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Author Topic: too strong colorfridging with Phase one P65+ shooting architecture  (Read 7911 times)
ryandutch
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« on: February 17, 2013, 07:25:10 PM »
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Hello , i recently bought a p65+ ...thinking it would be better then my Hasselblad 50MP

when shooting on a Cambo Rs with a 28 mm XL schneider with the nice centre filter , and 12 mm of shift to the right ...i get ...

a huge purple fringing ...  

and i thought mmmm

so i made a test setup at home camera fixed .. f 11    shot my LCC shot ,

then i changed backs to Hasselblad 50 Mp

did the same , no changes for the rest

and what did i see ...no purple extreme color fridging with the Hasselblad...  


since everybody is so into Phase ...   maybe share some experiances or help

here are the original files , and some tifs renderings to compare

because of the strong LCC correction , all the reds on the right side of the image are suppressed...


this doesn't look good for the P65...

i am very disappointed.

here are the original files , you can download as you like ....

also 2 tifs to directly compare...

i have no idea...

greetings Rien.



http://rvanr.com/filechute/2%20tifs%20.zip
http://rvanr.com/filechute/H3d-50%20at%20home.zip
http://rvanr.com/filechute/phase%20p65%20at%20home.zip
« Last Edit: February 17, 2013, 08:01:30 PM by ryandutch » Logged
FredBGG
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« Reply #1 on: February 17, 2013, 10:21:00 PM »
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Here are the tiffs:


Hasselblad 50


Phase 65+

On the right hand side of the frame....
Not only are the reds subdued, but so are the greens.
Neutrals seem to be a bit off too. Greenish shift.

Here is the uncorrected Phase One P65+.



Shows how much it needs to be corrected.

Here is the LCC


Looking that the problem area the levels are really crushed so there are few values that can be used
to make an accurate correction.

« Last Edit: February 17, 2013, 10:49:23 PM by FredBGG » Logged
FredBGG
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« Reply #2 on: February 17, 2013, 11:56:17 PM »
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A 12mm shift with the rear element so close to the sensor actually results in quite a high angle.
The difference in sensor design and how light hitting the sensors at such an angle effects the capture.

A retro focus lens design would reduce the angle at which the light hits the sensor, but then the 12mm shift would result in less
distortion correction.

It would be worth while seeing how good the P65+ is by not using lens shift and then correction the perspective distortion
in post..
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ErikKaffehr
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« Reply #3 on: February 18, 2013, 01:47:45 AM »
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Hi,

Just an observation, I would guess that a retrofocus lens would work much better. I think some of the Rodenstock HRs are retrofocus designs. All Hasselblad wide angles are retrofocus lenses except the SWC.

Shifting the lens exaggerates the problem.

The problem is that the light from the lens hits the sensor at very large angles, and that is causing a lot of problems. Retrofocus lenses (Distagons in "Zeiss speak") project the light at a much smaller angle and reduce problems.

Best regards
Erik
« Last Edit: February 18, 2013, 01:51:16 AM by ErikKaffehr » Logged

yaya
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« Reply #4 on: February 18, 2013, 03:35:35 AM »
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Hello , i recently bought a p65+ ...thinking it would be better then my Hasselblad 50MP

when shooting on a Cambo Rs with a 28 mm XL schneider with the nice centre filter , and 12 mm of shift to the right ...i get ...

a huge purple fringing ...  

and i thought mmmm

so i made a test setup at home camera fixed .. f 11    shot my LCC shot ,

then i changed backs to Hasselblad 50 Mp

did the same , no changes for the rest

and what did i see ...no purple extreme color fridging with the Hasselblad...  


since everybody is so into Phase ...   maybe share some experiances or help

here are the original files , and some tifs renderings to compare

because of the strong LCC correction , all the reds on the right side of the image are suppressed...


this doesn't look good for the P65...

i am very disappointed.

here are the original files , you can download as you like ....

also 2 tifs to directly compare...

i have no idea...

greetings Rien.



http://rvanr.com/filechute/2%20tifs%20.zip
http://rvanr.com/filechute/H3d-50%20at%20home.zip
http://rvanr.com/filechute/phase%20p65%20at%20home.zip


What happens when you shift the Hassy another 3mm so to get the same AOV as the Phase One?
« Last Edit: February 18, 2013, 03:50:52 AM by yaya » Logged

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« Reply #5 on: February 18, 2013, 03:41:51 AM »
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Rien here is a test you can make yourself.
I think the Correction File looks very dark so follow the manufacturer's recommendation on the exposure required.
That is the 1st step to try. Keep the same grey balance setting for both the image and correction file.

Another test you can try is to remove the centre filter take your shot then the second shot for the correction use your translucent perspex sheet and capture the file about 2 stops brighter than the main exposure but using time not f-stop and again respect the same grey balance on both then process and see what the results are I guess you have some option control over the amount of correction in the processing software.  Would love to hear if this is any better or worse than what you have now.
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FredBGG
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« Reply #6 on: February 18, 2013, 11:09:09 AM »
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What happens when you shift the Hassy another 3mm so to get the same AOV as the Phase One?


