Jump to content


Photo
- - - - -

Keldan 8x - flux or CRI?


  • Please log in to reply
14 replies to this topic

#1 TotDoc

TotDoc

    Clownfish

  • Member
  • Pip
  • 21 posts
  • Gender:Male
  • Location:Tampa, FL

Posted 12 November 2016 - 09:08 AM

I am planning on picking up some Keldan 8x lights this year, but I'm stuck on which model to pick up - the 12k flux or 8k CRI model.

 

I plan to do video in a mix of environments - largely cave and reef. And the reef will involve a significant amount of daytime use, possibly even with the cyan filters.

 

Being honest with myself, I likely don't NEED the 12k lumens from the 8x flux, but what I was hoping for is the ability to extend the duration of the light without needing a battery change by dialing the light down. For cave rebreather dives, run times can be rather long, and I didn't think that 45 minutes of burn time would quite cut it, otherwise the 4x with 7k lumens would likely have been enough.

 

Anyway, with keeping in mind that I was planning on running the lights at the second highest setting to keep light durations longer, it makes me a little hesitant to get the CRI model of the light, because of the drastically reduced lumen output. Certainly I don't NEED 12k lumens - although in bigger cave passage, there are certainly times I would like to dial it up. My concern is that the CRI version only has 8k lumens - and that is a big drop from the 12k on the flux version. Not only does that significantly decrease the available light output for big passage, but it makes me worried that I won't have enough headroom to decrease the light output for the majority of the dive to extend the burn time.

 

I have no doubt that the CRI version will make for some pretty video, especially on the reef. I just don't know if the lower CRI flux version will also be good enough. I am sure there are apparent differences in a side by side comparison, but I really don't know if I would see the difference without a direct comparison - I have never had the chance to work with high CRI lights before. So with all this in mind, I have a couple questions.

 

#1: 82 vs 96 CRI - is the CRI bump alone worth accepting a 33% decrease in lumen output from 12k to 8k?

 

#2: Even in a cave environment with no natural light, am I overestimating the importance of lumen output? For example - is 3-4k lumens enough, and 12k lumens would never really be useful anyway?

 

#3: If CRI of 82 IS good enough that the CRI version isn't really necessary, AND I am overestimating the importance of lumen output here, am I better off just getting the 4x lights at a significantly decreased cost?

 

Thanks for your input!

 



#2 Byron

Byron

    Triggerfish

  • Member
  • Pip
  • 45 posts

Posted 12 November 2016 - 01:01 PM

Great post, I shall be monitoring answers with interest


Sent from my iPhone using Tapatalk

#3 dreifish

dreifish

    Sting Ray

  • Member
  • PipPipPip
  • 205 posts
  • Gender:Male
  • Location:SE Asia

Posted 12 November 2016 - 11:17 PM

I think part of the answer will turn on what sort of camera you'll be filming with.

 

Inside a cave, you have no ambient light to outcompete, so the strength of your lights is less crucial if you have a camera that can film clean video in low light (e.g. ISO 3200, 6400 or even 12800 if filming with something like the Sony A7S/A7SII). This is great, because it means you can run your lights at lower power and still get nice footage. For reef shots, a camera with high sensitivity won't help much because it'll be equally sensitive to the ambient light, and what you want to do is have your torches brighter than the ambient light in order to bring back the full spectrum of colors. So, for reef scenes, the more powerful your lights, the better. 

 

Also keep in mind the inverse square law of illumination -- light intensity decreases proportionately with the square of the distance from the light source. What this means, in practice, is that no light will strongly illuminate objects very far away. Importantly, it also means that varying the distance to the object you're trying to illuminate will be more effective than increasing the power of the light source. 12k lumens may be 50% brighter than 8k lumens, but in terms of reach, you're only increasing the light's reach by around 22%. (In other words, the 12k lumen light will produce the same illumination at 1.22m away as the 8k light would produce at 1m away). I don't don't dive in caves, so I can't really opine about how much of a difference the stronger light would make from experience, but, based on the above, I would say there's diminishing returns to increasing light intensity if your goal is to illuminate more of the cave. 

