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I want to do some night flouro video on my next dive trip. I have a scubalamp video light that can light blue lights. I understand that i need a barrier filter on both my mask( to see) and my lense (to capture the flouro subjects. From long ago in my film days on land I had a boatload of Cokin filters. I sold most but still have the adapters and holders which will fit perfectly on my lens. I am trying to find what filter(s) will work best for captureing this so I do not have to do many night dives with different filters to hone in what the best ones are. Does anyone have a good starting point I can work from, and reccomendations fo a good mask yellow barrier?

Edited by aviator8

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Look at nightsea.com for all such info.

They just have a few barriers, one as a bungee, one as a threaded adapter. They don't discuss the details on the filter themselves. I was wanting to find which in the cokin lineup accomplish the same thing as I have the right holder for them already, and can thus just get an appropriate red(day), yellow (night), etc filter cheap on ebay. They also do not have any mask barriers that I find.

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Hi aviator8. The yellow barrier filters used in partnership with blue excitation lights for underwater fluoro photography are typically a deep yellow Wratten/Tiffen 12 or other manufacturer equivalents. I am not aware that Cokin make a Wratten 12 equivalent - I understand that their 001 yellow filter has a different spectral curve.

 

The precise results are liable to depend on the spectral composition of your blue video lights. Some photographers prefer to use yellow filters and masks produced by their blue light manufacturers to ensure an appropriate matching of light and filter spectrums. Firedive (https://firedivegear.com) produce custom yellow filters and masks that deliberately let a little of the blue excitation light through to the camera. This usually results in a deep blue as opposed to black background and slightly cooler images as the returning fluorescing green/orange/red light is mixed with some blue. Whether or not this is better than the more usual Wratten 12 filtration is down to personal preference.

 

Obviously for accurate preview of the scene, yellow mask and camera filters need to match. To accurately preview the results underwater on camera, you need to flip the mask up to view the LCD screen.

 

The fluorescent light produced by marine organisms is usually orders of magnitude less than that produced by normal reflected light so you will need to use high ISOs, particularly if you want to bring out the subtler oranges and reds that tend to be lower intensity than the prevalent fluoro-green. This also makes close-up photography easier than wide scenes where it is difficult to get large amounts of light onto the subject matter. Still shooters will more easily produce good quality results using blue excitation filtered strobes.

 

Mark

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@MarkD Thanks. I will look up the wratten 12 filter. I am using a scubalamp pv102 video light. Its specs state that he UV wavelength is 385nm. I do not think that they produce any barrier filters for thier lights, none that I can find anyway. as to background blue vs black, I an not too particular on that front.

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Posted (edited)

They just have a few barriers, one as a bungee, one as a threaded adapter. They don't discuss the details on the filter themselves. I was wanting to find which in the cokin lineup accomplish the same thing as I have the right holder for them already, and can thus just get an appropriate red(day), yellow (night), etc filter cheap on ebay. They also do not have any mask barriers that I find.

You've got to look beyond their products and go to the information and science pages. The guy who runs nightsea is the scientist that started this field. If necessary, send a query to him, Charley Mazel. Edited by tursiops

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Its specs state that he UV wavelength is 385nm.

 

As the visible light spectrum is usually regarded as starting at 400nm, if the UV torch truly produces a point wavelength of 385nm, no barrier filter would be needed. In practice, the light is likely to emit a spectrum of wavelengths extending to some degree into the visible range and so will be detectable both by eye and the camera sensor. (Do you see blue light when it is in "UV" mode?). The extent and intensity of this spread into the visible spectrum determines the need for yellow (minus blue) filtration. Wratten 12 filters have a sharp cutoff at about 500nm. Many lights designed for underwater fluoro photography actually produce a spectrum peaking around 455nm - visible blue light. This is because that higher wavelength is a more effective fluoro excitator than shorter wavelength true UV. Of course a downside of barrier filtration is that any fluoro effect below the cutoff frequency (say 500nm) will be lost. However without barrier filtration, lights with significant emission within the blue visible spectrum will tend to overpower the relatively weak fluorescence with their directly reflected blue light.

