How might the flash mode affect the exposure program on a point and shoot film camera? (Agfa Optima Sensor Flash)

Question

I have purchased an Agfa Optima Sensor Flash camera.

I've googled and had a read around, including the manual, and have figured out for the most part how I can expect the metering program to work when not using the flash, but not sure how it will work when I am using the flash.

Here is what I have learned so far, and my sources:

• You tell the camera the film speed (from 25 - 500)
• Shutter speeds range from 1/45 - 1/1000
• Aperture ranges from 2.8 - ? (have read 16 or 22)
• The system is shutter priority (apparently read this from a blog, no mentioned in manual)
• The flash is GN 12
• The focusing is manual (zone markings on one side, distance scale on the other)
• The shutter is electronically controlled
• The camera alerts you with a flashing light when the conditions are too dark and you can then swing up the pop up flash.

manual pdf - a helpful blog entry

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So my question is, assuming that the metering is shutter priority, what is likely to be happening when the flash is used?

The manual indicates

Flash range:

100 ASA: 0.9 - 3 m

200 ASA: 0.9 - 4 m

300 ASA: 0.9 - 6 m

400 ASA 0.9 - 8 m

My guess would be that the camera will revert to a slow shutter - maybe the 1/45, and only use this?

In this case what will be happening with the aperture? Will this also revert to a set setting?

The stated increase in flash range with film speed suggests that change in film speed will not result in a corresponding change in aperture when using flash. Am I right in presuming that the camera is probably not sophisticated enough to alter the aperture according to focus distance is set at?

If the aperture will be fixed any idea what aperture it would set itself to?

And if the exposure is totally fixed when using flash and i'm using 400 speed film I would have thought that the flash that can reach a subject at 8m is going to totally blow them out at 0.9 m, is this correct?

Finally: I realise that this is not an enormous issue - it's not a sophisticated camera and meant to be point and shoot. I'm mostly just asking for my own interest as to how cameras work, and I'm also going to take it to a party in a couple of days and was wondering what speed film to load (haven't used it yet), so this info could be helpful in making that decision.

Thanks!

Answer 1

It's impossible to say anything with complete certainty without having a working sample of the camera to test, but here are some likely guesses.

First, there's no reason to assume anything about the shutter speed. The Sensor Flash uses a leaf shutter, so as long as the flash duration is shorter than 1/1000, the flash can sync with the shutter at any speed. That does not mean that the shutter is not set to a slower speed; just that there is no reason to assume that it is. You'd have to test to find out for sure by taking at least two flash pictures, one under relatively low light conditions for the film you're using (and with the subject about two-thirds of the max flash distance away for that film speed), and one under brighter "fill flash" conditions (but not so bright that the scene would overexpose at 1/1000 and f/2.8 without the flash). As often as not, simple cameras are either in "flash mode" or they're not, and when they're in flash mode they do what they can to get the ambient out of the equation. That would mean that the highest shutter speed that allows for the flash duration would be selected rather than the lowest.

As for the flash exposure, I don't see any signs of a flash receptor anywhere on any of the photos of the camera, such as one might find on an "auto thyristor" flash of the period. (There may be one under the flash lens beside the reflector bowl, but if it's there it's not visible in the pictures.) That points to the camera using a "flashmatic" scheme, where the aperture is coupled to the focus ring (in this case, electronically — on many rangefinders the aperture and focus rings would be mechanically locked together in this mode) to automatically set a nearly-correct exposure based on the guide number, film speed and subject distance. The furthest distance is based on the guide number and film speed at f/2.8; the closest distance is likely limited by the near-focus limit of the lens.

This, however, is mostly speculation based on what's available on the links you provided (and the links from those links). You ought to be able to confirm the behaviour with a single roll of film if you know what you're looking for, but I would expect a high(ish) shutter speed (underexposed ambient) and a "flashmatic" aperture selection.