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Strobe temperature - cold or warm


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#1 aczyzyk

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Posted 14 September 2006 - 11:35 PM

What I understood reading other threads is that it is a matter of personal taste. The problem is I'm not sure what I prefer. I use warm ones and like the results, but maybe cold ones would be ok too.

Could you show me some samples of unadjusted shots with cold strobes? It would be ideal if there was also a shot of the same subject with warm ones for comparison.

Thanks,

Edited by aczyzyk, 14 September 2006 - 11:35 PM.

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#2 Alex_Mustard

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Posted 15 September 2006 - 04:51 AM

Strobe colour temperature will also effect your water colour. Sounds strange - read my article in UWP Magazine 30 - "Getting the Blues". Sorry for the short answer - I am off diving.

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#3 aczyzyk

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Posted 15 September 2006 - 05:06 AM

It does not sound strange at all, beacause I read your article already :blink:
What I understood is that if I'm happy with colder look of subjects than background remains nice (no need to adjust WB).
My problem is I'm not sure if I like colder look of subjects or not. I need to see some samples to get own my opinion.

I cannot make up my mind if I should get DS-125's or INONs (I love their compact size).
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#4 SilvioMarchena

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Posted 15 September 2006 - 01:30 PM

It does not sound strange at all,

Please forgive me for saying so, but I believe the notion that strobe temp affects ambient is real strange :blink: The predications for such a suggestion demand that everyone does, will or must enjoy only warmer light on subjects. It's really that simple. The opinion that *strobe color temp affects water color* is valid, for everyone else, only upon the condition that a person who likes warm temp on subjects all the time, for some reason goes out and buys cooler strobes and has a preference for water color that isn't dissimilar to Alex's.

What I understood is that if I'm happy with colder look of subjects than background remains nice (no need to adjust WB).

That's correct. But I think "nice" is relative----or better said: personal. I am not a big fan of the blue-screen blue that seems to be the rage on these forums. It is striking, but I don't find it necessarily pleasing.

My problem is I'm not sure if I like colder look of subjects or not. I need to see some samples to get own my opinion. I cannot make up my mind if I should get DS-125's or INONs (I love their compact size).

You may find that you like different temps for different shooting scenarios. I like warm strobe for macro and cooler for wide angle (note: I do not prefer a warm strobe for wide angle), so I carry both Inons and Ikes providing temp options as well as backups.
Cheers,
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#5 james

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Posted 16 September 2006 - 08:32 AM

Hi Manual,

Interesting post and I certainly see your point of view of subject warmth/coolness.

But that's not the point of Alex's post at all - or the article he wrote. His article raises awareness about the effect of strobe color temperature on the "two exposures" that we make when taking a wideangle photo - foreground/strobe and background/ambient.

Let's look at two examples:

If you shoot a 4300K strobe and set your white balance to 4300, you will end up w/ a "properly" exposed foreground and a certain colored water.

If you shoot a 5500K strobe and set your white balance to 5500, you will end up w/ a "properly" exposed foreground and a certain differently colored water.

In the above two examples, the foreground subject will look EXACTLY THE SAME however the ambient exposure will be different.

So in essence, your choice of strobe is affecting your ambient/background exposure.

Cheers
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#6 Alex_Mustard

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Posted 16 September 2006 - 08:52 AM

Thanks James. I should have written that in the article.

This is a new concept so it does have plenty of potential to confuse (as it did not matter in the days of film - as the water colour would remain the same - and the foreground colour would change with different colour temp strobes). But with digital the opposite is pretty much true, as in my experience auto-WB will follow the colour temp of your strobes - meaning that foregrounds will look correct (the auto-WB will pretty much do what James states) and therefore it will effect background blues.

You can check out the effect yourself. Open up a standard Wide Angle shot in a Raw converter and more the Colour Temperature slider between 4300K (a warm strobe) and 5500K (a cool strobe). Ignore the changes in the foreground - but watch what happens to the blue! See how a warm strobe (4300K) produces a richer blue.

Ikelite (purveyers of warm strobes for many years) should pay me! :blink:

Alex

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#7 james

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Posted 16 September 2006 - 08:57 AM

No problem Alex - you can send me my royalty check whenever it's convenient :-)

Cheers
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#8 Paul Kay

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Posted 16 September 2006 - 12:53 PM

James, as another 1D series user, what white balance temperature does ACR indicate if you use the 'white dropper' on a neutral in the foreground? I find the ACR indication to be way lower than I'd expect. Just curious as to why this should be rather than bothered (I'm using Seacam 100s - like Subtronic Gammas).
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#9 SilvioMarchena

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Posted 16 September 2006 - 02:02 PM

Hi Manual,
If you shoot a 4300K strobe and set your white balance to 4300, you will end up w/ a "properly" exposed foreground and a certain colored water.
If you shoot a 5500K strobe and set your white balance to 5500, you will end up w/ a "properly" exposed foreground and a certain differently colored water.

Hello James, I thank you for the comments.
With regard to the subject of strobes changing water color and your two examples------what is changing that water color is your selection of WB, not the strobe. It is really no more involved than that. To suggest that the strobe is changing water color requires a rather convoluted digression predicated upon, in the end, the choice of WB.

