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Old Oct 13, 2011, 1:01 PM   #11
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Yes, the A77 will be available soon (Sony Canada is already filling its pre-orders.) At this level, the differences are not very significant, but the A77 has more noise, less dynamic range and costs more than the Nikons.
You're only looking at a very small difference. For example, it takes 5 points on the overall sensor quality score (which is averaging multiple tests) to indicate a 1/3 stop difference.

"A 5-point difference on the scale corresponds to a gain or loss of sensitivity of 1/3 of a stop."

http://www.dxomark.com/index.php/About/Sensor-scores

Also, those tests do not take resolution or retained detail into consideration. If you don't look at retained detail, noise tests are not worth much, since you can have very low noise without much detail. ;-)

Click on the links about how Sensor Performance is measured and you'll even see them state that resolution (ability to render fine detail) is not taken into consideration for their test results:

http://www.dxomark.com/index.php/Abo.../Overall-Score

If you look at images at the same viewing/print sizes, the Sony A77 does quite well, and even with Noise Reduction, it's retaining more detail than competing cameras, thanks to it's higher resolution sensor.

For example, if you look at PopPhoto's test results, the A77 is still able to resolve 2620 lines per picture height of detail at ISO 1600, which is more than competing models can resolve at ISO 100.

See the comments about it in their tests:

http://www.popphoto.com/gear/2011/09...ng-aps-c-dslrs

To put that into perspective the Nikon D7000 is only able to resolve 2390 lines per picture height on their tests at ISO 100 (whereas the Sony A77 is still resolving more than 2600 lines at ISO 1600). If you think noise is too high at the print/viewing sizes you'll use, then use more NR (as you've got a lot more detail to work with using a 24MP Sensor).

http://www.popphoto.com/gallery/test...ge=4#container

As for the A580, I spent some time comparing images from the A580 (which is using a Sony 16MP CMOS APS-C size sensor like the D7000 uses with a traditional body design), and I'm impressed with what I see so far when viewing images at the same viewing sizes from the A580 and A77.

For example, when I use the Comparometer at Imaging Resource.com and look at ISO 6400 images sized to my display from both the A580 and A77 (using the test charts in simulated daylight lighting, as well as the mannequin in tungsten lighting), the A77 images appear to have better sharpness, saturation and contrast (perhaps even a bit too much for my tastes by default) without any noticeable increase in noise levels when you view them at the same size (versus viewing them at 100%, where the 24MP image is going to be larger). They were also using prerelease firmware (version 0.58), and newer firmware versions appear to retain more detail.
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Old Oct 13, 2011, 1:55 PM   #12
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You're only looking at a very small difference.
I said ...
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... At this level, the differences are not very significant ...
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Originally Posted by JimC View Post
For example, it takes 5 points on the overall sensor quality score (which is averaging multiple tests) to indicate a 1/3 stop difference.

"A 5-point difference on the scale corresponds to a gain or loss of sensitivity of 1/3 of a stop."

http://www.dxomark.com/index.php/About/Sensor-scores
I'm not looking at their predigested sensor scores; I'm looking at their raw measurements. Those measurements show that ...
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Also, those tests do not take resolution or retained detail into consideration. If you don't look at retained detail, noise tests are not worth much, since you can have very low noise without much detail. ;-)

Click on the links about how Sensor Performance is measured and you'll even see ...
Again, resolution isn't an issue for Dunes, as he'll be downsampling all his images anyway so they can be viewed on the web.
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Old Oct 13, 2011, 2:11 PM   #13
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The difference in noise is less than 1/2 stop. If the A77 was a half stop better, it would rate approx. ISO 1200 for their noise test (higher than the Nikon D7000 or A580 measured) versus 800. Not a big deal. As for DR, good luck getting anywhere near that much from either sensor after converting to JPEG if you don't want a totally flat image with virtually no contrast. Again, the difference is negligible and the A580, A77 and D7000 all measure over 13 stops (a couple of stops more than you can expect to get from any of them after conversion from raw if you don't want a very flat looking image).