 

Regarding 82CRI vs 96CRI -- I haven't seen any specific tests done underwater. I've used some 70CRI lights in the past and use 90CRI lights currently. My impression is that the higher CRI lights tend to produce richer shades of red and yellow. Is it a major difference? I doubt someone could look at footage blindly and tell you if it was filmed with 82CRI lights or 96CRI lights, because there's so many other variables confounding the final result (strength of the lights relative to the strength of the ambient light, etc)  Now, if you were comparing them side by side, you'd probably see a difference. Maybe. But even then you'd be confounding it because one light is stronger.

 

Once you add cyan filters, CRI goes out the window since by definition the cyan filters are stripping out the reds and the yellows. With cyan filters, neither light is going to have a particularly good CRI. 

 

If you're still confused, to what I did -- get the Gates GT14 lights. 90CRI and 14000 lumens -- best of both worlds :)



#4 TotDoc

TotDoc

    Clownfish

  • Member
  • Pip
  • 21 posts
  • Gender:Male
  • Location:Tampa, FL

Posted 13 November 2016 - 09:14 PM

I think part of the answer will turn on what sort of camera you'll be filming with.

 

Inside a cave, you have no ambient light to outcompete, so the strength of your lights is less crucial if you have a camera that can film clean video in low light (e.g. ISO 3200, 6400 or even 12800 if filming with something like the Sony A7S/A7SII). This is great, because it means you can run your lights at lower power and still get nice footage. For reef shots, a camera with high sensitivity won't help much because it'll be equally sensitive to the ambient light, and what you want to do is have your torches brighter than the ambient light in order to bring back the full spectrum of colors. So, for reef scenes, the more powerful your lights, the better. 

 

Also keep in mind the inverse square law of illumination -- light intensity decreases proportionately with the square of the distance from the light source. What this means, in practice, is that no light will strongly illuminate objects very far away. Importantly, it also means that varying the distance to the object you're trying to illuminate will be more effective than increasing the power of the light source. 12k lumens may be 50% brighter than 8k lumens, but in terms of reach, you're only increasing the light's reach by around 22%. (In other words, the 12k lumen light will produce the same illumination at 1.22m away as the 8k light would produce at 1m away). I don't don't dive in caves, so I can't really opine about how much of a difference the stronger light would make from experience, but, based on the above, I would say there's diminishing returns to increasing light intensity if your goal is to illuminate more of the cave. 

 

Regarding 82CRI vs 96CRI -- I haven't seen any specific tests done underwater. I've used some 70CRI lights in the past and use 90CRI lights currently. My impression is that the higher CRI lights tend to produce richer shades of red and yellow. Is it a major difference? I doubt someone could look at footage blindly and tell you if it was filmed with 82CRI lights or 96CRI lights, because there's so many other variables confounding the final result (strength of the lights relative to the strength of the ambient light, etc)  Now, if you were comparing them side by side, you'd probably see a difference. Maybe. But even then you'd be confounding it because one light is stronger.

 

Once you add cyan filters, CRI goes out the window since by definition the cyan filters are stripping out the reds and the yellows. With cyan filters, neither light is going to have a particularly good CRI. 

 

If you're still confused, to what I did -- get the Gates GT14 lights. 90CRI and 14000 lumens -- best of both worlds :)

That's really helpful information! Good point about the sensitivity of the camera. Unfortunately I am using an olympus OMD and a gopro for my video, not a high sensitivity monster like what you mentioned. I'll have to push some lumens to make things pretty! ;)

 

VERY good point about the filters, though. I guess if I am considering using those, I might as well go for the higher lumens for the reef work, and worry less about the CRI. I'm also happy to hear that there probably isn't a major difference between the 82 and 96 CRI lights if they are not side by side. I would really like to make sure I am getting good lighting if I am dropping this much cash on lights, but let's be honest - I'm not paying my bills based on this video.

