OK- forgive me if this has been answered before, tried to search a bit but kept coming up with more of the xs/xsi debate that wasn't exactly relevant.
To the point. Does the XS have an accurate enough AF system to reliably use with a 70-200 F4.
As per the specs the rebel xs has a center cross type sensor that's for f5.6 lenses whereas other cameras are eqipped with cross types are good for 2.8 lenses.
Now - I want to purchase a 70-200 F4 for the XS, Given all other factors being equal and the body is correctly calibrated - with the len's max aperture at F4 - and as I understand such things - the XS's focus system should be acceptable with this combination.
Is there any real reason to step up to a body with a faster AF sensor if I don't have any primes or zooms faster than F3.5. As I understand some things - if you look at the raw numbers it seems like a "duh" since F4 will never trigger the higher sensitivity system present in the other cameras and so the sensor of the XS should be more than sufficient, and almost ideal. OR is it possible that the systems with the 2.8 center point are more accurate in general?
Am I correct with my assumptions - or am I just getting hung up on techie crap?
Someday I "may" move to a 2.8 zoom like the 17-55, which would then necessitate a more accurate body. Although the likelyhood of moving to that grade of lens anytime soon is probably on par with getting hit by a meteorite. I have owned the tamron 2.8 and found it to be a great lens - but I found I liked the background separation and the overall effect far better when shooting people with the longer focal length of 55-250. Depending on how finances go for me - (right now - lke everyone else - it's forced some downsizing in my hobbies...) my only other upgrade plan is to try the 15-85 that's due out soon. I was able to borrow a 17-85 and found it to provide a bit more detail on cropped pictures than the kit lens (which I am not dissing at all - that thing is still probably beyond my photography skill at the moment...)