Bob Michaels
nobody special
I read a lot here about "high contrast" vs. "low contrast" lenses and do not understand any of it.
I adjust the contrast in every photo I make. Biggest impact with b&w is developing time. In the darkroom it was paper grades. In a digital file, either scanned film or a digital capture, it is with curves in Photoshop (or Lightroom). So I can not tell a high contrast lens from a low contrast one. So long as I have not messed up the exposure so I have blown highlights or blocked up shadows, my prints look the same without regard to the high / low contrast lens.
Now I am an image content and not an equipment oriented person. Please explain to me what the "lens contrast" thing is all about in terms of finished images.
I adjust the contrast in every photo I make. Biggest impact with b&w is developing time. In the darkroom it was paper grades. In a digital file, either scanned film or a digital capture, it is with curves in Photoshop (or Lightroom). So I can not tell a high contrast lens from a low contrast one. So long as I have not messed up the exposure so I have blown highlights or blocked up shadows, my prints look the same without regard to the high / low contrast lens.
Now I am an image content and not an equipment oriented person. Please explain to me what the "lens contrast" thing is all about in terms of finished images.
dnk512
Well-known
Like exposure you want to be close to perfect at the time you shoot. Yes, you can adjust later, but you are limiting your self if you start at the end of a range of values.
If you clip an image, whether on film or in a Digital file- that portion of the image is gone.
Low contrast lenses preserve shadows and highlights. They essentially compress the intensity range of the scene to one that can be recorded. Use a Summarit 5cm F1.5 and a Nikkor-SC 5cm F1.4 with the same film.
Low contrast lenses preserve shadows and highlights. They essentially compress the intensity range of the scene to one that can be recorded. Use a Summarit 5cm F1.5 and a Nikkor-SC 5cm F1.4 with the same film.
andredossantos
Well-known
For B&W, your development will have more of an effect than the lens (as you said).
However, for someone like me who shoots mostly slide film (and other color film) in some situations I take the rendering of the lens into account. During the middle of the day I'll grab a lens that will tamp down the contrast a bit.
However, for someone like me who shoots mostly slide film (and other color film) in some situations I take the rendering of the lens into account. During the middle of the day I'll grab a lens that will tamp down the contrast a bit.
peterm1
Veteran
Low contrast lenses can help with digital image capturing, I believe. Because digital technlogy is inherently limited - i.e. it has a tendancy to blow highlights even with what with film would be an OK dynamic range in the image being shot, having a low contrast lens could help when shooting digital by reducing the dynamic range in the image being captured (as "viewed" by the sensor.) This means the darks will be slightly less dark. I am not sure that these low contrast lenses would have a direct impact on highlights, however - ie they are still liekly to be very bright). But overall this means it should be slightly easier to capture an image that has neither excessively dark shadows nor blown highlights. To do this I would suggest when trying a low contrast lens to reduce the exposure slightly - the darker exposure itself means the highlights will end up less blown and because the lens itself is low contrast the shadows should also be less dense. Overall a better image results.
It is always a delicate balancing act - blown highlights look ugly and once blown, cannot be recovered - there is no longer any information there to recover. At the other end of the scale a too dark image can often be recovered somewhat - but at the cost of a lot of noise that degrades the image. By compressing the range of brightness values captured a low contrast lens makes it easier to improve the end result.
It is always a delicate balancing act - blown highlights look ugly and once blown, cannot be recovered - there is no longer any information there to recover. At the other end of the scale a too dark image can often be recovered somewhat - but at the cost of a lot of noise that degrades the image. By compressing the range of brightness values captured a low contrast lens makes it easier to improve the end result.
Bob Michaels
nobody special
Brian: Thanks. Actually I understand all the issues of capture that exceeds the tonal range threshold. I guess shooting the same b&w and chrome emulsions for 10+ years, I have learned how to expose to fit just about any scene onto the film regardless of lens contrast. Maybe digital, which I am not that knowledgeable about, requires a low contrast lens to fit some scenes with the sensor tonal range.
ferider
Veteran
It might be a bigger deal on digital. On film, in my experience, a tiny change in exposure (for example shooting @ ASA 80 compared to ASA 100) or development recipe has more impact than 50 years of lens development.