As for resolution, sure it makes a difference. That's why I'm seeing sharper images with better detail with no noticeable increase in noise *after* downsizing them to screen size when using the comparometer at imaging-resource.com to compare higher ISO images. Noise is less noticeable at smaller print and viewing sizes, so by starting out with more detail being captured from the higher resolution sensor, you're ending up with a nice image at viewing sizes you'd typically use after downsampling

Just use the comparometer at http://www.imaging-resource.com/IMCOMP/COMPS01.HTM and compare some of the higher ISO images (like the studio samples in simulated daylight lighting, and the mannequin in tungsten lighting) and you'll see what I mean.

When I look at ISO 6400 screen size images from the A580 and A77 side by side, the A77 images have more detail with no noticeable increase in objectionable noise levels, despite the better measurements at dxomark for the A580 (or D7000), since those measurements don't take detail captured into consideration, and you need to compare them at realistic sizes you'd use to tell how one camera will do compared to the other (since the 24MP images are larger to begin with, so comparing them at 100% is a waste of time compared to how you'll view or print them). Let your own eyes be the judge, viewing them and printing them at the sizes you'll use, not using some lab test that doesn't take resolution and retained detail into consideration
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Old Oct 13, 2011, 2:45 PM   #14
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Back to cameras- Canon 50D is thoroughly decent at high iso,has excellent lens availability and is built like a tank. A clean "low miles" example should be available for reasonable money now...
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Old Oct 13, 2011, 8:28 PM   #15
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Once more, I already said that the differences weren't very significant.

I went to Imaging-Resources' Comparometer, downloaded the full size images of the shots from four cameras (Sony A77 and A580, Nikon D7000 and D90), all shot at ISO 6400. I displayed them on my 1280x1024 screen using Microsoft Office Picture Manager, took screen dumps, cropped out the same areas of each photo and placed them alongside one another in a single image.

In the first, "Bottles", notice that the lighting is off for the D90 shot. See the glare on the bottles and labels that don't appear in the other shots. That makes the shot from the D90 difficult to compare with the others. There are other minor differences, but none are very significant.



In the second, "Fabrics", notice that the shadow on the wall is darker in the shot from the A77 than for the others. Also, I don't see any more detail in the downsampled images, but if you see more detail in the image from the A77, I think the difference in lighting could be the cause. Either that or it could be increased contrast, possibly resulting from the A77's slightly lower dynamic range.



The last is of the Proportional Scale. If any portion of the image should be able to show increased detail, it should be here. There's the small text in the center, and the numbers and increments on the circular scale, any of which should make any difference noticable. Just to help out a little, I magnified these images 2X before cropping to make any difference in detail easier to see.

I don't see it.
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Old Oct 13, 2011, 8:34 PM   #16
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For images that are to be significantly downsampled anyway, the extra resolution of the A77 is unnecessary. And the A580, D7000 and even the D90 have lower noise and greater dynamic range.
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Old Oct 14, 2011, 1:41 PM   #17
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It looks like they reshot all of the samples last week using Firmware Version 1.3. When I was comparing images, their samples were using Firmware version 0.58, and there was a distinct difference in sharpness, contrast, saturation and more (in favor of the A77) after downsampling the higher ISO speed images to screen size.

It looks like the newer firmware is probably doing a bit more smoothing of detail at higher ISO speeds using the default Auto NR, with lower contrast and saturation compared to the pre-release firmware. It looks like the saturation is even lower than models like the A580 now using the default settings.

In any event, you're just not going to see any difference to speak of at equivalent print and viewing sizes at higher iSO speed settings once you tweak settings to taste, or convert from RAW instead. Yet, at lower ISO speeds when you really need a larger print, the A77 is going to be very tough to beat (with higher measured detail from it's JPEG images at ISO 1600, compared to ISO 100 images from competing cameras using APS-C Size sensors).

