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Monday, March 07, 2011

Q&A: Bleeding Power from Big Lights with Big Mods

Manila-based Diego Lorenzo Jose asks:

Could you share how you use the ND gel sheets on your big lights? I'm wondering how I could maybe use them on my monolights with big modifiers like a giant octa or softbox.

The good news is that's actually pretty easy, Diego. And you might not even need to buy any ND gel, either.
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First off, Diego brings up a good point. Too much light output can be a problem with big lights even at the bottom of the range. That was one thing I had to solve with my Profoto Acutes. Lately, monobloc makers are getting savvy about this. Einsteins, for example, drop down to about 3 watt-seconds.

But even if your mono will go as low as you want, you might not want to hang out at the lowest power setting. For one thing, if a color shift is gonna happen, it tends to happen at the extreme end of the power range.

Another reason is that you lose flexibility. You cannot dial out more power from the bottom of the range if your light turns out to be too hot, or you need less depth of field.

Looking at some of Diego's recent work, I am gonna guess he is looking to combine big, soft light sources with wide open apertures. (A nice look.) With most big soft boxes and octas, doing that is easier than you think.

To avoid the problems above, consider setting your flash a couple of stops above the minimum power level. You'll still have a very fast recycle, but you will be in the middle of your power range for better color temperature. And/or you'll have the ability to dial the power up or down easily.

With ND (neutral density) gels, you can knock out some of that power very easily. And it's not as if you need to cover up every square inch of the front surface, as you might if you were gelling for exact color. If you can knock the light down before it gets to the front diffusor, you do not need to be so exact.

I like to use the internal baffle panel as a good platform from which to kill light. Just paper clip a piece of black construction paper to it, making it partially opaque. You get some spill around the edges, so it is not an exact science. But the general rule of thumb is to cover half of the panel to knock out one stop, 3/4 of it to knock out two stops, and so on.

If keeping the exact quality of the light is important, cover the panel in an even way -- in center, stripes, whatever. But you may find it easier to just work from one side, and you might end up creating a more interesting final light source in the process.

Diffuse the panel from one side and you'll get a light that is a little hotter on one side (or top or bottom) than the other. Rotate your light and see if this effect works for you in the final image. If not, blog the internal baffle more symmetrically.

While we are on the subject, you should experiment with your boxes and octas to see what kind of light quality you get without the baffle, or front panel, or both. It will be more specular, and can even act more like a giant, shiny beauty dish. Definitely worth your time to check it out.

But as for dropping the power, that's cheap and easy. It's getting all of that power in the first place that is expensive.


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19 Comments:

Blogger Josh said...

I often just take a piece of ND gel and gaffer tape it to the rods of the softbox right in front of the lightsource.You basically make a second diffuser panel out of ND gel. I have also used tissue paper when I was in a pinch. Works great, it's totally even, and it's really easy to do.

March 07, 2011 1:03 AM  
Blogger Diego Lorenzo Jose said...

Hi David! Not only am I interested in ND-gelling the big light sources, I'd also like to color-gel them (CTO, Plus-green etc) for various applications.

Thanks for the big help! I'm gonna play around with a few rolls of gels!

Diego

March 07, 2011 1:11 AM  
Blogger Simone said...

But is there any difference in gelling a light at the source (I usually fully cover the bulb with the gel, taking off the modeling light) and gelling the diffusers (that requires a larger gel, sometimes too large)?
I'm speaking of color gels but I think with the NDs it's almost the same thing.

March 07, 2011 7:41 AM  
Blogger John Perkins • Photographer said...

Great post. If anyone's interested in gelling their Paul C. Buff PLM's I just blogged about that Sunday here:

http://www.johnperkinsphotography.com/?p=57

Thanks.

March 07, 2011 9:42 AM  
Blogger Jon said...

YES!!!

I regularly use a 5 foot softbox without the front panel. I get amazing wraparound, I can get the box much closer to my subject than I otherwise could, and it's essentially a giant rectangular beauty dish with diffusion in the center and bounce around the sides.

I particularly love using it that way for high key shots. I position it 30 to 45 degrees above the subject's head and point down, as is common with a beauty dish. It not only lights the model nicely, but the floor of my high key cove as well, and that's often the hardest part to light in a high key setup.

LOVE softboxes without the front diffusion panel!

March 07, 2011 10:59 AM  
Blogger Stylish Imagery said...

An aspect of this that was not mentioned is the size of gel. You won't get the same result if you place a small gel close to the head, versus a big gel further from the head. Especially with CTO - the more effect will happen with the bigger the gel. You really need to use a white card to color correct the image.

March 07, 2011 1:20 PM  
Blogger Simon said...

Presuming you're taking your main light down, not just taking an accent to very low levels, or have some other reason to keep "other light" at the current level, you could just put an ND filter over your lens. Way less effort and cost for those situations that it's suitable--though I fully acknowledge that it's not always identical. I do this a lot to bring f/5.6 or wider into play in our glorious f/22 Colorado sunshine.

March 07, 2011 2:02 PM  
Blogger Rod Read said...

I took a photo of my back x-ray the other day, by paper clipping it to the top edge of my softbox.