Admittedly, it's one of my pet-peeves: we often see small web pictures as examples of photos taken with a "low-contrast" lens. Nobody knows what leveling, etc., was applied, in particular with B+W photos. And all scanned pictures have been leveled. The examples mean nothing.
Admittedly, it's one of my pet-peeves: we often see small web pictures as examples of photos taken with a "low-contrast" lens. Nobody knows what leveling, etc., was applied, in particular with B+W photos. And all scanned pictures have been leveled. The examples mean nothing.
ferider
Veteran
Take for example http://www.rangefinderforum.com/forums/showthread.php?threadid=111048. Great comparison.
However, the only way to know if the Canon has lower contrast than the ASPH, and not just lower transmission, is to look at histograms. Differences in transmission have big impact on color/contrast/etc., on both film and digital. Is the Canon an f1.4 or an f1.5 lens, physically ?
However, the only way to know if the Canon has lower contrast than the ASPH, and not just lower transmission, is to look at histograms. Differences in transmission have big impact on color/contrast/etc., on both film and digital. Is the Canon an f1.4 or an f1.5 lens, physically ?
MCTuomey
Veteran
Yet another reason why I'd like to see mtf charts made available.
ferider
Veteran
Yep. Or just share PS histograms, like this: http://www.flickr.com/photos/ferider/3682676506/
Roland.
Bob Michaels
nobody special
Yes, that was the sort of discussion that once again raised the question in my mind. For those of us that are only interested in the final output and consider histograms no more than one of the tools to get there, what is the difference in lens contrast?
No doubt in my mind that I could make identical final images (prints or JPGs) from those two lenses. And, I could make the matching images be high contrast, normal contrast or low contrast.
ferider
Veteran
Agree.
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maddoc
... likes film again.
I think a better term is "micro-contrast" that defines the quality of a lens to resolve in the region of 10lp/mm. A lens with high "micro-contrast" has a very good ability to resolve this line frequency ("Zeiss-look").
On the other hand, increasing image contrast can increase apparent image sharpness but does not increase resolution.
On the other hand, increasing image contrast can increase apparent image sharpness but does not increase resolution.
Brian Legge
Veteran
Framed like that, I prefer high micro-contrast and low contrast over all.
I'd rather find myself needing to increase the contrast down the road - starting with a negative that contains as much information as possible - than find myself with more blown highlights and more black than I'd prefer.
Yes, you can pull film and yes, lots of information can be pulled out of a negative but all things considered, if one lens provides more information than another to start with...
I'd rather find myself needing to increase the contrast down the road - starting with a negative that contains as much information as possible - than find myself with more blown highlights and more black than I'd prefer.
Yes, you can pull film and yes, lots of information can be pulled out of a negative but all things considered, if one lens provides more information than another to start with...
Bob Michaels
nobody special
Is not this what MTF measures? And, what makes an image "look sharp" in non technical terms?
And, is this related to "high contrast" vs. "low contrast" lenses as discussed here?
Once again, I only go by final images that look good or not. So I do not delve into these technical terms much. But I got curious. So bear with me.
maddoc
... likes film again.
An image "looks sharp" when the transition between bright and dark areas is hard. Imagine some leaves or hair against a bright background. If the transition from the darker hair / leaves to the bright background is abrupt and contains a large change of brightness than it is apparently sharp. A "soft contrast" lens like the 35mm Summilux-M pre-ASPH at f/1.4 shows a more smooth transition between bright and dark areas and the image appears to be more soft or less sharp.
Also non-coated lenses are often called "low-contrast" lenses. In this case, the lens flare softens the transition between bright and dark areas.
EDIT: A "high-contrast" lens when used at night to photograph a skyline of a big city, produces something like "sparkling lights", many bright spots well separated against the dark background.
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Bob Michaels
nobody special
My life is simpler because I only shoot iso 400 film (Neopan 400, lately Tri-X). The longer tonal range is always enough in direct noon day sun.
