The GetDPI Photography Forum

Great to see you here. Join our insightful photographic forum today and start tapping into a huge wealth of photographic knowledge. Completing our simple registration process will allow you to gain access to exclusive content, add your own topics and posts, share your work and connect with other members through your own private inbox! And don’t forget to say hi!

Issue with IQ180

Hello, I noticed that the bottom right of some IQ180 image (shot with 645DF+, 110ls) have a magenta cast. It's exactly one quarter of the frame (exactly 1/4 bottom right). I've read somewhere that there is kind of a "Quad channel" readout path out of the sensor. (I may be wrong tough). Any similar experience ?
The photo in attached is developed with lightroom 4.3 It is heavily underexposed, that is not the topic of the post. I see that a couple of pictures have the same issues.
Any help anyone ? I've posted a support request on phaseone.
Thanks for your feedback
 

pfigen

Member
What happens to the same file when you process it in Capture One? I've read elsewhere of people reporting "quadrant" effects when processing IQ180 files in LR - having something to do with the way the chip is tiled - something that C1 can compensate for and LR can't.
 

dougpeterson

Workshop Member
+1 check it in Capture One. If it shows up there then contact your dealer for a recalibration. If it only shows up in LightRoom then the issue is LightRoom and not the digital back.
 

avelpavel

New member
Hi, I had the same issue with my P65+ but in the first quarter of the file.

You can try to put this code in the folder name where you keep the raw files:

P1#1024-OFF#

es. in the folder called "raw" you add the code make it "raw P1#1024-OFF#"

The guy at P1 said this code stops Capture one to over correct the file. I don't know if it works with the P65 only or with every back.

By the way it's a strange behaviour from C1 I think.

Rob
 

avelpavel

New member
I forget to add that I have seen this issue in C1, sometimes even on Lightroom but I like better C1 for developing Phase files.

Rob
 

dougpeterson

Workshop Member
Again, if you see any form of tiling in Capture One with supported lenses with any reasonable photographic adjustment (e.g. +4 stops, +50 contrast, +50 saturation is not a reasonable adjustment) the back should be recalibrated.

This is not something that is considered acceptable as Avel's post seems to imply. The fix he posts was a specific and temporary fix; Capture One has since been improved to address the underlying issue that specific fix was meant to address and is not recommended in Capture One v7.
 
Last edited:

avelpavel

New member
I know Doug that a strong underexposure or extreme adjustments bring only troubles.
I find some issues in images that I usually shoot like the example I attach. The fix code seems to work with C1 7.1.1 as I had this issue now and my back has just been recalibrated... By the way when I use the code on raw files I made before the recalibration of the back everything is fine. (I posted an image at iso 200 but it's visibile at 100 too...)

Rob
 

dougpeterson

Workshop Member
I know Doug that a strong underexposure or extreme adjustments bring only troubles.
I find some issues in images that I usually shoot like the example I attach. The fix code seems to work with C1 7.1.1 as I had this issue now and my back has just been recalibrated... By the way when I use the code on raw files I made before the recalibration of the back everything is fine. (I posted an image at iso 200 but it's visibile at 100 too...)

Rob
Interesting. This does not match my understanding or expectations. I'd investigate further with your dealer.
 

bcooter

New member
Interesting. This does not match my understanding or expectations. I'd investigate further with your dealer.

You know. I thought I was going crazy.

For years when I shot talent vertical the legs would also be magenta
if I processed the faces to a golden brown tone.

I see this all the time with my p21+ and even more with my p30+ and thought it was just that faces and legs were different tones.

I usually just select out the legs and change the hue/sat and match it, though on this image with the fish net hose it's harder to do.



You can see it slightly in this image though I've painted a lot of the skin to match.



I thought it was just ambient bounce or just the way the kodak sensors worked, though it's not lighting as the top image was tungsten the bottom was studio flash.

(these are very small low rez jpegs so there are some artifacts and it's kind of difficult to exactly see it, but once again I've seen it so much, I just thought it was normal.

