Site Sponsors
Results 1 to 26 of 26

Thread: Blown highlights on Leaf back

  1. #1
    Senior Member
    Join Date
    Dec 2008
    Location
    Los Gatos, CA
    Posts
    340
    Post Thanks / Like

    Blown highlights on Leaf back

    The specular highlights on my Valeo 22 seem to blow out in a quite unappealing fashion that I never noticed on my DSLR. Is this to be expected? It's like shooting slide film, only worse.

    I realize that digital in general doesn't provide the highlight latitude that print film does, but I didn't expect an MFDB to be more intolerant than a DSLR. It would seem the only answer would be to ETTL.

    Or, the other possibility is that Leaf software handles the .mos files in a significantly better manner than LR3?

    I am hesitant to use the MFDB outdoors, because unless I ensure I underexpose to retain the sky, I'll likely get ugly banding.

    Thoughts? Known equipment limitation, or operator error?

  2. #2
    Senior Member Graham Mitchell's Avatar
    Join Date
    Nov 2007
    Location
    London/Kiev
    Posts
    1,079
    Post Thanks / Like

    Re: Blown highlights on Leaf back

    Does the highlight recovery tool in LR3 not help ?

  3. #3
    Senior Member johnnygoesdigital's Avatar
    Join Date
    Mar 2010
    Posts
    1,579
    Post Thanks / Like

    Re: Blown highlights on Leaf back

    Sometimes exposure meters need to be calibrated. Just for fun, use the zone exposure method to try to determine if your meter is off. Using the spot setting, find a scene and determine which area is zone 5 (18% gray), take a meter reading. If you don't have a gray card, usually, grass is close. Take a meter reading on a bright sky or other area that might be blown, and increase the exposure 2 stops from your first reading. This corresponds to + 2 stops from middle gray (18%) Highlighted areas usually aren't placed higher than zone 7, in digital cameras. Check your histogram, and look for any blown highlights.

  4. #4
    Workshop Member
    Join Date
    May 2008
    Location
    NYC
    Posts
    3,274
    Post Thanks / Like
    Images
    7

    Re: Blown highlights on Leaf back

    Several people here would love to help you but without
    - an image illustrating what you mean we can only guess at what you mean
    - details on where and how you are processing your image (specific version numbers and settings)

    Uploading a raw file to something like yousendit for a few of us to download and play with would also be helpful.

  5. #5
    Senior Member
    Join Date
    Dec 2008
    Location
    Los Gatos, CA
    Posts
    340
    Post Thanks / Like

    Re: Blown highlights on Leaf back

    Quote Originally Posted by Graham Mitchell View Post
    Does the highlight recovery tool in LR3 not help ?
    It doesn't help as much as it does "normally", but I suspect that's because when all three channels are blown, there's nothing to recover

  6. #6
    Senior Member
    Join Date
    Dec 2008
    Location
    Los Gatos, CA
    Posts
    340
    Post Thanks / Like

    Re: Blown highlights on Leaf back

    Quote Originally Posted by johnnygoesdigital View Post
    Sometimes exposure meters need to be calibrated. Just for fun, use the zone exposure method to try to determine if your meter is off. Using the spot setting, find a scene and determine which area is zone 5 (18% gray), take a meter reading. If you don't have a gray card, usually, grass is close. Take a meter reading on a bright sky or other area that might be blown, and increase the exposure 2 stops from your first reading. This corresponds to + 2 stops from middle gray (18%) Highlighted areas usually aren't placed higher than zone 7, in digital cameras. Check your histogram, and look for any blown highlights.
    Johnny,

    It's not the auto metering per se, because I'm just talking about the nature of the blown highlights. Regardless of what the meter says, a "properly exposed" image seems to need to be exposed to the left to avoid blowing any highlights.

    Subjectively, I don't have to try to avoid this as much with my DSLR, but it may be due to the JPG engine, or the RAW engine, or the Dynamic Range Optimization, or the converter in LR3.

    So, generically, the question was if other MFDB users had seen a similar phenomenon. I suspect it's the nature of the beast, but wanted to make sure it wasn't just LR3 being lazy with the processing.

    All this talk of increased dynamic range makes me think I can be sloppier with exposure, but if that means I have to be careful to underexpose to avoid ANY clipping, so be it.

    Does that clarify?