Here is one that shows the advantage. It has a negro face in shadow and a white shrimp boat in direct sun (no clouds, no haze) I did not even try to meter. I just determined how much exposure I could stand on the white boat and boots without blowing highlights and how little I could get by with on the face. All done using Sunny 16 and understanding the film tonal range. This was with a CV 25mm but I don't know if that is a high contrast or low contrast lens.
Brian Legge
Veteran
You sir are a better photographer than I. Given the range of zones I'd expect in a shoot like that, I would have lost detail in the extremes. I've been cutting back on development recently trying to cut the global contrast a bit but still... I doubt I would have nailed the exposure that well even with metering.
Great work though, technical stuff aside. Given the images I've seen you share here I think you can just keep ignoring the this stuff discussed here.
Great work though, technical stuff aside. Given the images I've seen you share here I think you can just keep ignoring the this stuff discussed here.
Sonnar2
Well-known
Given the fact that the CV 25/4 is definitely a high-contrast lens, some people might say that it would increase tonalty, both the dark and the light area of a picture, such increasing the range beyond limit on film or digital. Your picture proofes that this is not a must.
With a low contrast lens in the same situation (i.e. Canon 25/3.5 RF) it would be much harder to keep details both in the shadow and sunny areas.
With a low contrast lens in the same situation (i.e. Canon 25/3.5 RF) it would be much harder to keep details both in the shadow and sunny areas.
Roger Hicks
Veteran
Dear Bob,
Think of it in terms of flare factor. If the subject brightness range is 256:1 and the brightness range of the projected image is 256:1, then the lens has a flare factor of 1. A good LF camera with a well-blacked bellows and 3- or 4-glass coated lens can come surprisingly close to this. If the projected image is 128:1, then the lens/camera combination has a flare factor of 2.
Flare is the result of spare light bouncing around in the lens and camera body. Obviously its effect is negligible in the brightest areas, and most marked in the darkest. This alters the effective shape of the characteristic curve as well as lowering contrast, so even with B+W it is impossible to compensate exactly via increased development. The tonality is, therefore ALWAYS different.
This is why some people used to love uncoated (or at least, low-contrast) lenses with B+W. Because the shadows were, after all, receiving more light, the effective film speed was raised and you could develop it a little more to get the contrast back, also gaining a little speed through increased development. All this made up for light losses reflected back out through the lens, thereby giving it a lower T/stop
With slide or digital, where the exposure is keyed to the highlights instead of the shadows, you will always get more detail in the shadows, and the effect in the highlights will be negligible. It's a question of striking a balance so that you don't lose fine detail through excessive flare on the one hand or simple underexposure on the other.
With all that theory out of the way, the simple truth is that within normal limits, the importance of variations in lens contrast is (like most other things in photography) grossly exaggerated by those who think they understand more than they do.
Cheers,
R.
Think of it in terms of flare factor. If the subject brightness range is 256:1 and the brightness range of the projected image is 256:1, then the lens has a flare factor of 1. A good LF camera with a well-blacked bellows and 3- or 4-glass coated lens can come surprisingly close to this. If the projected image is 128:1, then the lens/camera combination has a flare factor of 2.
Flare is the result of spare light bouncing around in the lens and camera body. Obviously its effect is negligible in the brightest areas, and most marked in the darkest. This alters the effective shape of the characteristic curve as well as lowering contrast, so even with B+W it is impossible to compensate exactly via increased development. The tonality is, therefore ALWAYS different.
This is why some people used to love uncoated (or at least, low-contrast) lenses with B+W. Because the shadows were, after all, receiving more light, the effective film speed was raised and you could develop it a little more to get the contrast back, also gaining a little speed through increased development. All this made up for light losses reflected back out through the lens, thereby giving it a lower T/stop
With slide or digital, where the exposure is keyed to the highlights instead of the shadows, you will always get more detail in the shadows, and the effect in the highlights will be negligible. It's a question of striking a balance so that you don't lose fine detail through excessive flare on the one hand or simple underexposure on the other.
With all that theory out of the way, the simple truth is that within normal limits, the importance of variations in lens contrast is (like most other things in photography) grossly exaggerated by those who think they understand more than they do.
Cheers,
R.