So my current issues are:
1) I want a general improvement in the sharpness of my pics as I tend to like having them printed reasonably large and I think the current EFS lenses just won't give me the image quality I would like.
What size are your prints?
Are you shooting RAW and doing some post processing later? If not, then perhaps you should.
2) Shooting around dusk with my 18-135 walkabout (even in dark shade sometimes), I am either getting blurred photos due to having to drop the shutter speed to low (even with IS) or bumping the ISO too high and getting unacceptable levels of noise.
Well, there is Sigma 18-35/1.8, but you won't like the focal range
I have been purchasing my recent lenses with a view to eventually going full frame (can't wait to play with the 70-300 - my first L lens)
My thoughts have been to upgrade to a 6D with a 24-105 as a walkabout, use the 70-300L as my long lens, a 16-35 F4 as my wide angle and keep the 50 1.8 and 85 1.8 for portraits and shallow DOF as well as low light. The 6D will solve my issues with noise and ISO whilst the L series lenses will solve my sharpness problems.
I have read about the 6D AF issues, and don't think that will be an issue for me as most of my shots are static and for the odd shot of action I can use the centre point and crop later.
Works for me
The area I want some feedback on is the 24-105. From all that I have read the newer 24-70 is lots better, but I won't go with that lens as that would give me a similar range on FF to the original 18-55 on crop that I found too limiting initially. I know that the 24-105 will be shorter than the 18-135 (equivalent approx. 216 mm), but I think I could live with 105, but definitely not 70 on the long end. I have read plenty of reviews and opinions on the 24-105 to believe that as an L lens it is pretty average and has a lot of distortion at around 24mm.
So my questions are:
1) Will the 24-105 provide a significant IQ improvement when used on FF compared to using the 18-135 STM on a crop. I am not interested in using the 24-105 on a crop camera, so many of the comments I have read which compare using both on a crop camera are not applicable to my scenario as in that case they would only be using the centre of the 24-105 not the full view.
I think that even the old EF 28-135 IS USM on 6D would be better than EF-S 18-135 on a Rebel.
2) Should I stick with the 18-135 STM and wait for the 7D mkii which I expect will also have significantly improved noise / ISO and will solve that problem for me, but will then still leave me with the image quality issues from the EFS lens, as I don't see any better quality walkabout lens that will suit me if using a crop sensor. (The 24-105 would not be wide enough for me on a crop).
So what do you think - 6D, 24-105, 16-35 F4, 70-300L or 7D mkii, EFS 10-22, EFS 18-135 STM, 70-300L.
Wait for Photokina first. 6D Mark II may be coming soon as well
6D, 24-105, 16-35 F4, 70-300L would definitely give you more potential.