  7. #7
    Senior Member
    Join Date
    Jan 2011
    Location
    Palo Alto, CA
    Posts
    621
    Post Thanks / Like
    Images
    1

    Re: Blown highlights on Leaf back

    You mention specular highlights; are you using a polarizing filter to try to reduce them?

    I have never been able to control true specular highlights: they are essentially direct sun reflections... About all you can do to reduce them is to use a pol filter.

    As for dynamic range recording ability of film (positive) vs 35mm digital vs MFDB, I have found that most of the increase in dynamic range in MF comes from the recovery of shadow detail. There is a bit greater capture ability with MFDB on the right side, but most is on the left. Though I try to move my histogram data as far to the right as possible, I try never to clip the highlights. When in doubt I'll make several exposures starting as far right as possible and then decreasing the exposure for 2 or 3 stops.

    I use Capture 1 for MFDB processing primarily because of LCC. I have been told its RAW processor is better at drawing out information than LR and I have no reason to doubt that it is at least as good (I continue to use LR for cataloging).

    Hope this helps a bit,
    Bob

  8. #8
    Senior Member
    Join Date
    Dec 2008
    Location
    Los Gatos, CA
    Posts
    340
    Post Thanks / Like

    Re: Blown highlights on Leaf back

    Quote Originally Posted by dougpetersonci View Post
    Several people here would love to help you but without
    - an image illustrating what you mean we can only guess at what you mean
    - details on where and how you are processing your image (specific version numbers and settings)

    Uploading a raw file to something like yousendit for a few of us to download and play with would also be helpful.
    Doug,

    I did mention LR3, but I probably could have spelled it out.

    Here's an example specifically of the highlights, but my general comments about exposing sky is related.

    In fact, in a related issue, anything with "pure" color seems to blow a channel much quicker than I would expect. Here's an example where the histogram doesn't show anything blown, but the detail in the bright yellow areas is gone.

    It seems as if the CFA has extra dense coloring or something, so it enhances the saturation so much that it's hard to take pictures of anything vivid without it oversaturating.

    Hope that helps you help me.




  9. #9
    Senior Member
    Join Date
    Dec 2008
    Location
    Los Gatos, CA
    Posts
    340
    Post Thanks / Like

    Re: Blown highlights on Leaf back

    Quote Originally Posted by rga View Post
    You mention specular highlights; are you using a polarizing filter to try to reduce them?

    I have never been able to control true specular highlights: they are essentially direct sun reflections... About all you can do to reduce them is to use a pol filter.

    As for dynamic range recording ability of film (positive) vs 35mm digital vs MFDB, I have found that most of the increase in dynamic range in MF comes from the recovery of shadow detail. There is a bit greater capture ability with MFDB on the right side, but most is on the left. Though I try to move my histogram data as far to the right as possible, I try never to clip the highlights. When in doubt I'll make several exposures starting as far right as possible and then decreasing the exposure for 2 or 3 stops.

    I use Capture 1 for MFDB processing primarily because of LCC. I have been told its RAW processor is better at drawing out information than LR and I have no reason to doubt that it is at least as good (I continue to use LR for cataloging).

    Hope this helps a bit,
    Bob
    Bob,

    That helps. You've confirmed my suspicions at least. Do they end up looking jagged as in the examples above?

    I never got used to C1 when I had a Phase back, and the last program I used from Leaf crashed my computer. Maybe I need to try it again.

    And thanks for reminding me about Cpols. That would definitely help with outdoor shots in general. Duh.

  10. #10
    Member
    Join Date
    Aug 2008
    Location
    Austria
    Posts
    86
    Post Thanks / Like

    Re: Blown highlights on Leaf back

    I found that setting the curves in LR3 to linear helps a lot when working with the files from my digital back.
    Philipp Derganz Photography
    Fotograf Wien Österreich

  11. #11
    Senior Member Thierry's Avatar
    Join Date
    Jun 2011
    Location
    Switzerland
    Posts
    329
    Post Thanks / Like

    Re: Blown highlights on Leaf back

    This first image is showing "blooming" effect, an effect which was typical for older generations of sensors. It happens when the pixels are over-saturated with light photons and then filling up the neighbour pixels.
    The manufacturers did overcome this issue with so-called "anti-blooming" built-in the electronics of the back to avoid or reduce blooming.

    I am not sure if the Valeo did already have "anti-blooming" built-in.

