Film - Camera ISO 800, flash ISO 400 - Which ISO to Meter With?

Hello everybody,

 

This is my first quest for advice here.

I very much appreciate the help in advanced, so thank you.

 

I am shooting an ISO 800 film and my camera is set to ISO 800, but my flash ISO only goes as far as 400.

 

On my light meter should I meter with the camera ISO or flash ISO?

Will two differing ISO's cause any problems?

 

I am using a Minolta XD7 camera with a Minolta 320x flash unit.

 

I understand this might be a silly question!

I'm sorry, I posted this in the wrong group but I've not worked out how to remove it yet!

I'm not familiar with Minolta stuff, so 3 cases:

1. Is the XD7 already TTL metering flash? - if so set flash to TTL camera to it#s 800 ISO film read the aperture provided for ISO 400 stick to it and be lucky that the flash will put out enough power or recharge faster.
   
2. if your flash is a "dedicated" computer flash just forcing the camera on sync speed, pick an autothyristor mode and stop your lens one stop further down than suggested by the flash for ISO 400 i.e.: read f5.6, set f8
   
3. If you are going to use Minolta's awesome hand held flash meters: set yours to ISO 800, the flash to some manual output and go ahead.
   

If you are using just the camera's usual light meter and have no TTL flash control metering won't tell you anything about the flash, just about the ambient light you are facing.

Jochen,

 

Thanks for the reply. It's much appreciated.

It's not TTL, just an automatic flash unit.

 

I think I understood your second piece of advice there.

So move one stop down for ISO 800, and two stops for 1600 for example?

 

This might be a little trickier, but if using two flashes.

One on camera, a second on tripod at a different distance - both connected via PC sync port (with splitter cable).

 

How would I work out the compensations?

 

Many thanks

So move one stop down for ISO 800, and two stops for 1600 for example?

Yes.

The average automatic flash seems to have according to it's sliders 1 or more automatic ranges for a fixed light level and any iso change only impacts the matching aperture.

if using two flashes.

One on camera, a second on tripod at a different distance - both connected via PC sync port (with splitter cable).

 

How would I work out the compensations?

On negative film: Basically not at all, in the "simply do nothing" way.

You can be lucky, decide your off camera flash to be the main light, put it on auto for f8, decide the on camera flash to be a fill light and put it on auto for f5.6. The lucky part would be both automatic modes working out. With the camera set to f8 for the stronger flash the f5.6 flash should just fill some shadows but not matter for the exposure.

The usual approach is to achieve the same via manual modes according to guide number math and flash subject distance or power throttling via modifiers and with a flash meter as reference. With 2 similar flashes at the same subject distance you should gain one f-stop. Moving the 2nd, ii.e. "fill" to 1.4x the 1st's distance you bring it one stop down and make it irrelevant for your exposure calculations.

 

Flash is tricky. Yes, people mastered it in the past. During the late 80s my physics teacher summarized: "If photography required the precision of a moon landing, we wouldn't have seen a single image yet."

 

Best solid advice I can come up with:

1. Get hold of a used copy of "Light Science and Magic" a ++awesome book! entirely worth it#s less than US$10 (used & dog eared)
   
2. Grab something digital to dabble with. A very vintage 6MP DSLR with even just an adapted 50mm lens should do well enough for learning lighting. - You need manual mode, a prime with realistic aperture engraving and maybe whatever it takes to bring your flashes' sync voltage down to a safe level. Cheapest approach is a safe voltage flash on camera and the rest triggered via an optical slave. - Your goal will be to predict film exposures according to the digital's histogram.
   

All of that should be US$/€ 100 in total on a good day and maybe 150 if you go wild and impatient. It might still take (parts of) 2 rolls to get your digital camera calibrated to become a prediction of the film exposures. - At least to me ISO ratings of digital cameras and flash meters did rarely match. - I didn't shoot enough film to tell if my meters were spot on for that. (But at work a Samsung at base ISO 200 seems to require at least half an f-stop more light than a Leica at base ISO 160.)

I think spending on a digital test rig should pay off quickly, compared to the cost of re-shooting, bracketing, Polaroids, test shootings etc. Flash meters seem nice to have / probably quite essential for film shooters but also usually more expensive than a most basic DSLR.

 

I see little sense in going for an all TTL flash film rig*. You'll depend on the used market. Devices will be electronic and close to past their intended shelf time but maybe still expensive and most likely no longer easy to get. The mid 80s TTL flash systems I am recalling did not offer exposure compensation for individual flashes, so dialing the fill 1 stop down is not necessarily possible. And as soon as you want to change systems, you'll have to buy all flashes and TTL cables new, for the one you are moving to. I am not even sure if off camera TTL flash cables work properly. - I need to dial a compensation into a Yongnuo flash, when I use it wired to a Pentax K10D with a different 3rd party's cable. On top of all of that: TTL is a dumb auto mode that can be fooled by your subject. // *= Clarifying: A single TTL flash for a matching film body is nice to have, convenient to shoot etc. - I am just questioning that TTL works spot on, straight out of the box, if you want to use multiple flashes. My admittedly spoiled by digital POV: If you are down to trial & error, you can also shoot in manual mode from the start, to keep things constant (and cheaper).

Jochen, I can't thank you enough for all the advice.

 

I replied to your message on the other thread, as I had accidentally created this post in the wrong section so I will remove it here now.

 

But I just wanted to say a big thanks for all the help today again. I am so appreciative.

Also managed to find a used copy of Light & Science, can't wait to get reading. :D

I'm sorry, I posted this in the wrong group but I've not worked out how to remove it yet!

 

Hello ijowski and welcome,

 

Users cannot edit, nor remove the commentaries that they publish on Photo.net. That is explained in the Terms of Use and User Guidelines.

 

However Users do have ten minutes (10) edit time after posting a commentary, to make a correction, this edit time was created to address typos, spelling and grammar mistakes, etc.

 

I shall close this conversation and I shall leave a reference Link to your other conversation in the Beginner Forum.

 

Please see the conversation in Beginner Forum HERE

 

William