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12-15-2017, 01:33 AM   #16
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I thought my DFA 100mm WR Macro was neutral, but after comparing identical shots to other lenses, it has a magenta cast. I find it hard to find a "neutral" lens. Imho the best way would be what clackers said. Make a little controlled setup and swap lenses only.

12-15-2017, 02:14 AM - 1 Like   #17
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QuoteOriginally posted by swanlefitte Quote
I hear how different lens are warm and cool and give good skin color. I just got a color chart. I would like a "control" lens to compare the others against.
Or is there an alternative control. Direct sensor to reality is impossible. A clinically true lens seems my closest bet or a good known correction of a lens.
For your Pentax K-S2, I'd suggest the Sigma 35mm f/1.4 DG HSM Art or from your own kit, the Pentax 40mm f/2.8 XS pancake.

But there are many factors that affect color balance even if you're shooting RAW. And RAW images from a Canon CMOS will have a different color balance bias than one on a Sony or Toshiba or Samsung CMOS, Kodak CCD, or Sigma Foveon, etc.

If you knew the exact color temperature of your light source, you could set your WB to custom match it. But because of human color perception, unless you have an image with 18% grey and skin tone, your brain will alter your perception of the skin tone. A green background will make skin tone look more magenta, while a red background will make skin tone more cyan, etc.

Then you go down the rabbit hole of color print profiles and monitor calibration. In your printer settings, are you setting it to "perceptual", "relative colormetric", or "absolute colormetric"?

In my experience, Zeiss and Sigma Art lenses are amongst the most "clinical", but because most human subjects look better warmer, the truly neutral more 'clinical' lenses have a rendering that is relatively colder/cooler.

If you want to compare your own lenses, I'd suggest shooting RAW with a full spectrum light source and manual WB to match. Shoot a grey scale image. That may be the easiest way to see which white/grey/blacks are warmer, which are cooler, and which is the most neutral.
12-15-2017, 04:14 AM   #18
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QuoteOriginally posted by swanlefitte Quote
I hear how different lens are warm and cool and give good skin color. I just got a color chart. I would like a "control" lens to compare the others against.
Or is there an alternative control. Direct sensor to reality is impossible. A clinically true lens seems my closest bet or a good known correction of a lens.
I'd ask what's your output likely to be. From start to finish. From lighting, through post processing, via full colour management, to final output. Any lens will alter the transmitted colours, some more than others, and will be different in different conditions. The perception of the final colours and their interaction with each other needs to be considered. So to get to your accurate /controlled colour output, I'd say, it's more than just a lens' rendering, as understood from a test chart.
12-15-2017, 05:30 AM   #19
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I think this lens comparison is going to take me on a long journey of learning from the responses. Like sitting in on a lecture and end up staying for the entire course.

12-15-2017, 08:19 AM   #20
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QuoteOriginally posted by swanlefitte Quote
I hear how different lens are warm and cool and give good skin color. I just got a color chart. I would like a "control" lens to compare the others against.
So you just want to figure out the difference between lenses? You will need setup and then compare in PP.
Setup: Tripod, 2 sec timer, ISO 100, raw dng, bright full spectrum lights (or bright daylight). Use greycard with your first lens to set WB and keep that custom WB setting for all next lenses.
PP: Open the dng, turn sharpening and NR to low settings and note the WB setting. Colour profile also affect this, I recommend you use embedded before making your own.

The lens with most "neutral" colours is, in my opinion, a modern macro prime. Most modern Pentax primes have great colours, with very little colour cast. Macro lenses have the most clinical look. Pentax cameras tend to set a WB that is slightly magenta imo. (all WB settings, except the custom set one), maybe this is why your DFA 100mm seems magenta. If you use Adobe's definition of Daylight WB, it is more green. Note that different brands give different values to preset WB. AWB on the other hand tries to neutralize any WB to whatever the manufacturer believes to be natural. Pentax seems to believe a tinge of magenta is natural.

That said, if you bought a colour passport checker thingy (or camera calibration or whatever), it probably comes with instructions how to get the right results. Maybe you need to search online for more instructions. Another problem is the monitor calibration. If the monitor is off, then all "correct" WB and camera profiles will look odd. Raw software allows you to make your own colour profiles, but for that you should look at the forums of that software.

Edit: Also, remember that "true" colours don't exist and that most photos do not need that. Very few photos need true colours (archival photos, product photos). There is only so much "truth" you can get in the digital camera chain. You have Bayer sensor (RGB with different amounts of each colour), ISO noise colour artifacts, Camera colour profile, colour space (sRGB, AdobeRGB..), White balance shift, Raw software colour profile (can use camera's embedded profile, or not), and finally the monitor colours (or printer calibration if you are doing prints). There are so many variables that most of us have no chance of ironing them all out. Its just not cost effective to try and you usually get more attractive results with slight colour shifts anyway

Last edited by Na Horuk; 12-15-2017 at 08:35 AM.
12-15-2017, 11:34 AM   #21
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QuoteOriginally posted by Na Horuk Quote
Setup: Tripod, 2 sec timer, ISO 100, raw dng, bright full spectrum lights (or bright daylight). Use greycard with your first lens to set WB and keep that custom WB setting for all next lenses.
This comes back to the OP's original request in that the "first lens" takes the position as being the reference color rendering for the full series. They would prefer to have a "neutral" optic in that position. In my opinion, the lens survey is of limited value except for those with particularly inquiring minds. The quality of light coupled with RAW conversion/in-camera JPEG configuration have greater influence over color rendering than the lens mounted.


