Mamiya RB67 help with fill in flash.

[pityacka]

I have a RB67. Also have a Panasonic PE 201 C flashgun, which I have used with 35 mm cameras. I attached it to the 67 and connected it to the camera with the synch cord. No film in the camera as I was wanting to see if the flashgun would fire. The flash fires at all speeds.
The flashgun has a GN of 20 at ISO 100. It can be set to Auto, or Manual. Instructions with the gun state Aperture F2.8 covers 1.5m-7.0m; and with aperture of F4, covers 1.0m - 5.0m., when the gun is used in the Auto mode.
Manual mode is fairly simple as there is a table on the reverse of the gun - select distance, then read down and select aperture corresponding to the ISO film being used.
I want advice re fill in flash when using the above gun. I have read pages in a couple of photo books but have not grasped the formula completely. I believe it to be along the lines of take a meter reading as normal, then close down the lens to stop the flashlight burning out the subject.
Anyone here who can explain the principle in a clear manner ? I suppose once I grasp the ins and outs, and have done it a few times, then it will be straight forward for me. Initially I will be using colour neg. film to master the technique (hopefully) and then use colour slide film.
Looking forward to helpful answers.

 

[Ian C]

We had a similar discussion earlier this month.

(there was a url link here which no longer exists)

Fill flash is most often used in outdoor portraits. For example, in sensor-automatic mode, if you’re using ASA 100 film and have set the shutter speed for exposure at f/4 within the stated 1m to 5m subject distance specified by the flash instructions, you achieve -1f fill flash by setting the ASA on the flash to 200. The flash portion of the exposure will provide enough light to satisfy an ASA 200 film.

At the same time the ambient light will supply the light necessary for the ASA 100 film in the camera. This results in a -1f fill flash. The fill from the flash will lighten shadows in the eye sockets, under the chin, and so forth, as well as providing a bit of “sparkle” to the eyes without overexposing the rest of the subject.

If you wanted -(4/3)f, you’d set the film speed on the flash 4/3 stops faster to ASA 250.

The film speeds on the flash unit are in 1/3-stop increments: 25, 40, 50, 64, 80, 100, 125, 160, 200, 250, 320, 400. Some units allow higher film speeds.

 

[markbarendt]

I'm not familiar with your flash gun specifically but with my Nikon speed lights the auto/aperture setting works well.

First thing to understand about a flash gun is that it only has two luminance settings, on or off. On is always "fully on".

Second, The flash gun capacitors can only sustain the on status for a very short time, 1/1000th of a second is a very, very long on time for a flash. This means the camera shutter on the RB has no effect on how much of the flash reaches the film. A full power 1/1000th duration flash easily fits inside the 1/400th minimum shutter speed. This is actually true for most any camera that does flash, the sync speed is normally much slower than flash duration.

Third, as far as the RB itself is concerned the only things that affect the flash exposure are the film's ISO and the aperture. This leaves shutter speed available to control ambient/background exposure separately from the flash exposure.

Forth, the auto mode on flash guns typically have a sensor on the gun that measures how much light gets bounced back to the gun and adjusts the flash duration accordingly, this measurment is fully independent of the camera. So from your example in auto, lens at F4 and subject at 5 meters, you may get a full power pop because the flash gun is at its range limit, but at F4 and 1 meter the flash gun's sensor will see a lot more light bounce back and the computer in the flash gun will turn off the flash bulb early, at maybe 1/9572nd of a second. The subject gets the same exposure either way.

So now to answer your question on not blowing out the subject.

If you have your flash set up to reflect the film's ISO and lens aperture in use the subject will be exposed properly.

IMO flash rarely blows out the subject, the problem is the rest of the frame is underexposed.

Using a slower lens shutter speed allows more ambient/background exposure and reduces the difference between the flash exposure and the background exposure.

In general higher ISO films and larger apertures make balancing the two exposures easier.

 

[markbarendt]

There are also other techniques to help balance the exposures, if your flash gun's head tilts and or swivels you can bounce the light around the room. It helps if the gun has zoom, adjust the zoom for a wide lens, aim it at the ceiling and slightly forward, in auto.

The gun turns the ceiling into a big reflector that can light most of the room instead of just the subject.

 

[MattKing]

I'm going to differ a bit from Ian C here.

In my experience, most auto flashes don't have a control that changes the light output when you change the ISO setting.

What they have is a dial or a scale that tells you to change the aperture you set on the camera when you use a different ISO film (or digital ISO setting).

So changing the ISO setting on the flash from 100 to 200 doesn't do anything to vary the flash output - it just changes the aperture recommendation for your camera.

Here is what I find works:

1) I check the scale/dial on my flash and find an auto range that will recommend use of something like f/4.0 for the distances I am working with and the film I am shooting with.
2) I set the flash to that auto range.
3) I meter the ambient light and determine what exposure I need to set to use f/5.6 (one stop less than f/4.0) and set those settings on the camera.
4) I take my photograph with the camera and flash set to those settings.