    Thierry

    Quote Originally Posted by gsking View Post
    Doug,



    Thierry Hagenauer
    [email protected]

  12. #12
    Senior Member johnnygoesdigital's Avatar
    Join Date
    Mar 2010
    Posts
    1,579
    Post Thanks / Like

    Re: Blown highlights on Leaf back

    gsking,

    Yes, got it. As mentioned above I agree that's it's possible the photons are spilling over to other sites. I'm not familiar with your DB, but if you have options over the DRO, than I would dial that back a bit.

  13. #13
    Senior Member
    Join Date
    Jan 2011
    Location
    Palo Alto, CA
    Posts
    621
    Post Thanks / Like
    Images
    1

    Re: Blown highlights on Leaf back

    Quote Originally Posted by gsking View Post
    Bob,

    That helps. You've confirmed my suspicions at least. Do they end up looking jagged as in the examples above?

    I never got used to C1 when I had a Phase back, and the last program I used from Leaf crashed my computer. Maybe I need to try it again.

    And thanks for reminding me about Cpols. That would definitely help with outdoor shots in general. Duh.
    Personally, I think this scene (from the black gloves to the direct reflection of the light) is beyond the capabilities of any single exposure using any recording medium available to consumers.

    So we'll have to give on something; either lose the details of the black gloves and control the star shape of the reflected light, or get the blooming and details of the black gloves. My guess is that the range of this shot is way beyond 20 stops....

    It would be fun to try an HDR image on this: not overly cooked, but naturally blended...

    As for the flower, it definitely looks over exposed. Go out and play with a polarizing filter (it doesn't need to be circular unless your rig is autofocus) and then watch your histogram. Record it so that the highlights are just touching on the right side. Then try C1 and bring up the shadows (use the HDR sliders to protect the highlights and bring in the shadows). You may be really amazed at how much data can be recovered from the right side; I always am. You should also take a shot where the highlights are just barely clipped on the right and see if that works too.

    Good luck and let us know your results!
    Bob

  14. #14
    Senior Member
    Join Date
    Dec 2008
    Location
    Los Gatos, CA
    Posts
    340
    Post Thanks / Like

    Re: Blown highlights on Leaf back

    Quote Originally Posted by rga View Post
    Personally, I think this scene (from the black gloves to the direct reflection of the light) is beyond the capabilities of any single exposure using any recording medium available to consumers.

    So we'll have to give on something; either lose the details of the black gloves and control the star shape of the reflected light, or get the blooming and details of the black gloves. My guess is that the range of this shot is way beyond 20 stops....

    It would be fun to try an HDR image on this: not overly cooked, but naturally blended...

    As for the flower, it definitely looks over exposed. Go out and play with a polarizing filter (it doesn't need to be circular unless your rig is autofocus) and then watch your histogram. Record it so that the highlights are just touching on the right side. Then try C1 and bring up the shadows (use the HDR sliders to protect the highlights and bring in the shadows). You may be really amazed at how much data can be recovered from the right side; I always am. You should also take a shot where the highlights are just barely clipped on the right and see if that works too.

    Good luck and let us know your results!
    Bob

    Thanks for the input. I think I'm just spoiled by some of the "C-41-like" dynamic range compression from my A700. As you all noted, you can't overcome the physics of photosite saturation, and it just shows up more significantly with a minimally processed MFDB output.

    As an aside, there was nothing magical about that shot. I was just testing the focusing accuracy of my RZ67.

    Ironically, my next shoot is studio shots indoors. At ISO 25, I doubt my weak strobes (300ws and 160ws) will be even able to CREATE blown highlights. So I should be safe.

    And I'll put my 58mm polarizer on top of my desk.

    Much appreciated for everyone's comments.
    Greg

  15. #15
    Senior Member
    Join Date
    Nov 2008
    Location
    Chicago
    Posts
    548
    Post Thanks / Like

    Re: Blown highlights on Leaf back

    I've found some pretty good lattitude in the backs, even better perhaps than film.

    Here are some shots from a Leaf AFI 7 II back. In bright light, the white cloth still has detail in the sunlight, and there is information still in the shadows. Grainy, but no noise reduction has been applied. Pretty much straight C1 on a shot with ISO at 200. Crops are supposedly 100% if I got this right....
    Last edited by Geoff; 24th July 2012 at 15:42.