 

As much as I love your suggestion of getting the best of both worlds with the gates lights, they are just outside of my pricepoint. I really wish I could pull those off - they look awesome!

 

Anyway, thanks so much for all your input!



#5 Robotten-usa

Robotten-usa

    Starfish

  • Member
  • Pip
  • 7 posts

Posted 29 July 2017 - 02:16 PM

I am not sure if this thread is alive but here goes:

 

I have recently purchased 2 Keldan 8x Flux Video lights with the blue medium M1 filter attachments http://keldanlights.....html?ridcat=66 from the wetpixel classified forum. They are the 12,000 lumen, 82 CRI version.  I am now looking further into this and am trying to determine if I need to add one of Keldan's red filters to the camera lens when using the lights.  These remind me of the RED filters from Backscatter's GoPro FLip system.  Here is a link to Keldan Spectrum filters. http://keldanlights....ters/index.html  I am shooting a Sony a7RII with 90 mm Macro and 16-35 Wide angle setup.  Also, have 2 z240 INON strobes.  

 

Thanks for any input...



#6 bubffm

bubffm

    Sting Ray

  • Member
  • PipPipPip
  • 279 posts
  • Gender:Male
  • Location:Germany

Posted 30 July 2017 - 03:58 AM

Hi,

 

I own the Keldan M1 Blue Filters as well. I did not try them out with Keldan's own red filter but with the URPRO red filter on my Gates AX100 setup. Honestly, I was not all that impressed with the results. 

 

The filters absorb an absolutely ENORMOUS amount of light. Your 12,000 lumens will go down to effective around 6.000 lumens with those filters on. For good reason, you see the guys in the marketing-clip for those filters using a total of four Keldan lights... They are good for very specific situations, like where you are in a cave, want to film out into the blue and avoid "red" walls left and right.  Or if you are on a shark dive, getting really close and want to avoid red belly's.  For anything else, forget them. 

 

Mine are sitting in the drawer pretty much unused, probably should go into classified as well :)

 

Burkhard



#7 Davide DB

Davide DB

    Tiger Shark

  • Member
  • PipPipPipPip
  • 613 posts
  • Gender:Male
  • Location:Rome, Italy

Posted 31 July 2017 - 06:12 AM

I have a pair of (old) Luna-8 CRI. Maybe 6000 lumen or less. Before of these I had a pair of FIX 5000 lumen. 

I was satisfied with my FIX except for lumne output. I mostly do tech dives with older camera and more (light) is better. Nowadays I thing that 6000 lumen is the bare minimum.

Despite of light power I love my Keldan. I cannot say that in water the light is different but I realize that since I use them my video colors are nearly ok out of the camera. I mean that I spend less time in post to get colors right (err, actually colors I like).

Now with newer camera you can easily work at ISO 1600 and beyond while on my camera ISO 1000 is the highest I can afford.

I agree that on shallow waters you need very high power lights. I find deeper shots quite easy because you have just to manage light output and nothing else. On shallows shot it's very tricky to get good color rendering.


Disclaimer: Your new gear will not make you produce any better art than you already do.
https://vimeo.com/bocio/

#8 Laval

Laval

    Hermit Crab

  • Member
  • Pip
  • 3 posts
  • Gender:Male
  • Location:Toronto
  • Interests:UW videography: macro and wide angle

Posted 14 September 2017 - 05:36 PM

Hi,

 

I own the Keldan M1 Blue Filters as well. I did not try them out with Keldan's own red filter but with the URPRO red filter on my Gates AX100 setup. Honestly, I was not all that impressed with the results. 

 

The filters absorb an absolutely ENORMOUS amount of light. Your 12,000 lumens will go down to effective around 6.000 lumens with those filters on. For good reason, you see the guys in the marketing-clip for those filters using a total of four Keldan lights... They are good for very specific situations, like where you are in a cave, want to film out into the blue and avoid "red" walls left and right.  Or if you are on a shark dive, getting really close and want to avoid red belly's.  For anything else, forget them. 

