strobe lights and contrast

[fix-erUpper]

Hi. I'm curious about the relative contrast measured from model lights compared to strobe lighting. If I compose a model using model lights, and use a spot meter to determine the contrast (f-stop range) between the most important shadow and the most important highlight, will that same contrast be maintained when the strobes are fired?

 

[MattKing]

Hi. I'm curious about the relative contrast measured from model lights compared to strobe lighting. If I compose a model using model lights, and use a spot meter to determine the contrast (f-stop range) between the most important shadow and the most important highlight, will that same contrast be maintained when the strobes are fired?

Interesting first post.

It depends on your lights.

Some modeling lights do a very good job of "modeling" the character of the flash tubes, while others don't.

The location, shape and built in diffusion in the modeling light all have an effect on the result.

As does the relative response of the flash tubes and modeling lights to any variable power settings on the units.

 

[ParkerSmithPhoto]

You need a flash meter. Personally, I just take one reading with the flash meter and then do the rest of it visually. I've never bothered with lighting ratios or any of that. It's an unnecessary complication. Shoot a Polaroid or use a DSLR and make the adjustments as you SEE them.

 

[RalphLambrecht]

Hi. I'm curious about the relative contrast measured from model lights compared to strobe lighting. If I compose a model using model lights, and use a spot meter to determine the contrast (f-stop range) between the most important shadow and the most important highlight, will that same contrast be maintained when the strobes are fired?

to be sireI'd measure the contrast with a light meter.model lights give an indication when placing the lights but they are not an accurate prediction of the actual flash lighting situation.:alternatively, you could use a Polaroid or a digital camera to judge the lighting ratio.

 

[Mainecoonmaniac]

I think the contrast is dependent on how big the tube is. The bigger the light source, the less contrast. The small the light source, the more specular. The size of the light source is also relative. The closer the light source, the light will be relatively bigger.

An example is the sun. It's huge physically, but because of it's distance, the relatively small. That's why the sun without clouds is high in contrast i.e. specular.

Please feel free to correct me if I'm wrong with any of these points I've made.

 

[David Allen]

Hi. I'm curious about the relative contrast measured from model lights compared to strobe lighting. If I compose a model using model lights, and use a spot meter to determine the contrast (f-stop range) between the most important shadow and the most important highlight, will that same contrast be maintained when the strobes are fired?

Modelling lights are there to enable you to judge direction and spot bad reflections. They are not a reliable indication of contrast ratio - for this you need to meter the scene with a flash meter in just the same way you need to meter a scene outdoors.

Bests,

David.
www.dsallen.de

 

[Mainecoonmaniac]

+1

Modelling lights are there to enable you to judge direction and spot bad reflections. They are not a reliable indication of contrast ratio - for this you need to meter the scene with a flash meter in just the same way you need to meter a scene outdoors.

Bests,

David.
www.dsallen.de

I rarely find modeling lights match the strobe. When I shot commercially back in the film days, plenty of Polaroids were shot proofing. Some modeling lights are tungsten and the glowing filament was smaller than the strobe tube which was a circle and much bigger. I prefer hot lights over strobes because what you see is what you get.

 

[ParkerSmithPhoto]

The Paul C. Buff strobes actually have a well designed system that allows you to preview the strobes with the modeling lights. However, now that the pinheads in DC have banned incandescent bulbs, finding 150W modeling lamps that don't cost a fortune is very difficult. Alas...

 

[fotch]

................. I prefer hot lights over strobes because what you see is what you get.

One thing that bugs me about Hot Lights is the bugs that land on the bulb (some are hot enough to fry bacon) and cook. Even in the winter, sleeping bugs wake up, because of the heat, and land on the bulbs. Iki-poo

 

[TheFlyingCamera]

You can gauge relative contrast from modeling lights (ie, will this create a deep shadow, a bright highlight, etc) but not actual contrast. For that you absolutely need a flash meter.

