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Author Topic: Counting Ants  (Read 21041 times)
61Dynamic
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« Reply #60 on: March 31, 2006, 12:43:48 PM »
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There is definitely a cast in the P45 image not present in the Leaf image.

I brought the images into PS so the effect can be more easily seen. I set a neutral point in Levels for each back by selecting a point to the left of the "EF" text. Than I matched the luminosity between the two backs using curves (again sampling the same point) and cranked up the saturation.

Attached is the result for anyone is interested (resized for web viewing).
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Nick Rains
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« Reply #61 on: April 01, 2006, 04:58:55 AM »
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When C1 detects a phase file there will be,in this window,a
list of any LCC calibration files you have saved and can apply where neccessary

Mark
[a href=\"index.php?act=findpost&pid=61390\"][{POST_SNAPBACK}][/a]

LCC files are specific to the lens, back and the shift/tilt settings. Without the lens and the back it is not possible for anyone else to correct the colour shifts unless the back owner supplied a set of LLC files with the P45 captures. Better to correct the files before delivery methinks...

It is my understanding that the colour shifts are a trade off between colour fidelity and resolution in the lens design. The Schneider Digitars exhibit this shift as reported, but are way sharper that normal glass such as Hasselblad. The P45 surpasses the res of most other lenses and thus on a 'normal' camera only generates more pixels, not more detail. MR alludes to this in his write-up and I have seen it for myself.

However, I have not used normal LF lenses (my Schneiders, Fujinons and Rodenstocks) on the P45 since the Horseman camera, that I used for my own article a few weeks ago on LL, needs dedicated lens mounts. I cannot say if the back is the culprit or the lenses, I am just passing on what I was told by the Phase One guys.
« Last Edit: April 01, 2006, 05:00:45 AM by Nick Rains » Logged

Nick Rains
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« Reply #62 on: April 01, 2006, 05:59:18 AM »
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Nick

This is a good point.  It is probably why I get more cast with my 250SA CFE than my wider MF lenses.  The Superachromats are highly color corrected and sharper than most other MF lenses.  They are also uncoated.  

With the Superachromats and the 24mm Digitar on the Horseman, I feel I need to take a LCC reference shot every time I move the camera.  Otherwise I am not satisfied that the cast is completely removed.  Do you agree (at least with respect to the Digitar)?
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Quentin
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« Reply #63 on: April 01, 2006, 02:45:28 PM »
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The Dalsa chip is supposed to be better at avoiding colour shifts.  Something to do with the depth of the wells in which the photosites sit.

Quentin
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Quentin Bargate, ARPS, Author, photographer entrepreneur and senior partner of Bargate Murray, Law Firm of the Year 2013
free1000
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« Reply #64 on: April 17, 2006, 06:57:01 AM »
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This color shift effect is not the same as vignetting. It is a real and annoying problem. I had it with my Kodak SLR/c. It is to do with the sensor design.

Experience seems to point to this being a bigger problem with the larger resolution chips. The problem is usually worse with wide angle lenses where the light rays are at a steeper angle of incidence to the sensor plane.

From various sources I have assembled the following summary.

Aptus 22 - No problems of this kind
Phase One P25 - Some problems of this kind compensated with Capture 1 and LCC shots
Phase One P45 - More extreme version of P25
Aptus 75 - Some problems reported with Wide angle lenses (eg: Schneider 35XL) but only at shifts of  20mm +

People differ about whether this is a problem for them or not. For me it is a potential problem.

I would like to go down the Aptus 75 route. My worry is that there may be subtle issues with wides with non extreme shift angles. These issues might only emerge when photographing, say, a minimalist white interior... but then it would necessitate more work in post.
 
I notice that the Rodenstock Sironar Digital 35 has a wider image circle, and longer flange focal length than the Schneider 35XL. Perhaps it will suffer less than the Schneider 35XL when used with the Aptus 75 as the angle of incidence of the light rays will be lesser than with the Schneider. However... all this is making me quite concerned as it is virtually impossible to test all the options prior to purchase.  I have no information about the distortion or other characteristics of the Rodenstock lens and dealers do not typically stock them. In addition, the exotic platform I would need to mount the 35 on means that the lens I would like to test needs a weird and wonderful mount!

My gut feel is that we are still at the bleeding edge, where purchasing decisions might need to be reversed at significant cost if errors are made.

The lack of standardisation in the camera platform area is a real minefield. For example. I can buy a sliding adapter for my Cambo Ultima. But it only allows switching between portrait and landscape format if I buy an H1 fitting digital back...

However, I already posess a full suite of Mamiya lenses, and do not want to have to replace the Mamiya with Hassleblad gear.  

So far I can't find a way of using MFDB for my work without buying at least one (and possible two) new camera platforms. (I already possess two view camera, one MF and Canon SLR platforms, so I am running out of glass cabinet space!)