The result?

a) Those parts of the scene that are lit by both the flash and the ambient light receive a half stop more exposure than might be ideal - generally well within the tolerances of negative film;
b) Those parts of the scene that are lit by only the ambient light receive ideal exposure; and
c) Those parts of the scene that are lit by only the flash receive one stop less exposure than might be ideal for the main part of a scene, but still enough to preserve most shadow detail and the sense that those parts are slightly shaded.

The balance between ambient and fill light can be varied according to preference. In addition, you may want to change the balance if you change to slide film, due to slide film's narrower tolerance for over-exposure or (to a lesser extent) under-exposure.

If you find you like using fill flash, you may also want to experiment with reflectors.

And if you start using a lot of fill flash you will almost certainly start looking at bigger, more powerful flashes, because there will be many times you will want to use something like f/16 instead of f/5.6.

 

[Ric Trexell]

Fill flash and Pop Photography,

There is a great article in the 1999 issue of Popular Photograpy on using fill flash with a manual camera. It gives you all the info you will need to get the different ratios of 3:1, 2:1 and whatever you want. I have a copy and guard it with my life, but I suppose there is a way to get it on CD or d/l from Pop Photography. One thing you have to realize when you say that you are worried about blowing out the scene, the suns light is many times stronger than your flash, and what you are adding is only a small percentage of light. It might be too light indoors, but generally, it is not that much outside unless ofcourse your subject is up close. The easiest way is to use a flash meter. Expensive but if you do a lot of this type of work, it will pay for itself in a short time.

 

[ic-racer]

A tiny flash like that with a medium format camera will require some experimentation. For example, outdoors trying to flash-fill in a sunlight shot if you are shooting at f11 that flash isn't going to do much even on full power, unless you are up really close.

 

[John Koehrer]

I'm going to differ a bit from Ian C here.

In my experience, most auto flashes don't have a control that changes the light output when you change the ISO setting.

What they have is a dial or a scale that tells you to change the aperture you set on the camera when you use a different ISO film (or digital ISO setting).

So changing the ISO setting on the flash from 100 to 200 doesn't do anything to vary the flash output - it just changes the aperture recommendation for your camera.

Here is what I find works:

1) I check the scale/dial on my flash and find an auto range that will recommend use of something like f/4.0 for the distances I am working with and the film I am shooting with.
2) I set the flash to that auto range.
3) I meter the ambient light and determine what exposure I need to set to use f/5.6 (one stop less than f/4.0) and set those settings on the camera.
4) I take my photograph with the camera and flash set to those settings.

The result?

a) Those parts of the scene that are lit by both the flash and the ambient light receive a half stop more exposure than might be ideal - generally well within the tolerances of negative film;
b) Those parts of the scene that are lit by only the ambient light receive ideal exposure; and
c) Those parts of the scene that are lit by only the flash receive one stop less exposure than might be ideal for the main part of a scene, but still enough to preserve most shadow detail and the sense that those parts are slightly shaded.

The balance between ambient and fill light can be varied according to preference. In addition, you may want to change the balance if you change to slide film, due to slide film's narrower tolerance for over-exposure or (to a lesser extent) under-exposure.

If you find you like using fill flash, you may also want to experiment with reflectors.

And if you start using a lot of fill flash you will almost certainly start looking at bigger, more powerful flashes, because there will be many times you will want to use something like f/16 instead of f/5.6.

This is also the simplest way I've*found(for me). others like using math or counting on fingers and toes.......
A good reliable flash like the Vivitar 283/285 give a goodly bit of light in a modest size. Both are rated at GN110(ft).
The 285 comes with the ability to control the output in manual and the 283 has a unit that replaces the sensor that does the same thing.

 

[pityacka]

Thank you all for your input. I will sit down and study them thoroughly, and all will probably sink in eventually. Apologies for the late reply as I have not been near the computer for a couple of days.

 

[Pfiltz]

I'd like to add 1 more perspective.

For me. Light is light.

Whether it be reflected with a reflector, studio strobe, speed light, etc... when trying to balance it with natural ambient light.

Along with film backs, tripod, cable release, etc... I ALWAYS have my Sekonic Light Meter with me.

I always meter two things when working outside. I meter the scene [subject] that's sitting in either open shade, broad daylight, or what ever. Then I meter the reflected light, strobe, or speed light that's going to hit the subject.

Now I'm just trying to match the two numbers together.

I used an off camera 550ex, and triggered it with a pocket wizard, connected to my RB67 via sync cable.

Once I dialed in the 550 to get close to the sunlight hitting her from behind, I popped the shot.

Hope that helps

Ektar 100, RB67 w/50mm

-

This shot I used the same 550ex in a photoflex mini softbox. Metering was done in the same fashion.

 

[pityacka]

thanks for your comments, Pfiltz. Two beautiful exposed photos. Looks like I will have to do some learning to reach that standard. I think the basics are seeping into my brain.