Balancing strobes using film

How does one balance the background ambient light with strobes more easily with a film camera? If I used my digital camera I could do it by playing around with the setting until I found the look like. I know how to light the model using the light.

 

The equipment I have:

Mamiya RZ67, 110mm and 180mm lens

Sekonic L-308 light meter

Einstein strobe light with cyber commander

Film with iso 125 to 400

I know the max shutter speed of 1/400th is very slow for day time use unless I raise the aperture. But that wouldn't look so good with portraits when trying to isolate the subject. I could use a ND filter, I do have one in fact. It just make focusing with the rz67 much more difficult. I'm not against using it.

 

Ok lets I go out for a shoot and I didn't bring my D7000 to help find to settings I like. How would I know how bright the background is? Do I point the light meter behind the model and take a reading?

 

Sorry if this is a dumb question. I would like to go out on shoots without relying on my d7000 for help. I also want to get to the point where I'm spending less time messing around with equipment and shooting more.

What I recall a la film and metering is that you do several readings. One with ambient for background in reflected mode. For both f stop and shutter for desired exposure.. Then match the f stop (1) with the strobes power on model with incident meter reading at subject for 1:1 subject to bgrnd. And decide on the ratio you desire to finesse the two. I look forward to more recent user guidance naturally but this is a starting point if you like. I do not think it would be different strategy for digital as for film actually. With digital of course you can do more guess work and chimp away. Less scientifically so to speak as you see results and titrate same. Ultimately, the balance o model and backgrnd will have to be by some testing and different f exposures. Am I getting close enough old timer portraitists, --- anybody?

Balancing ambient and flash? Dead easy! First decide what balance you want. The usual (and best starting point) is 100% ambient and 50% flash. This commonly called "fill flash". Use the flash meter to find what f-stop the flash requires for full exposure. Stop the lens down one stop smaller that this. Set the camera shutter speed so that it combines with this smaller f-stop to give full exposure to the ambient light. Shoot! Voila : 100% ambient + 50% flash. If you don't like the original f-stop suggested by the flash meter change the power of the flash to get a f-stop you like more ... and start again.

Balancing ambient and flash? Dead easy! First decide what balance you want. The usual (and best starting point) is 100% ambient and 50% flash. This commonly called "fill flash". Use the flash meter to find what f-stop the flash requires for full exposure. Stop the lens down one stop smaller that this. Set the camera shutter speed so that it combines with this smaller f-stop to give full exposure to the ambient light. Shoot! Voila : 100% ambient + 50% flash. If you don't like the original f-stop suggested by the flash meter change the power of the flash to get a f-stop you like more ... and start again.

 

you make it sound so easy. Honestly I wish we still had Polaroid backs to help.

you make it sound so easy. Honestly I wish we still had Polaroid backs to help.

 

You should be able to find a Polaroid back for your RZ(they were not uncommon) and at least for the time being FP-100C is still available for reasonable prices if you look for it. Just don't get used to using it.

 

If only the same could be said of 4x5 instant film...the holders are cheap, but the film isn't.

I think you should not use ISO 400 film as you're afraid of slow shutter speed of 1/400.

I think you should not use ISO 400 film as you're afraid of slow shutter speed of 1/400.

 

Good point.

 

As a general rule, my go to B&W portrait film is FP4+, and my color portrait film is Portra 160. If they're still too fast, I find that I can pretty safely get good results rating either film at EI 100(standard development), although for FP4+ I've gone lower and pulled.

 

With that said, at typical portrait distances you tend to not get a lot of DOF even around f/8 in 6x7. Unlike with 35mm/Full Frame Digital/APS-C, getting enough DOF for your subject can be more of an issue than having too much. This gets even more true with larger and larger film formats.

Good point.

 

As a general rule, my go to B&W portrait film is FP4+, and my color portrait film is Portra 160. If they're still too fast, I find that I can pretty safely get good results rating either film at EI 100(standard development), although for FP4+ I've gone lower and pulled.

 

With that said, at typical portrait distances you tend to not get a lot of DOF even around f/8 in 6x7. Unlike with 35mm/Full Frame Digital/APS-C, getting enough DOF for your subject can be more of an issue than having too much. This gets even more true with larger and larger film formats.

 

Agree! I wouldn't worry about too much DOF and shutter speed of 1/400 is plenty. I rare use shutter speed above that even with a DSLR.

I am trying to picture the scenario of which you are speaking. I suppose the model is in the shade and the background is in sunlight or the model is in the shade of a porch or is indoors in front of a large picture window. The math is simple enough. Note the aperture setting needed for a good flash shot from the flash to subject distance. Let us say it is f/8. Take a meter reading of the outdoors (incident meter, reflective off a gray card, etc.) See what shutter speed would correspond with an aperture setting of f/8. Let us say the outdoor setting would be 1/125 sec at f/8. Set the shutter speed to 1/125 with the lens at f/8 (flash also at f/8) and take the shot.

It has to be in 2 interconnected parts. They are separate, but will be combined later. Then you interlace them.

 

1: set an exposure for the background ignoring the model. Remember one exposure setting is many combinations of speed aperture & film speed.

 

2: figure out how well lit you want the subject to be. (Matching background, standing out a little from background, or a little darker for back-lit look.)

 

Now you have 2 exposures to meld together.You work out your lighting exposure for the subject, ignoring the background that you have set already.

change the speed aperture/combination without modifying the overall exposure value so that the chosen F-stop matches the flash exposure (+/- any slight accenting as mentioned before.)