The problem with the P65+ is more than 3mm (on the sensor) from the right edge so I don't think that is the issue.
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Paul2660
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« Reply #7 on: February 18, 2013, 12:40:53 PM »
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On the P65+ or IQ160, if you have that much fringing, you have lost too much color and or detail that I don't think it's going to be recoverable with a LCC.

The Schneider 28mm has trouble with the P65+ on up from Phase with a shift much past 8mm.  You have another option, the Rodenstock 28mm, which will easily shift to about
10mm with none of this problem.  You will start to hit the outer edge of image circle, and get a hard vignetting which ruins the image in another way.  I have always called this
"the disc"  shows up in all the Rodenstocks eventually but on the 28mm with it's 70mm circle you hit on a shift "left and right" at about 7mm.  Rise and Fall you can get about 10mm
before this shows up, due to the sensor layout.

The best solution would be the 32mm Rodenstock if you have the budget.  You should get 12mm to 14mm before you hit the disc and the lens will be sharp all the way across the frame.

Paul Caldwell
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« Reply #8 on: February 18, 2013, 12:45:31 PM »
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Cambo might need to restate that.   It's the lens.  and the IQ180 is even more limited than the 160. 

The P65+ and higher will easily shift to 15mm to 20mm it's very dependent on the lens being used.  The Schneider 28mm is not one that will work well with these backs.

My experience: from various lenses I own.  This is all left and right shift.

Rod 28mm,  8mm max (limited by the disc) not the sensor or lens, it would easily make 10mm
Schneider 35mm, 12mm max, even here there is pretty harsh magenta cast but most times LCC will take it out.  Blue sky is an exception
Schneider 43mm, 18mm max here slight color fade, but recoverable very little magenta cast
Schneider 60mm, 25mm max.  slight color shifts but details at F16 are still strong and image is very good.

Paul Caldwell

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« Reply #9 on: February 18, 2013, 01:11:11 PM »
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No bashing of brands intended, just difference in results.  Not an architecture shooter so I am only speaking for landscapes.  However I can see where rise and fall are very important for this type of work.

Interesting on your results as I had the same issue with casts on the 28mm Rodenstock, until I added the physical CF.  It made a huge difference for me, however it does limit you as in many areas, filters for one.  I see no loss of details but a huge gain in both color and cast.  Plus the fact that it balances out the frame so well.    I still find the 28mm Rodenstock to be my sharpest lens, and just wish it would shift to 10mm (again only limitation I see is the disc which gives the hard corner vignetting).

More good reading on both the 28's here:
http://www.getdpi.com/forum/lens-accessory-reviews/34991-rodenstock-28mm-hr-vs-schneider-super-digitar-28xl.html

I don't think it's the image circle, but instead the retrofocus or non-retrofocus design.  It's always a trade off as the Schneiders have less distortion, but more cast.  

Curious, have you looked at the Hcam and one or both of the Canon TS-E's?  Here is a link where a good discussion was on this site.

http://www.luminous-landscape.com/forum/index.php?topic=75282.0

You have the Rod 32mm, which is supposed to be the very best even on the IQ180.  I have never worked with it, just too expensive and heavy.

Paul Caldwell


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yaya
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« Reply #10 on: February 18, 2013, 01:48:52 PM »
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Hi Rien,

Since you already own the Rodenstock 32mm then perhaps you can use that one with the P65+ as it'll give you more or less the same AOV as the 28mm (with the 50MP back) and more or less the same perspective control (i.e. amount of useable shift). That way you will still enjoy the extra resolution and portability at the cost of a heavier lens

Just a suggestion...

Yair
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mjon
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« Reply #11 on: February 18, 2013, 03:40:21 PM »
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A perhaps strange suggestion: rotate the back by 180 degrees and check if this makes a difference. I had a Dalsa sensor back which showed uncorrectible files in one orientation and usable ones in the other one, both with the SK 28 and SK 43 and extreme movements.

Mjon
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FredBGG
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« Reply #12 on: February 18, 2013, 09:26:54 PM »
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A perhaps strange suggestion: rotate the back by 180 degrees and check if this makes a difference. I had a Dalsa sensor back which showed uncorrectible files in one orientation and usable ones in the other one, both with the SK 28 and SK 43 and extreme movements.

Mjon
Very good suggestion. To some extent all wide angles with shift used with digital sensors will preform better in one direction than the other, hence the
rumors of some lenses having a bad corner or something.

For example look at the Canon 17mm TS. While the problem is not lens color cast, there is a difference depending on how the light hits the sensor.