  16. #16
    Senior Member
    Join Date
    Dec 2008
    Location
    Los Gatos, CA
    Posts
    340
    Post Thanks / Like

    Re: Blown highlights on Leaf back

    Geoff,

    Interesting. Those look very flat to me, very much like C-41, or more. The sky not only looks mid-tone, but it looks more grey than a "saturated" blue.

    Maybe mine would look the same if I was more deliberate to avoid overexposure, but I usually still end up with over-amped colors like the one in the flower. I need to turn down the saturation somewhere.

    Hmm...I guess I'll have to compare apples to apples and see how my camera compares to my DSLR in identical exposures.

  17. #17
    Senior Member
    Join Date
    Nov 2008
    Location
    Chicago
    Posts
    548
    Post Thanks / Like

    Re: Blown highlights on Leaf back

    Leaf has a bunch of different profile settings for the backs. I don't know which ones you have, but there is a big difference in importing between portrait and product, with portrait being softer and less harsh than product. For delicate scenes, portrait is preferred. For more sharply defined and contrasty results, product.

    These do look awfully flat, moreso than they did in C1. I brought them through Aperture and into jpgs, maybe something got lost along the way. There is a lot of flexibility to be found typically in the Leaf files, IMHO tho. They are quite elastic.

  18. #18
    Shelby Lewis
    Guest

    Re: Blown highlights on Leaf back

    I love starting with my leaf files in a very flat state... it always seems as though I can push them in so many directions with the amount of latitude offered by the subtle gradations of tone offered by a flat import.

    It's totally a personal preference... but it makes dealing with highlights and shadow considerations a bit more easy for me, personally.

  19. #19
    Senior Member
    Join Date
    Dec 2008
    Location
    Los Gatos, CA
    Posts
    340
    Post Thanks / Like

    Re: Blown highlights on Leaf back

    I tried all the settings. Yes, product was even worse. I use only portrait now. No HS settings here.

    I WISH I could get my files to start that flat. I just can't figure out what the trick is. That's the way they come out...oversaturated.

    Greg

  20. #20
    Senior Member
    Join Date
    Jan 2011
    Location
    Palo Alto, CA
    Posts
    621
    Post Thanks / Like
    Images
    1

    Re: Blown highlights on Leaf back

    Quote Originally Posted by gsking View Post
    I tried all the settings. Yes, product was even worse.
    I WISH I could get my files to start that flat. I just can't figure out what the trick is. That's the way they come out...oversaturated.
    Greg
    Buy a Phase One?

    (sorry; couldn't resist...)

  21. #21
    Senior Member
    Join Date
    Dec 2008
    Location
    Los Gatos, CA
    Posts
    340
    Post Thanks / Like

    Re: Blown highlights on Leaf back

    Quote Originally Posted by rga View Post
    Buy a Phase One?

    (sorry; couldn't resist...)
    My H11 did the same thing.

    Which means...it must be me...or all backs.

    Oh, you mean a NEW ONE? Hmm...doubt I'd live through explaining that one to the wife. I'm this close to dumping all my MF gear and going with an A850/900 and having $2000-3000 to show for it.

  22. #22
    Shelby Lewis
    Guest

    Re: Blown highlights on Leaf back

    Is that Valeo 22 a Kodak or Dalsa sensor? I assume Dalsa, but I've been wrong too many times before to be sure, ha.

    Really... I think the scenes you've shown are at fault, not the back. They're all way extended in tonality. Lots of DR. That's tough on any cam, much less an older sensor. Find something a bit less challenging and give it a shot.

  23. #23
    Senior Member yaya's Avatar
    Join Date
    Dec 2007
    Location
    London, UK
    Posts
    1,168
    Post Thanks / Like
    Images
    38

    Re: Blown highlights on Leaf back

    The anti blooming mechanism on the Valeo can be tuned in the factory to some extent but this will be a costly service for this older model. So careful exposure & polarising filter might be the way to go

    Fo a flat look you can tweak the curve in Leaf Capture and use Profoto RGB as the input profile

    HTH
    Yair Shahar | Product Manager | Phase One | Mamiya Leaf
    e: [email protected] | m: +44(0)77 8992 8199 | yaya's blog

  24. #24
    Senior Member
    Join Date
    Dec 2008
    Location
    Los Gatos, CA
    Posts
    340
    Post Thanks / Like

    Re: Blown highlights on Leaf back

    Thanks, guys. Sounds like I just need to play with it more, be careful with my exposure, and doublecheck my settings.