 

Mine are sitting in the drawer pretty much unused, probably should go into classified as well :)

 

Burkhard

 

 

In addition to Burkhard's comment above, could someone who has been using red lens filter and and Keldan Ambient Light Filters (http://keldanlights....nt-filters.html) share their experience as well?

 

I am considering buying Keldan video lights (8X 11000lm CRI92) in combination with a red lens filter and ambient light filters.  From my correspondence with Keldan and this forum, I see some theoretical  benefits of using this set up.  For example, if I am shooting a giant manta say at 30-40 ft (10-13m) and I have red lens filter and lights with ambient filters on, and I will start shooting when manta is far away from me, red lens filter will help to correct color, but lights will have no impact because of the distance.  Then, when manta get closer, ambient light filter will compensate (cancel) red lens filter and I will get a perfect white manta's belly.  Am I correct? 

 

This is all theory, at least my understanding of it.   

My camera is Sony A7Rii.

Many thanks.

 

#9 rollin

rollin

    Triggerfish

  • Member
  • Pip
  • 35 posts
  • Gender:Male
  • Location:Belgium
  • Interests:Aquatic ecology, wildlife photography

Posted 15 September 2017 - 01:55 AM

Keldan and Gates are very tempting, but quiet expensive. Are the Kraken lights an alternative? (called Weefine in Europe) The Solar 5000 has a cri of ra80 according to their site. This seems OK for the price.
 


Edited by rollin, 15 September 2017 - 07:21 AM.


#10 kc_moses

kc_moses

    Great Hammerhead

  • Member
  • PipPipPipPip
  • 826 posts
  • Gender:Male
  • Location:South Florida
  • Interests:Cooking, baking, diving, videography, landscape and food photography.

Posted 15 September 2017 - 05:18 AM

 

 

 

In addition to Burkhard's comment above, could someone who has been using red lens filter and and Keldan Ambient Light Filters (http://keldanlights....nt-filters.html) share their experience as well?

 

I am considering buying Keldan video lights (8X 11000lm CRI92) in combination with a red lens filter and ambient light filters.  From my correspondence with Keldan and this forum, I see some theoretical  benefits of using this set up.  For example, if I am shooting a giant manta say at 30-40 ft (10-13m) and I have red lens filter and lights with ambient filters on, and I will start shooting when manta is far away from me, red lens filter will help to correct color, but lights will have no impact because of the distance.  Then, when manta get closer, ambient light filter will compensate (cancel) red lens filter and I will get a perfect white manta's belly.  Am I correct? 

 

This is all theory, at least my understanding of it.   

My camera is Sony A7Rii.

Many thanks.

 

 

Here is your answer:

 



#11 Laval

Laval

    Hermit Crab

  • Member
  • Pip
  • 3 posts
  • Gender:Male
  • Location:Toronto
  • Interests:UW videography: macro and wide angle

Posted 16 September 2017 - 10:32 AM

Thank you for the link.



#12 Pyroracer

Pyroracer

    Clownfish

  • Member
  • Pip
  • 22 posts

Posted 02 December 2017 - 08:04 PM

Here is your answer:

 

Has anyone else tried this? The red filters together with the ambient light filters. I'd be interested to know your experience and if it has helped lessen the work needed for color grading in post. 



#13 kmhanson

kmhanson

    Clownfish

  • Member
  • Pip
  • 21 posts

Posted 04 December 2017 - 03:56 PM

Has anyone else tried this? The red filters together with the ambient light filters. I'd be interested to know your experience and if it has helped lessen the work needed for color grading in post. 

 

Yes, I have this setup. It is great for a mixed environment where you are shooting ambient and then move to an area (or the animal gets closer) where you want lights. You don't need to change white balance. I love that you sometimes can't even tell there are lights being used....like on schooling fish! 

