retcgav8r

<p>Many, many thanks to you all for your insights. The reality appears to be that if I had bottomless pockets and didn't care about traveling light, the 2.8L IS III would be perfect. Since it would be a stretch to buy it, and I probably want to travel lighter, I'm looking at the other options you have provided. Again, thank you all.<br>

Bob</p>

<p >Anthony, I did that last night (using my EF 28-105mm and the EF-S 17-55mm) and was surprised that the scene was the same. I've done more research, which clarified nothing, but after cogitating a while, I think I have it figured out: the crop factor is merely the difference between the view seen by a full-frame sensor vs. that seen by an APS-C sensor <em>using the </em><em><strong>same</strong></em><em> lens</em>. Since I'm not using a full-frame camera at all, the crop factor is irrelevant. On my 7D, an EF lens performs the same as an EF-S lens in terms of field of view for any given focal length. The truth is in the testing.</p>

<p >Does this sound correct?</p>

<p >As to the original question, it's clear that I need to borrow, rent or steal both the 70-200/2.8 and the 70-200/4 to determine which I “need.” Thanks to you all for your insights.</p>

<p >Thanks to all for the added inputs. David, your Vancouver Island locale must provide many subjects similar to my Sitka area.</p>

<p >Larry and JDM, thanks for your comments. Yes, I know what focal length is; I think we're mired in semantics here. The key word in my original statement was “effective,” as in, “...with an effective zoom range of 112-320mm on the cropped sensor...” Here is my analogy (please correct me if I am wrong): Were we to take a picture on the 7D of a given scene with an EF-S lens at 55mm, and another of the same scene with an EF lens at 55mm, the latter photo would appear to have been shot with a longer lens. You would get the same effect by cropping the first photo and enlarging it to the original size. The physical characteristics of focal length (depth of field and distance foreshortening for a couple) would be identical in the two photos, but the subject in the EF lens photo would be larger and would appear to have been taken at a focal length of 88mm.</p>

<p >I'm sure this has been argued ad infinitum by others. Until something better comes along, the conversion to an equivalent 35mm focal length for cropped-sensor cameras is a handy tool.</p>

<p>Gentlemen, thank you all. You've given me a lot of alternatives to consider, and several lenses I hadn't even looked at. The big question is affordability, and whether some of the less expensive alternatives will do what I think I need to do. It's time for more research. Again, thanks very much.</p>

<p>David, my indoor shooting is often in auditoriums and similar venues (awards ceremonies, school concerts, Russian Dancers, Native Dancers, etc), hence the desire for the f/2.8L.<br>

Thanks for your comments on the EF 70-200mm f/4L IS. That would probably work for most of my needs. Eagles and puffins are often very close, but the 2.0 extender might be better for whales.</p>

<p >A reality check would be a big help to me in choosing a new telephoto lens.</p>

<p >For over a year I've been lusting after the expensive, and heavy, Canon EF 70-200mm f/2.8L IS II USM lens. Each time I start looking at other options, I'll read something about how great is the EF 70-200mm f/2.8L IS II USM, and I'm back to square one.</p>

<p >I'm a serious amateur with an EOS 7D, an EF-S 17-55mm f/2.8 IS USM lens, and an EF 28-105mm f/3.5-4.5 (which was a kit lens for a film SLR from many years ago). With the cropped sensor 7D, the EF 28-105 gives me an effective zoom range of 45-168mm, which fits nicely with my EF-S 17-55, but doesn't give me much long range zoom.</p>

<p >Much of my photography is indoors with available light, thus the draw of the f/2.8 lenses. I also shoot a fair amount of Southeast Alaskan wildlife (eagles, whales, sea otters, puffins, etc) and could really use a longer telephoto. I'm now thinking of the 70-200 f/2.8L and a 1.4 extender.</p>

<p >Were I to get the EF 70-200 lens, with an effective zoom range of 112-320mm on the cropped sensor 7D, I'd have a gap between 55mm (on my EF-S 17-55) and 112mm (the low end of the EF 70-200). I'm thinking the sharpness of the EF-S 17-55 combined with the high resolution of the 7D would give me enough flexibility to cover that gap. Does that sound feasible?</p>

<p >Any comments about my desired lineup, or suggestions about other combinations, would be appreciated. Many thanks.</p>