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12-15-2017, 12:20 PM   #22
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QuoteOriginally posted by IgorZ Quote
The problem with pinhole is that you need to use film
What's the reasoning here? I've taken pinhole photos with my digital sensors just fine using both homemade and commercially available pinholes.
12-15-2017, 01:45 PM   #23
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QuoteOriginally posted by stevebrot Quote
The quality of light coupled with RAW conversion/in-camera JPEG configuration have greater influence over color rendering than the lens mounted.
Well, colour cast can be an issue particularly with older lenses. But modern AWB mitigates this, and PP can remove it further. Still, this is exactly why I wrote the rest of my post. Reference lens can be great, but you will still see a colour cast if you don't calibrate the whole chain of actions, from WB to Software to monitor, printer.

Actually the idea of a pinhole lens is really interesting! There are plenty of pinhole lenses available online an you can even make your own out of a dark, dark material (so it doesn't shine its own colour cast). I guess you can't get more natural input than an empty hole.

12-15-2017, 02:36 PM   #24
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QuoteOriginally posted by fehknt Quote
What's the reasoning here? I've taken pinhole photos with my digital sensors just fine using both homemade and commercially available pinholes.
I have a commercially made pinhole (f/150) and it works fine on film, but not on digital. I was told the reason is that film emulsion is thin enough to tolerate light hitting it at various angles but that digital sensors need the light to hit it directly (90 degrees to the sensor). On film, I can get a relatively sharp, wide angle image with tons of vignetting. On an APS-C sensor, it's unacceptably soft.

Can you post examples of some of your 'fine' images made with a commercially made pinhole and any details?
12-15-2017, 04:10 PM   #25
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QuoteOriginally posted by fehknt Quote
What's the reasoning here? I've taken pinhole photos with my digital sensors just fine using both homemade and commercially available pinholes.
You are right. I just had a good old pinhole camera in mind...
12-15-2017, 06:06 PM   #26
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QuoteOriginally posted by Alex645 Quote
I have a commercially made pinhole (f/150) and it works fine on film, but not on digital. I was told the reason is that film emulsion is thin enough to tolerate light hitting it at various angles but that digital sensors need the light to hit it directly (90 degrees to the sensor). On film, I can get a relatively sharp, wide angle image with tons of vignetting. On an APS-C sensor, it's unacceptably soft.

Can you post examples of some of your 'fine' images made with a commercially made pinhole and any details?
This is sort of true and sort of not. Digital sensors are less receptive than film to light at extreme angles but the light doesn't have to be exactly 90. The fact that so many large aperture and wide angle lenses work on digital suggests that the corners of the sensor are sensitive to light down to maybe 45 or so.

For various reasons, the "best" pinhole images do come from large format film cameras with the pinhole operating as a wide-angle lens (say a 150 mm @ f/400). A lens-cap pinhole on a DSLR will work, acting as about 46 mm lens but the resolution will be quite low (only a few hundred lines of resolution total). A lens-cap pinhole on a mirrorless camera will work, acting as a much wider lens but the resolution will also be low and it will have vignetting in the corners.

A pinhole image from a FF DSLR isn't going to win any awards but it will have sufficient resolution to get a good color target image that shows the sensor's response to color with no color shifts from glass or coatings.
12-15-2017, 10:29 PM   #27
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My pinhole images are hazy enough that the contrast is reduced, and therefore the colors aren't particular accurate, so I'm not sure that's a particularly good control.
12-16-2017, 05:50 AM   #28
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QuoteOriginally posted by leekil Quote
My pinhole images are hazy enough that the contrast is reduced, and therefore the colors aren't particular accurate, so I'm not sure that's a particularly good control.
Two questions:

What's the pinhole made of? I've seen some where the hole is a bit reflective inside and that will scatter light.

Do you have a really deep lens hood on it? The effective image circle on a pinhole is huge. With no hood more than 10X as much light will be bouncing around the mirrorbox and fogging the image as is part of the image.
12-16-2017, 11:09 AM   #29
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QuoteOriginally posted by swanlefitte Quote
What lens has the most clinical colour?
Have you considered using a Colorchecker Passport? it would ensure correct colours at the time of taking, as part of a colour managed workflow.
12-16-2017, 07:00 PM   #30
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I just set up my dkc color chart and tested a couple flashes at a couple fstops and power settings and 4 lenses. my yongnuo says its 5600k so my raws were set to that. The nikon sb 28 was slightly less blue. both had RGB getting higher. The fstop and power were barely different. I tried my sigma 70, my 77 limited and my 50-200 DAL. The reading on the white was very similar the most extreme RGB was around 243,246,253 with the sigma. The 50-200 was about 3 points off white 244,245, 247. I pulled out my nikkor 105 2.5ai and it too had white very close.
So how can I find a difference or is the human eye that good at tiny differences? By the way my auto white balance is way off.
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