Hmmm maybe I could use my x-ray as an ND filter... It can't be that far off neutral.

March 07, 2011 3:26 PM  
Blogger Brent said...

Why ND Gel your lights, when you could ND Filter your Camera? I'd rather use some Lee's to get shallow DOF then reduce my light output, and the amount of control I have over the situation

Further more, why not just use a smaller light with your big softbox/ octa ect... I routinely use a HSF or my Quantum in my 50" Softbox or 5ft octa

www.eyslerimaging.com

March 07, 2011 5:00 PM  
Blogger budrowilson said...

Putting an ND filter over the lens blocks all light (ambient and strobe) equally. Sometimes, you don't want to block out the ambient. In fact, blocking the ambient light can also lead to an inability to autofocus.

If we're talking about noon on a bright, sunny day, then yes, an ND filter over the lens makes perfect sense if you want to use studio strobes. However, once the ambient drops, an ND over your monolights tends to make more sense when it comes to balance and ease of shooting...

March 07, 2011 11:37 PM  
Blogger Stylish Imagery said...

Why not ND your lens? Focus problems. I have a new Nikon 85/1.4 G - and even with no ND filter it rarely focuses easily in the studio.

March 08, 2011 3:18 AM  
Blogger Brent said...

Bud, I of course agree to your point there, when we are talking about mixing strives and ambient.

However the original post, both in terms of Hobby's responce and the original questionares work, both seem to be along the lines of a controlled environment, so I'm assuming at sync speed.

Further, as I said before, if you are mixing with ambient, why not switch down to a HSF, my location lighting bag consists of a sb80, a qflash and a b1600, which I use interchangeably in any modifier I have depending on the amount of light I need in that location.

Stylish.... Your in a studio, why not use the modeling lights to make it easier... You have a nikon, its actually good at focusing in the dark, try my mark II sometime.... I actually picked up a tt1 transmitter just because I can use the ste2 ontop for focus assist. I don't have any tt5 recievers, or ever use ttl.


www.eyslerimaging.com

March 08, 2011 9:01 AM  
Blogger Jeff Freeman said...

Dave,

Thought that while my humor might have been a little off, poking fun at your "blog" the light (instead of block light typo) might have been a little off, I thought the SB900 was also a viable backup solution, and all of it didn't fall into this definition of a reason to spam / block my comment:

> While links to your site are permitted, comments which appear to exist primarily to let other people know about your site will not be moderated into publication.

I've had comments previously posted. Just asking you to reconsider as I am still looking forward to the workshop here in Portland.

Anyway it was meant to be helpful and participate in legit discussion. I'm guessing you were skimming too quickly to get the intended read on it, as you likely have 80 million last second things to do to prep for the crazy tour.

Cheers,
Jeff

March 08, 2011 11:39 AM  
Blogger David said...

Jeff-

I do not remember the comment you left -- it might have been eaten up by the cloud, to be honest. But I do place a much higher bar (which admittedly can vary) on comments that link back to another site.

I get a lot, lot, lot of that -- sometimes multiple comments with "helpful links" :) -- in a 5-minute period.

Not calling you a spammer. Just saying that if you are also trying to point people to your site, you have to be a better commenter, too.

If I didn't do that, you would not want to see the comments section -- trust me.

The comments exist primarily to continue/broaden the discussions on the posts. Everything else -- incl posting of links -- is quite secondary to that.

If it makes any difference, I just resounded to this with the entire amount of 'net time I had on my iPhone while changing planes at Chicago Midway.

Hope that puts it into context, and see you in PDX.

:)

-D

March 08, 2011 12:27 PM  
Blogger theotherme said...

"while changing planes at Chicago Midway."

Aren't you supposed to be on a BUS? lol

See you in Chicago!

March 08, 2011 7:03 PM  
Blogger Logan365 said...

or you could add a nd filter to your lens if budget allows, then you could shoot outside at 1.4 or 2.8 as well.

March 09, 2011 9:53 AM  
Blogger Diego Lorenzo Jose said...

Brent > While using an ND filter is great at times, most of the time I don't like it because looking through the viewfinder gets so dark and can be difficult to focus. I'd prefer a bright viewfinder.

I'm not against using an ND filter, but if I can get the same results without using one, I'd prefer not to. If needed, then I will :)

March 09, 2011 10:01 AM  
Blogger Adam Krause said...

I almost always use ND gels with my acute packs when shoot inside. I find it very important to blend ambient light and the strobes to get a rich color palette . In my kit I have 8.5x11 inch sections of ND, ranging from 8 stops to 2 stops. This helps me get readings of f2.8 and 4's out of an acute 2400 pack when shooting at 800 iso at 30th of a second!!!!

here is an example: http://www.adamkrausephoto.com/client/Zoe/adamkrausesample.jpg

March 16, 2011 6:20 PM  
Blogger Diego Lorenzo Jose said...

Hi David,

Is it possible gel a studio light with a PLM (86") modifier mounted? I just got one and would appreciate some tips if it's possible. Not just to ND gel it but also for coloring on-location.

Many thanks!

Diego

May 04, 2011 10:27 PM  

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