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As the visible light spectrum is usually regarded as starting at 400nm, if the UV torch truly produces a point wavelength of 385nm, no barrier filter would be needed. In practice, the light is likely to emit a spectrum of wavelengths extending to some degree into the visible range and so will be detectable both by eye and the camera sensor. (Do you see blue light when it is in "UV" mode?). The extent and intensity of this spread into the visible spectrum determines the need for yellow (minus blue) filtration. Wratten 12 filters have a sharp cutoff at about 500nm. Many lights designed for underwater fluoro photography actually produce a spectrum peaking around 455nm - visible blue light. This is because that higher wavelength is a more effective fluoro excitator than shorter wavelength true UV. Of course a downside of barrier filtration is that any fluoro effect below the cutoff frequency (say 500nm) will be lost. However without barrier filtration, lights with significant emission within the blue visible spectrum will tend to overpower the relatively weak fluorescence with their directly reflected blue light.

Hmmm well it seams the manufactures specs are off then as I do see visible blue light. It would be nice to know exactly what frequency it peaks and drops off at so that I can choose an appropriate filter.

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Hmmm well it seams the manufactures specs are off then as I do see visible blue light. It would be nice to know exactly what frequency it peaks and drops off at so that I can choose an appropriate filter.

I'll mention nightsea.com again.

Try looking at:

http://www.nightsea.com/articles/underwater-fluorescence-faq/

Especially this:

 

Do the NIGHTSEA lights emit ultraviolet light?

NIGHTSEA’s lights are designed to emit a carefully controlled range of blue, not ultraviolet, wavelengths. We started out with ultraviolet a long time ago, but with a combination of science and experiment learned that blue provides a far superior experience. There are some things that fluoresce under UV but not blue, but overall more things fluoresce, and fluoresce more brightly, when illuminated with the right blue light and viewed through the yellow barrier filter.

For more information see our articles explaining Why NIGHTSEA uses blue light for underwater fluorescence and The role of the barrier filter in fluorescence viewing and photography.

Also, see http://www.nightsea.com/articles/barrier-filter/and this:

For best results the spectral properties of the barrier filter should be closely matched to the spectral properties of the excitation light source. If the barrier filter transmits some of the light coming from the source, that light will show up in the photograph. If the barrier filter is too deeply colored it will block all of the excitation, but it will also block some of the fluorescence. If the matching is done right you will be able to see as much fluorescence as possible, with strong contrast and little to no interference from the excitation source.

I suppose one easy way to do this would be look at your excitation light through your barrier filter; it you see nothing, you've matched it!

http://www.nightsea.com/resources/is a major source of information. the set of articles under "Knowledge" are particularly interesting.

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I'll mention nightsea.com again.

Try looking at:

http://www.nightsea.com/articles/underwater-fluorescence-faq/

Especially this:

 

Do the NIGHTSEA lights emit ultraviolet light?

NIGHTSEA’s lights are designed to emit a carefully controlled range of blue, not ultraviolet, wavelengths. We started out with ultraviolet a long time ago, but with a combination of science and experiment learned that blue provides a far superior experience. There are some things that fluoresce under UV but not blue, but overall more things fluoresce, and fluoresce more brightly, when illuminated with the right blue light and viewed through the yellow barrier filter.

For more information see our articles explaining Why NIGHTSEA uses blue light for underwater fluorescence and The role of the barrier filter in fluorescence viewing and photography.

Also, see http://www.nightsea.com/articles/barrier-filter/and this:

For best results the spectral properties of the barrier filter should be closely matched to the spectral properties of the excitation light source. If the barrier filter transmits some of the light coming from the source, that light will show up in the photograph. If the barrier filter is too deeply colored it will block all of the excitation, but it will also block some of the fluorescence. If the matching is done right you will be able to see as much fluorescence as possible, with strong contrast and little to no interference from the excitation source.