There's a RZ67 Polaroidback (with a 'P' adapter) for sale for US $59 on eBay (American seller)

and as mentioned you can still get Fuji F P 100 even if the production has recently been ended

I think you should not use ISO 400 film as you're afraid of slow shutter speed of 1/400.

I was planning on pulling the film to iso 100 or 125 if possible.

I was planning on pulling the film to iso 100 or 125 if possible.

 

Are you shooting color or B&W?

 

If it's color, I'd STRONGLY advise using one of the native 160 speed portrait films on the market, whether Kodak or Fuji. My experience with pulling color negative film is that it often results in muddy colors and almost unusable low contrast. Either of these films will handle 1/3 or 2/3 stop of overexposure gracefully(normal development) if you need to do so to get larger apertures.

 

If you're shooting B&W, I'd again advise you to use an ASA 100 or 125 film. TMX-100, FP4+, and Delta 100 would all serve you nicely although I'd give FP4+ the nod and Delta 100 as a second choice. I find TMX to be a bit high contrast. You can pull these slightly if you want to knock down contrast, but don't go crazy(I wouldn't go below EI80 or so on FP4+, but this is something you'll want to experiment with yourself before actually doing your photo shoot). I'd be tempted to use Plus-X in that situation, but don't go crawling for outdated film of unknown origin(I think the newest 120 Plus-X would probably be 25 years or better expired now).

 

If you pull a film like Tri-X by two stops, you'll be dealing with uncomfortably short development times and also VERY low contrast. If I had to do it, I'd use a dilute high contrast developer like Rodinal(which should give you reasonable development times also) but I'd still rather just start with a slower film. My experience is that T-grain films work best when shot at an EI somewhere close to box speed.

Well, let's start with what you can't control, and that's the ambient light.

 

1) Take a meter reading of the background and see what aperture is indicated at whatever shutter speed you choose, with/without ND filter.

 

2) Move your meter to the subject position and incident meter the flash.

 

3) Adjust the flash power to match the ambient aperture chosen. Remembering to figure the ND filter factor in, if used.

 

However, light is additive. If the same ambient light is falling on the subject as on the background, then the flash light will overlight the subject. So for the scenario you describe to work, the subject will need to be in the shade, or indoors with the BG visible through a window.

 

If what you're talking about is adding flash fill to a contrasty subject, that's different. Best option there is to use the flash Guide Number (the real one established by using your flashmeter) and setting the flash power 2 or 3 stops wider than the ambient aperture. By "wider" I mean at a smaller aperture number. I.e. if the ambient light needs an aperture of f/5.6 then set the flash power for an aperture of f/2.8.

I was planning on pulling the film to iso 100 or 125 if possible.

 

Why use a fast film then pull? It's not like an emergency.

Few in this modern age use flash guide numbers. Anyway, these are published values provided by the flash unit manual. You can also easily compute the guide number for yourself but I will save that for a separate question.

 

A syncro-sunlight method based on the published guide number: Let’s say for this lash-up the guide number is 90. Also, it is good to set the power of the flash is 1 f-stop or 2 f-stop subordinate to the ambient sunlight. This maintains the shadows cast by the sunlight. We need these shadows to give an illusion of depth to our 2D media.

 

 

We compose our portrait consulting a handheld or built-in meter. We are advised to shoot at f/8. Now divide the guide number by the aperture thus 90 by 8 = 11.

 

 

This math tells us that if the flash is positioned 11 feet from the subject, the flash intensity and the sunlight intensity will match (equivalent). To force the flash to be subordinate by 1 f-stop, we can cut its power in half. For 2 f-stops we cut its power to ¼. No power settings? We are forced to place the flash further back from the subject. For 1 f-stop, multiply distance by 1.4 = 11 X 1.4 = 15 feet. For another f-stop reduction does this again thus 15 X 1.4 = 20 feet. I know this antique method will rub some wrong but it is a proven technique.

Since film use denies such luxuries as balanced TTL flash exposure, then use of antique methods like Guide Numbers is almost mandatory.

 

However, I'd suggest working differently from Alan's method.

 

The OP's Einstein flash has power control, so:

 

First, compile a list of GNs for all possible power settings of your flash by using your flashmeter at a distance of 2 meters and with your favoured film speed. Then you just need to multiply the indicated f-number by 2 to get the Guide Number. Print out those GNs as a chart relating distance to aperture for all power settings. This saves any division by root 2 or suchlike faffing about in the field.

 

Once you have your chart; you can then see what power setting gives you your required aperture at whatever flash-to-subject distance is used.

 

Fill flash doesn't need to be accurate to more than about half-a-stop, so you can approximate distances or apertures to the nearest foot or half-stop.

 

Set the power on the flash and the job is done!

 

I'd also advise against using only a 1 stop difference between ambient and flash fill for two reasons. 1) The result will look far too flat and artificial. 2) Light is additive and the total exposure will be half a stop over unless you juggle both flash and ambient settings.

 

I'd suggest 2 stops difference at the very least. This looks much more natural and only introduces a negligible quarter-stop error.

Edited June 23, 2017 by rodeo_joe|1

PS published Guide Numbers are always wrong!

At least for small speedlights and such.

 

For reasons best known to themselves, all makers of all speedlights and on-camera flash units simply lie about their power to the tune of one whole stop (at least).

 

Measure any speedlight with a flashmeter and you'll see that it's so.

 

For the real Guide Number, either measure it with a meter, or simply divide the maker's published number by root2 (1.4). Or use the next stop wider than what's given in the published GN.