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Need help with my gear (Phase One + ZD Back)

MaxKißler

New member
Doug,

do you have any experience with equally underexposed images taken with a different back?
Comparable to the two images I posted before.

Maybe the ZD Back is just not good at contra-light shots? What do you think, is there something wrong with it? I get the same results no matter what raw developer I use...
 

djonesii

Workshop Member
I have been using my ZD for a while now.

Quite simply, as a raw converter, Lightroom 2.6 sucks relative to the C1. I get tons of those weird green bits in the shadows from LR, where they are totally not there in C1.

I more or less only use LR for the BW presets when using my ZD. Not near the same problem when converting Nikon.

While you cannot pull the same detail, try shooting a JPEG, and it will eliminate the converter from the sequence. No green bits in the JPEG, and it's almost certainly not the hardware.

On the other hand, clearly, when there is light, the ZD is a great value if you compare it to a D3X or a Canon Mark IV!

Just my 2cents, YMMV.

Dave
 

John Black

Active member
You're trying recover 3 to 4 stops of shadow detail in these images, and that's just not realistic. With a ZD you can boost the shadows 1 to 2 stops in most cases and be fine.
 

Anders_HK

Member
The phrase you are looking for is "purple blobs" - a google search for "Mamiya ZD purploe blobs" will uncover a lot of information about this.
@ Max,

The purple blobs was not same issue but another that photographer Frank Doorhof wrote of that was limited to a faulty ZDs in a certain batch/batches of ZD back only. What you are experiencing appear to be exact same as I wrote of under title "ZD has Problem" at www.luminous-landscape.com ; http://www.luminous-landscape.com/forum/index.php?topic=22698.0

Above was what I pointed out nearly three years ago. What I pointed out then was that there were from what I had learnt issues relating to the then "limited" design of the ZD - both hardware and firmware side. Leaf Aptus 22 has identical sensor from Dalsa and has per what I know not had same problem, thus what I was told in late 2007 frank makes sense. Per posts here on Getdpi I thought Phase One and Mamiya had reduced that problem, however what you show in photos seem very identical to way I would have expected my old ZD camera to perform. I sold it at loss because it was simply unusable product for my landscape photography, namely when you have much light and same time shadow in photo. However it also showed this when exposing neutral to test sample filling half frame with white and remaining with near black subject under diffused natural lighting indoors.

I went with Leaf Aptus 65 and have had no similar problem.

With above experience and I recommend you following:

1. Get Capture One since it is developed by Phase One who owns major controlling share in Mamiya. If any software includes a fix to tune down the problem, it is likely Capture One. I also recommend that software because it is way better than any other raw converter I have used. Capture One also works excellent for my Leaf Aptus files with conversion profiles direct implemented with Leaf, thus if anyone have made good for ZD it must be them.

2. It might not be popular among many, but crush the black by adjusting the black point to give less shadow details. That should reduce the problem.

3. With Capture One PRO I can guess it can also work to tune down the issue by color adjusting with a narrow focus on the purple that ZD creates by using the color tool.

4. I recommend testing your ZD back and doing so also of others in the shop you bought it from have. When Mamiya agent here in Hong Kong tested in early 2008 they found frank same problem on each ZD back and ZD camera they had in stock, simply by photographing a test chart with neutral exposure and observing purple in black frame on test chart...

5. You may also wish to do a thorough search on www.luminous-landscape.com to read up on problems of ZD and what serial numbers those had to ensure that you was correctly sold a new and not old ZD. The critical is the last letter in ZD serial number (or was it the the first?). There is different numbering of ZD back and ZD camera.

Regards
Anders
 

Jan Brittenson

Senior Subscriber Member
This looks like an IR hot spot. It's caused by optical reflections. Curiously I've only seen it on film with a Schneider 72XL (on 617) AND center filter. Taking off he CF would make it go away. In that case it was probably an IR reflection between the ND portion of the filter and front element of the lens. In your case, because the spot mimics the sky highlights I'd suspect it's a reflection that involves an in-focus part of the image path; almost certainly between the back of the lens and IR filter. A different lens might make it go away.

It could also be something about early versions of the ZD back reflecting between the image chip and the IR filter. I've never seen it on mine though and I shoot into sun and bright sky a lot.
 

MaxKißler

New member
Thanks for all your help.

It all sounds very plausible to me yet it's still confusing... Today I checked my images again and it appears to occur only on the lower bottom part when there is little contrast. Probably because those parts are most likely to be underexposed. As John suggested, it might be to much for the ZD to recover those details.