I suppose one easy way to do this would be look at your excitation light through your barrier filter; it you see nothing, you've matched it!

http://www.nightsea.com/resources/is a major source of information. the set of articles under "Knowledge" are particularly interesting.

I spent some time reading through the articles there. The problem i have is that not knowing what wavelength my lights are using and the manufacture reported wavelength obviously being wrong I don't know how to match a barrier filter. The easiest would be like you said to test various with my light. However I don't have one to test so buying a bunch just to see would seem to be kind of wasteful. I emailed SubaLamp to see if they have better information on the blue wavelength being transmitted.

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I spent some time reading through the articles there. The problem i have is that not knowing what wavelength my lights are using and the manufacture reported wavelength obviously being wrong I don't know how to match a barrier filter. The easiest would be like you said to test various with my light. However I don't have one to test so buying a bunch just to see would seem to be kind of wasteful. I emailed SubaLamp to see if they have better information on the blue wavelength being transmitted.

 

If the filters are cheap, testing is probably your best bet. Note that not all light manufacturers are 100% accurate in the specs they claim for their products, so that will likely add another variable to your research. With a flip adapter you can try each filter as a wet lens on each subject to determine your favorite results for that scene. If this is for photography, camera sensor size and ISO capabilities (and strength of light source) will also play a major role in the final image. Just my thoughts :- ). Good luck!

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If the filters are cheap, testing is probably your best bet. Note that not all light manufacturers are 100% accurate in the specs they claim for their products, so that will likely add another variable to your research. With a flip adapter you can try each filter as a wet lens on each subject to determine your favorite results for that scene. If this is for photography, camera sensor size and ISO capabilities (and strength of light source) will also play a major role in the final image. Just my thoughts :- ). Good luck!

I'll be shooting with a Sony RX100V for both video and still. I will most likely have to get pretty high up with ISO. I was looking at screw on filters for 67mm threads. That's really my only option for wet WA lens. Foe my macro wet lens I could crew a flip down adapter to the front but that would just be swinging one filter in. Is there a product you know that supports flipping in multiple filters? I'd love to be able to pick up an adapter where I can have several filter options ready to just swing in place. like reds for day video then yellows for night flouro. That would preclude my WA and macro from shooting but if it simplified for now I think it would work fine.

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Is there a product you know that supports flipping in multiple filters? I'd love to be able to pick up an adapter where I can have several filter options ready to just swing in place. like reds for day video then yellows for night flouro.

 

Just google for '67mm double flip' or '67mm triple flip' and you'll get plenty of options. Most of them are disgustingly expensive though.

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Just google for '67mm double flip' or '67mm triple flip' and you'll get plenty of options. Most of them are disgustingly expensive though.

Uhhh yeah, thats nuts. Think i will screw them in myself.

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Uhhh yeah, thats nuts. Think i will screw them in myself.

Yea price is high on those. I usually just screw my macro diopter in and out, laying it in the sand if setting up a shot without it. You could keep the filters in a little pouch attached to your BCD as well, or pick up a dual lens caddy to store them on your strobe arms.

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Posted (edited)

I think I have a decent non expensive way to move forward. I found this on here:

 

http://wetpixel.com/forums/index.php?showtopic=60293&hl=%2Bvideo+%2Bfilter.

 

Post 4 was very helpful. It included reference to people and material referenced above. What I found particularly helpful was the second link in that post where a guy did spectral analysis on various specific filters elements and shows the results. That then led me to Rosco and Lee filters and the site pnta.com where I could look at spectral graphs of every filter by both companies. Based on the research and data presented I was able to pick out various filters to try as barriers that will range from 500nm cutoff leading to no blue being shown to a 450-500nm cutoff that will allow a range of blue to show back adding the additional color interest to any flouro video. I bought several gels to play with and a ring adapter for my cokin P holder. There should be enough to cut filters and mask barriers for those I settle on since the gels ate 20x24 inches in addition i got a yellow #2208 plexiglass sheet to make a test filter and mask. Since I was at it I got various red to amber gels to use for video on my RX100 V since it does not in camera whitebalance well and can not shoot RAW video. I also picked up a cokin red polarizer to try to see if it varies its red intensity and spectral response for shallow to deep. I was able to get all this for around $100.

