Mamiya RZ/Portra 400 flash exposure Vs Nikon D200

Hi all, I have been delving into flash portraits with my RZ67 and Portra 400. As a check, I set my Nikon D200 (Dont worry APUGer's -its a camera from the future ;)) with ISO at 400 to match the portra and both at f22. The D200 shutter speed was at 1/250 and the RZ at 1/400.

I expected the exposures on the RZ to mirror the ones from the D200. When I developed the images from the RZ, they were all around 1.5 to 2 stops overexposed!

Is it that the film is just more sensitive to the flash type of light?? Confused!

Paul

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Originally Posted by 10speeduk

Hi all, I have been delving into flash portraits with my RZ67 and Portra 400. As a check, I set my Nikon D200 (Dont worry APUGer's -its a camera from the future ;)) with ISO at 400 to match the portra and both at f22. The D200 shutter speed was at 1/250 and the RZ at 1/400.

I expected the exposures on the RZ to mirror the ones from the D200. When I developed the images from the RZ, they were all around 1.5 to 2 stops overexposed!

Is it that the film is just more sensitive to the flash type of light?? Confused!

Paul

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Paul, I think you'll find the D200 is a camera from the past. Well, a number of things could be going on to introduce the perceived discrepancy between film and digital. Were both cameras functioning correctly? Sticky aperture blades are easily seen, but a 'slow' leaf shutter in an ageing RZ would only be confirmed with proper test gear. Did you develop correctly? You'd only know if you processed a control strip etc. Fortunately, colour neg is very tolerant of overexposure.

I'm no expert, but I remember reading how even when set at the same speed, a digital sensor isn't necessarily the same sensitivity as film of the same speed. If you are going to use a digital SLR as a meter for film, I would suggest doing tests to see ths ISO it needs to be set to get the exposure you expect on film.

Thanks Neil and Ian C, I guess it could be a quirk with my gear. Either the RZ, D200 or a mixture. I will perform the same test but this time deliberately under-expose the RZ film by 1 stop and see if that sees things heading in the right direction. My D200 is tempermental as is the RZ, so who knows. Cheers Paul

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Originally Posted by edcculus

I'm no expert, but I remember reading how even when set at the same speed, a digital sensor isn't necessarily the same sensitivity as film of the same speed. If you are going to use a digital SLR as a meter for film, I would suggest doing tests to see ths ISO it needs to be set to get the exposure you expect on film.

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I have heard the exact same thing. I have never tested it though.

Funny, my experience is the opposite; the DSLR sensors being more sensitive than the ISO number indicates. If I metered a studio flash setup with a handheld flash exposure meter, my 35mm slides were properly exposed while the DSLRs (Canon & Nikon, various models) were showing overexposure by 1/2 to 1 stop.

Thanks guys, at least I know I am not mental and this sort of thing does happen for the same setups! Luckily, lightroom saved my ass, as I managed to drop the exposure without ruining the images, hence my guess at around 1.5 stops over exposure.

When you say the Portra was "overexposed", on what basis are you making this judgement? Scans? My guess is that you're scanning and your inversion process is wrong, e.g. incorrect selection of white-point.

I ask because you can overexpose Portra by 3 stops and have it print nearly identically to a normal exposure. Being C41, it's extremely overexposure-tolerant and therefore I doubt that you could even tell that a properly-printed image was 1.5 stops overexposed by looking at it. You could probably tell with a side-by-side A/B comparison but the differences will be subtle, e.g. increased shadow detail and slightly reduced highlight contrast.

If you want to check your DSLR-preview/metering skills, expose some chromes. They too should come out right if you do it carefully.

A DSLR is a perfectly valid means of checking an exposure but you need to make sure that it is setup correctly, i.e. make sure the dynamic-range optimisations are all disabled. The ISO film speed standard is a standard (from ISO, who'd have guessed?), and the digital world follows it just as rigorously as film manufacturers.

My answer, get a light meter! :)


~Stone

Mamiya: 7 II, RZ67 Pro II / Canon: 1V, AE-1, 5DmkII / Kodak: No 1 Pocket Autographic, No 1A Pocket Autographic | Sent w/ iPhone using Tapatalk