topic Re: Issue with Magenta Tinting in EOS DSLR & Mirrorless Cameras

Issue with Magenta Tinting

FelixA7 — Tue, 19 Oct 2021 19:49:56 GMT

Hi all,

I own an EOS t7i and, in the last 7 months or so, I've struggled with magenta tinting of my photographs. No amount of white balance adjusting helps to bring the coloration back to what it is in real life. I could make the colors have a green or gold hue, but those look even more unnatural than the magenta.

I am separately an astrophotographer and several of my astrophotographs, when perfectly tracking at long exposures, have a field of tiny, magenta/red grain to them. I've tried various astrophotography specific approaches to eliminate the grain, which some of the professionals in the field refer to as "walking grain." None of those approaches have worked. I'm wondering whether that tinted grain is related to the magenta base that I get when using auto whitebalance.

Thanks!

Felix

P.S. This is my first time posting on this forum and I apologize if this topic has been covered elsewhere.

Re: Issue with Magenta Tinting

jrhoffman75 — Tue, 19 Oct 2021 23:05:33 GMT

Welcome to the forum.

Can you post a link to a Dropbox or One Drive folder where you can post a RAW file f the images that you are describing?

Re: Issue with Magenta Tinting

FelixA7 — Wed, 20 Oct 2021 13:16:15 GMT

Hi!

Thanks for asking for the images. Here's a link to the folder: https://www.dropbox.com/sh/qclaw34fjkh1g38/AACih13aYJrhJ6Tql1dgBZkaa?dl=0. If you look hard at the astrophotograph, you can see the fine red grain.

If you look at the photos of the elephant paintings and one of the figure drawings (be warned, the figure is unclothed but it's a drawing) you will notice the magenta tint. The second figure drawing shows the image after I changed the white balance. You can see that, even though the magenta is gone, there is still a tint -- a kind of drabness to the image. That is present regardless of exposure.

Note -- I included an iphone photo of the elephant drawing that shows what the elephant painting looks like in real life.

Felix

Re: Issue with Magenta Tinting

jrhoffman75 — Wed, 20 Oct 2021 16:30:10 GMT

I can't tell anything meaningful about the sky photo since Canon DPP considers it an unrecognized file type. Can you post in DropBox the out of camera file?

The other images are off-color because of a white balance problem.

I am assuming that the door moulding should be white and the models hair black.

By doing that the images look correct.

What lighting type are you shooting in?

Re: Issue with Magenta Tinting

ebiggs1 — Wed, 20 Oct 2021 16:46:48 GMT

The images are so small its difficult to do any real adjustments. But Photoshop has no problem placing ther color balance and WB wherever you want it.

My guesses!

The star shot is just too pixelated to work on.

Re: Issue with Magenta Tinting

FelixA7 — Wed, 20 Oct 2021 17:13:45 GMT

Thank you for your great comments. I can adjust the color balance in photoshop, but I was hoping to figure out what is off with the color balance in the camera itself.

I am shooting photos of my drawings in an interior space with two studio lights, set to warm light, directed at the drawing from 45 degree angles. The lighting doesn’t matter — I can go in and set the white balance accordingly and there’s still the magenta tint or, less frequently a greenish tint. The tint drowns out the colors.

I’ll get a better JPEG of the astrophotograph. Out of the camera, the image is okay. It’s when dozens of images are stacked and processed that the red grain becomes pronounced.

Re: Issue with Magenta Tinting

FelixA7 — Wed, 20 Oct 2021 17:17:11 GMT

Here's a smaller photo of a galaxy. You can see the red grain when you zoom in.

Re: Issue with Magenta Tinting

ebiggs1 — Wed, 20 Oct 2021 19:20:39 GMT

"... there’s still the magenta tint or, less frequently a greenish tint."

OK here is what you need to do. First reset the camera back to Canon defaults. Menus, Tools, Clear all settings and Clear all custom settings. Important do both. Now set the camera to P mode. One shot, not Ai-servo and just one center focus point. ISO 200 and auto WB. Preferably Raw but foe this test jpg is OK.

Go outside on a nice day and take some random shots of varying subjects. Look them over in PS without adjustment. If they look great, there is nothing wrong with your camera and all the tinting is coming from you. My guess that will be the case but let's make sure. Do the test.

