Imperfect comparison of a900 and RX100 at roughly same focal length

Started Jan 5, 2013 | Discussions thread
OP Docno Veteran Member • Posts: 4,797
Re: Comparison of full-sized images of the RX100 and the A900: Would this be worthwhile?

Robsphoto wrote:

Docno wrote:

First, this comparison is NOT perfect, so easy with the flames please. It's very 'quick and dirty' as I have real work this weekend.

Anyway, a900 with 70-300mmG set to roughly 100mm. RX100 zoomed to max. [It's difficulty to get the same focal length across these two cameras, but I think I got it fairly close.] Same ISO 200 and aperture settings (yes, equivalency can be debated, since these cameras are so different). Focus is on the black building at centre.

Shot in RAW and loaded into ACR and processed with the same settings (i.e., sharpness and noise reduction and white balance settings are identical). Then moved to Photoshop CS6 as 16bit files and resized for printing to A4 size using Perfect Resize (Genuine Fractals).

So basically, we see two images with roughly the same field of view (approx 100mm) as they would print to A4 size. What I'm crudely trying to do is to simulate what A4 prints would look like coming out of these two cameras with have different sensor sizes and pixel densities. Check them out in 'original size' ... they look blurry as embedded files here. I'll let you figure out which image comes from which camera.

A very interesting test which certainly shows the RX100 has performed very well in comparison with the A900 using the 70-300mmG lens. However, the areas of bush, for example, in the pictures perhaps shows the A900 to have produced a more pleasing result.

I think I might have done such a test using the CZ24-70 or a good prime, because this is an advantage of a camera such as the A900, as discussed recently here:

I see that the image size of both the photos is 2806 x 1984 pixels. If the image sizes were not reduced, the A900 image size would be 6048 x 4032 pixels and the RX100 image size would be 5472 x 3648 pixels.

I can understand why the resizing has been done, but do you think there is some merit in examining 100% crops from the original images without any resizing taking place

This would mean that the crop from the A900 would be larger than the crop from the RX100, but perhaps this doesn't matter because the A900 has the potential to capture more detail etc because its image size is greater than that of the RX100?

Yes, this is why no test will ever be conclusive. As you say, a crop of the same portion of the image will be larger in MP for the a900 (assuming the same starting focal length). My point was more to show that the an RX100 when printed at the same as an a900 image, can be hard to distinguish in terms of image quality (hard, not impossible). As for the merit of 100% zooming, I do think we're too preoccupied with it and we forget how we actually use the images we produce. We usually ​don't​ share/print 100% crops..

I was taking a few pics today with the A55 plus the 18-250mm lens (27mm - 375mm in 35mm terms), and being able to take a 27mm pic one minute followed by a 375mm pic the next, means that you can do so much more than with the RX100! But, I still really like my RX100 and its very good image quality.



Examples of crops showing the amazing detail that can be captured by the Sony A900!

Yes, we have a lot more flexibility with the a900, but it's amazing how well that little pocketable RX100 does in the right circumstances. I ​may ​have got a better photo with the a900 than the RX100 one below, but then again, I would never take the a900 to that club...

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NEX-7, Sony a900; SEL18-200mm, CZ135mm, CZ24-70mm, SAL70-300mmG, 50mm F1.4, 100mm F2.8 macro, KM17-35mm, CZ16-80mm, KM11-18mm, SAL18-250mm

 Docno's gear list:Docno's gear list
Sony RX1 Sony RX100 IV Sony Alpha 7R II Sony 70-300mm F4.5-5.6 G SSM Sony 135mm F1.8 ZA Carl Zeiss Sonnar T* +6 more
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