 

[Mainecoonmaniac]

I know what you mean

One thing that bugs me about Hot Lights is the bugs that land on the bulb (some are hot enough to fry bacon) and cook. Even in the winter, sleeping bugs wake up, because of the heat, and land on the bulbs. Iki-poo

They are hard to tweak. You always have to have gloves at the ready. One of the photographer I worked for in LA assisted a photographer that used flash bulbs. He told me he had to use oven mitts to replaced the spent bulb. If you forgot, you'd burn your hand. I don't think they were the peanut sized one either. They were size of light bulbs with Edison sockets.

 

[wildbill]

you're gonna need a flash meter. Has anyone mentioned that?

 

[fix-erUpper]

Thanks everyone for your comments. Several people have mentioned flash meters. I use a flash meter, but what does that measure?, the flash intensity. It gives me a middle grey value. It doesn't tell me how black the black is or how white the white is. It doesn't give me the contrast range of the scene. But through trial and lots of error, I now use a flash meter to determine an exposure and then I give two more stops more exposure to ensure I have lots of detail in the black. But, quite often my highlights need lots of tricks to print because they are too hot. I want more control over the contrast then trial and error and I'm tired of water baths, masking and flashing to control the highlights. Are polaroids or a digital camera my only way out?? BTW, I am shooting a 4x5 with Tri-x film @120ASA. I do like hot lights, but they take more finagling to control, in my limited experience.

 

[MattKing]

Thanks everyone for your comments. Several people have mentioned flash meters. I use a flash meter, but what does that measure?, the flash intensity. It gives me a middle grey value. It doesn't tell me how black the black is or how white the white is. It doesn't give me the contrast range of the scene. But through trial and lots of error, I now use a flash meter to determine an exposure and then I give two more stops more exposure to ensure I have lots of detail in the black. But, quite often my highlights need lots of tricks to print because they are too hot. I want more control over the contrast then trial and error and I'm tired of water baths, masking and flashing to control the highlights. Are polaroids or a digital camera my only way out?? BTW, I am shooting a 4x5 with Tri-x film @120ASA. I do like hot lights, but they take more finagling to control, in my limited experience.

Many of the modern flash meters have a reflected light mode.

If you are using a flash meter, and then adding two stops to ensure detail in the black, you are bound to have blown out highlights.

You need to use your lighting and/or reflectors to ensure that the shadow illumination is sufficient, and use multiple flash meter readings to confirm that.

The modeling lights can certainly help you to initially set up your lights and reflectors. Then use your flash meter to fine tune "main", "fill" and additional lighting.

 

[TheFlyingCamera]

Thanks everyone for your comments. Several people have mentioned flash meters. I use a flash meter, but what does that measure?, the flash intensity. It gives me a middle grey value. It doesn't tell me how black the black is or how white the white is. It doesn't give me the contrast range of the scene. But through trial and lots of error, I now use a flash meter to determine an exposure and then I give two more stops more exposure to ensure I have lots of detail in the black. But, quite often my highlights need lots of tricks to print because they are too hot. I want more control over the contrast then trial and error and I'm tired of water baths, masking and flashing to control the highlights. Are polaroids or a digital camera my only way out?? BTW, I am shooting a 4x5 with Tri-x film @120ASA. I do like hot lights, but they take more finagling to control, in my limited experience.

You need to learn how to use your flash meter. You absolutely can determine contrast with one, if you use it right. If you have an incident meter, you take a reading off your main light, with the dome facing the camera. If you have other lights in your setup, you shield the incident dome from the other lights with your hand and your body. If you have only one light, the reading from the incident reading is of course your correct exposure. If you have multiple lights, you take readings from your main to determine base exposure, your fill light to determine contrast ratio, and any additional lights to determine their effect on what they're pointed at. I won't go into it at length here, as there are entire books devoted to explaining determining and setting lighting ratios.

 

[M Carter]

I use Speedotron packs and heads. Even with the packs that have dial-down power and dimmers to balance the modeling lights on each channel, there's no really accurate way to balance the modeling light output to the strobe output. And I have many packs that use Combine/Isolate switches and choice of output channel to set primary power to the head - on those, there's just a model on-off switch. I can't imagine trying to suss out if the modeling light on a 400WS head (whether a monolight, a head assigned to a single pack, or one of several heads on one pack) is congruent with the flash output of the stuff cranked up to 1200ws.