Would that line of code in V7 fix this?

Thanks

BC
 

chrismuc

Member
I had a similar magenta/green color cast issue with longer focal length lenses with my brand new IQ180, just half/half, not a quarter of the sensor (see sample). I reported to Phase One Germany, uploaded some raw files for them and they immediately offered to exchange the back. The replaced back just arrived and is working fine now. So such casts seem to be caused by a miscalibration of the back, not by the typical corner cast using (symmetrical) wide angle lenses.
 

avelpavel

New member
I don't know if the pink cast on legs comes from the lens flare or the raw developer. It will be worth to try and convert a raw file of them to see the difference. (Maybe my eyes are doing wrong but I can see a different noise pattern with the code on, I like to use the P65 at 400iso for the grain it gets out with no correction in C1, all slider to 0, it seems better...)

rob

Roberto Pastrovicchio Photography . Italy . +39 329 9617876 . [email protected]
 

bcooter

New member
I had a similar magenta/green color cast issue with longer focal length lenses with my brand new IQ180, just half/half, not a quarter of the sensor (see sample). I reported to Phase One Germany, uploaded some raw files for them and they immediately offered to exchange the back. The replaced back just arrived and is working fine now. So such casts seem to be caused by a miscalibration of the back, not by the typical corner cast using (symmetrical) wide angle lenses.
I think what I'm seeing is light fall off. Both of those images were shot with spots and as the light falsl off, it's like pulling a darker curve, it usually goes warmer.

I looked at a pentax 645d article and though the photos are a little challanged, it had brown faces and magenta toned legs.

Shooting with the Pentax 645D: Test Images

So maybe it's not the sensor or software maybe it's just how the light falls off.

IMO

BC
 

Shashin

Well-known member
BC, the OP is taking about sensor split.

As far as increased magenta in the shadows in the 645D because of light fall off goes, never seen it. Your examples could just be showing a gold reflector influencing the face, but not the legs. Who knows what else is influencing the color in those shots. And I have never heard of a magenta/yellow shift--yellow/blue or magenta/green is the usual combination.
 

bcooter

New member
BC, the OP is taking about sensor split.

As far as increased magenta in the shadows in the 645D because of light fall off goes, never seen it. Your examples could just be showing a gold reflector influencing the face, but not the legs. Who knows what else is influencing the color in those shots. And I have never heard of a magenta/yellow shift--yellow/blue or magenta/green is the usual combination.
I know the other was sensor split, but I thought maybe they were related.

The pentax sample link I posted is the problem with posting links. I have no clue how they shot it.

I do know that my p21+ and more with the p30+ I see magenta on the bottom half of the frames in the way it renders red/yellow. Like I mentioned I've selected out legs and mid lower body of lingerie models so many times and changed the color, I should keep it on a photoshop action.

It's really not that problematic, because the upside of ccd's is they see a lot of color the down side is if there is any changes in skin tone or color it shows.

I always assumed it was that faces received more sun and had a different color than legs and that could be it.

The only cmos color I've ever really liked is the original 1ds which was global but at least pretty global.

This from a 1ds.



IMO

BC
 

yaya

Active member
BC, two things you can do:

Turn the camera 180 degrees and see if the different hues change places

Shoot two separate (horizontal) frames of the upper and lower body and put them side-by-side or as layers in PS to see if there's a real difference

In my experience legs & hands always tend to show more magenta and sometimes cyan tones, also they usually don't wear makeup on their legs, at least not as much as on their faces...
 

Pics2

New member
+1 for Yair.
BC, I have obvious magenta cast at the bottom part, too. Actually, it's more like bottom right. To save you some time, instead of doing selective color correction in PS, why don't you do LCC correction in P1 at the beginning of a shooting with the same lighting/lens combination. Even though it's wide angle lenses that ask for LCC, I see this magenta cast with 120mm macro lens, too. But, P1 does really great job, no problems at all.
I can't recommend this to CollPixPhotography, because it seems like he was shooting from a helicopter.
 
Top