 

There are negatives as outlined by previous posters.

 

-kevin



#14 dreifish

dreifish

    Sting Ray

  • Member
  • PipPipPip
  • 205 posts
  • Gender:Male
  • Location:SE Asia

Posted 06 December 2017 - 12:11 AM

 

Yes, I have this setup. It is great for a mixed environment where you are shooting ambient and then move to an area (or the animal gets closer) where you want lights. You don't need to change white balance. I love that you sometimes can't even tell there are lights being used....like on schooling fish! 

 

There are negatives as outlined by previous posters.

 

-kevin

... there's a reason you can't even tell that the lights are being used -- because they're essentially outputting so little light after the addition of the filters that it barely makes a difference whether you have the lights on or not except in extreme situations where the foreground subject is practically touching your dome and you need to fill in those shadows. 

 

They're nice for that use case, but that's about it. Don't expect them to matter in the majority of your shooting.

 

As for the red filter on the lens, basically what this does is the equivalent of setting a much higher (warmer) white balance in camera. So it can be helpful if your camera otherwise can't push a very warm white balance for video (Sony is the worst offender here), but completely unnecessary if your camera can (e.g. Canon DSLRs). But consider this -- those really high white balance settings tend to be needed at significant depth, where your ambient light video isn't going to look great (or natural) anyway, because you're trying to bring back colors that simply aren't there anymore. 



#15 Pyroracer

Pyroracer

    Clownfish

  • Member
  • Pip
  • 22 posts

Posted 07 December 2017 - 04:31 AM

 

 

 

In addition to Burkhard's comment above, could someone who has been using red lens filter and and Keldan Ambient Light Filters (http://keldanlights....nt-filters.html) share their experience as well?

 

I am considering buying Keldan video lights (8X 11000lm CRI92) in combination with a red lens filter and ambient light filters.  From my correspondence with Keldan and this forum, I see some theoretical  benefits of using this set up.  For example, if I am shooting a giant manta say at 30-40 ft (10-13m) and I have red lens filter and lights with ambient filters on, and I will start shooting when manta is far away from me, red lens filter will help to correct color, but lights will have no impact because of the distance.  Then, when manta get closer, ambient light filter will compensate (cancel) red lens filter and I will get a perfect white manta's belly.  Am I correct? 

 

This is all theory, at least my understanding of it.   

My camera is Sony A7Rii.

Many thanks.

 

 

 

 

 

Yes, I have this setup. It is great for a mixed environment where you are shooting ambient and then move to an area (or the animal gets closer) where you want lights. You don't need to change white balance. I love that you sometimes can't even tell there are lights being used....like on schooling fish! 

 

There are negatives as outlined by previous posters.

 

-kevin

 

 

... there's a reason you can't even tell that the lights are being used -- because they're essentially outputting so little light after the addition of the filters that it barely makes a difference whether you have the lights on or not except in extreme situations where the foreground subject is practically touching your dome and you need to fill in those shadows. 

 

They're nice for that use case, but that's about it. Don't expect them to matter in the majority of your shooting.

 

As for the red filter on the lens, basically what this does is the equivalent of setting a much higher (warmer) white balance in camera. So it can be helpful if your camera otherwise can't push a very warm white balance for video (Sony is the worst offender here), but completely unnecessary if your camera can (e.g. Canon DSLRs). But consider this -- those really high white balance settings tend to be needed at significant depth, where your ambient light video isn't going to look great (or natural) anyway, because you're trying to bring back colors that simply aren't there anymore. 

Thanks for the feedback guys. Seems like this is a good path for my offending Sony a6500 =p I plan on getting the Keldan 8x as well with the filters as it's really hard to get a good WB with the Sony's. I remember my go pro days when using a red filter and sola f2000 lights was a world of a difference. 

I wonder how your experience is Laval with your Sony A7Rii. I know the WB on that is just as bad and we always get an error when doing manual WB although I know they work.