[DSLRnovice]

The other day I noticed that colors appeared to be washed out when using a Takumar 135/2.8 lens, compared to the latest Pentax 28-105. What I found out was that if I set the white balance to manual, the colors and contrast were basically the same. Since I shoot mostly RAW, I can change the settings later, but it is nice to know that my lenses are not so different from one another. There is something going on with the K-1 in the auto white balance when using older lenses.

[pathdoc]

Interesting.

I've noticed differences here and there, but the only time I really need to do a forced WB with my K-1 (and K-5) is with my Super Tak 50/1.4; that thing is radioactive, and no matter how much I've put it in the sun it still won't de-yellow (and I'm not going to buy a special lamp for just one lens). That one works nicely on the "muted" setting.

[photoptimist]

Every lens has a slightly different effect on color transmission depending on the types of glass in the elements and the coatings. Modern lenses communicate their identity to the camera and a database in the firmware has the color corrections for that lens to get a more accurate rendering of the scene. But if you use RAW or manual white-balance, those corrections are not applied (unless you RAW developer also has a lens database).

[DSLRnovice]

As I understand it, even when shooting RAW, the camera records the settings for viewing purposes that would have been saved in the JPG. That is why the view I see in the playback screen displays the variations between what either manual or AWB would be. And I take it the same goes for DCU. I should have been specific in that I was referring to the how the camera displays the image.

Prints from color negs hid the differences between lenses until I did my own in the darkroom. I had thought AWB would have the same effect as the automatic color balancing done in photo labs of the "dark ages."

[stevebrot]

Auto white balance is based on an analysis of the spectral distribution in the image. It works the same regardless of the lens mounted. As noted above, in the full technical sense any white balance setting on the camera only applies to JPEG capture or in-camera RAW development. RAW captures have no (as in none, zero, nada) white balance applied to the capture. That being said, the camera's setting is retained in the the makernotes section of the EXIF metadata and is available for use by RAW processing software to potentially be applied in PP.

The software that comes with Pentax cameras will take advantage of the value from the metadata as will many 3rd-party products, though with potential for some proprietary tweaks. A good example would be Adobe Lightroom. I use LR 5.7 and if white balance from the EXIF is 6200K, the value assigned on import might be 6250K with a slight warming tint applied. The general appearance is usually very close to that of the full-resolution embedded JPEG* that was generated using the 6200K value.

BTW...the custom image settings (bright, nature, muted, bleach bypass, monochrome, etc.) from the 4-way controller are completely separate from and unrelated to white balance, though many of the same rules do apply in that they only apply to JPEG and RAW processed in-camera or by the Pentax software.


Steve

* The embedded JPEG preview images reflect the camera's JPEG image settings. If the white balance was set to "tungsten" and shot outside in the sun, the embedded image will have a decided bluish tint. Likewise, the same is true for custom image settings. If monochrome, the preview JPEGs will be B&W.

[stevebrot]

I had thought AWB would have the same effect as the automatic color balancing done in photo labs of the "dark ages."

AWB works smilarly to the automatic color balance done by a minilab, though there are limits. If you shoot daylight film under tungsten light, there is little that can be done using filtration after the fact to make things right. Similarly, AWB can be fooled by some lighting and subjects.

For example, I was tasked with shooting an event at my church a few weeks ago. I have photographed using the stage lighting there before with good results and was confident with using AWB for my work. I was very surprised to find later that my K-3 chose a value that was much higher than it should have been resulting in some very orange people. Strangely, wood work and furnishings in the background looked quite normal. After a little asking around, I found that the spotlights for the main part of the platform had been upgraded to LED a week or so before. I am not sure, but I suspect that AWB was confused by the mix of foreground and background illumination as well as unexpected spectra from the LED spots. Next time, I will use a fixed value off a gray card and will also take a gray card image to use in PP if needed.

P.S. As for your original observation, various lenses will impart a little different tint and/or spectral distribution to the image beyond the actual scene illumination. That two different lenses might result in different AWB is to be expected. Strangely, it may also be expected that the same manual WB applied for the two may result in similar results. There is more to color perception than white balance and it is often difficult to see a difference between what should be two very different values.


Steve