Hello from Santa Cruz, California

[Pete Nelson]

Hi: Thanks for letting me join; I'd like to introduce myself briefly...

 

I'm a marine scientist who's previously worked on UV vision and UV physiological ecology
in fishes (mostly coral reef species). I haven't worked on UV
biology in nearly 20 years but a new project on juvenile Chinook salmon
includes a component where UV photography may be quite important. To be frank,

my primary motivation for joining is the hope that I may get some help in

determining some reasonable options for pursuing this aspect of my project. Hopefully

I'll be able to contribute though too!

 

Cheers, Pete Nelson

 

 

[nfoto]

Most welcome to UVP and given your history and experience, your contributions are eagerly awaited

 

Many moons ago I did spectral underwater profiling, from UV to near IR. Most of our inland water had very low UV penetration, except for a few highly acified lakes. Inland waters of the deep forests on the border between Norway and Sweden went the opposite direction and had highest transmittance in deep red and NIR.

[dabateman]

Welcome. 

Feel free to ask any question.  You may also be more help than you realize.  Not many of us work under water, but some whom have passed through have. I haven't yet even taken a photo under water,  even though one of the first cameras I ever bought was to do just that back in 2007. It just didn't work out. I still have the underwear housing, but maybe not the camera.

I will be interested in seeing your images. 

[Nate]

Welcome Pete! 

I can't help with anything for underwater, but would sure like to see and maybe learn some things about it.

[lukaszgryglicki]

Hi, nice to see you there!

 

[Bill De Jager]

Welcome, Pete. I'm just over the hill in the Bay Area. 

 

 

[Daniel Csati]

Nice, welcome Pete

[Doug A]

Welcome Pete. Looking forward to your posts and learning about underwater UV.

Thanks,

Doug A

[Andy Perrin]

Hi! Nice to meet you! Are you doing underwater UV reflectography or UV fluorescence pics? 

[Pete Nelson]

Thank you all so much. I'm really impressed by how helpful folks are on this site--yeah, I hope I can contribute too! I'll have to look to see if I can dig up some of my old UV imagery, mostly underwater UV video. Please don't get too excited though as I'm a little dubious about how findable it will prove to be. 

In a nutshell, my most immediate objective is taking UV reflective images of juvenile salmon out of the water. The goal is to determine whether swabbing their sides for mucus (needed for genetic analysis of their run-type) has deleterious impacts on their ability to handle environmental levels of solar UV radiation, and the idea is that UV imagery may be a helpful way to quickly and qualitatively assess the status of their mucus layer.

 

We know that many fishes sequester UV-absorbing compounds (mycosporine-like amino acids, usually "MAAs"), and that these figure in UV protection for shallow-water marine species. We also know that removing or rubbing away that mucus "shows up" when you photograph a fish with the appropriate gear, appearing as a light or bright area where the dark (UV-absorbing) mucus has been removed. (In fact, this is how Jill Zamzow discovered that fish have UV-absorbing compounds in their mucus--she was video taping a Hawaiian toby (a small puffer, Canthigaster jactator) that we'd caught earlier that morning using a series of notch-filters, and noticed that relatively deep in the UV (ca 360 nm? it was a long time ago!) the fish had a strange white ring around its nose. Turns out that our dipnet had a hole in it, and the toby, trying to swim down out of the net, had its nose in the hole and rubbed off its mucus just there.)

 

My hope is that I can identify a cheap digital camera and lens that will at allow for some proof-of-concept images. At one time I had a Sony F717 and some low pass filters (plus IR filter, probably) that was semi-functional. I'll see if I still have that gear around and if it'll power up! I'm hoping that something like a Nikon D70 and a 50mm f/1.8 would at least provide that proof-of-concept. For the time being, I expect I'd try natural (sun) light first. One potential issue is that these fish will be very much alive, so there's a need to use a relatively fast shutter speed (1/125 at least?). After all, the goal is to keep them healthy!

 

Cheers, Pete

[Andy Perrin]

"Fast shutter speed" and "UV photo in sun" are usually not very compatible objectives! I think your road ahead requires artificial light source, not just sunlight. A flash would get you to where you need to be probably. I do not think this project can succeed in sunlight alone. Typically I can get a decent sunlight photo in UV with like F/4 ISO1600 1/30". You would have to raise the ISO significantly to like 6400, which is doable I guess barely, but don't expect quality. However 1/125" for a flopping fish may be too slow also...

 

Quote

Nikon D70 and a 50mm f/1.8

Typical lenses do not pass UV well. A significant part of the life of this forum is the search for suitable ordinary lenses that coincidentally pass enough UV and are also sharp. If you choose a lens at random, it is unlikely to give good results. Also is your D70 converted by removal of the IR blocker filter? Converting is necessary. We can recommend lenses that are affordable. I think you will need to be able to focus relatively close to the lens to snap a fish in the other hand. Something like the 50mm EL-Nikkor with some extension and a helicoid might do it?