There are three ways to approach this:

Get a flash SPOT meter (Minolta Spotmeter F comes to mine) and use your version of the zone system - I'd still feel iffy about that, having come from a commercial fashion/product background... you'd really want to have your zone system-ish workflow down and be very well versed in developing for highlights, and keep very organized notes on set.

A polaroid back (Kinda sucks that there's only ONE emulsion still in production...). This weekend I'm experimenting with ND and exposure levels to match Fuji 3000 to my HP5+ workflow... but someday I'll run out of Fuji 3000 and that will be the end of that. Polaroid was **the** way to handle this, especially for commercial shooting.

A digital camera to act as a polaroid back. I can dial in the JPEG engine of my DSLR to approximate the contrast of a given film and save those profiles. Along with a spot meter, this is probably the best way to shoot when time and money are at stake (you've hired models and a stylist for your own stuff or are shooting for a client). I've found, for instance, my DSLR gets more shadow detail than my film/processing combo of choice and trusting just the DSLR can bite me at printing time. (The pro polaroid films were very well balanced to the films you'd use with them and very repeatable). The DSLR is the best analog to the polaroid days, in my opinion. It's of immense value to step back and see the shot and think it over. Especially using strobes, where you can't truly see what the light is actually doing.

I often run the HDMI output of my DSLR to a 7" production monitor which has been calibrated - really helps to be able to see the image a lot larger. (I shoot video so I have a lot of toys...)

 

[M Carter]

You need to learn how to use your flash meter. You absolutely can determine contrast with one, if you use it right. If you have an incident meter, you take a reading off your main light, with the dome facing the camera. If you have other lights in your setup, you shield the incident dome from the other lights with your hand and your body. If you have only one light, the reading from the incident reading is of course your correct exposure. If you have multiple lights, you take readings from your main to determine base exposure, your fill light to determine contrast ratio, and any additional lights to determine their effect on what they're pointed at. I won't go into it at length here, as there are entire books devoted to explaining determining and setting lighting ratios.

A incident meter can work, but it's a ballpark solution - you have to take into account the reflectivity of the surfaces being lit. A flash spot meter would give you much more precision.

I'm thinking back to the commercial film days, where we used a lot of polaroid on set, for every format from 35 to 8x10. Hey, that stuff was expensive and generated a ton of goopy toxic trash, and I (and many others) prided ourselves on not just running sheet after sheet of polaroid during setup.

Even so, after years of client shooting, there was always a surprise. Hard kicker light for hair and cheekbones, holding some shadow detail, or getting a pure white cyc background... they all took tweaks based on the subject, props, setting, etc. I did find that spot metering was often pretty essential before the first 'roid. Even if it was just a 200mm lens on an SLR set to "spot".

 

[fix-erUpper]

A incident meter can work, but it's a ballpark solution - you have to take into account the reflectivity of the surfaces being lit. A flash spot meter would give you much more precision.

I'm thinking back to the commercial film days, where we used a lot of polaroid on set, for every format from 35 to 8x10. Hey, that stuff was expensive and generated a ton of goopy toxic trash, and I (and many others) prided ourselves on not just running sheet after sheet of polaroid during setup.

Even so, after years of client shooting, there was always a surprise. Hard kicker light for hair and cheekbones, holding some shadow detail, or getting a pure white cyc background... they all took tweaks based on the subject, props, setting, etc. I did find that spot metering was often pretty essential before the first 'roid. Even if it was just a 200mm lens on an SLR set to "spot".

Thanks M Carter! I think you might be the first to appreciate/understand my problem, which apparently, was poorly explained to this community. I did not know that there was such a think as a "Flash Spot' meter and thank you for a meter recommendation (and thanks MattKing). I am well versed in zone placement, N+ (and ++) and N- (and --) developing, and that is the control I am looking for in the studio. My empirical method of 2-stop more exposure to ensure details in the blacks still results in highlights with great detail on my negatives, but of coarse depending on the scene this may/may not result in negatives that are easy to print. Hence my need to know the subject contrast and not just the incident light contrast in order to determine developing times. Thanks again!

