Author Topic: A900 Pixel/Micron Question  (Read 2998 times)

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Offline viperry

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A900 Pixel/Micron Question
« on: February 12, 2009, 12:29:36 AM »
I have a question about using a megapixel adjustment on any of the alpha series cameras. I am looking at getting an A900 however I think that 24.6 would often be too large and I would down size to the 14mp option. My question is when using a smaller resolution setting will this actually crop the area of the sensor being used or will the entire sensor be used? With larger microns we have larger noise right, so in a way to avoid noise I could see 14mp while using all of the 35.9MM of the camera being a good way to reduce noise, if it is not the other way around where part of the sensor is just not being used.


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Offline Stef.

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Re: A900 Pixel/Micron Question
« Reply #1 on: February 12, 2009, 01:11:11 AM »
Viperry- first of all welcome should I have not said it yet. I am not a specialist in micron questions so this is just what I know:
1) no it is not using a smaller/cropped sensor
2) yes using approx. half the amount of pixels is THE way to decrease noise- now there are debates whether you can achieve the same result with ACR- Adobe's raw converter by basically changing the output to a smaller file
3) If you want to shoot with half the pixels in camera than you have to shoot in Jpeg X Fine and lower the pixel size in the menu system. In other words if shooting in RAW than you can only lower the pixel size in the RAW converter but not in camera.
I do know that David Kilpatrick over at photoclubalpha has proven it and I have tried it but you would have to dig in his archive.
Hope this helps?
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« Last Edit: February 12, 2009, 02:19:43 AM by Stef. »
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Offline Stef.

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Re: A900 Pixel/Micron Question
« Reply #2 on: February 12, 2009, 02:38:57 AM »
O.K. here are some examples: Shot @ ISO 3200 no noise reduction in post-processing.

This first one is the overall scene no noise reduction in ACR and set to low in camera. The raw file was converted in ACR and the output is 11mp:



This is a 100% crop of the 11mp RAW output (size reduced in ACR)


This is a 100% crop of the full size RAW file:


This is a 100% crop of the full size Jpeg (24mp):


This is a 100% crop of the smaller Jpeg- reduced in camera to 13mp:


In a nutshell: the way forward IMHO is to shoot in RAW and reduce the file size in ACR. Don't forget no noise reduction was used! Jpegs with the A900 and high ISO are way too mushy. The A900 is also not really meant to be used in Jpeg.

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Offline Stef.

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Re: A900 Pixel/Micron Question
« Reply #3 on: February 12, 2009, 02:47:56 AM »
Here are the above RAW files- the first one full size and the second one with in ACR reduced file size. In both cases I applied "Neat Image" in auto setting- so no fine tuning:

Full size RAW 100% crop:


Reduced RAW size 100% crop:


Here it becomes pretty clear the the reduced file size in ACR does help the noise issue. Please don't forget I did not fine tune anything here but set everything to auto.
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Offline viperry

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Re: A900 Pixel/Micron Question
« Reply #4 on: February 17, 2009, 06:35:55 AM »
Does ACR, come with CS4, Lightroom or Photoshop. Because i do have the camera raw plugin and all that but how can I access ACR. Last stupid question I promise.

Offline Stef.

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Re: A900 Pixel/Micron Question
« Reply #5 on: February 17, 2009, 05:02:35 PM »
Never such thing as a stupid question! ACR comes with Photoshop/Lightroom and Elements. Once you double click a raw file it should automatically open up in ACR. Also go to the Adobe website and make sure you donwload the newest version:
http://www.adobe.com/products/photoshop/cameraraw.html

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