Long-Term Lens-Buying Plan - Advice Please!

DSLR noob · Aug 20, 2007

If you look at the 70-200 and a X1.4 tele converter, it becomes a 280mm f/4 lens, so getting that would keep you in the range of that extra 100mm you wanted AND keep you from getting the slower glass, which sounds like you'd love. So I say get the 70-200 first, if you want even more range for astronomy work, get a teleconverter, THEN go for the 24-70. As for the wide angle, even if you say 18mm isn't enough, remember if you get a nice Canon brand 16-35 2.8 L, you could stay in the L series 2.8 range from 16 to 200 with minimal overlap, and have a an extension of 200-280 at f/4. Then when you DID get a full frame, the 16 would be much wider than your 18mm is on your crop body.

astrostu · Aug 20, 2007

DSLR noob said:
If you look at the 70-200 and a X1.4 tele converter, it becomes a 280mm f/4 lens, so getting that would keep you in the range of that extra 100mm you wanted AND keep you from getting the slower glass, which sounds like you'd love. So I say get the 70-200 first, if you want even more range for astronomy work, get a teleconverter, THEN go for the 24-70. As for the wide angle, even if you say 18mm isn't enough, remember if you get a nice Canon brand 16-35 2.8 L, you could stay in the L series 2.8 range from 16 to 200 with minimal overlap, and have a an extension of 200-280 at f/4. Then when you DID get a full frame, the 16 would be much wider than your 18mm is on your crop body.

I dunno ... what you say makes sense in the short-term, but it's much more expensive (on the low end). As I said before, I'm not too concerned about the high end (as in more focal length) because of the asymptotic behavior of the longer focal lengths.

What's really a pain (and this is a bit of a rant) is that 18 mm on a cropped sensor gives 64° across, whereas on a full-frame it's 90°. Going down to 16 mm is only 70°*across - a 6° gain, or less than 10% wider. Even 12 mm on a cropped sensor will only give 86° across. Whereas on a full-frame I can get 65° with a 28 mm lens, and I can get up to 112° with a 12 mm. Not fair! Almost makes me want to move my timetable up for getting my 5D (or its successor) from Summer '09/'10 to something sooner. But at this point I'd rather invest in glass and definitely wait for that low-end pro body to be updated.