 

Visible reference (iPhone 6S Plus)

post-94-0-81553600-1488248319.jpg

 

780BP30 filter, halogen light, F5.6 1/800" ISO400

post-94-0-75431500-1488248367.jpg

 

1064BP25 filter, halogen light, F5.6 1/60" ISO800

post-94-0-88232000-1488248505.jpg

 

Thorlabs 1" 50mm lens (AR 1050-1620nm) projected on upconverting phosphor screen, halogen light, roughly F4 (eyeballing it!), 10" ISO400

post-94-0-19896500-1488248643.jpg

 

2mm UG11(or possibly unknown glass)+1.75mm S8612, Tuofeng nominal-365nm torch, F16 15" ISO100

post-94-0-69687200-1488248975.jpg

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These Chestnuts surprised me in IR. I guess I thought they would not be so IR-reflective.

 

They look cool in UV. (So many things don't!)

You could make a nice triptych portrait of just the Chestnuts.

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Andy Perrin
It's pricy, but they sell a sample size for about $100 or so and you really only need one piece, at least for small things.
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Andy Perrin

Chestnuts on cutting board, sunshine (the previous pic was with the very-narrowband Tuofeng torch).

 

Lens was 80mm EL-Nikkor 5.6, white balance was in-camera with PTFE. Filter was 2mm UG11 (probably knockoff), and 1.75mm S8612.

 

F/16 5" ISO400

post-94-0-14291500-1488655005.jpg

 

F/16 6" ISO400

post-94-0-40705800-1488655097.jpg

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Andy Perrin
Well these are crops so I wouldn't read into that so much. (Cropped for artistic intent, of course.) But actually even the originals are very sharp at the corners at this F-number, so your conclusion is true. I was lucky on the 2nd try, with the EL-Nikkor 80mm/5.6.
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Andy Perrin

Here is the actual corner at 1:1.

post-94-0-90228200-1488658248.jpg

 

1:1 crop, unedited except for the auto-noise reduction, white balance, and exposure from PhotoNinja.

post-94-0-16420000-1488658260.jpg

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I made some test with a sharpness chart I found on gogle image:

 

f/16 is very good in the center but not so much in the corner, where f/22 performes better. Surprisingly, f/45 is the best of all in the corner, but is worst in the center!

In my case, f/22 is the best in the whole frame. Unfortunately it is not very convenient for shooting, it is just too dark!!

 

I think I will try to save for another EL-Nikkor 80mm, maybe there is some difference between the old models.

If only I could have the Coastal... or even better, the UV Nikkor clone.. but that's for later :D

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Andy Perrin
At F/45, you don't have a lens, you have a pinhole camera! You may as well just get rid of the glass altogether and increase the transmission.
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Have you all tested those lenses to determine where diffraction sets in?

 

 

I'm fascinated by these chestnuts. They're so photogenic. "-)

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Oh, maybe your camera is an APS-C, which explains why the corner of your pictures are better than mines, since I use a full frame camera.
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