I appreciate Alex's methodology, as it applies to his preferences, but obtaining the same blues he likes is just as easily accomplished with a 5500k, 4300k, 5700k or 5400k strobe with that camera set at an appropriate WB, and just as easily you can render a purple water color using the same strobes with a WB setting much much warmer than daylight. I think of strobe and WB, or strobe and emulsion, in a way very similar to balanced light photography. You must balance your strobe temp with your WB temp in a way that renders both artificial and ambient lit portions of the image to your liking. In this case none of the strobe temps currently availble on the market will preclude one from obtaining "richer blues".

To suggest only warm strobes produce bluer blues is to disregard a photographer's preference of foreground color and to exclude the use of a cooler strobe to acquire those results. Because if a shooter likes a more daylight temp in the foreground, and shoots with a warm strobe he will have to cool the image and there goes the "richer blue" the warm strobe is supposed to render.

In regard to Alex's comment that in the film days water color remained the same I have to disagree. With film your emulsion preference, just like your WB preference with digital, had a massive effect on water color regardless of strobe choice. With film, people who really cared/care about such things would, or do, choose emulsions based upon any number of properties, but one of them was almost always how the film rendered the blue water. And during this selection process one would also see which strobe rendered foreground subjects to a personal preference, but no one ever said it was the strobe choice which changed the water color. With film your water color never changed due to strobe temp, but rather due to emuslion and shutter speed. With digital it is precisely the same, except WB replaces the emulsion factor.
Cheers,
Manaul


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#10 acroporas

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Posted 16 September 2006 - 05:05 PM

James, as another 1D series user, what white balance temperature does ACR indicate if you use the 'white dropper' on a neutral in the foreground? I find the ACR indication to be way lower than I'd expect. Just curious as to why this should be rather than bothered (I'm using Seacam 100s - like Subtronic Gammas).


Even more odd, if I set my 5D to K WB and set it to 4800. When I open up the raw up in ACR. ACR says the "as shot" WB is 4300?
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#11 Paul Kay

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Posted 18 September 2006 - 02:06 AM

Hmmm. Must be something to do with Photoshop's interpretation of the Canon data OR somethings very odd about the EXIF info!

To comment on WB. If you shoot RAW then white balance for the foreground (stobe lit) subject matter, then the colour temperature of the strobe WILL affect the water colour. If on the other hand you white balance for a warm foreground with a warm colour temperature strobe, then it won't. But it depends on your preferences. Colour temperature of strobes can be modified for many reasons and background water colour is one.
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#12 manatee19

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Posted 18 September 2006 - 03:55 AM

Talking about film days, I remember that I switched to Ektachrome when I had to shoot in the BVIs in the summertime simply because Kodachrome would always render the water as a greenish mixture.

This is a very interesting topic worth discussing and testing as well.

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#13 SilvioMarchena

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Posted 18 September 2006 - 02:56 PM

To comment on WB. If you shoot RAW then white balance for the foreground (stobe lit) subject matter, then the colour temperature of the strobe WILL affect the water colour. If on the other hand you white balance for a warm foreground with a warm colour temperature strobe, then it won't. But it depends on your preferences.

What Alex said in his article is that you set a cooler WB to capture a bluer ambient background water and the warmer temp strobe will compensate to produce a not-as-cool artificially lit foreground. It's a simple measure that has been around for a long time. Shoot a bluer-biased film for blue water and then light the foreground with a warm strobe to compensate for the blue bias. I heard this in seminars given by Marty Snyderman, Frank Fennel and, I believe, one by Paul Tzimoulis years and years ago. And that is a photographic strategy that I have no argument with. It works. And Alex is as correct today as those three men were two decades ago. I am also quite certain I have read articles, from years ago, by Stephen Frink discussing the matching of strobe temps and emulsions for rendering bluer backgrounds with warmer foregrounds. Velvia and SB-104? It's really old and proven techniques.

And none of those guys ever said a warm strobe makes water bluer.

The plain and simple statement that warm strobes render a bluer blue is simply wrong. Strobe temp does not affect water color (see my rather obvious example below), in this case WB does. Yes, I understand that it may seem silly to make such a distinction, but I believe there is a need to avoid casual unqualified statements that over time become accepted realities. I mean, digital capture is nice, and it may seem magical at times, but it cannot change the laws of physics. And warm strobes do not render bluer water.

If he had only said; "Warm strobes will compensate for a higher WB setting and allow you to make the water look as if contains more blue color, yet maintain comparatively more warmth in your foreground. And if you like cooler foregrounds you can obtain the same blue water with a cooler strobe too"------I would have kept my mouth shut :blush:

Example:
Set in-camera WB at a numerical temp, any temp, shoot the same scene, with same camera settings, with a 5700K strobe and a 4800k strobe. Is there any difference in water color? Open that same image in PS and slide the WB slider left or right to the same extent for each pic. Is there any difference in water color between the two pics at the same WB settings? Strobe temps don't do a thing to the water color.
Cheers,
Manaul


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#14 DuikKees

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Posted 18 September 2006 - 10:55 PM

Manaul, Strobes don't do anything to any color. If a snail is red it will stay red no matter how many strobes you point at it.

