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View Full Version : my first flash for Spotmatic and some metering woes!


kez2
21-01-2008, 16:55
Hello,

I shoot film with an Pentax Spotmatic SP II.

I would like to purchase my first hotshoe flash unit– which I intend to convert into a DIY ringflash.

Before buying, I would like to get a couple of questions answered if possible:

I intend to use coloured filters on my lens.
(Sometimes, up to 5 at a time- for special effects!)
These reduce the amount of light hitting the film.
This is not a problem using the camera's internal metering with a constant light source as the reading is taken through the lens anyway!

However, with a flash, I have been advised to buy a specialised Flash meter; presumably the internal meter will be inadequate.

If I do so, how do I compensate for those coloured filters on the lens; the flash meter is obviously unaware that they are there?
Do I have to figure out the difference in light (in f-stops) that they make using the internal meter with a constant light source, and then add it on to the exposure that is recommended by the flash meter?

Or could I simply look through the viewfinder when I fire the flash and see what point the needle jumps to.
I somehow doubt it is that responsive, but it's an idea.

If I do need to buy a light meter. Are there any you would recommend (new, or second hand) that are cheap, simple, and will do flash, incident, and spot readings?

Thanks very much for the help!

dazzajl
21-01-2008, 17:05
If you're happy to do a little math and have the time to do it, then there's no need for a light meter.

You can work out the aperture you'll need, or the flash power if you work it back the other way from the known bits of your setup. If you have the distance to subject (of the light), the power of the flash and speed of the film, you can work out the aperture required. The adjustment required for the filters, as you said, will be the same as under a constant light source.

If maths make your head hurt, then a flash meter will be a good idea. :lol: