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Brett Allbritton

Krasnogorsk-3 Question: Is the Meteor 5-1's apeture wrong?

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Hey everyone,

I'm getting ready for a film challenge where our entire short will be made on a single 100 ft reel of Kodak 7219 and shot on a Krasnogorsk-3.

In preparation for the shoot I decided to do a lens test with the stock Meteor 5-1 lens on my original Blackmagic Pocket Camera. Surprisingly though, my footage all seemed to be about a stop under exposed. I know that the aperture of a lens doesn't always let in as much light as it should and that T-stops are supposed to correct for this, right? So is this the case here?

Have those of you that use the Krasnogorsk-3 encountered this problem? Does this mean that when shooting I should meter for 250 instead 500 to get proper exposure? Any thoughts?

Edited by Brett Allbritton
Felt it was a bit unclear and cluttered.

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Overexposing film is a good tool for general use if you want more density, usually never a bad practice. 
 

as for the lens, I’ve owned a few, and they were notorious for poor quality after all these years. They are pretty easy to disassemble and adjust. 

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I doubt the zoom is losing a whole stop in transmission. Typically a zoom from that era might lose a third to a half a stop. If the front or rear element coating is badly scratched or if an internal element is fogged you might lose some contrast.

 

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Thanks, guys. With that in mind I'll likely overexpose a bit to be safe.

I don't think anything is scratched or fogged, the camera and lens seem to be in really great condition. It's one of the later models (it actually says "Krasnogorsk-3" instead of using the Russian alphabet interestingly enough) and I even sent it to Bernie O'Doherty at Super 16 Inc shortly after getting it to remove the loop formers and check everything out for me.

Granted, I am somewhat guessing that it's losing a full stop, I didn't use a grey card for this test because I was really looking at sharpness. Perhaps I should redo it with a grey card.

My big fear is that maybe my light meter is wrong, but it seemed to work fine when I used it with another camera and lens.

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I don't know if you tried using other manual lenses with the pocket and an external light meter before with different results, but in my experience the BM cameras are the ones who are not rated properly, I mean pretty much all manufacturers "lie" when it comes to ISO on their cameras. I have a BM Ursa Mini 4.6k and since I like using my external light meter I shot some tests to determine where middle gray was, long story short I determined that I had to use ISO 250 on my light meter when the camera is set to ISO 800 to get what I consider proper exposure. Manufacturers, specially at the time when those cameras came out were trying to under expose images to protect the highlights and sell the idea of a wider dynamic range.

If you read the manual you will find a scale where they place "middle gray" at 38 IRE not at 50 IRE which is in the middle. I have a Sony camera from the same time period and with S-Log2 they were placing middle gray at 27 IRE, that sells the idea of higher ISOs on their cameras and help them to protect the highlights avoiding blown up highlights and making their cameras look "better".

Most people don't use the middle gray method, they use false color, zebra, wave form scopes and that kind of stuff, most people don't use an external light meter these days and RAW and LOG formats allow them to say their cameras are rated at ISO standards, but it's tricky. The Meteor lens is not rated on T-Stops as you mentioned before, so add another factor there, I would say one third less of light maybe.

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