 

[M Carter]

Fixer, even a long lens on a good SLR or DSLR can function as a flash spot meter if it's synched to trigger the flash.

(With the SLR solution, you have to dial the knob to get the reading from spot to spot - with a dedicated flash meter you can get the actual reading instantly. IE, meter your shadow with the spot meter, you'll get 1/4 second and you can zone up to 1/16 and see how that compares to nuetral gray or an incident reading. With the DSLR, you take your shadow reading, it's way underexposed, and you hit and miss til you set the shutter to 1/4. Then you shift to a gray card and click - overexposed, dial, click, dial, click).

The only affordable spot meter that does flash (far as I know) would be a used Minolta Spot Meter F - about $125 - $200 used. It has a PC outlet. New meters with spot functions are PRICEY bastards!!!

I do think the best way to go is:

Use spot metering;

Do some tests with your film and dev combo, and leave the set up. Get a print at normal paper contrast, and shoot the same setup with your DSLR. Convert to monochrome in camera (if your DSLR will do that, most current ones should) and see how it compares with highlight and shadow detail. Dial in a custom JPEG setting that approximates your film/dev/paper response and save it with a name that makes sense. It may take several shots to dial it in, but then it's done. (And an HDMI TV or monitor is pretty kickass when doing this as well).

This is really, really helpful due to the nature of flash - often there will be a little ping or reflection or something "off" in softness or falloff that you're just not seeing with model lights. And, it's really huge to me - HUGE - to see the shot as a shot - a static frame - vs. through a viewfinder. I always discover things when studying a polaroid (or screen) that I didn't really "see".

I just did the film/dev paper test, and then today I tested some FUJI 3000 Polaroid (So camera exposure settings changed as my film/dev works best at 200-320 ASA and the Fuji is... 3200). Very close match, but significantly less shadow detail. So if I use the Fuji on set, I'll need to remind myself "the shadows are there!" and not over compensate. Sort of a moot point, as 3000 was discontinued last year. I'll buy a few more packs and stash 'em in the fridge...

I do like using the Polaroid, but the DSLR will really be the only likely visual solution long-term. Good luck as you progress with this!

 

[TheFlyingCamera]

A incident meter can work, but it's a ballpark solution - you have to take into account the reflectivity of the surfaces being lit. A flash spot meter would give you much more precision.

I'm thinking back to the commercial film days, where we used a lot of polaroid on set, for every format from 35 to 8x10. Hey, that stuff was expensive and generated a ton of goopy toxic trash, and I (and many others) prided ourselves on not just running sheet after sheet of polaroid during setup.

Even so, after years of client shooting, there was always a surprise. Hard kicker light for hair and cheekbones, holding some shadow detail, or getting a pure white cyc background... they all took tweaks based on the subject, props, setting, etc. I did find that spot metering was often pretty essential before the first 'roid. Even if it was just a 200mm lens on an SLR set to "spot".

Again, if you know what you're doing, taking incident readings can be very precise. You have to know how to take the reading to get the information out of it you want.

I would second your recommendation of the Minolta Spotmeter F for studio strobe use, if you want to go down that route. I would not recommend using a 35mm SLR as a spot meter - the only 35mm film SLR that I know of that had TTL flash metering for non-dedicated strobes was the Contax RTS III. Fantastic camera, but using it as an ersatz flash meter would be a royal pain in the ass. Your DSLR solution might work, but again, unless that's your final product (the JPEG/RAW file), it's like hauling around a 10 lb sledge to hammer finish nails. And it's not a fair approximation because the output media are totally different - one is producing an image using transmitted light on a virtual surface and is dependent upon hardware calibration. The other final output is reflected light on an opaque physical surface. It's not fair to either medium to judge one against the other. And again, unless you've done your profiling and calibration, you can't transfer the exposure readings from your DSLR to your film camera and expect them to produce the same result.

 

[fix-erUpper]

Just bought a Minolta Spot Meter F from KEH. $150. THANKS!!