Canon 600D, 60D or a used 7D?

Hi Chris, comments on your comments below:

CrisKey wrote:

With 450 I have done satisfying shoots using raw and post-processing. Detail and color response was very good. Often I have decided to avoid some scenarios due to some lens-camera limitations. So low light and actions where you need a faster AF.

I think that a 50mm f/1.8 would probably blow your mind in terms of what it can do that your superzoom can't. As for AF performance, this is probably the Tamron and not the 450D. See below for more details.

I don't know which one I have bought. On the lens I can read DI II Tamron 18-270mm 1:3.5-6.3 obviously with VC.

That is the old, non-PZD (which is Tamron's version of Canon's USM) version. Newer 18-270 PZD's will be faster, as will any ring USM Canon. (I believe even the Canon 55-250 would be quite a bit faster.)

In other words, your limiting factor is not the camera's AF system, it is the AF motor in your lens.

Yes I was on track side Hard task and at the end I fixed the focus at a know point.

Even track side, I would expect my 55-250 to be able to keep up at least some of the time, but Canon ring USM would be ideal.

Yes for sure my technique could be improved.

Given what you said, part of what I'm thinking is allowing AI Servo focus about a second or 1.5 seconds to lock on to the car before squeezing the trigger.

Why 7D could focus and others don't?

It has a higher-sensitivity focus point that the others lack. I forget the details. However, if you use a fast lens (50mm f/1.8 or 50mm f/1.4, for example), then any body will be able to focus in just about any light where you can see clearly.

I actually had essentially no problems using the center focus point on my 500D for these two galleries with my 50mm f/1.8. The 50mm f/1.8 has a focus motor that is arguably worse then the one in your 18-270, but it delivers about 10x as much light to the sensor (both AF and imaging) at comparable focal lengths.

• https://picasaweb.google.com/116145794197181982819/20120128PuertoVallartaIMSParty?authuser=0&authkey=Gv1sRgCPvv6cTumpjnoQE&feat=directlink

• https://picasaweb.google.com/116145794197181982819/20121228PuertoVallartaAcrobatsFireDancers?authuser=0&feat=directlink

I have just downloaded this Dx0 software soon I test it with my photos.

Post some before & after - I'm curious as to what it will actually do with an 18-270. It did wonders with the corners of the photos we took with the Canon 28-135 when we had it. It also allows me to push my good 'ol 18-55 IS in situations where it would normally show CA.

In defense of the 18-270

I would invite folks to take a look at the Flickriver lens explorer page for the lens:
http://flickriver.com/lenses/tamron/tamronaf18270mmf3563diiivcldasphericalif/

Its the only super zoom where I see the long end used to good effect often. All of the others seem to produce their best photos between 18mm and 35mm. As a result, it is on my "wanted lens" list ... below a UWA and a fast kit zoom, but it is still there.

Battery Grip

My hands aren't very big, but they still get strained when handling the 500D with a somewhat-heavy 100mm Macro lens. (The old, larger 300D is actually much more comfortable.) However if you get a battery grip, your pinky suddenly has something to hold on to. It makes the camera much more pleasant to hold with a heavy lens.

There are good 3rd-party battery grips available ... including some that appear to come from the contract manufacturer that makes the things for Canon in the first place.

It also makes you look like a pro, which can be a bad thing.