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Thread: Underexposing the A900 :)

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    Senior Member douglasf13's Avatar
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    Underexposing the A900 :)

    In light () of some questions about uniWB, I also wanted to pass on a little info regarding the A900 and......underexposure??

    According to some sources and examples that I've seen, it appears that, similar to shooting MFDB, the A900 may perform better in lowlight by actually boosting exposure in the RAW converter, rather than using ISO 800+, and it would be great if we could get a larger sampling of shooters to test this out. I have tested this myself, but haven't been able to develop the pics yet due to a recent studio move. However, I've seen many examples, and it looks promising. Granted, different scenes and lighting scenarios will likely vary this technique.

    Essentially, if you meter a scene at ISO 1600, f4, 1/30, rather than shooting with these settings, shoot at ISO 400, f4, 1/30, and then boost by +2EV in your RAW converter. The caveat being that you have to use an excellent RAW converter, so ACR/Lightroom users should avoid this technique. Apparently, RPP is very good for this, and has a useful EV+ compensation that compresses highlights, but I've heard that other converters like Aperture and C1 work well, too.

    Personally, like fotografz, I rather like the grain of the A900 noise, but I'm giving this a shot in order to get to know my camera better.

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    Senior Member edwardkaraa's Avatar
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    Re: Underexposing the A900 :)

    That's a very interesting idea. Will try a comparison this weekend.

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    Re: Underexposing the A900 :)

    Jono Slack can help you on this one I believe.
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    Re: Underexposing the A900 :)

    HI There
    I have a busy weekend ahead, but I'll certainly give it a go, it actually goes against all my instincts with the A900: I've felt that under such circumstances you get much better results by doing exactly the opposite:
    i.e. by over-exposing and then reducing the exposure in processing (I had been using 1 stop).

    If anyone else is trying it, why not give that a go as well, i.e.

    if you meter a scene at ISO 1600, f4, 1/30
    shoot it at ISO 400 f4 1/30
    and also at:
    ISO 1600 f4 1/15
    or equivalent.

    Just this guy you know

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    Senior Member edwardkaraa's Avatar
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    Re: Underexposing the A900 :)

    Ok, I have done it, and got some strange results. I shot in RAW and converted via IDC3 NR off. I shot at ISO 400 normal exposure as a refrence, then 400 -2, 1600, 1600 -2, 6400. The software pushed files are definitely better, but IDC seems to be cranking up the default sharpening on the 1600 and 6400 files a lot for some obscure reason.

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    Administrator, Instructor Guy Mancuso's Avatar
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    Re: Underexposing the A900 :)

    Quote Originally Posted by douglasf13 View Post
    In light () of some questions about uniWB, I also wanted to pass on a little info regarding the A900 and......underexposure??

    According to some sources and examples that I've seen, it appears that, similar to shooting MFDB, the A900 may perform better in lowlight by actually boosting exposure in the RAW converter, rather than using ISO 800+, and it would be great if we could get a larger sampling of shooters to test this out. I have tested this myself, but haven't been able to develop the pics yet due to a recent studio move. However, I've seen many examples, and it looks promising. Granted, different scenes and lighting scenarios will likely vary this technique.

    Essentially, if you meter a scene at ISO 1600, f4, 1/30, rather than shooting with these settings, shoot at ISO 400, f4, 1/30, and then boost by +2EV in your RAW converter. The caveat being that you have to use an excellent RAW converter, so ACR/Lightroom users should avoid this technique. Apparently, RPP is very good for this, and has a useful EV+ compensation that compresses highlights, but I've heard that other converters like Aperture and C1 work well, too.

    Personally, like fotografz, I rather like the grain of the A900 noise, but I'm giving this a shot in order to get to know my camera better.
    This is true in MF I can sneak in a underexposed by a stop or two at ISO 800 with my Phase back and in C1 can pull the rabbit out of the hat much better than shooting at ISO 1600. C1 is very friendly when is come to noise. Many M8 shooters find much better results at high ISO in C1 compared to others. This maybe the raw converter of choice here. If someone wants to send me some raw shots with the A900 underexposed I can process them if you don't have the program and post the results. Just use yousendit in a zip file and i can download that and give it a whirl for you folks. I have come close to hitting the buy button 6 times in the last 2 days. Dead serious, I just keep backing off it and that is not me at all. LOL
    Photography is all about experimentation and without it you will never learn art.

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    Senior Member edwardkaraa's Avatar
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    Re: Underexposing the A900 :)

    100% crop 1:

    iso 400

    Attachment 12185

    iso 400 pushed to 1600

    Attachment 12186

    iso 1600

    Attachment 12187

    iso 1600 pushed to 6400

    Attachment 12188

    iso 6400

    Attachment 12189
    Last edited by edwardkaraa; 13th August 2009 at 12:22.

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    Re: Underexposing the A900 :)

    100% crop 2

    iso 400

    Attachment 12190

    iso 400 pushed to 1600

    Attachment 12191

    iso 1600

    Attachment 12192

    iso 1600 pushed to 6400

    Attachment 12193

    iso 6400

    Attachment 12194
    Last edited by edwardkaraa; 13th August 2009 at 12:22.

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    Senior Member edwardkaraa's Avatar
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    Re: Underexposing the A900 :)

    Full image:

    ZA 24-70 at 24mm f/5.6 at all ISO

    Attachment 12195
    Last edited by edwardkaraa; 13th August 2009 at 12:22.

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    Member picman's Avatar
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    Re: Underexposing the A900 :)

    Quote Originally Posted by Guy Mancuso View Post
    C1 is very friendly when is come to noise. Many M8 shooters find much better results at high ISO in C1 compared to others. This maybe the raw converter of choice here.
    I have just got my A900 + ZA24-70 and am doing some tests with various raw converters: Aperture, Lightroom, Capture One and Raw Developer. After these preliminary tests I concur with what Guy said above. Capture One seems to do the best job and the GUI is really good.