 

Here are the filters I will be testing out for flouro and day video

 

flouro:

yellow #2208 transparent plexiglass 1/16 inch 12x12

a made in chine cokin p yellow conversion filter that just appears to be he right color yellow. No stats to verify.

Lee filter yellow 101

Lee filters Spring yellow 100

Lee filter medium yellow 010

Rosco filter Canary 312

 

for daytime video:

a made in china cokin p color conversion filter orange that looks like it may work no published data though

Cokin P161 red polarizer

made i chine 67mm threaded Red "dive filter"

Rosco 22 deep amber

Rosco 25 orange red

Rosco 26 light red

 

 

Hopefully this give me a good mix where I can settle on 1 or two reds that work in the day to get my temp fairly close and a couple yellows that let me vary keeping some blue or going no blue in flouro.

Edited by aviator8

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Hi aviator8. Are you sure those gels you are referencing are optical gels? They look like lighting gels to me - 20x24 inches. If so, they aren't suitable for use as barrier filters in front of a camera lens. They are designed to be placed in front of theatre or filming lights. Of course Lee and others do make a more limited range of optical gels but they are far more expensive.

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Hi aviator8. Are you sure those gels you are referencing are optical gels? They look like lighting gels to me - 20x24 inches. If so, they aren't suitable for use as barrier filters in front of a camera lens. They are designed to be placed in front of theatre or filming lights. Of course Lee and others do make a more limited range of optical gels but they are far more expensive.

they many not be. to be honest I think they are lighting gels. I will have to see how they look with some tests when they get here.

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I think I have a decent non expensive way to move forward. I found this on here:

 

http://wetpixel.com/forums/index.php?showtopic=60293&hl=%2Bvideo+%2Bfilter.

 

Post 4 was very helpful. It included reference to people and material referenced above. What I found particularly helpful was the second link in that post where a guy did spectral analysis on various specific filters elements and shows the results. That then led me to Rosco and Lee filters and the site pnta.com where I could look at spectral graphs of every filter by both companies. Based on the research and data presented I was able to pick out various filters to try as barriers that will range from 500nm cutoff leading to no blue being shown to a 450-500nm cutoff that will allow a range of blue to show back adding the additional color interest to any flouro video. I bought several gels to play with and a ring adapter for my cokin P holder. There should be enough to cut filters and mask barriers for those I settle on since the gels ate 20x24 inches in addition i got a yellow #2208 plexiglass sheet to make a test filter and mask. Since I was at it I got various red to amber gels to use for video on my RX100 V since it does not in camera whitebalance well and can not shoot RAW video. I also picked up a cokin red polarizer to try to see if it varies its red intensity and spectral response for shallow to deep. I was able to get all this for around $100.

 

Here are the filters I will be testing out for flouro and day video

 

flouro:

yellow #2208 transparent plexiglass 1/16 inch 12x12

a made in chine cokin p yellow conversion filter that just appears to be he right color yellow. No stats to verify.

Lee filter yellow 101

Lee filters Spring yellow 100

Lee filter medium yellow 010

Rosco filter Canary 312

 

for daytime video:

a made in china cokin p color conversion filter orange that looks like it may work no published data though

Cokin P161 red polarizer

made i chine 67mm threaded Red "dive filter"

Rosco 22 deep amber

Rosco 25 orange red

Rosco 26 light red

 

 

Hopefully this give me a good mix where I can settle on 1 or two reds that work in the day to get my temp fairly close and a couple yellows that let me vary keeping some blue or going no blue in flouro.

 

Glad somebody found it useful :)

You might want to email Scubalamp and check the wavelength of the blue light...just to make sure it does excite the right spectrum in connection with teh filters. Filter wise, did you consider Wratten 8,9 or 12? There is quite a few on ebay US, rather cheapish.

