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If you've purchased one of Sony's new translucent mirror cameras recently (as of Dec/2010), and have wondered about how it really compares to a traditional DSLR as far as image quality is concerned, and if there is such a thing as a "penalty" resulting from a mirror that doesn't flip up and out of the way to fully expose the camera sensor, then you may find some interesting comparisons below.

 

This page will attempt to point out some troubles the A33, (and probably the A55) have with bright/dark transitions from the image central area, and to a lesser extend, additional color fringing along the sides, as compared to a traditional DSLR, like the Sony A700.

 

I should also make clear that I'm not sure what the cause of the additional color fringing is, I'm simply pointing it out in an unscientific manner.  The images below were taken with the Sony A33, and a Sony A700, with a quick high ISO comp using the A900.  The Sony 85mm F/2.8 lens was used for all comps (except high ISO), because that's the lens I had on the camera at the outset, so I just used it for continuity.  I tested two different A33 cameras, and both (unfortunately) performed the same, so I don't think I received two bad cameras.   

 

The first image below, and the center crops were taken while I was hiking the local mountains, so I didn't have the A700 on hand for a direct comparison.  While taking these shots and reviewing them on the LCD, I realized the huge amount of color fringing the A33 was producing in the centers, even stopped down at F/5.6.  I know the image is very high key, and one normally wouldn't use F/2.8 for a shot like this, but there is still more color fringing present with a small aperture compared to a conventional DSLR.

 

December2010/a33over.jpg
Full image from A33, F/2.8 with Sony 85mm F/2.8 lens.
December2010/a33a28.jpg
Center crop, F/2.8 with Sony 85mm F/2.8 lens.
December2010/a33a40b.jpg
Center crop, F/4 with Sony 85mm F/2.8 lens.
December2010/a33a56.jpg
Center crop, F/5.6 with Sony 85mm F/2.8 lens.
December2010/a33a80.jpg
Center crop, F/8 with Sony 85mm F/2.8 lens.

 
Yes, the F/2.8 shot looks awful.  Fortunately, the more you close the aperture, the less severe the color fringing is.  It never seems to be completely gone.  Notice how the shot at F/2.8 looks sharpest, although there could be heat shimmer present since the strip mall is about 4 miles (6km) away, and that could explain some variations in sharpness, or maybe the camera just can't focus exactly the same from shot-to-shot.  The shots above were hand-held using auto-focus.  On a side note; the A33 doesn't seem to be quite as precise at focusing as the A700, but that's to be expected as the A700 is a much more expensive, semi-pro model.  
 
 
Direct comps with A700 next.  

           A33 at F/2.8

             A700 at F/2.8

December2010/a33cucf2.jpg
December2010/a700cucf.jpg

 

The images in this section are direct comparisons with the A700.  It's easy to see here the A700 doesn't have near the massive color fringing visible on the truck door reflections, even at F/2.8.  Look at the sharp white lines directly below the top reflections (above black arrows) on the A33, those are caused by the translucent mirror, and don't show up much unless you look closely.  There are more reflection crops below.  Crops are taken from the center of the image.

 

More color fringing along the sides of the image.

 

December2010/a33cfday2.jpg
A33 left side crop, F/5.6 with Sony 85mm F/2.8 lens.
December2010/a700cfday.jpg
A700 left side crop, F/5.6 with Sony 85mm F/2.8 lens.

 

The above extreme left side (middle area) 100% crops are probably more realistic image representations to make comparisons with than the previous crops, but there is still a fairly significant amount of color fringing emanating from the A33, (top) as compared to the A700 (bottom).  I've highlighted a few areas with arrows to check out, and I see more color fringing present in some places with the A33, and also a sudden appearance of color fringing with the A33 where none is present on the A700, see the lower right arrow by the VW bug wheel. There is a slight noticeable resolution gain with the A33.

 

Stadium lights.

 

December2010/a33cfnt2.jpg
A33 Center crop, F/5.6 ISO 400 with Sony 85mm F/2.8 lens.
December2010/a700cfnt.jpg
A700 Center crop, F/5.6 ISO 400 with Sony 85mm F/2.8 lens.

 

This is a good comparison between the A33 (top) and A700 (bottom) at F/5.6.  Notice the additional color fringing on the A33, and the reflections (indicated by red arrows) below each light (in my direction) on the A33 crop, which I believe comes from the translucent mirror.

 

High ISO shots.

 

December2010/a331600.jpg
A33 ISO 1600 RAW
December2010/a7001600.jpg
A700 ISO 1600 RAW
December2010/a9001600.jpg
A900 ISO 1600 RAW
December2010/a33200.jpg
A33 ISO 200 RAW

 

Here I've taken RAW images from the A33, A700 and A900, all at ISO 1600 (except the last shot), and processed them with a simple noise color slider to 50 on each image, then cropped and saved them to a jpeg for upload to the site.  Lenses used, the Sigma 10-20mm at 20mm for the A33-A700, and the Sony CZ 16-35mm at 30mm for the A900.

 

The A33 RAW shot is pretty grainy without some sort of heavy noise reduction, that was surprising as I initially thought the in-camera jpeg noise reduction processing was pretty light.  The A700 (with Ver 3) looks like it has more luminance smoothing applied, even in RAW, but it looks better than the A33 to me, and the actual resolution is about the same.  If you applied more smoothing to the A33 image, which it needs, you'd have less resolution than what you see here.  The third image down is the RAW A900 (ver 1.00) at ISO 1600, down-sampled to the A700 size and cropped, and that looks real good to me, in fact......the last image is the A33 at ISO 200, and when you compare that crop to the A900 at ISO 1600, you can see there isn't much difference in resolution or overall image quality.

 

To sum up the ISO 1600 image quality, the brand new A33 comes in last, the three year old A700 is second, and the two year old A900 is best, but that's not really a very fair comparison as the A900 is far more expensive and capable than the consumer grade A33.  The additional color fringing on the A33/55 is a real problem for me, and it sure seems the old A700 is superior in image quality than the new translucent mirror cameras. 

 

Let's keep the mirror for now. I seriously think Sony doesn't have the translucent mirror technology perfected yet; hopefully they'll figure out a firmware update, or some type of fix to correct the color fringing issue, and to a lesser extent, the mirror ghosting problems.  If Sony comes out with a translucent mirror replacement for the A700 with image quality like you see here, they may be laughed out of the intermediate an pro markets forever.