    Capture One however does not have a slide show feature which e.g. Aperture does. What is the best way of getting a slide show once you have treated all your photos in Capture One? Load them into Aperture? But will that have an influence on what you've done in C1?

    Cheers, Bob.

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    Re: Underexposing the A900 :)

    Bob , Bridge has a nice slide show program built in and can go manual mode or set to a timed mode. No extra cost either if you have PS

    Just load your finished tifs or jpegs. C1 is non destructive like most raw converters so you can always reset to the original
    Photography is all about experimentation and without it you will never learn art.

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    Re: Underexposing the A900 :)

    Thanks for all of your work, Edward. AFAIK, IDC and ACR aren't nearly as good with this technique as other converters, so now I'm really anxious to see what happens with C1. Apparently, with RPP, it may be good to not go over ISO 200, because the demoisacing is so well done! RPP isn't very workflow friendly though

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    Re: Underexposing the A900 :)

    Quote Originally Posted by Guy Mancuso View Post
    Bob , Bridge has a nice slide show program built in and can go manual mode or set to a timed mode. No extra cost either if you have PS

    Just load your finished tifs or jpegs. C1 is non destructive like most raw converters so you can always reset to the original
    Thanks Guy, I will give that a try.

    Cheers, Bob.

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    Senior Member edwardkaraa's Avatar
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    Re: Underexposing the A900 :)

    Quote Originally Posted by douglasf13 View Post
    Thanks for all of your work, Edward. AFAIK, IDC and ACR aren't nearly as good with this technique as other converters, so now I'm really anxious to see what happens with C1. Apparently, with RPP, it may be good to not go over ISO 200, because the demoisacing is so well done! RPP isn't very workflow friendly though
    You're welcome. I'm also very curious to know how the A900 behaves at high iso. Honestly I have tried all converters that work on windows, and from the color rendition point of view, as is usual with all brands, the manufacturers converter produces the best color and has the worst features and GUI. That's why I'm sticking to IDC for now despite its weakness at high iso, which I seldom use. I'm sure Sony will get it right eventually, especially if they take a close look at what Canon has done with the excellent DPP.

    I have pixel peeped the above files with and without NR (only chrome, I never do luminance NR) and I have to say there is something wrong happening with the pushed files. The native ones are much better. It seems that IDC applies some NR or reduces sharpness on files that are brightened too much in order to reduce the resulting noise. Even with NR off, they look like they've had some luminance noise smoothing. I'm very interested to see what can be done with other converters.

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    Re: Underexposing the A900 :)

    Hi Edward
    I have C1 and Aperture . . . and I'll do what I can.
    I'd still like to see what happens when you over-expose though.

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    Re: Underexposing the A900 :)

    Quote Originally Posted by jonoslack View Post
    Hi Edward
    I have C1 and Aperture . . . and I'll do what I can.
    I'd still like to see what happens when you over-expose though.
    I'm sure that overexposing with the A900 will definitely reduce the noise, as is common with all Dslr. The A900 might have an advantage here because of the extra DR in the highlights. I will do that during the weekend and maybe start another thread so that we don't cause any confusion with 2 separate issues. I still find that it defeats the purpose to overexpose at high iso. Still if we can show that iso 1600 overexposed by 1 stop and pulled in the raw converter is cleaner than iso 800 exposed normally, that would be very interesting. This is basically what the camera does with iso 100 and it is definitely cleaner than the native iso 200.

    Will be looking forward to see your tests with C1

    Cheers,
    Edward

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    Re: Underexposing the A900 :)

    Yeah, that makes sense, Edward. IDC is great for out of camera color, but it is pretty much at the bottom of the barrel for demoisacing and added NR, along with ACR. I was surprised that these comparisons were as close as they were. We need some C1, RPP, Aperture, Raw Therapee action to really see some difference, I believe. Another thing to consider is trying ISO 1600 boosted up from ISO 200. In RPP, that supposedly works well, but I'm not on Mac
    Last edited by douglasf13; 13th February 2009 at 12:07.

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    Re: Underexposing the A900 :)

    HI Guys
    Well, I've been fiddling about with this, rather sceptical to be honest!
    I'm afraid I haven't had time to do any proper comparisons, but I am convinced.

    Having said that, I think things might not be quite as straightforward as they might seem. Just a couple of quick samples:

    These are 100% crops (handheld unfortunately). The first is at 400 ISO with -2 stop compensation, the second is at 1600 ISO




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    Re: Underexposing the A900 :)

    Pretty straightforward you might think.
    I did some other tests indoors, with mixed lighting, and this time on a tripod. The result was much MUCH less convincing.

    Here is a test with 800 ISO with -1 stop EQ, against ISO 1600 (second shot)





    There seems to be more clumpy colour noise in the 800 ISO shot.

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    Re: Underexposing the A900 :)

    For those in C1 try chroma noise around 60 and luminance around 20. Should be just before smearing occurs
    Photography is all about experimentation and without it you will never learn art.

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    Re: Underexposing the A900 :)

    Jono, this trick shouldn't work over ISO 400, as that is supposedly where the ADCs start behaving badly. If anything, try lower than 400, not higher. As I understand it, with some converters, the max ISO to try is 400, an with others its 200. Thanks for the work


    p.s. thanks for the NR tip, Guy. Also, for those wondering, it's still good to try and get your histogram to the right with this technique, just like other high ISO shots.
    Last edited by douglasf13; 15th February 2009 at 17:21.

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