Recording animal-view videos of the natural world using a novel camera system and software package

[StephanN]

I hope this has not been posted already:

 

Recording animal-view videos of the natural world using a novel camera system and software package | PLOS Biology

 

 

[colinbm]

Looks like something someone could have a lot of fun with.

[JCDowdy]

This reminds me of the apparatus that Alex H used some years ago.

 

[Kai]

Very interesting material. Many thanks for the hint, Stephan!

[Andrea B.]

I saw that article to which Stephan linked. The first thing I was wondering was why they showed the Bee View using any red!! Bees cannot detect red.

 

I would like to get more info about this camera.

[Andrew Dayer]

Thanks for posting this link @StephanN. Very pertinent to a block of work I'm about to start.

The hardware uses a stock and a UV capable camera viewing the same scene via:

• Thorlabs longpass dichroic mirror/beamsplitter DMLP425R https://www.thorlabs.com/newgrouppage9.cfm?objectgroup_id=3313&pn=DMLP425R
• Semrock shortpass filter to cut out UV wavelengths >~380nm in the UV path. FF01-390/SP-25 https://www.idex-hs.com/store/product-detail/ff01_390_sp_25/fl-009649?

Minimal IR contamination is documented in the paper. Anyone have experience of this approach for imaging or the Semrock filters?

The lens used is "80 mm f/5.6 EL-Nikkor enlarger lens", presumably the pre-N metal version. They don't mention its been out of production for quite a few years.

 

Also interesting that the technqiue appears to work for UVR / multispectral video.

There's a lot to unpick here, for me at least.
 

[Andy Perrin]

The claimed out of band OD of that filter looks excellent. They say OD5 and better. That is certainly good enough to use on its own in normal sunlight. The price however seems rather high — is a Baader U less expensive? I think it might be. And for a 25mm filter!

[ulf]

Also the specification for angle of incidence is 0 +-5 degrees!

[Stefano]

As for BrightLine filters, I use two of them (340/26 and 387/11) for the red and green channels for UV TriColour photography: https://www.ultravioletphotography.com/content/index.php?/topic/4861-testing-a-svbony-05x-focal-reducer-lens-for-photography-and-uv-tricolour

 

They leak longwave NIR (not a fault of my filters, and agrees with their specified transmission curve), but since they leak past ~900 nm, some "U" glass (like 4 mm ZWB1), blocks the leak while passing UV. For the 387/11 I use Chinese BG39 (or similar) to block IR.

 

As a bonus, I used my 340/26 stacked with a Hoya R72 for "deep NIR" photography, with nice results.

 

They are designed for 0° incidence, and will noticeably change their transmission when used at an angle, just like my BrightLine 540/35 filter goes from green to blue if you tilt it by ~45-60°. When strongly tilted, the blocking also becomes worse, and my BrightLine UV filters visibly leak orange and I think green if I look at a lightbulb through them at extreme angles (like 60° or more). They are otherwise fine, and work well.

 

The only way to use interference filters on wide-angle lenses without issues seems to be to use strongly retrofocus lenses with telecentric projection onto the sensor and rear-mount the filter. Or, theoretically, you would need a dome-shaped filter, but that's unlikely to ever happen.