@ John
I read a lot on pebbleplace.com which also encouraged me to get the back and since you once owned a ZD camera I'm sure you know better how far one can push it and still get good results.

@ Anders
Yeah, I read those aswell. Unfortunately a refurbished Leaf Aptus 54 (not even the "s" version) costs about four times as much as the ZD Back so I won't regret my purchase that soon.

@ Jan
It will be difficult to check as I have to aquire another lens first... My budget is very very limited. ;-)

Now the only thing that really bugs me is not to know whether some other ZD users might be able to pull shadows comparable to mine in the images obove with the same piece of equipment and without having these ugly blobs...
 

fotografz

Well-known member
I've yet to see that kind of discoloration from any back ... all the way from my first Kodak Proback up to now. I wouldn't care what the cause was, it would be unacceptable. The issue is well documented.

So, if I were you, I'd still explore returning the back as defective. I guess it will depend on how long it's been since you bought it off of e-bay (That was error number 1. Never buy without return privileges, and it's always better to buy from an authorized or highly trusted dealer). Have you contacted the seller?

There are some limitations to a ZD, but this shouldn't be one of them. However, the images you posted are grossly underexposed. The only way to shoot something that's lit like that is to expose for the midtones and let the sky go ... or to make multiple exposures on a tripod and marry the images in post processing.

-Marc
 

Guy Mancuso

Administrator, Instructor
Max i owned the ZD back a couple years ago and actually my first back. Mine did not perform like this in anyway. To me this just flat out looks defective. I'm going to have to agree with Marc here.
 

Anders_HK

Member
I've yet to see that kind of discoloration from any back ... all the way from my first Kodak Proback up to now. I wouldn't care what the cause was, it would be unacceptable. The issue is well documented.

So, if I were you, I'd still explore returning the back as defective. I guess it will depend on how long it's been since you bought it off of e-bay (That was error number 1. Never buy without return privileges, and it's always better to buy from an authorized or highly trusted dealer). Have you contacted the seller?

There are some limitations to a ZD, but this shouldn't be one of them. However, the images you posted are grossly underexposed. The only way to shoot something that's lit like that is to expose for the midtones and let the sky go ... or to make multiple exposures on a tripod and marry the images in post processing.

-Marc
One thing that was said around three years ago of ZD was that it needs ALOT of light. To my observation it seemed that people using it in studio and in sunny climates thus seemed to experience less purple artifacts, simply because they had alot of light. Again the purple blobs were looking different and were clear purple blobs, not what Max showed above. The purple artifacts on other hand (posted by Max above) showed up in shadow and darker areas, just like did on mine (even around -2 stop). There must still be numerous such ZD floating around on used market thus one can urge people to be cautious. One could wish Mamiya would have been honest and took them all back... and reimbursed us who lost on them... However, what I stated above can possibly help to tune down the problem, as of course to use it in conditions with lots of light and reasonably even light. Do try Capture One. Newer ZDs may partially be much improved due to Capture One and maybe some firmware fix to tune down the issue. However, one could guess that Phase One did not spend too much $$ into ZD, thus did not fix hardware part. At least that is my guess. Reading between the lines, simply seemed they failed to proper develop ZD and released it to bring in revenue... Will not comment my personal opinion. :angel:

Max, please post back more of what direction you take and what you discover. Will be interesting to hear of. One could hope that software and firmware side to have improved in three years time. And sincere wish you best luck. And yes, my Aptus 65 cost me $$ and I bought new. It was f^&*^%#@ spent of $, simply because wanted have quality digital to enjoy advanced digital photography, not dslr. The contrast with Leaf is also truly excellent support, and fast such. For expensive gear that and reliable is very important.

Regards
Anders
 
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dougpeterson

Workshop Member
@ Max,

The purple blobs was not same issue but another that photographer Frank Doorhof wrote of that was limited to a faulty ZDs in a certain batch/batches of ZD back only. What you are experiencing appear to be exact same as I wrote of under title "ZD has Problem" at www.luminous-landscape.com ; http://www.luminous-landscape.com/forum/index.php?topic=22698.0
Posts like this is why GetDPI is such a great resource! Thanks for taking the time to elaborate so fully on your experience.

Thanks!

P.S. semantics wise I think for many people "purple blobs" became a descriptor of BOTH the worm issue and the very-low-frequency shadow color accuracy issue.
 

djonesii

Workshop Member
As I have said, before, if the ergonomics of the ZD were better, I would be thrilled with the price performance ratio. When Processed in C1, mine seems to hold both highlights and shadaows pretty well. I'm not in the position where I have a good feeling for how many stops, but way better than my D300. The following crops show both resolution and ability to get highlight detail.

