What makes one lens better than another for a particular application.

[Dylan Couper]

I know I'm no Jeff Donald, but I because the chip is smaller than the 35mm frame size, you are only getting the 'cropped' image area, and there is no actual magnification going on.
Plus, I think you mean a 1:1.6 ratio, not a 1:6.

[John Locke]

Thanks, Dylan. Yep, that's what I meant. Thanks for pointing that out. I'm so used to calculating with 1.6 that I'm just using a verbal/written shortcut...bad habit.

It's really hard deciding which lenses to use with the 10D. The assortment that I picked out as ideal for non-digital over the years doesn't necessarily apply due to the decreased image area. Why get a 300mm if I'm going to have to back all the way to Osaka to get more than just the subject's nose in the frame?

[Jeff Donald]

Dylan is correct, the chip size is just a crop of the center portion of the image circle. However, when the image is printed to standard sizes (4x6, 5x7, 8x10 etc.) the net effect is the image is magnified an additional 1.6x (vs. 35mm film) to fill the given print size.

If you are reconsidering lens for the 10D, here's some food for thought. The optical quality of today's lenses are near the pinnacle of design and affordability. How much more can they be improved? On the other hand digital cameras are in their relative infancy. New models with major changes are appearing yearly (or even sooner). In a few years, cameras with full frame sensors will be much more affordable. I see a future where photographers keep their set of lenses for a long time and change camera bodies every few years.

With that in mind, I would still consider the 300mm 2.8 A great lens on either size chip. The 200mm F1.8 was recently discontinued. Could a new version with IS be on the horizon? Only Canon knows for certain and they're not saying. Don't overlook the 70-200mm F2.8 L series zoom. That lens works great on either chip size and can be coupled with the 1.4x tele-convertor. for some extra reach. The 70-200mm may be your short term answer for a long lens.

[Adrian Douglas]

Tex you know how much I love my 70-200 and it's the older non-IS version. The newer IS version would be an excellent lens for your portrait work as the IS will allow you to handhold shots at speeds lower than 1/250 which is the lowest I go with my lens due to it's weight/length.

Oh, and I was refering to the optical zoom compression effect Jeff refered to not digital zoom. Jeff answered my question so thanks to all.

[John Locke]

Yep...you inspired me already with the 70-200 IS. It and the 16-35 are on my shopping list for this weekend. The 20% point credit at Bic is just too good to pass up.

[Adrian Douglas]

If your still looking for a good strap I just saw the guitarist from Jane's Addiction playing with a Louis Vitton strap, maybe they make camera straps too. It's just what you need to be taken seriously in Tokyo.

[John Locke]

That'd go great with my LV leather pants.

[Jeff Price]

<<<-- Originally posted by Dylan Couper : I know I'm no Jeff Donald, but I because the chip is smaller than the 35mm frame size, you are only getting the 'cropped' image area, and there is no actual magnification going on.
Plus, I think you mean a 1:1.6 ratio, not a 1:6. -->>>

There's a very nice discussion in the latest 'Outdoor Photographer' on why cropping is not really the best term for what is going on (cropping referring to cutting a piece out of an entire image versus purely a difference in magnification to begin with). It covers the use of similar lenses in different formats as an analogy.