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Thread: A900 downsampling

  1. #1
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    A900 downsampling

    Hi All,

    I continue my testing of the A900 and looking very hard at how to best process the Raw files and provide the best IQ. I have now discovered (this maybe old news to many) the threads discussing shooting in craw and downsampling the images to a 12 mpix image size, this seems to provide some advantages when trying to look at the higher iso and noise performance of this great camera.

    I wanted to ask what the views were from other users on this topic as a preferred workflow and method to gain the best result. I was very interested that using this approach you can get the files to be very close to D3 IQ at 1600 and 3200 as these are the sensitivities I am most interested in. It seems from David Kilpatrick that the A900 in this way will provide or have the edge in detail?

    Thanks

    Rodney

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    Re: A900 downsampling

    Quote Originally Posted by hobbsr View Post
    Hi All,

    I continue my testing of the A900 and looking very hard at how to best process the Raw files and provide the best IQ. I have now discovered (this maybe old news to many) the threads discussing shooting in craw and downsampling the images to a 12 mpix image size, this seems to provide some advantages when trying to look at the higher iso and noise performance of this great camera.

    I wanted to ask what the views were from other users on this topic as a preferred workflow and method to gain the best result. I was very interested that using this approach you can get the files to be very close to D3 IQ at 1600 and 3200 as these are the sensitivities I am most interested in. It seems from David Kilpatrick that the A900 in this way will provide or have the edge in detail?

    Thanks

    Rodney
    Explain the down sampling process please ... I don't understand it.

    Thanks,

    -Marc

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    Re: A900 downsampling

    Hi,

    In an original look/review when the Sony A900 was released, by David Kilpatirck http://www.photoclubalpha.com/2008/0...tokina-part-1/

    He posted in this article a sampe image with the following:

    "An 11.2 megapixel version of this shot can be opened by clicking the picture. Why 11.2 megapixels? It is processed from a cRAW file using ACR 4.6 RC, and this is one of the downsized options you get. The Alpha 900 native resolution is the maximum size in the list of exported sizes now. While ISO 3200 is not going to beat a Nikon D3 (etc) when viewed pixel for pixel, 24.5 megapixels versus 12.2, when you reduce the size of the A900 image to closely match the D3 size results in similar conditions give the A900 an edge in detail resolution – and slightly less mushy noise."

    I hope that explains what i am referring to.

    Rodney

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    adamhumza
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    Re: A900 downsampling

    I am disagree with fotografz
    sorry fotografz if you mind

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    Senior Member ecsh's Avatar
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    Re: A900 downsampling

    Boy, am i lost in this thread, adam, what are you disagreeing about?

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    Senior Member edwardkaraa's Avatar
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    Re: A900 downsampling

    I am not sure what the subject is about. I agree that if you downsize high-iso A900 files to 12mp, they can favourably compare to those of the D3. But what's the point? If the files have to be printed, then the final output size will decide how much uprezzing or downrezzing to be done. If the point is to compare files on screen at 100%, then yes, but why would you want to do that?
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    Re: A900 downsampling

    Edward is right on the money, IMO. Assuming that one's output is either print or web-sized jpegs, there really isn't much point discussing downsizing. The only reason to downsize the A900 files to 12MP is to either, save space, or provide a level playing field when comparing it to other cameras. The latter, of course, not really providing any real world use. If you want to compare the high ISO of the A900 with other cameras in a useful manor, I'd say making prints of the same size would be more appropriate. Everything else is academic.

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    Re: A900 downsampling

    Quote Originally Posted by adamhumza View Post
    I am disagree with fotografz
    sorry fotografz if you mind
    Disagree with what?

    I simply did not understand how to down sample. How can you disagree with something that I don't understand?

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    Re: A900 downsampling

    Quote Originally Posted by douglasf13 View Post
    Edward is right on the money, IMO. Assuming that one's output is either print or web-sized jpegs, there really isn't much point discussing downsizing. The only reason to downsize the A900 files to 12MP is to either, save space, or provide a level playing field when comparing it to other cameras. The latter, of course, not really providing any real world use. If you want to compare the high ISO of the A900 with other cameras in a useful manor, I'd say making prints of the same size would be more appropriate. Everything else is academic.
    Yes, that is why I did not understand what down sampling was supposed to accomplish. I thought perhaps I was missing something.

    Getting the white balance and exposure correct does more to help with the high ISO noise than most anything you can do.

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    Subscriber Member Corlan F.'s Avatar
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    Re: A900 downsampling

    Quote Originally Posted by fotografz View Post
    Disagree with what?

    I simply did not understand how to down sample. How can you disagree with something that I don't understand?
    Another spammer trying to get max. clicks on unrelated links in his signature?

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    Re: A900 downsampling

    Hi All,

    I was simply seeing if anybody here was using this approach as from what I have read it improves the IQ for output, yes you are reducing the file, but it seems in doing so you can improve the IQ of the file before you then print. I am trying to test this to see how much of a different it does make. It was not about doing this just to compare with other cameras. I think that overall by doing this you can retain higher detail and reduce the noise effect in the image hence this would be of interest to other A900 users, so I thought.

    Regards

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    Re: A900 downsampling

    The only usefullness of such a process, outside of saving hard drive space, is for pixel peeping. Comparing prints is a more realistic approach.

  13. #13
    m_appeal
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    Re: A900 downsampling

    Quote Originally Posted by edwardkaraa View Post
    I am not sure what the subject is about. I agree that if you downsize high-iso A900 files to 12mp, they can favourably compare to those of the D3. But what's the point?
    Doesn't that mean that at equal print sizes A900 is almost as good as D700 up to ISO 3200...so really it's almost as good of a high ISO camera (apart from D700's superior AF). Downsampling just shows that the difference is not big when resolution is equal. From what I understand, D700 would be quite a bit better at ISO 6400 though...

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    Re: A900 downsampling

    Quote Originally Posted by m_appeal View Post
    Doesn't that mean that at equal print sizes A900 is almost as good as D700 up to ISO 3200...so really it's almost as good of a high ISO camera (apart from D700's superior AF). Downsampling just shows that the difference is not big when resolution is equal. From what I understand, D700 would be quite a bit better at ISO 6400 though...
    I have an a850, but not a d700. I needed a full frame camera that excels at low ISO, and produces high MP files that I regularly print at A2 or larger. That my collection of full frame A mount lenses fit was also a big plus.

    If I needed a good all around full frame camera, shot a lot of low light action, and seldom printed over A3, the d700 would be at the top of my list.

    It sounds to me as if you're trying to find the right camera for you. If that's the case, why not list your shooting requirements. Perhaps someone could offer a recommendation you haven't previously thought of.

    Regards,
    Graham

  15. #15
    m_appeal
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    Re: A900 downsampling

    I've had the D700 before... never had the A900 but after owning 1ds mk III / 5d mk II I can't go back... way more detail with the higher MP cameras.

    Also, while D700/D3 are good at high ISO, I am just wondering what the point of buying a D700 for high ISO is if you can get close to the same performance in print out of an A900 (at least up to ISO 3200, not higher), and at lower ISO below ISO 1600, A900 will no doubt be superior in detail. Undoubtedly A900 will have a lot more noise when that big file is viewed at 100 percent in comparison with the D700... but if it has roughly the same amount of noise when viewed at 12 MP, doesn't that mean that the resulting print out of A900 at high ISO won't be worse than the print out of a D700 at equivalent size?

    If I were shooting ISO 6400 or higher (although again you wouldn't be using that for big prints?), I would buy the D700. Or if I needed AF for sports... otherwise for IQ up to ISO 3200, I am not sure why buy the D700?

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    Re: A900 downsampling

    Quote Originally Posted by m_appeal View Post
    I've had the D700 before... never had the A900 but after owning 1ds mk III / 5d mk II I can't go back... way more detail with the higher MP cameras.

    Also, while D700/D3 are good at high ISO, I am just wondering what the point of buying a D700 for high ISO is if you can get close to the same performance in print out of an A900 (at least up to ISO 3200, not higher), and at lower ISO below ISO 1600, A900 will no doubt be superior in detail. Undoubtedly A900 will have a lot more noise when that big file is viewed at 100 percent in comparison with the D700... but if it has roughly the same amount of noise when viewed at 12 MP, doesn't that mean that the resulting print out of A900 at high ISO won't be worse than the print out of a D700 at equivalent size?



    If I were shooting ISO 6400 or higher (although again you wouldn't be using that for big prints?), I would buy the D700. Or if I needed AF for sports... otherwise for IQ up to ISO 3200, I am not sure why buy the D700?
    I believe that the D700 is still around a stop better than the A900 at ISO 3200 when printed to the same size. I would say that these cameras meet in the middle more around the ISO ~800-1250 range. The bottom line is that owning both cameras is ideal for most uses.

    p.s. that doesn't mean that the A900 is necessarily unusable at higher ISOs, but, rather, that it doesn't compare to the Nikon 12MP FF cameras in that regard.
    Last edited by douglasf13; 3rd November 2009 at 07:35.

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    Re: A900 downsampling

    [QUOTE=m_appeal;151469]I've had the D700 before... never had the A900 but after owning 1ds mk III / 5d mk II I can't go back... way more detail with the higher MP cameras.

    It would appear you've tried all the players in the full-frame category at this price range, so the a850/a900 would be your only option. As far as an answer to your original question, I've never down-sampled and printed a file I've shot. I don't think I've ever made an exposure over 800 ISO, so I can't even offer an informed opinion.

    May I suggest you download one of the many a900 high ISO raw's available on the web and perform your own tests. That would probably best answer your question as you would be using the same work flow as you would a file of your own. Imaging Resource has raws of their a900 test available (http://www.imaging-resource.com/PRODS/AA900/AA900A.HTM), and I'm sure you can find other sources.

    Regards,
    Graham

  18. #18
    m_appeal
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    Re: A900 downsampling

    Quote Originally Posted by douglasf13 View Post
    I believe that the D700 is still around a stop better than the A900 at ISO 3200 when printed to the same size.
    Well, I presume it would be better, but how much... Has anyone done tests? I have never compared the 2, but I'm just going by what someone who owns a A900 and owned D700 before told me and of course that David Kilpatrick article .

  19. #19
    m_appeal
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    Re: A900 downsampling

    [QUOTE=GrahamB;151486]
    Quote Originally Posted by m_appeal View Post
    May I suggest you download one of the many a900 high ISO raw's available on the web and perform your own tests. That would probably best answer your question as you would be using the same work flow as you would a file of your own. Imaging Resource has raws of their a900 test available (http://www.imaging-resource.com/PRODS/AA900/AA900A.HTM), and I'm sure you can find other sources.
    I've downloaded some RAW samples of A900 at high ISO, and they were quite disappointing, even in DXO, but I don't know if they were properly exposed... And I've never downsampled or actually printed them.
    Last edited by m_appeal; 3rd November 2009 at 08:06.

  20. #20
    Senior Member edwardkaraa's Avatar
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    Re: A900 downsampling

    All that I can say is that I have shot quite a bit at ISO 1600-3200 and with the proper NR I have printed them at 8x12 and they looked very nice. As a matter of fact, (subjectively) much nicer than what I used to get with the 1Ds2.
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