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06/10/2011 07:40:50 AM · #1 |
| I'm really late in asking this, but I hear the terms being through around that 'this lens' has more saturate colors and 'that lens' more contrast etc....I'm wondering, at the end of the day, since it's all being put through a processor in the camera and stored using different picture profiles etc, does it not make those comments less valid? If I want more saturation or contrast I'd add it in PP. If I wanted to skip the PP part, just adjust in camera. BUT how does one kind of glass capture more or less saturation/contrast exactly? |
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06/10/2011 09:37:56 AM · #2 |
The way I understand it, the biggest factor is with imperfections in the glass. The more expensive the glass, the fewer the microscopic imperfection. Each and every imperfection in the glass will refract the light differently. This different refraction will mean some of the light either won't hit the sensor, or will hit it in a completely incorrect place. So the more imperfections in the glass, the more refractions, and the less contrast/saturation of light in the correct places.
With multi-element lenses, each piece of glass will have its own imperfections. As the light travels through all of the elements, the effect is multiplied and the contrast/saturation suffers further. That's why you hear of glass with fewer elements often being sharper.
I think coatings also play some part in this, but I don't really know what.
If I'm wrong, I apologize and am anxious to hear why. |
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06/10/2011 12:46:32 PM · #3 |
Yep, it's all about stray light. Better coatings, more sophisticated (not necessarily more complicated) design, and a raft of other things affect how much light takes unwanted paths.
Try this: open an image in Ps, then create a layer on top and fill it with pure white. Now reduce opacity to 0%. Your image appears as it should. Now increase opacity slightly, and watch the saturation and contrast go to heck. this is exactly what happens when stray light enters a lens and bounces around, or when light is scattered or reflected along unintended paths from optical surfaces.
ETA:
Yes, both contrast and saturation can be increased in post, in fact it's one of the easiest things to correct. But as you do, you are "stretching" the data across a greater number of values, and there is only so much stretching you can do without starting to see artifacts, such as posterization.
Message edited by author 2011-06-10 12:48:13.
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06/10/2011 01:45:38 PM · #4 |
I thought this article might be interesting enough to share.
Pictures taken with a cracked lens. I imagine this would be like an "extreme" of what cheap glass does. |
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06/10/2011 03:35:55 PM · #5 |
I have a couple of older manual Ai Nikkors, a 35-50 zoom, and 50-135 f4-4.5 which have an unmistakable strong color contrast in the photos made with them, compared to other lenses in my collection. This was a big thing back in the days of silver and chemicals, but not so much today, although I do enjoy seeing the direct "from camera" results with these two lenses.
Part of what makes the "ED" and "L" glass so expensive is the precision manufacture, and composition of the elements to give the images produced the best possible resolution, contrast, and sharpness straight from the sensor. You can improve the shots from lower quality glass some in processing, but there is nothing like having excellent images to begin with directly from the camera. The better glass really shows it's value when shooting into bright light and in other difficult situations.
Stray light is another good reason to use a lens hood as often as is practical.
That's a pretty messed up lens in the "this article" link posted.
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06/10/2011 03:57:13 PM · #6 |
I really noticed this while camping. I got home to process my images and I couldn't believe the glare I was getting.
I needed to clean the UV filter on my 17-40L, it was really dirty. |
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06/10/2011 04:26:34 PM · #7 |
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