24-105 or 17-55


New Member
Dec 4, 2011
Hi guys,

I tried searching for comparison in this forums but not able to find any. Separately, I have read feedback/comments regarding both lens from this forum and other common reviews from the web.
I do know each lens has their own pro and cons, but I would like to know if putting this 2 lens together, which is a better buy/use.

I use 550D now and may plan to upgrade to 7D, not full frame. I usually shoot during outings with family members, so long focal range is not the priority as mainly shoot group photos. Neither is ultra wide that important since I seldom shoot landscape. If surrounding is dark, I will use flashgun/tripod.

What I understand (correct me if I am wrong):
> For 24-105, on a APS-C, is the effective focal length 38.4-168 due to the 1.6x?
> This means it has further reach, but not wide enough.

> For 17-55, this is a faster lens due to the f2.8.
> But shorter focal length at 17-55, but good for wide angle.

I think the price is very close and both has IS & USM. I think the IQ is equal here? Both are solid built, similar weight and size. Assume I ignore the min and max focal length of each lens and compare similar range, say 38.4-55mm, what would the difference be?

Thanks guys for reading this.


Staff member
Jan 3, 2008
Pasir Ris
The focal length if a lens is ALWAYS the same, regardless whether you use APS-C or Full Frame camera. It is defined by the specifics of the glass elements. The 'crop factor' or 'focal length multiplier' needs to be applied to both lenses when used on APS-C bodies and will result in a narrower Field of View. Reason is the smaller sensor of your camera, compared to Full Frame.
For comparison of details you can also check photozone.de and many other review sites. Finally, rent both for a weekend and you might find the answer. My personal view is shaped by experience and preferences, so I should not comment on that. Best is what fits best to you.


New Member
Dec 4, 2011
I have read his thread, and other threads regarding these 2 lens.
I understand that the type of lens will depend on my shooting style, which at the moment leans slightly towards group/individual photos during outings/holidays.
Good idea about renting the lens though, might just give it a try.

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