Upgrading Advice Appreciated

[alexsandro2012]

Hi,
I currently own a 7D which is my second body after a XSi that was my very first dslr. I am planning on upgrading to a 5D Mark III before the end of the year but I cannot keep the 7D so my EF-S lenses will become useless.
Here is my question: A friend is selling her Canon 28-300 L and I am thinking that this could be a great upgrade opportunity to move from my EF 70-300mm f/4-5.6 IS USM and have a single EF lens for travel with a great zoom range and L quality. Is this right? Will I get better performance than with my 70-300 USM and my EF-s 17-55 f/2.8 (which the 28-300 would also replace)?
My current lenses are:
- Canon EF 50mm f/1.4 USM
- Canon EF 100mm f/2.8 Macro USM
- Canon EF 70-300mm f/4-5.6 IS USM (selling it if I get the 28-300 L)
- Canon EF-S 17-55mm f/2.8 IS USM (selling it when I get the 5D Mark III, but I will really miss this lens (maybe getting a 24-105 if I don't purchase the 28-300... options are welcome)
- Sigma 10-20mm f/4-5.6 EX DC HSM (which is not going to work with the full frame and I will miss... for sure I will end up getting a Sigma 12-24)
Thank you!

[Random Orbits]

The 28-300 is not as good as the 17-55, and it is heavy at about 4 lb to use as a general purpose lens.  A superzoom can have its place in situations where changing lenses is undesirable, but L lenses with smaller zoom ratios will deliver better IQ.  I would suggest getting the combo 5DIII/24-105 instead if you like using mid-range zooms.  Another way to do it is to skip the mid-range zoom entirely, something like the 16-35, 50 and 70-300.

[brad-man]

I would agree with RO about the ef28-300. If you don't need a very wide lens, I would suggest the Tamron SP 24-70mm f/2.8 DI VC USD and the ef70-200 f/4 IS for really good IQ. If you need the extra reach, substitute the ef70-300 for the magnificent ef70-200...

[Rat]

I would thoroughly re-research the sigma 12-24, I've heard bad stories about it - and especially on 3rd party lenses, the 5D3 will show you all the problems with corner sharpness, CA and vignetting that, as an aps-c-user, you've so far only read about My aps-c UWA (Tokina 12-24) got replaced by a 17-40 when I got the 5D3, which is roughly as wide - but I don't use it as much, because the 24-105@ff has a divine reach.

About the 28-300 - it's very bulky to call a 'travel lens', very heavy too. Don't think you'll be wanting to lug that around for days on end - speaking of which, just why is your friend selling hers? Both the 24-105 and the 70-200/4's are half its weight - your bag won't be lighter, but what you have in your hands will. And you're in for a bit of a shock to see just how versatile any 70-x00 lens is at full-frame - so I too second the suggestion to buy the 70-200/4IS over the 28-300, unless you really hate switching lenses.

Mind you, switching from 300@aps-c to 200@ff is a serious detriment to your tele reach. Happened to me too, I don't mind as much since I don't shoot tele often, but I just got me a 1.4 extender all the same. Of course, there's lots of good stories about the 70-300L too, but the 70-200's are legend for a reason

[rpt]

What do you shoot at the 300 end on APS-C? You will need to go to 400mm or 500mm to get to an equivalent focal length.

[Menace]

For me, 28-300 is way too heavy to lug around all day - my two go to lenses are the 24-105 and the 70-200 2.8 IS II and switching between them doesn't take that long.

I'd suggest the above two lens option for you too.

Cheers

[M.ST]

Buy the new EF 24-70 2.8 II L lens and hold the EF 70-300 IS or replace the EF 70-300 IS for a 70-200 2.8 II IS L. If you use the EF 70-300 IS L lens you see on a FF body CA´s. The EF 70-300 IS L performs better on a APS-C camera.

But if you want the widest focal lenght from the EF 70-300 IS you must buy a very expensive EF 500 IS for the 5D Mark III.

[bbasiaga]

I've always wanted to try one of those super zooms.  I could see how there would definitely be a trade off in weight and IQ (to some extent).

I can vouch for the 70-200mm versatility on full frame.  I use the F4 L IS version and love it.  Light and easy to wield.  I did, however, miss the long end of 300mm on a crop.  So I eventually added a 100-400 F4.5-5.6L IS to the kit.  If you shop used you can get both of those for less than the 70-200 F2.8 L II and a 2x TC.  The 70-300L interests me as well, but the above post about visible CA is the first I've heard of any flaws.  I havent researched it thoroughly though. 

On the wide end, thr canon 17-40 F4 L does a great job, and is a lot cheaper than the 16-35.  With the awesome high ISO performance of the 5D Mk III I'd save the bucks on the lens if you decide to get a zoom in that range. 

-Brian