    I mainly wanted to make sure I wasn't doing something basically wrong and easily fixable.

    Greg

  25. #25
    Senior Member ondebanks's Avatar
    Join Date
    Feb 2009
    Posts
    518
    Post Thanks / Like

    Re: Blown highlights on Leaf back

    Hi Gregory,

    That's a nice example of CCD blooming from the metallic surfaces in your first shot.

    Blooming is one area of MFD where there should be no mystique, as the datasheets from both manufacturers (Dalsa and Kodak) address anti-blooming performance.

    Your sensor is a Dalsa (Shelby: all Leafs from the Valeo on are Dalsa; you have to go back about a dozen years to the Leaf C-MOST, I think, to find a non-Dalsa-sensored Leaf back [the C-MOST used a Fill Factory sensor]; I'm sure Yair can confirm this).

    All Kodak MF CCD data sheets state something like "A lateral overflow drain (LOD) suppresses image blooming..." and specify "Blooming Protection" of typically 1000x to 1500X saturation exposure...at 4ms exposure time (1/250 sec). Kodak datasheets include a graph showing how longer exposure times increase this figure and shorter times decrease it. This is because it takes time for the excess electrons to pass into the LOD and be removed: the LOD "sink" electronics have current limits; and current of course is dQ/dt, electrons per second. So if a given flux multiple above saturation isn't reached until a longer time has passed, more of the excess electrons have been drained before the exposure is terminated and the image is read out. Rainfall is a nice analogy: if 3 inches of rain falls on a city over 24 hours, the drains can conduct it away. If the same 3 inches falls in 3 hours, the drains can be overwhelmed and the city floods [this happened in Dublin a month ago: http://en.wikipedia.org/wiki/2011_Eu...loods#Ireland].

    Interestingly, Kodak MF CCD anti-blooming performance is NOT getting any better with newer sensors. The KAF-40000, in my view the overall best MF sensor to date (Pentax 645D and Hasselblad H4D-40), is specced at 1400x saturation. Whereas, the old KAF-16803 (Kodak Pro Back, Hasselblad CFV-16, PhaseOne H20/P20 etc.) is actually specced better, at 1600x saturation. The KAF-50000 (H4D-50) is only 800x saturation!

    As for Dalsa? Their "VNS" serves the role of Kodak's "LOD": "VNS drains superfluous electrons as a result of overexposure. In other words, it only sinks current. During high overexposure, a total current of 5 to 10mA through all VNS connections together may be expected." If I'm reading their datasheets correctly, i.e. if they are using the same basis for their specifications of "Overexposure handling" as Kodak uses, then they are performing significantly worse than Kodak. All their MF sensors (such as the FTF4052C and FTF5066C, used in all the 22 and 33 MP backs, including your Valeo) are specced at only 200x the saturation level; that's 2 to 3 stops less tolerant of overexposure than the Kodaks. Sorry to be the bearer of bad news! OTOH, I calculate that the FTF4052C has an unusually deep full well capacity/saturation level (170,000 e- vs. 100,000 e- for the equivalent Kodak KAF-22000), so that is more like 340x for the Dalsa and 1000x for the Kodak on a normalized comparison basis; a 1.5 stop difference. But taking FWCs into account like this doesn't significantly alter the 2-3 stop disadvantage of the other Dalsa sensors.

    One other thing. The anti-blooming performance of MF CCDs appears to be way poorer than that of CMOS DSLRs. If I shoot directly into the sun with my Kodak digital back (exposing for the foreground), the blooming either side of the solar disk covers up to one third the height of the image! I don't have an example to hand, but I'm sure I've done the same with a Canon 5DII and not seen blooming like this.

    Ray

  26. #26
    Senior Member
    Join Date
    Dec 2008
    Location
    Los Gatos, CA
    Posts
    340
    Post Thanks / Like

    Re: Blown highlights on Leaf back

    Cool stuff, Ray. Thanks for the boatload of technical info.

    If I have time this weekend, I should compare the Valeo to my A550 14mp CMOS. It looks like I won't be getting a 24mp Sony body anytime soon, so it may be interesting to see how totally different technology handles the same scene.

    Greg

Tags for this Thread

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •