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Author Topic: Help, Purple Haze  (Read 8350 times)

LA30

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Help, Purple Haze
« on: August 15, 2007, 05:01:02 pm »

While on a paying job today I put a 1 year old B+W slim circular polarizer on my Hasselblad HC 50mm lens with Phase P30+ back.  Daylight white balance 200/sec f5.6 iso 200 IIQ rawfile (large raw file).  I am getting a pretty bad purple haze on her chest and hair.  It was a reflection from the direct sun.  I have some frames like this, it looks like CA??  Is there anyway to get ride of this now that the shot is over with besides photoshop??  I had to use the polarizer for the sky, and it wasn't in every frame so I didn't pick up on it.  The rawfile was processed with latest C1 Pro, full res adobe 1998 16bit tiff converted to srgb 8 bit 100% crop no sharpening to post.

B+W Filter says on edge  "77 slim ksm c-pol mrc"


Any help would be greatly appreciated.



Ken[attachment=3053:attachment]
« Last Edit: August 20, 2007, 12:10:30 am by kenscott30 »
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RicAgu

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Help, Purple Haze
« Reply #1 on: August 15, 2007, 05:44:51 pm »

Try procesing it out into ProPhoto RGB 16 bit instead of adobe 1998.  You should be doing that anyway.  Do all retouching in that and then convert as needed to web, print or client requirements.

I haven't seen this happen with B&W polarizers, I have seen color casts with cheaper brand filters and polarizers.

Anytime shooting with anything in front of the lens you should process out one shot on location from every scene.  I learned this the hardway early on.  there is something about digitalbacks and filters that don't seem to work together.  At least this has been my experience.


Best of luck

Ric
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LA30

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Help, Purple Haze
« Reply #2 on: August 15, 2007, 06:29:35 pm »

Quote
Try procesing it out into ProPhoto RGB 16 bit instead of adobe 1998........
Ric
[a href=\"index.php?act=findpost&pid=133497\"][{POST_SNAPBACK}][/a]

I tried it Ric, prophoto...It didn't help :^(  I will consider ProPhoto from now on.  It is pretty big but so is the range of the P30+.

Ken
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RicAgu

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Help, Purple Haze
« Reply #3 on: August 15, 2007, 06:52:44 pm »

Sorry about that Ken,

I would send the raw file to Phase and contact your dealer and send it to them.  See what they c an say about it and let us know where you land with Phase and your dealer.


It would be good if they informed us of this before we experienced it on our own.  But they rather speak of the drawbacks their backs produce.

Best of Luck,

Ric
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bcroslin

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Help, Purple Haze
« Reply #4 on: August 15, 2007, 09:01:59 pm »

Quote
Try procesing it out into ProPhoto RGB 16 bit instead of adobe 1998.  You should be doing that anyway.
Ric,

Why Prophoto instead of Adobe 1998? Does it make that much of a difference during post?

(sorry to thread jack)
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LA30

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« Reply #5 on: August 15, 2007, 09:06:02 pm »

Thanks,

Nothing a little de-saturation and hue shift and rubber stamp can't fix...OH, I will just tell the client that.  That I am shooting with the latest technology.....oh, wait my 5D won't do that..Maybe I just shoot with that...

I will try to get the file to my dealer and Phase rep and let you guys know.... Definitely stinks.

Ken
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Jack Varney

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Help, Purple Haze
« Reply #6 on: August 15, 2007, 09:12:54 pm »

The angle at which the color arrives and is reflected from the subjects seems to be consistent on the left model on her upper forehead, tip of her ear, purse strap and on two spots on the top button of the jacket. It is also in portions of her jacket that face that same direction. But where the cheek, chest and jacket is turned toward the camera position and downward it does not appear. It also appears in the hair of the second model perhaps from a similar angle. I also note that the tops of the windows on the building in the background have a similar cast.

Can this be a colored directional reflection from the windows hitting these parts of the subjects?
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Jack Varney

LA30

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Help, Purple Haze
« Reply #7 on: August 15, 2007, 09:14:23 pm »

Quote
Ric,

Why Prophoto instead of Adobe 1998? Does it make that much of a difference during post?

(sorry to thread jack)
[{POST_SNAPBACK}][/a]

Talk about a jacking.....Well there is a lot of debate here...Oh, god...anyway....Prophoto is a BIG space, bigger than 1998.  Some folks say, "Great! All my colors FIT into Prophoto, it must be good because I don't clip any of my colors..."  Others say that you need to think about where the end result is so you can better target the initial 16bit RGB space as you don't want to assign all those values for colors that aren't there in the first place.  In fact wasting values.....I am sure that there are others that can speak more eloquently on this.  Read the late and great Bruce Fraser book on Color Management.  Or just google "prophoto vs adobe 1998" and sit back with a cup of coffee.

[a href=\"http://en.wikipedia.org/wiki/ProPhoto_RGB_color_space]http://en.wikipedia.org/wiki/ProPhoto_RGB_color_space[/url]

Ok, back to my purple dilemma!

ken
« Last Edit: August 15, 2007, 09:19:20 pm by kenscott30 »
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LA30

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« Reply #8 on: August 15, 2007, 09:16:53 pm »

Quote
The angle at which the color arrives and is reflected from the subjects seems to be consistent on the left model on her upper forehead, tip of her ear, purse strap and on two spots on the top button of the jacket. It is also in portions of her jacket that face that same direction. But where the cheek, chest and jacket is turned toward the camera position and downward it does not appear. It also appears in the hair of the second model perhaps from a similar angle. I also note that the tops of the windows on the building in the background have a similar cast.

Can this be a colored directional reflection from the windows hitting these parts of the subjects?
[a href=\"index.php?act=findpost&pid=133524\"][{POST_SNAPBACK}][/a]


Nice Jack.  I did notice the windows...maybe the windows have some sort of coating, UV or sun blocking tint that is not playing nice with the filter...

Ken
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RicAgu

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Help, Purple Haze
« Reply #9 on: August 16, 2007, 09:01:16 pm »

Hey Bob,

I have gotten better results using proPhoto.  Maybe it is me, I don't know.  But we do all final master work in ProPhoto and then send files according to the need of output.  

When it comes to color correction and tweaking I have worked with both on the same file and preferred the ProPhoto.  I did it blind to working with my retoucher and told her to rename them so I wouldn't know which was which.  I always pick the Pro Photo.

Look forward to hearing what Phase and your dealer have to say.

Best,

Ric
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LA30

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Help, Purple Haze
« Reply #10 on: August 16, 2007, 09:30:39 pm »

Good to know Ric.  I will look into it.

As far as Phase Dealers...I was on the job again today and at another big commercial building.  I took out the polarizing filter and my polarized sun glasses and sure enough at the right angle I could see the purple on a few of the windows.  So it was the coating on the glass, I could see it with my eyes.  It was a very very windy day the other day and we had all hands on deck, producer, stylist assistant all helping out, 2 guys on a 6' umbrella.  
We broke a 6X6 bounch in half during that shot.  We didn't have anyone checking the files 1 by 1.  We didn't have a lot of time and when we looked at a few frames they looked fine.  Again, we didn't look at every frame.  I think that only about 20 or so have this purple...It is something to know for next time....  So to sum up, sunglasses and filter did it to the naked eye as well as chip.  

Thanks for working with me on this.


Ken
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clawery

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Help, Purple Haze
« Reply #11 on: August 16, 2007, 10:46:32 pm »

Quote
While on a paying job today I put a 1 year old B+W slim circular polarizer on my Hasselblad HC 50mm lens with Phase P30+ back.  Daylight white balance 200/sec f5.6 iso 200 IIQ rawfile (large raw file).  I am getting a pretty bad purple haze on her chest and hair.  It was a reflection from the direct sun.  I have some frames like this, it looks like CA??  Is there anyway to get ride of this now that the shot is over with besides photoshop??  I had to use the polarizer for the sky, and it wasn't in every frame so I didn't pick up on it.  The rawfile was processed with latest C1 Pro, full res adobe 1998 16bit tiff converted to srgb 8 bit 100% crop no sharpening to post.

