Which gels for balancing strobes with artificial light

[feppe]

I have Elinchrom D-Lite it 4s, and have an upcoming shoot in a rented apartment with light fixtures - some fluorescent, some incandescent. I've only shot in studio with strobes thus far, so using gels for color correction is a new concept for me.

I believe this kit (http://www.bhphotovideo.com/c/product/45233-REG/Rosco_RS090901210_10_x_12_25.html) should cover my bases with CTO and green filters. Is this something which would be sufficient for both small format digital, and MF and LF film, or do I need some other filters as well?

Also, I understand that with fluorescent I should use a shutter speed of 1/100 or 1/50 in Europe (50hz electricity) to ensure even color balance from shot to shot.

[Kirk Gittings]

Thats what I used for film, but frankly I haven't jelled a light since going digital. I correct in post. I let the incandescents go warm (tweaking it with HSL in LR or saturation adjustment layers in PS) and correcting the the green cast from the fluorescents in the same.

[feppe]

It sounds like a huge PITA in post with mixed sources? For example, having background in orange cast and subject in mostly in good color balance, but with some bleed from ambient light, more in some places, less in others.

I scan my slides, but would prefer to do things right in-camera unless it really is easier to do in post.

[Heroique]

I’ve enjoyed success with Lee’s filter set for shooting w/ tungsten film under fluorescent lighting.

Depending on one’s equipment, technique & aims, the set can also useful under mixed lighting.

Here’s a lot more detail...

The set includes 7 4”x4” polyester filters – that is, 3 filters for your lens, plus 4 filters to place over your flash (to make sure its light is also appropriate).

The 3 lens filters (framed 4”x4”) convert light to Tungsten, 3200 Kelvin:
1) FL3600-B: Balances warm-white tubes
2) FL4300-B: Balances white tubes
3) FL5700-B: Balances daylight/cool white tubes

The 4 flash filters (unframed 4”x4”) are:
1) Full CTO
2) ½ CTO
3) Quarter CTO
4) Plus-Green

Lee recommends “starting points” for combining the lens filters w/ the flash filters.

For example:

1) FL3600-B: use “½ CTO” + “Plus-Green”
2) FL4300-B: use “¼ CTO” + “Plus-Green”
3) FL5700-B: use “Plus Green”

-----
And w/ tungsten film, under tungsten (not fluorescent) lighting, one can use the flash filters (w/o the lens filters) to correct the flash. For example, the “Full-CTO” would change one’s flash to tungsten levels, about 3200 Kelvin. Or the “Full-CTO” + “Quarter-CTO” would warm flash a bit more…

[Peter De Smidt]

If you shoot film, you'll have to pick daylight or tungsten film, and you'll want to balance your light sources to that standard, keeping in mind that some variation could be aesthetically effective, such as tungsten source appearing a bit warm. I suggest using tungsten balanced film. You'll then need to gel your flashes, possibly with a full-cto (color temp orange). You'd then need to wrap the fluorescent light sources with the proper gels. If they're long tubes, you'll need bigger gels than listed in your kit. Make sure not to start a fire! This is especially true of the gels on your strobes. Make sure there's some space for air movement, and don't use the modeling lights for any longer than you need to. I had some diffusion mylar get a little toasted the other day. You're going to have to run some tests.

With digital, white balance to tungsten and then gel the other sources as before.

Since you're going to be doing some tests anyway, you might as well try Kirk's way as well, since it's a lot easier, and he knows what he's talking about. (Check out his site.)

[Frank Petronio]

A modern film like Portra 400 color negative will be more forgiving than the old over-saturated chromes we used to have.

It is quite expensive to gel a lot of existing lights... you might do better with a Photoshop class.

[Uri A]

I always have a few sheets of half and full CTO and a few wooden clothes pegs in my tripod bag .. costs a few bucks and can save hours of retouching.

[feppe]

Yes, I'm aware of Kirk's (and Frank's) credentials :) I'm looking for the least painless and most cost-effective solution.

I'm quite proficient with PS, but from past experience color balancing in post is difficult especially with mixed lighting - that's why I thought it might make more sense to balance it in-camera with lights.

Peter (and others): since I'm scanning the chromes anyway, wouldn't it work to try to balance Astia to a common denominator using gels at lights, eg. CTO. The resulting color balance would be off, but it would be consistently off across the frame - and could be easily tweaked with a global adjustment in PS/LR.

I know that's probably frowned upon by purists, but on surface it sounds like it would work? I don't do darkroom, and only shoot color slides. It would be quicker to fix a global balance over fixing each color source, bleed-through and reflection.

Or am I making it too complicated?

[Peter De Smidt]

I'm looking for the least painless and most cost-effective solution.

Yet you want to shoot 4x5 Provia in a mixed light situation. ;)


since I'm scanning the chromes anyway, wouldn't it work to try to balance Astia to a common denominator using gels at lights, eg. CTO. The resulting color balance would be off, but it would be consistently off across the frame - and could be easily tweaked with a global adjustment in PS/LR.

I'm not sure what you're suggesting. If you use a daylight film, like Provia, you can put the appropriate blue filter on the camera to make the film neutralish with tungsten lights. You would then still need to add magenta gels to the fluorescent lights (and possibly some cto) and cto gels to your flashes.

If what you're suggesting is to do what I just said but omitting the blue filter on the camera, then it could work ok, but it's possible that you max out the yellow response of the film, which could lead to poor color even after the global correction.