Shift to -12mm


compared to shift +12mm


I once saw a guy shooting with the canon 24mm TS with the camera upside down...... at first I wondered what the hell he was upto...
« Last Edit: February 18, 2013, 11:12:37 PM by FredBGG » Logged
julienlanoo
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« Reply #13 on: February 19, 2013, 03:30:58 AM »
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Mhm thats it, the Dalsa s don t work well with shift, i ve hot a P45+ i want and can buy bigger but at phase one its only Dalsa now Sad, so as i love the phase one software i ll stay with that,..
Or might go to the hassy 50,
Question is who s still developping Kodak sensors on MF?..
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Paul2660
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« Reply #14 on: February 19, 2013, 06:08:45 AM »
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Dalsa's do fine with shift as I posted before.  They are just more dependent on the lenses used.  They don't like the wider Schneiders i.e. the 24mm, 28mm.  If you want 15mm of shift on a wide with a P65+  you have to look to the Rodenstocks preferably the 32mm.  The 60mp Dalsa's from Phase one have quite a bit more leeway with shift once you get to the 43mm Schneider or the 40mm Rodenstock both of these lenses can shift to 15mm.  I often shift my 43mm Schneider to 18mm. 

If you get up to the IQ180, then the list of wide lenses that handle shift well, gets much shorter. 

Paul Caldwell
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« Reply #15 on: February 19, 2013, 06:30:56 AM »
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If you get up to the IQ180, then the list of wide lenses that handle shift well, gets much shorter.

I know I am not helping, but I wonder sometime whether some MF users would not be sharing a form of masochism...  Huh

Pay 40,000+ US$ to get an amazing sensor you hope to mount on the most delightfully exotic 10,000 US$ LF camera... only to find out that you can't get the colors right with some of the best 4,000 US$ MFD lenses on earth. Wink

There must be a common sense black hole nearby.

Cheers,
Bernard
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« Reply #16 on: February 19, 2013, 07:55:25 AM »
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I agree it does make you wonder at times.   Smiley

Paul Caldwell
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« Reply #17 on: February 19, 2013, 11:27:36 AM »
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I agree it does make you wonder at times.   Smiley

Paul Caldwell

In part it is about the sensor supplier and what field they are in principally.

Dalsa is part of Teledyne that is principally a military, scientific and industrial equipment supplier.
There isn't really much of a military or scientific need for lens shifting so it's not a priority in their designs.

Kodak, Canon and Nikon/Minolta-Sony are companies that have a long history in the visual art of photography
so their approach is different.

MFD is unfortunately limited by the sensors available in MF sizes and neither Phase, Hasselblad or Sinar have the resources to develop their own sensors.


 

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Doug Peterson
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« Reply #18 on: February 19, 2013, 11:30:59 AM »
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I know I am not helping, but I wonder sometime whether some MF users would not be sharing a form of masochism...  Huh

Pay 40,000+ US$ to get an amazing sensor you hope to mount on the most delightfully exotic 10,000 US$ LF camera... only to find out that you can't get the colors right with some of the best 4,000 US$ MFD lenses on earth. Wink

There must be a common sense black hole nearby.

In my opinion you should never be "finding this out" only after the purchase. Any dealer worth a darn is helping you at every stage of your decision making progress pick out the best back for your needs. This is like saying that you buy a Nikon and a View Camera with dSLR and then "find out" that the mirror-box/chassis/flange-distance severely limit your range of movement and lens selection.

Every combination of camera equipment has inherent advantages/disadvantages. A good dealer aligns them with your budget and priorities, and makes sure you have the option to TEST it in a real world scenario whenever applicable.

If you upgrade from a standard sedan to a porche you may also need to upgrade your tires. It's even possible that the porche would do less well than the standard sedan if you tried to use the same tires.
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« Reply #19 on: February 19, 2013, 11:33:17 AM »
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In part it is about the sensor supplier and what field they are in principally.

Dalsa is part of Teledyne that is principally a military, scientific and industrial equipment supplier.
There isn't really much of a military or scientific need for lens shifting so it's not a priority in their designs.

Kodak, Canon and Nikon/Minolta-Sony are companies that have a long history in the visual art of photography
so their approach is different.

MFD is unfortunately limited by the sensors available in MF sizes and neither Phase, Hasselblad or Sinar have the resources to develop their own sensors.

I find much of this post very misleading. I don't have enough time or patience to make a complete reply. But suffice to say that implying Dalsa's sensor designs are less photographically oriented because their parent company has many areas of business is complete BS. Do you know how many non-photographic endeavors Kodak, Canon, and Nikon/Minolta-Sony are engaged in??

Ask 100 photographers who have used both Dalsa and Kodak sensors in a variety of situations for an extended period of time: "which sensor do you find more photographically pleasing, with more natural tonality and better color" and see what you get. Or just google "dalsa vs. kodak".
« Last Edit: February 19, 2013, 12:08:03 PM by Doug Peterson » Logged

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