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Author Topic: differ brightness of the lenses  (Read 4246 times)

Claude

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differ brightness of the lenses
« on: November 14, 2013, 02:12:06 PM »
Hello,

I have 12 nikkor 50mm lenses and I notice that 3 of them give darker images than others.
Fist I thought that is some defect of lenses but almost half of lenses are a bit different than others.

I didn't notice big problem with mesh generation. I am not sure if it is defect or normal variable in brightness of lenses. I don't know if Nikon service will want to repair or replace my darker lensses with more average lenses.

The most important I wonder if it have influence on quality of mesh generation?

What do you think about it?

polygon

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Re: differ brightness of the lenses
« Reply #1 on: November 14, 2013, 09:43:09 PM »
did you try to switch the lenses?

do you use flashlight?

Claude

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Re: differ brightness of the lenses
« Reply #2 on: November 15, 2013, 06:02:42 PM »
Hi,

Yes I was switching lenses a lot and always specific lenses are darker. The body has nothing to do with this problem.

Yes I use flesh light but I don't think it have make difference in this case. I swith lenses few times and I know that lenses has this problem.

Any suggestion?

chadfx

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Re: differ brightness of the lenses
« Reply #3 on: November 15, 2013, 06:59:19 PM »
You can always send the faulty lenses in for repair. Sometimes the elements get out of alignment, etc. They should at least be able to test them out and let you know if they are within factory tolerances. Are they darker at every f-stop? Only around the edges (ie. vignetting?) (which usually shows up at wide open apertures...but that would normally not be a setting you would use for Photoscan, anyway)

Theoretically you could counteract the darkening in a tool like Lightroom, which also can correct for vignetting. I always use it to remove chromatic aberrations as well. If you know which lenses are darker, you could also change the exposure settings on those cameras to compensate. (ie. set exposure compensation to +1/2 stop, etc)

I've used Lightroom to balance exposures when there has been some variation, and it seems to work just fine. (make sure NOT to use ANY distortion correction, though!)

maddin

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Re: differ brightness of the lenses
« Reply #4 on: November 15, 2013, 08:50:08 PM »
How strong is the brightness difference? You could try to color-calibrate them to compensate for any differences. I know that for professional stereo camera recordings, the lens pairs are manually matched (get 50 lenses and pick the two most similar ones), so I guess it's not uncommon for two lenses to be slightly different.

If the difference is very strong, I would bring them back to the dealer.
Can you post some sample pictures?

Martin