[lukaszgryglicki]

50/1.8 AF-D is actually quite good in UV, tested it many times. It is my fav "UV-lens" that also have AF (best for all my AF lenses).

50/1.2 AI is better - but thsi is rather because of sheer speed, 50/1.8 AI pancake is also good.

 

 

[Andy Perrin]

12 minutes ago, lukaszgryglicki said:

50/1.8 AF-D is actually quite good in UV, tested it many times. It is my fav "UV-lens" that also have AF (best for all my AF lenses).

50/1.2 AI is better - but thsi is rather because of sheer speed, 50/1.8 AI pancake is also good.

 

 

Maybe he will get lucky then!

[lukaszgryglicki]

Others cheap that I've found good in UV are Nikkor 200/4 Non-AI (4 elements), Nikkor 35/1.4 Ai-S (thorium), 100/2.8 Series-E, and EL-Nikkors 80/5.6, 105/5.6 and 135/5.6

 

[ulf]

One thing to consider too is the material of the window in the underwater housing, if the camera will be submerged in such a housing.

Polycarbonate materials normally have a rather steep cutoff just where UV begins around 400nm.. PMMA, perspex (plexiglas) is a better material in that aspect.

 

There are special sun bench grade materials that are good.

[dabateman]

The Nikon E 50mm f1.8 was tested here:

https://www.ultravioletphotography.com/content/index.php?/topic/2062-first-use-of-kolari-uv-filter-in-portrait/

 

The Nikon Af 50mm f1.8 D was tested here:

https://kolarivision.com/uv-photography-uv-filter-test/

 

I saw an other test with a Nikon 50mm, but I didn't think it let in much below 380nm.

 

For cheap UV video the camera that I would play with, especially if in University setting is a Raspberry pi HQ camera.  The stock off the shelf HQ is sensitive to UV from as deep as 360nm. It has an odd CM500 filter that you can keep or push out for IR response.  The stock camera with a S8612 filter and Zwb2 filter is my UV Raspberry pi module. 

[nfoto]

A Nikon SE 50mm f/1.8 is dirt cheap and in combination with a D40 or D70 in working order might be just the proof-of-concept gear you need. Worth a try at least.

 

For the UV underwater scenes,  a housing with glass dome port probably is the better option (if available).

[otoien]

At least Subal provides glass ports for their housings, the port I have for the AF 20mm is made of uncoated glass. I suspect some other high quality suppliers have that too, although some might be coated, which could potentially attenuate UV.

[Andrea B.]

I think I would recommend going with an older converted Panasonic Lumix camera with one of the G designations or an older Sony NEX. Both are quite competent at UV and can be bought used from Ebay or KEH.com. The Lumix G line is also good at UV video. Either one of these cameras will be much better than a Nikon D70, but you would have to pay for conversion to full spectrum. 

 

You would also need a mount adapter to use one of the Nikon lenses on a Lumix or on a NEX. They can be found on Ebay or from Fotodioxpro.com and don't cost too much.

 

If the proof of concept fails or your project doesn't go anywhere, then you can sell the converted Lumix G or NEX and get some of your $$ back.

 

I am not sure your 1/125" speed is achievable even in very strong sunlight unless ISO is cranked up quite high. But this creates lots of noise in UV photos. We would typically recommend a UV flash to get faster exposure times. There is also the possibility of using a 365 nm UV-Led flashlight (torch). They don't cost much. Look here for more info about gear: Best Basic Gear: Goggles, Filters, Torches

 

If somebody can hold the fish by tail and head for a few seconds, then you can use slower exposure times. There will be a *lot* of trial-and-error in working out the best balance of exposure time, aperture and ISO to get your photos. I'm thinking you won't need to stop down much past f/5.6 for photographing fish from the side and you might be able to go wider. So that will help to keep speed fast and ISO around 800.

 

 

[Pete Nelson]

All fantastic, helpful comments! Thank you so much. We might be able to place the fish briefly beneath a piece of UV-transparent acrylic to minimize the movement and improve image quality. UVA, 320-400 nm, is really what we're interested in. Luckily, we don't have any need to image these fish underwater; adding a housing to the equation increases costs and complexity considerably. 

 

I've attached a nice summary paper by one of my colleagues that includes some interesting (if not "beautiful") images and some good basic biology about UV vision and color in marine fishes. Zamzow08AmSci.pdf

[Andy Perrin]

Ok sounds good. I think you know what you need now: a commercial UV filter or stack (don’t forget most UV glasses transmit enough IR to wipe out the UV signal unless you add an additional IR blocker filter like S8612), a converted camera, and most likely a UV converted flash for best results. It seems like you have a lens that may be adequate to begin with.