Nikon 100% crop:
50mm lens 1.8, 1/500


Mamiya:

150mm 3.2 1/500

( I'm have not gone to DOF master, but I'm confident, they are both thin!)

Note the details in the fine hairs above the lips, and the lips. I think the Mamiya is better.

Going back and reviewing, I would say the character of the my problem areas in the shadows in not near the same type of greens as the OP. I'll post some examples soon.

Dave
 

MaxKißler

New member
Hi everyone,

I did some rudiculous test shots today and it appears to be some sort of reflections that only appear in underexposed parts of an image. I shot towards lit windows while the foreground was underexposed. When I processed the files and pulled up shadows, purple areas in the shape of my windows appeared. Especially when these parts where underexposed below 3 f stops. I'll redo this test tomorrow and show you the results.

I still believe this happens due to the 12 bits which don't seem to have enough colour information.

@ Anders
Thanks for sharing your experiences. As I already mentioned I bought it via ebay so there is no chance of returning it. I agree with you that Mamiya should have taken action in the first place. However, the back works fine, except for those "contra-light" situations and I really enjoy using it.

BTW I didn't expect the AF on my PhaseOne body to be that fast!
 

MaxKißler

New member
@ Dave
My ZD Back works quite well under controlled conditions, even if I'm just using my tiny Metz flash. What I'm concerned about are these weird magenta reflections occurring only when shooting towards the source of light.
 

Steve Hendrix

Well-known member
Hi everyone,

I did some rudiculous test shots today and it appears to be some sort of reflections that only appear in underexposed parts of an image. I shot towards lit windows while the foreground was underexposed. When I processed the files and pulled up shadows, purple areas in the shape of my windows appeared. Especially when these parts where underexposed below 3 f stops. I'll redo this test tomorrow and show you the results.

I still believe this happens due to the 12 bits which don't seem to have enough colour information.

@ Anders
Thanks for sharing your experiences. As I already mentioned I bought it via ebay so there is no chance of returning it. I agree with you that Mamiya should have taken action in the first place. However, the back works fine, except for those "contra-light" situations and I really enjoy using it.

BTW I didn't expect the AF on my PhaseOne body to be that fast!
Max

In my opinion, there is probably nothing wrong with your back.

At ISO 100, you are 2 stops pushed from the base ISO of 25. If you push underexposed low key subject matter 2 stops with anything, this or something like it will often be the result.

Attached below is a crop of an ISO 400 shot from the same sensor pushed 2 stops (though in a Leaf Aptus 22).

There are ways to reduce the effect, sometimes just using a white balance dropper to click on the area, if it is a reasonably neutral area, like a sidewalk or a street. Also, you can use the Color Editor in Capture One to select the purple globs and desaturate them.


Steve Hendrix
 

djonesii

Workshop Member
I went out to my files, and pulled an example a bit more severe than the one Steve shows above. I think that it really points out what is by now all too well know, the ZD is a good light back.


This is at ISO 400, and with a continuous light source, both highlights and shadows opened up full on the C1 sliders. In this silly case, we get both green and purple artifacts.

I'm not sure how a "modern" back would deal with this, but that is one that that I would expect to be better on the newer ones.

For my use, in almost all cases, I can just crank up the power on the strobes and shoot at ISO 50/F8, and there, the ZD is just fine.

Dave
 

Steve Hendrix

Well-known member
I went out to my files, and pulled an example a bit more severe than the one Steve shows above. I think that it really points out what is by now all too well know, the ZD is a good light back.

This is at ISO 400, and with a continuous light source, both highlights and shadows opened up full on the C1 sliders. In this silly case, we get both green and purple artifacts.

I'm not sure how a "modern" back would deal with this, but that is one that that I would expect to be better on the newer ones.

For my use, in almost all cases, I can just crank up the power on the strobes and shoot at ISO 50/F8, and there, the ZD is just fine.

Dave

I would say modern backs handle this better, though it is still a situation that I would try to avoid or use best practices to reduce the effect in post.


Steve Hendrix
 

dougpeterson

Workshop Member
All backs fall apart somewhere. The pertinent question is when and how.

The examples posted by Dave and Steve show grain and low frequency color noise.

The examples posted by the OP show grain and ULTRA LOW frequency color noise which more or less looks like large color banding.

Low frequency color noise can be relatively easily removed by increasing color noise suppression. Large areas of color banding are much more troublesome to deal with in post.
 
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