Good luck and have fun! And post your findings when you are back - dyi fluro guide in teh making :D

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Glad somebody found it useful :)

You might want to email Scubalamp and check the wavelength of the blue light...just to make sure it does excite the right spectrum in connection with teh filters. Filter wise, did you consider Wratten 8,9 or 12? There is quite a few on ebay US, rather cheapish.

Good luck and have fun! And post your findings when you are back - dyi fluro guide in teh making :D

I will post back what I find. I am not sure how many dives I will have but will be able to give some of this a try. I did email scubalamp but they have not answered my question on wavelength. They were very responsive to getting me new o rings though. I did not get any wratten filters but may look if I have time. 12 was recommended but I read somewhere that 15 may let more of the blue wavelength in.

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Posted (edited)

can anyone tell me how I post images in a post? I have tried a few times to post a reply in this thread with some results to a few filter experiments. I can only seem to cut and past the images into the post but when i post it says saving, then the post goes away and never shows up. I do not see an attach option.

 

 

nevermind I figured it out below

Edited by aviator8

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Posted (edited)

Tonight I was able to try some experimentation with the various filter options I have. I cut the gels and plexiglass to fit my Cokin adapter and set everything up on my rig. I set focal length to 60mm, ss 1/60th, f 2.5, and let iso autoadjust. In all pictures it auto selected 3200. I went out with my light in my yard and found a centipede that fluoresced pretty strongly and chose that as my subject. With each filter I shot five frames and tried to keep the same distance but it was dark and i was walking inside and out with each filter to write everything down so there is some variability. I selected the best shot from each group and cropped each so that the centipede is about the same size in each, and i showed some light spill in the right side of the frame on the mulch he was on to judge how much of the blue is making it through the barrier.


The order of shots were as follows


yellow #2208 transparent plexiglass 1/16 inch 12x12
post-90621-0-76737400-1555506453_thumb.jpg
chinese sources cokin p yellow conversion filter that just appears to be he right color yellow.

post-90621-0-18072600-1555506466_thumb.jpg

Lee filter medium yellow 010

post-90621-0-94088400-1555506485_thumb.jpg
Rosco filter Canary 312

post-90621-0-56019500-1555506511_thumb.jpg
Lee filters Spring yellow 100

post-90621-0-08330500-1555506520_thumb.jpg
Lee filter yellow 101
post-90621-0-95706300-1555506525_thumb.jpg


The Chinese sourced cokin sized filter appears to my eye to be the same as the yellow 2208 plexiglass sheet i bought and the images look nearly the same. These were the best to my eye. The lee 101 was a runner up followed by Lee medium yellow 010. The others I did not like. the two acrylic/plexiglass filters do have better optical quality in the samples.

Edited by aviator8

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Now that is some alien thing...didnt even realized they glow :)

Thanks for the pics. Lee 101 indeed looks most balanced. Curious about spring yellow 100 though, kinda like this neonish green. Judging by the wavelength, seems it lets a bit blue in..now if only I can find a glass equivalent...

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Posted (edited)

Now that is some alien thing...didnt even realized they glow :)

Thanks for the pics. Lee 101 indeed looks most balanced. Curious about spring yellow 100 though, kinda like this neonish green. Judging by the wavelength, seems it lets a bit blue in..now if only I can find a glass equivalent...

You feel the 101 looks the most balanced? I felt the 2208 did. and that is easy to get in an acrylic filter that is good enough for shooting. As for the bug that's the only thing in my yard I found that fluoresced. Under normal lights it is black and red. When i turned the light on they popped up all over, far more than I thought were there.

Edited by aviator8

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To give you an idea of the filters relative shades and color here is a picture of them I took the test pictures using them in order from left to right. The ones on top are just extras I cut from the gels. The one you asked about that gave a bluish neon color is the second from the right and has an almost neon yellow color which was the one most unlike the others. I bought gels purely based on their published spectral graphs and where they began to cut out blues.

 

post-90621-0-35407000-1555550598_thumb.jpg

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