B+W Filter says on edge  "77 slim ksm c-pol mrc"
Any help would be greatly appreciated.
I couldn't get the image to upload to LLforum so see it here...

http://www.kenscottphoto.com/xxxxxx_2686.jpg
Ken
[a href=\"index.php?act=findpost&pid=133489\"][{POST_SNAPBACK}][/a]

Have you tried color editor in C1Pro? You could select the color amd take it out. Nerd more help contact Tim Palmer at Capture Integration. (404)522-7662
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bcroslin

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Help, Purple Haze
« Reply #12 on: August 18, 2007, 05:10:51 pm »

Ric and Ken - thanks for the info!

And now, back to your regularly scheduled purple haze!

 
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Bob Croslin, Photographer
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nicolaasdb

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Help, Purple Haze
« Reply #13 on: August 18, 2007, 06:20:10 pm »

open them up in lightroom and take the purple out in the color correction section they have a slider for purple (there are actual 3 sliders- hue, saturation, luminance) this will take care of your problem.

Ofcourse you can go the long route (manufactures, salesrep etc) and bitch about the problem to your client, but this will not make them feel any better and they will think it is your problem....they want an image not your technical problems!

goodluck
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LA30

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Help, Purple Haze
« Reply #14 on: August 18, 2007, 06:34:52 pm »

Quote
open them up in lightroom and take the purple out in the color correction section they have a slider for purple (there are actual 3 sliders- hue, saturation, luminance) this will take care of your problem.

Ofcourse you can go the long route (manufactures, salesrep etc) and bitch about the problem to your client, but this will not make them feel any better and they will think it is your problem....they want an image not your technical problems!

goodluck
[a href=\"index.php?act=findpost&pid=134038\"][{POST_SNAPBACK}][/a]


Ah, lightroom, it doesn't YET work on the P30+ files when shooting to a card.

Ken
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nicolaasdb

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« Reply #15 on: August 18, 2007, 06:51:10 pm »

you download them to your computer first...and I have read that you can use phase one files in photoshop cs3....you should be able to open them in ACR and take the purple out....the same sliders as in LR.
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Michael Bailey

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Help, Purple Haze
« Reply #16 on: August 18, 2007, 09:46:52 pm »

Ken,

I'm not a medium format digital guy, but I'll try two answers out on you anyway.

As for the cause of the problem, to my eye it's a clear case of weird, very hard light coming off a window in the tall building in back. I don't see it as a camera problem.

As for a solution, I tried the Color Replacement Brush in Photoshop. (Set to Color, Contiguous, Tolerance in range of 20-30.) I've attached my result. I made sure not to spend more than five minutes on it--I didn't want to recommend a solution that would be unrealistic, and I'm lazy. Since you'll be working on bigger and better files, I'm sure your results will be better than mine.

For what it's worth...

MB
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vgogolak

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Help, Purple Haze
« Reply #17 on: August 19, 2007, 03:58:17 pm »

Quote
Sorry about that Ken,

I would send the raw file to Phase and contact your dealer and send it to them.  See what they c an say about it and let us know where you land with Phase and your dealer.
It would be good if they informed us of this before we experienced it on our own.  But they rather speak of the drawbacks their backs produce.

Best of Luck,

Ric
[a href=\"index.php?act=findpost&pid=133505\"][{POST_SNAPBACK}][/a]

Why would Phase be involved? This seems like a straightforward optical effect from a polarizer and reflected light. Note that the affected light is also off a 'reflective' surface (skin, likely with oils) and the filter.

The sensor sees what is there. I doubt very much whether the IR coating or the sensor itself has anything to do with this. Throw on a film back and I believe you will see the same thing.

regards
Victor
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LA30

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Help, Purple Haze
« Reply #18 on: August 20, 2007, 08:19:42 am »

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Why would Phase be involved? This seems like a straightforward optical effect from a polarizer and reflected light. Note that the affected light is also off a 'reflective' surface (skin, likely with oils) and the filter.

The sensor sees what is there. I doubt very much whether the IR coating or the sensor itself has anything to do with this. Throw on a film back and I believe you will see the same thing.

regards
Victor
[a href=\"index.php?act=findpost&pid=134173\"][{POST_SNAPBACK}][/a]

Yes Victor,

After some discussion and my confirmation seeing this effect from another commercial building it has nothing to do with the back.

Thanks

Ken
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