Re: Issue with Magenta Tinting

jrhoffman75 — Wed, 20 Oct 2021 20:13:19 GMT

@FelixA7 wrote:
Here's a smaller photo of a galaxy. You can see the red grain when you zoom in.

There is a good chance that is color noise from a high ISO. What were the shooting conditions?

Here is your first image, first as posted imported into Lightroom and second, with color noise and luminance noise correction applied.

Your base image is very good; nice point stars. No lens aberrations.

Re: Issue with Magenta Tinting

ebiggs1 — Wed, 20 Oct 2021 19:43:57 GMT

On your sky shot a simple WB adjustment in levels produces this. I have no idea if it is correct. The center of your star cluster is drastically overexposed so defining WB is more difficult.

I see lots of color in the out lying starts so I imagine it is close. More time in PS and a better exposure would yield nice results.

Re: Issue with Magenta Tinting

ebiggs1 — Wed, 20 Oct 2021 19:49:23 GMT

"I own an EOS t7i and ..."

... and what lens are you using? Perhaps it has excessive chromatic aberration. If it is the kit lens I suggest you get a better lens for astro work.

Re: Issue with Magenta Tinting

jrhoffman75 — Wed, 20 Oct 2021 20:23:11 GMT

Did you take a dark frame image as well as multiple sky images?

The stacking software may have the capability of zeroing out the sensor noise by subtacting the dark frame image info from the sky images.

Re: Issue with Magenta Tinting

jrhoffman75 — Wed, 20 Oct 2021 20:36:48 GMT

@FelixA7 wrote:
Here's a smaller photo of a galaxy. You can see the red grain when you zoom in.

Here is the image as imported into Lightroom with color noise and luminance noise adjustment applied. Masking and sharpening to accentuate the stars.

Nice point stars. No clipping anywhere in the image.

Since it was a jpeg I couldn't adjust color temperature, but generally astro shots look good at around 4000K or so.

Re: Issue with Magenta Tinting

ebiggs1 — Wed, 20 Oct 2021 20:56:33 GMT

John, I believe the OP has a camera setting and/or photo shoot set-up issue more than a camera fault. The reset and outdoors test will confirm it.

Re: Issue with Magenta Tinting

jrhoffman75 — Wed, 20 Oct 2021 21:27:21 GMT

@ebiggs1 wrote:
John, I believe the OP has a camera setting and/or photo shoot set-up issue more than a camera fault. The reset and outdoors test will confirm it.

I agree.

Based on his astrophotography images I consider the results to be expected. The T7i isn't a high ISO champ.

I think the room environment for the easel shot is challenging the capability of the camera auto WB capability. Room seems to have a green bias when the adjusted image is available. Red/magenta is opposite green on the color wheel.

Your advice for an outdoor shot is right on.

Re: Issue with Magenta Tinting

FelixA7 — Fri, 18 Mar 2022 01:21:52 GMT

Hi all!!

I’m sorry for the 6 month delay in responding to all the great responses. I’m so appreciative. So, I reset the settings as per the recommendation of multiple people who posted above. My outdoor shots were clear of the magenta! Even at iso 800 and 1600. I struggled with white balance indoors, however. I used all the various pre-set lighting condition options for WB. All of them tilted one way or another — too green or too magenta. And, when I tried to correct afterwards, there was always a lingering hue.

But, over time, all the old magenta issues returned. As I used remote/wifi settings, set different focus distributions and switched back and forth to RAW …:

what’s more, I was never able to get rid of the red grain in the astrophotography. Note that, for the deep sky photos, I’m hooking my t7i to an 80 mm or 230 mm aperture (not FL) telescope with high quality glass. The shots are guided electronically to control for periodic mount error. I use a field flattener. I am taking dozens of frames and then stacking them with a special astrophotography program. I use Darks, Flats and Bias frames for calibration. That red grain is a problem even in the individual frames, but it really flares up after stacking and after I use levels and curves to draw out the nebulosity around the stars.

What John Hoffman did in Lightroom is amazing. I will play with those corrections when I next process astrophotographs. However, I do feel like some of the nebulosity and faint shapes are lost after the Lightroom adjustments. And I worry that, when I have hours and hours of stacked exposures, there will be even more nebulously and subtle color to lose.

the telescopes, by the way, are f/4.5 and f/10 respectively.