Also, you really can't go by tests that don't take retained detail into consideration (as in the DxOMark test series). Your D90 is actually a pretty good example of that. If you read through it's review at some of the sites that compared image quality with the older D300, you'll see comments from experienced reviewers that no amount of settings changes allowed the D90 to match the image quality produced by the D300, shooting in RAW or JPEG. For example, see the comments on this page comparing JPEG output from a D90 against a D300 in controlled conditions:

"...no amount of re-shooting could get the D90 to match the D300's output"

http://www.dpreview.com/reviews/nikond90/page29.asp

Note the comments about RAW files, too:

"..for those people hoping that the D90 would effectively be a half-price D300, the RAW results appear consistent with those from the JPEGs"

http://www.dpreview.com/reviews/nikond90/page33.asp

Yet, if you went by the DxOMark tests, you'd think the D90 output would be better:

http://www.dxomark.com/index.php/Cameras/Compare-Camera-Sensors/Compare-cameras-side-by-side/%28appareil1%29/439|0/%28brand%29/Nikon/%28appareil2%29/440|0/%28brand2%29/Nikon

The DxOMark tests do not take resolution or retained detail into consideration, at all; and do not take into consideration how different demosaic algorithms may work with a given sensor model (since you have to convert from RAW to have a usable image, and they don't measure anything but raw data before any demosaic process).

Their tests also don't take into consideration how sensors may compare using different lighting temperatures, as you may find very different response curves and RGB multipliers may be needed to correct the color to get a final [viewable] image, when comparing images from different sensors in different lighting types, and that also impacts Dynamic Range (since more boost to a given channel may be needed to correct output for viewing, and one channel may be prone to blowing before another).

In any event, you're splitting hairs between the image quality between any of the dSLR models being discussed for screen size images, especially once you convert to a usable image format and compare them at the sizes you'll likely use and tweak in camera processing settings to taste (or convert from RAW instead).

I only pointed out my observations since the A77 was being discussed earlier in this thread. BTW, you'll find a small set of samples (although the weather wasn't great for most) from one in the A77 preview here; and you can expect to see a full set of samples in more conditions at various ISO speeds once we have a chance to review one and put it "through it's paces".

http://www.steves-digicams.com/camer...hotos-159.html

As for what the OP really needs, there are many variables involved. It sounds like the primary reason for buying a camera is for portraits in low light. Yet, my guess is that it will be used in a wider variety of conditions over time.

So, to the OP... I'd compare features (thinking about the ones you may want to use), try the cameras out in person, and decide if one has something you like over another (including build quality and ergonomics, video features if that's something you may want to use a camera for, etc.). You may find that the "fun factor" is much greater with one model versus another, with features that open up more possibilities for how you'll use a camera over the time you plan on keeping one.

Ditto for researching available lenses that do what you need.
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Old Oct 16, 2011, 4:17 AM   #18
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Thank you all for your input.

I'm not an expert with SLRs and my experience is very limited (Nikon D70s) and I'm not very good with statistics and numbers and I appreciate all the information you guys provided. It clearly shows how D90 is out of their league in that test you provided!

I can see that Sony DSLRs (A77 and even A580) look promising but it all depends on the price and the lens I am going to use. I really want one lens and only one good lens for portraits (fast one at least 1.8 aperture). If I can find a Camera Body and a Lens recommendation for great price (higher value) it would save me all the trouble of pondering which road to take.

I am biased towards Nikon because I am familiar with their system. So, that's always going to be a plus with my decision making. I think I need to go pay Sony SLRs a visit and see what they can offer.

Any rough estimation of Sony Camera body prices and lenses too? (is there a good portrait lens for Sony).. I know I was in love with the 85mm Nikkor 1.8 (or was it 1.4?) it had a BEAUTIFUL bokeh effect.
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Old Oct 16, 2011, 4:24 AM   #19
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Oh I just realized that A77 is not an SLR!

I think this might be an advantage, isn't it?

I read that the focus is faster and video capturing is much better than that of a DSLR.. can someone confirm this?
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Old Oct 16, 2011, 5:58 AM   #20
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The A77 is an interchangeable lens camera- call it what you want...!
It sure is a speedy performer though...!
http://www.ephotozine.com/article/so...-preview-17300
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