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Old Mar 15, 2011, 8:10 AM   #11
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It also has a 'Full Frame' image sensor, which is a handicap. It captures the portion of the image circle where most of the flaws appear, the portion of the image circle that is cropped off by an APS-C image sensor.
You worry about the corners too much. The corners are irrelevant for the vast majority of my photos (they wouldn't be in focus anyway). ;-)

If I were shooting all landscapes, perhaps I'd see it differently.

Even though the A900 has much higher resolution, it's still got lower pixel density compared to the A700 (or any Sony model using 12MP or higher resolution APS-C size sensors). That places less demand on the lens quality needed for best results (line pairs per millimeter the lens needs to be capable of resolving), so that you'll get better per pixel sharpness.

The difference isn't quite as dramatic as you may see using sensors of the same resolution (for example, a Nikon D300 versus D3, where you'll see much better results with a D3 as far as resolving ability with a given lens). See my post here for a discussion with links to lens reviews showing how the D3 outperforms it with the same lenses:

http://forums.steves-digicams.com/wh...ml#post1161469

But, from my experience using both Sony APS-C and Full Frame models, the full frame models give better per pixel sharpness with the same lens. For example, both of my Tamron AF lenses (SP 20-40mm f/2.7-3.5 and SP 35-105mm f/2.8) are noticeably better on a full frame camera (Sony A850/A900) when compared to using them on the A700.
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Old Mar 15, 2011, 9:57 AM   #12
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Absolutely. Sometimes the camera is the bottleneck, and sometimes the lens is the bottleneck. When the lens is good, the camera is the bottleneck.

The Sony/Zeiss 85/1.4 on an A700 will produce an image that is very similar to the Sony/Zeiss 135/1.8 on an A900, but, compared to the center, the corners will be sharper on the A700. That is, there will be a greater drop-off in sharpness with the A900. Yes, for sports/action/wildlife, macro, or portrait, that's not going to make much difference. But for landscape or event photography, the edges and corners can be just as important as the center.

And this shouldn't be about what is good enough; it should be about which is better. 24MP is better than 12MP or even 16MP, but APS-C is better than 'Full Frame' in that it extracts the best part of the image circle to use for its images. If the A900 were 12MP or the A700 were 24MP, we wouldn't be having this conversation. This is about trade-offs and where we're prepared to make them.

If you've got a lens that performs sub-par on your A700, it's still going to be sub-par on an A900. How much below par it is will be clearer, though.
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Old Mar 15, 2011, 9:51 PM   #13
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Thanks again for all the input and information. I feel I learned something from this inquiry and have decided as follows:

Keep the A700 with the 18-250 welded on. I really do like this combo.

For the A900 I will keep my hope alive that someone will come out with a lens in that focal range.

The 70-400mmG and the Tammy 28-75mm f/2.8 will serve me well on either camera.

I do very little landscape shooting, mainly sports with the grand kids, (Soccer, Indoor volleyball, Swimming) some birding, and the usual family stuff.

If the Sony 70-300mmG were wider, I would grab one tomorrow.
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Old Mar 15, 2011, 9:53 PM   #14
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Sorry Duplicate
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Old Mar 16, 2011, 12:24 PM   #15
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Focus accuracy is also very good (an understatement from what I've seen with them, probably because a lot of lenses are "tuned" for 35mm cameras). But, I would suggest upgrading it to the latest V2 firmware for better AF speed (as your A900 will probably feel a bit "sluggish" compared to your A700 without it if you're shooting in demanding conditions). Get it here:

http://support.sony-europe.com/dime/...AC&m=DSLR-A900
The V2 Firmware Upgrade for the A900 (and A850) is available on Sony USA's website, too.

http://esupport.sony.com/US/perl/sel...ER&PRODTYPE=76
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Old Mar 17, 2011, 5:26 PM   #16
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I have the a900 and i LOVE it. I use it with the SAL2470f/2.8, Sigma 70200f/2.8, KM Beercan70-210 and SAL50f/1.8. I just sold my a700 with SAL1680CZ so i can get the a77 when it comes out.
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Old Mar 17, 2011, 7:04 PM   #17
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I have the a900 and i LOVE it. I use it with the ... SAL50f/1.8.
You know that the SAL-50F18 is a DT lens, right?
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Old Mar 18, 2011, 12:09 AM   #19
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TCav,

yeah the 50f/1.8 is DT but the 50f/1.4 is not..sorry I missed type. i have the 50f/1.4
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