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Very Low Light Stuff


thehouseflogger

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I think you guys are going around about two different kinds of contrast-sean is talking about scene brightness difference, ie; the total ev difference between absolute white and black, and alan is talking about contrast as differentiation of adjacent tones.

 

jumping in the middle here :D I'd say you are both right.

 

low contrast lenses can compress the total scene brightness in such a way as to record it successfully (compression), and high contrast lenses can achieve better differentiation between tones when there is little difference ie; shadow tone differentiation.

 

I always liked zeiss for it's "high" contrast, iow, it would let me shoot back lit and flared and not have total mush on the neg. Part of that is flare resistance and the other part is high contrast. Some leica lenses let me compress hi contrast scenes because they lift shadow and middle tones (making the overall image flatter in general-lower contrast) but then later in post I can move the information around to my liking.

 

Ultimately it is all compression however.

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As I illustrated, it certainly does make it a lower contrast lens.

 

There are confounding variables in your test. Your fogging not only lowers contrast but also obscures some resolution, etc. If you really want to test this you'll need to use two lenses of different contrast levels.

 

Sean

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I think you guys are going around about two different kinds of contrast-sean is talking about scene brightness difference, ie; the total ev difference between absolute white and black, and alan is talking about contrast as differentiation of adjacent tones.

 

I've written about both. Higher contrast lenses favor the latter, sometimes at the expense of the former. Low contrast lenses favor the latter sometimes at the expense of the former. As we talked about much earlier in this thread, there are always trade-offs.

 

In some cases, one can regain the tonal separation in post. One can't however, regain shadow detail that reaches the noise floor. As I've been writing since about 2004, I like higher contrast lenses with lower contrast subjects and moderate contrast lenses with higher contrast subjects.

 

I think some people may still have trouble understanding both sides of the coin.

 

Cheers,

 

Sean

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There are confounding variables in your test. Your fogging not only lowers contrast but also obscures some resolution, etc. If you really want to test this you'll need to use two lenses of different contrast levels.

 

Sean

 

I wasn't really testing resolution, just what happens to an image when lens contrast is altered. What got me thinking was something I read in the book "Photographic Lenses" by C.B. Neblette. He wrote, "The effect of flare on the image may be likened to the haze of an early summer morning; it reduces image contrast particularly in the shadow portions. This affects both b/w and color photography, but in color there is an added drawback: the color of the image is also degraded. If the flare consists of white light, the colors are simply desaturated; if colored, the image colors are overlaid with ghost color. In a subject area with a large background area of a definite color, the background color is spread over the image."

 

So I had a little time this evening and was curious to see what I could do with the raw images form my little example. I adjusted the tone map of the control image and the one I breathed on. I applied equal levels of sharpening. The foggy image turns out to have a fair amount of detail, it mostly is degraded losing contrast, especially in the shadows.

 

The first is the breathed on image overall, then cropped then adjusted. Finally is the control image that wasn't breathed on. lens was a 60mm Micro Nikkor at 2.8 on a 5D.

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Hi Alan,

 

While they aren't the same as two lenses of different contrast, it is interesting to look at these experiments you're doing. What's your sense about the loss of shadow detail in the fogged version? Earlier you had talked about loss of detail in association with this.

 

The reason resolution comes into play is because the perception of shadow detail (or detail at any tonal level for that matter) is affected by resolution.

 

Cheers,

 

Sean

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Actually, this has really got me thinking, although I have to give up on it for now. I have an early shoot tomorrow. I was really surprised that the sharpness was not very degraded after I breathed on the lens.

 

I plan to rig up some kind of test that greatly exceeds the sensor's ability yet has detail in the shadows and highlights. I thought I had done that with the light bulb, but I don't think it went far enough - it needs to get to the point where detail can't be recovered. Plus shooting into a light bulb had to cause some flare in my control image.

 

I shouldn't spend my time on this but I am curious. This must be tapping in to my old photo science days as a student.

 

Anyhow, getting back to the OP's images. I can't see how it will help to have the shadows less contrasty due to flare from a low contrast lens. There already is almost no contrast in the shadows, that is one of the problems. What they need is some illumination so that there will be some contrast in the shadows.

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If you get a chance Enrico, read James Agee's introduction to Helen Levitt's "A Way Of Seeing". I think it might interest you.

 

Cheers,

 

Sean

 

I sure will, Sean, thank you for the advice. Hope to find the book in Italy someway. Shouldn't be much difficult.

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  • 2 weeks later...

Ducking under my desk, and claiming no artistic merit at all, but here is ISO 2500,

1/6th (handheld without problem btw), at f1.2. So there was no light at all, basically.

I add a crop of a nice shadowy area... Look at the highlight intruding on the trailer btw. It must be the Nokton 35/1.2 doing that. No noise reduction and ACR set at default NR.

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