The difficultly with all of this is that light sources can vary from standard, and how all the various light sources and filters effect the film can be a little unpredictable. Thus, the need for Polaroids, which unfortunately didn't match the chromes all that well, and as a result took a lot of experience to interpret correctly.

For all of this see Norman McGrath's pre-digital book on architectural photography.

Using a digital camera, and "proofing" the setup on site with big files would be a huge help, even though the response of the digital sensor will not be exactly the same as the response of the film.

The number of light sources, whether there will be movement in the frame, and how much depth of filed you need effect what makes the most sense to do. When you filter, you lose light; and when you get long exposures, you'll get color shifts on your film. Tungsten film tends to minimize that.

[Daniel Stone]

an FLD(flourescent to daylight) filter(s) for the fluorescent bulbs, and a CTB(LEE #201 filter) for converting tungsten to daylight.

just be aware, that not all bulbs are the same, and variance in tungsten and flourescent bulbs in terms of color temperature is quite common. When using more "professional" bulbs like those in Arri/Mole "hotlights", those bulbs are built to a higher standard than your run-of-the-mill household bulb.

not to dissuade you, but getting a couple sheets each of FLD and CTB filters will help convert your mixed sources more towards a daylight balance.

best of luck!

-Dan

[Uri A]

I assisted many big-name architectural & interiors photogs in NY, Paris, Sydney, etc for many years.

I agree w you about getting it right in camera. This is how the pros did it when I was assisting - because they had to. No retouching budgets back then :) But that takes time and effort and some equipment - There's no magic film or trick that'll get it right for you! You need to balance every single light source.

As Dan says, there's many different bulbs and CTs out there, so if you want to get it right in camera, as Heroique says, carry a swag of gels & filters (all this stuff is practically free second hand, now that everyone can "fix it in post"). CT meters which used to cost $2000 are very cheap now too.. although none of this absolves you of the need to shoot some polaroids.

It doesn't have to be LF .. just use a MF polaroid back on your smaller cameras. Even if the polaroid doesn't "match" the chromes, as Peter correctly suggests, all you are looking for is a correct balance of colours, even if they aren't 100% realistic - although I actually think FP100C is a pretty decent reflection of daylight colour; certainly better than the old 669's used to be..

Finally, although you are committed to chromes, I have to agree with the comment about Velvia/Astia simply being the wrong tool for the job. These films are made for landscapes and are very unforgiving of mixed CTs. If you want saturation, bump it up in the scan! In all my years I never saw a pro shoot these films for interiors/architecture. Most common was E100G, which is a fine film. I would suggest pushing 1/3 stop from the exposure on FP100C to clean out the highlights a little and boom - perfect every time.

Good luck!

[Uri A]

About the shutter speeds: I think you'll find that on 100 speed film, indoors and wanting to achieve decent depth of field, you'll probably be shooting much slower speeds (1/15 and slower) and flickering won't be an issue.

[feppe]

Thanks for all the tips - this is (perhaps not surprisingly) complicated. The shoots are portraits and pinups, not architecture, which is why I'm shooting Astia (and testing EPP). So longer shutter speeds are not really an option.

I'm an amateur so I have all the time in the world for post processing, but would obviously prefer to spend more time shooting than in front of the computer. I'm using digital for chimping so that should help with balancing the lights. As suggested, using gels to get a "correct" color balance in-camera although it might not be realistic, throwing in a ColorChecker Passport for main light balancing, and fixing rest in post seems to be the best approach.

Do they make 5600K light bulbs to replace those in the fixtures? Then I would only have the fluorescents to worry about.

[Peter De Smidt]

Sure, for instance: http://www.bhphotovideo.com/bnh/controller/home?O=Search&A=details&Q=&sku=19239&is=REG&addedTroughType=search

Note that these bulbs run hot! You can also get high cri daylight cfl bulbs, which'll run a lot cooler.

[Frank Petronio]

Well if you are trying to do portraits and pin-ups with short shutter speeds yet also desiring to capture the mixed ambient lighting then you are setting yourself up for a very challenging situation.

Filtering your lens will only kill your film speed. You really should use Portra 400 for the speed. And you should probably swap the fluorescent tubes with Daylight-Full Spectrum tubes (expensive) and put the strongest wattage gelled Halogens in the incandescent fixtures so you have the brightest possible ambient light. And shoot close to wide open. And use experienced models who take direction and can hold still for longer exposures, down into the 1/8-sec range.

And a lot of testing....

Most sane photographers would only do this with digital as you are approaching the limits of what can be done economically and physically.

[Henry Ambrose]

I appreciate you wanting to do this the old way. But you're not going to get there by asking questions. You have to film test every part of lighting you're using or you're guessing, no matter who told you it would work.

Use color negative and correct after you scan. Everything else is way harder and costs lots more. Let the incandescent lights look a little warm, the fluorescents a bit cool - don't correct them completely. That's how they really look compared to daylight.

You're lighting the models with your daylight flash so they'll be fine - there's nothing to fix there other than maybe a bit of pollution that might occur from your ambient sources.

[feppe]

I'm not trying to capture the ambient lights - if strobes overpower them, great, makes my life easier. Obviously they will show up when they're in the frame, but if there's limited or no impact from them on the subject or background, it sounds like I should be ok.

And that's how I learned to stop worrying and love the... unfiltered lights?

Thanks again, time to start doing testing and preparation!

[Uri A]

This (http://www.amazon.com/Morris-Slave-Flash-Seconds-Number/dp/B000B75VSS) is what you need.

Have fun!

[Frank Petronio]

Ah I remember those little Morris flashes.

Glad I forgot them!