I think you are a bit on the letter with this. It is quite obvious that strobes can't change watercolor. I think we all understand it is just a WB-thing.

But thanks for the thourough example. :blush:

Edited by DuikKees, 18 September 2006 - 10:59 PM.


#15 Paul Kay

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Posted 18 September 2006 - 11:30 PM

Manaul

Whilst you make a perfectly valid and theoretically correct point very well, you will see from my previous comment on colour temperature designations from my Canon that this may actually not be quite as easy in practice!
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#16 davichin

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Posted 19 September 2006 - 01:57 AM

Even more odd, if I set my 5D to K WB and set it to 4800. When I open up the raw up in ACR. ACR says the "as shot" WB is 4300?


That also happens to me, nikon user. :blush: it shows "As Shot" temp around 800 degrees less than I shot
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#17 Alex_Mustard

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Posted 19 September 2006 - 04:13 AM

I don't know how many times to type the same thing. But here we go again...

A foreground strobe lit subject should have a "correct" look underwater. If we shoot with a warm strobe then we or the camera has to cool down the WB of the image slightly to render this correctly. If we use a cool strobe we have to warm up the WB slightly to render this correctly. These small WB changes to correct the foreground also have an effect on the background colour. Of course a strobe cannot effect the water colour - but when we adjust the WB to get a correct foreground it has that effect.


We seem to be arguing over semantics. The only thing that will change water colour is the WB. However using different colour temp strobes necessitates using different colour temp WB - to render the foreground subject correctly - and therefore produces a different background colour.

To complicate the picture we also have differences between cameras. Yesterday on my boat we had 4 Canon 5Ds, a variety of Nikons (D100, D70, D200, D2X) and a Fuji S2. The Nikons all produced blue water (as it was underwater yesterday), while the S2 was slightly greener than reality and the 5Ds were all very green - and nothing like it really was. These were all taken of the same subjects on the same dive. Patrick mentionned something similar a couple of days ago.

The differences were very pronounced on the LCD screens, but when I was looking at the images in the evening - when they had been WB corrected in Photoshop - the 5D blues generally were blue again.

Steve Frink is diving with us today, so I will be interested to see how his 1Ds Mk2 compares to the other DSLRs. Certainly from his finished images he gets great blues - which look exactly the same as the ones I get from my Nikon - he gave a talk last night.

Alex

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#18 SilvioMarchena

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Posted 19 September 2006 - 09:45 AM

Manaul, Strobes don't do anything to any color.

Then don't say they do. There are people who may read in on this forum from time time looking, but not asking, for info. And somebody who possibly doesn't have your depth of understanding on this point may be caused to believe he/she has to get a warm strobe in order to obtain deeper blues.

In my mind that is a shame and potential waste of money, all because the obvious, as you claim it to be, wasn't presented with a clarity obvious to people who did not read Alex's article or do not yet have a firm grasp of digital means.
Cheers,
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#19 SilvioMarchena

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Posted 19 September 2006 - 11:46 AM

We seem to be arguing over semantics.


For many of us whose words carry little weight, semantics seldom matter. But you cut a fairly authoritative presence on these forums. And when you say "warm strobes give you better blues", assuming everyone within reading distance fully understands what your intent is or is completely at ease with digital means, then to chance for a distribution of misinformation is rather high. Rather than arguing, I have simply been offering a qualifier to your short statement on this point (though I understand that being in some disagrement with you, on this forum, is not looked upon kindly). Let's be honest, depending on what you prefer in your foreground you can use any strobe, or no strobe, to create the same blue. And depending on the time of day a cool strobe might be preferable for no reason other than it projects better in a medium mostly devoid of red and yellow, let alone that your preference is for daylight rather than something warmer.

I believe I have already said this, but I see your article as spot on with accurate methodology. The technique has been around for decades, well thought out, widely taught and proven. My first exposure to it was a very long time ago when the burning question for uw-photographers was "How do you get a blue, rather than purple, water background and pleasing flesh tones in the foreground?". The only difference is that you are substituting WB/strobe temp where I and others were at the time taught to factor for emulsion bias/strobe temp.

The only thing that will change water colour is the WB.

Shutter speed will have a dramatic effect on the depth of blue in the water. Sorry, couldn't resist :blush:
Cheers,
Manaul


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#20 Paul Kay

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Posted 19 September 2006 - 11:50 AM

To get back to the original question.

I can't show you the difference between using warm and cold strobes because I use warm strobes only. However for what it is worth, here are the advantages:

A warm strobe will tend to counteract any coldness caused by the light travelling through water and 'cooling' down - the amount will depend on the flash to subject distance and the water 'cooling factor' both of which may be variables.

Also as a result of this skin tones will generally tend to render better.

Adjustment of the background colour may achieve results as discussed already.

I wouldn't go back to a colder strobe now although for macro its colour is less of an issue. Given the choice I'd always go for a warmer strobe.
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