Add this to issues like this color cast... and I am finding the process of getting into MF digital extremely complicated and error prone.
« Last Edit: April 17, 2006, 07:03:40 AM by free1000 » Logged

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bjornaagedk
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« Reply #65 on: April 17, 2006, 10:42:43 AM »
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I recently had the opportunity to test a Phase p45 back side by side with a Leaf Aptus 75 in my studio.
My setup: Camera: Cambo Ultima 23 view camera, Lens: Schneider Apo-Digitar 120mm/5,6 Macro, Light: 1 strobe softbox apx. 1m above subject.

See the test images with 20mm shift and make your own conclusion!

http://homepage.mac.com/reklamefoto/FileSharing19.html

The P45 images are processed in C1Pro software without LCC.
The Leaf images are processed in Leaf Capture 10.
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Jack Flesher
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« Reply #66 on: April 17, 2006, 03:43:43 PM »
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I recently had the opportunity to test a Phase p45 back side by side with a Leaf Aptus 75 in my studio.
My setup: Camera: Cambo Ultima 23 view camera, Lens: Schneider Apo-Digitar 120mm/5,6 Macro, Light: 1 strobe softbox apx. 1m above subject.

See the test images with 20mm shift and make your own conclusion!

http://homepage.mac.com/reklamefoto/FileSharing19.html

The P45 images are processed in C1Pro software without LCC.
The Leaf images are processed in Leaf Capture 10.
[a href=\"index.php?act=findpost&pid=62796\"][{POST_SNAPBACK}][/a]

Great test!  Pretty well sums up the issue on color-cast!

I do however have a question on ultimate resolution -- How does ultra-fine detail compare between the two backs?  I ask because dealing with the color-cast may be worth the hassel if the P45 delivers significantly better resolution.

Thanks!
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mtomalty
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« Reply #67 on: April 17, 2006, 05:20:26 PM »
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Is there any reason why the test frame >P45_shift20mm+LCC.tif< appears
overall green AFTER the LCC correction has been applied ?

I'm not a fan of the LCC routine and,as such,will more likely consider the A75,but from
my experience using a properly done LCC file  results in an almost perfectly corrected image
which this frame clearly is not.

Mark
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Jack Flesher
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« Reply #68 on: April 17, 2006, 05:31:21 PM »
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Is there any reason why the test frame >P45_shift20mm+LCC.tif< appears
overall green AFTER the LCC correction has been applied ?

I'm not a fan of the LCC routine and,as such,will more likely consider the A75,but from
my experience using a properly done LCC file  results in an almost perfectly corrected image
which this frame clearly is not.

Mark
[a href=\"index.php?act=findpost&pid=62850\"][{POST_SNAPBACK}][/a]

Mark:  I don't think he actually applied the correction to image shown, but rather just posted the correction file so folks could see what it looked like.
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ddolde
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« Reply #69 on: April 17, 2006, 06:15:28 PM »
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The Leaf backs have other problems that the Phase backs do not have.  Lousy software for one and it's Mac only for now.  

Dave Gallagher at Capture Integration in Atlanta told me they have decided to no longer sell Leaf due to problems with the software, overheating and crashing problems.

So beware if you are considering a Leaf.  The lens cast issue may be minor in perspective.
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dazzajl
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« Reply #70 on: April 18, 2006, 08:43:34 AM »
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I've not had any problems with the leaf software at all. I know it's not the best capture/process software package available but it's always worked well within its spec for me.

As for overheating, that may be an issue that exists with integrated screens but my Valeo is often  on for very long periods of time and I've never had any problems with it.
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mtomalty
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« Reply #71 on: April 18, 2006, 09:14:00 AM »
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Mark:  I don't think he actually applied the correction to image shown, but rather just posted the correction file so folks could see what it looked like.

Jack

I'm not so sure.  The frame that I mentioned (P45_Shift20mm+LCC.tif) is accompanied
be a line of red text that states "Lens Cast Correction added in C1 Pro".  Seems to indicate that
this frame has had the correction applied.

Mark
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mtomalty
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« Reply #72 on: April 18, 2006, 09:27:09 AM »
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The Leaf backs have other problems that the Phase backs do not have.  Lousy software for one and it's Mac only for now. 

Doug,
Have you used the Leaf software to arrive at this conclusion?
By almost all accounts,firsthand by me and secondhand by others, v10 from Leaf is as
problem free as anyone elses.
Previous versions were problematic,admittedly,but a lot of bad press that now circulates is based
on references in old postings sourced from different forums.
v10 is certainly not as all encompassing as C1 but,then again,it's free and while the native
software is Mac only Leaf files are supported by a host of other Raw converters including
Adobe Camera Raw and  Raw Developer.

Mark
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bjornaagedk
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« Reply #73 on: April 18, 2006, 09:38:11 AM »
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Jack

I'm not so sure.  The frame that I mentioned (P45_Shift20mm+LCC.tif) is accompanied
be a line of red text that states "Lens Cast Correction added in C1 Pro".  Seems to indicate that
this frame has had the correction applied.

Mark
[a href=\"index.php?act=findpost&pid=62931\"][{POST_SNAPBACK}][/a]


I have just processed the images in C1Pro again to clear things up.

1) Gray balance set in "center" - file, WhiBal card. The settings transfered to the other images.
2) 4 new RGB images processed.

B
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