burkphoto Loc: High Point, NC

In a word, no. I tested both on a 7D several years ago, and liked the Tamron's overall qualities better:

f/2.8 maximum aperture, usable wide open to f/9, best between f/4 and f/8. Sweet spot at f/6.3. (The 24-105 was no better at f/4 than the Tamron. It, too, was usable to f/9, beyond which, diffraction degrades the image.)

Better, faster focusing in low light because f/2.8 lenses work better with Canon AF, and are easier to see through for MF.

Macro zoom mode for 1:4 close-up work (not true macro). Very versatile on a copy stand between 40 and 60mm.

The Tamron is a GREAT portrait lens at 60 to 75mm on APS-C Canons. So is your 70-200, wide open, from 70-200mm!

The only thing I truly liked better about the 24-105 was the longer reach. But you already have that covered with a phenomenal lens in the 70-200 zoom.

Put the Tamron on one body and the 70-200 on the other, and you can cover most anything.

One last thought: Both the Tamron and the Canon 24-105 are older lens designs. The 24-105 should be due for an upgrade. Tamron has a 24-70 VC lens that competes well with Canon's 24-70L glass.

CraigFair Loc: Santa Maria, CA.

Not quite sure why you want to trade a f/2.8 Macro Lens for an f/4 Lens.
You lose a lot of low light & bokeh capabilities also shooting close-ups.
But the 70-200mm f/2.8 is already an even better portrait Lens.
Craig

Bill Emmett Loc: Bow, New Hampshire

My two cents. Since I own and shoot in the realm of the OP I'd look at a entirely different approach. Since the OP likes to shoot landscapes, he should look at a ultra wide lens, like the Canon EF-S 10-22mm for the best image quality. A Tamron SP 24-70 f2.8 VC USM for image quality, stabilization, and for indoor/outdoor portraits, and low light. The Op already owns the very best Canon EF 70-200mm f2.8L IS II USM lens. Keep in mind the angle of view of both the 24-70, and 70-200mm on both his cropped sensor cameras. The only regret with these lenses will be the 10-22mm, if the Op decides to go full frame in the future, and even then just one lens change would be in mix. I'd suggest a 16-35mm f2.8L quality lens. But, I wouldn't suggest a ultra wide, with a bulbous front element.

B

pithydoug Loc: Catskill Mountains, NY

I must have missed some other dialog. Would you care to offer some details to the above statement? Seems like you are comparing a watermelon with broccoli and one is better than the other.

CraigFair Loc: Santa Maria, CA.

I think that's just what he's telling you don't compare the watermelon with the broccoli.
Craig

burkphoto Loc: High Point, NC

The 24-105 is not in the same league as the new 70-200 f/2.8 IS USM II. Not even close. It's L glass, but early L glass. Build quality is great, but image quality is so-so by comparison.

imagemeister Loc: mid east Florida

And, it is not nearly wide enough on crop frame .....

burkphoto Loc: High Point, NC

Yeah, but wide is a problem on APS-C. 10-20 or 10-22 is about as wide as it gets.

pithydoug Loc: Catskill Mountains, NY

So how or who comes to this conclusion? Are you comparing the lenses in the 70-105 range where they overlap? I will agree that the 2.8 is better but when you say one is so-so in comparison, I have difference in opinion.

imagemeister Loc: mid east Florida

Look at the numbers by reputable testers and compare !

Gifted One Loc: S. E. Idaho

There is the Korean prime 8 mm. A bit whacky for my taste also. I have seen some that are very sharp and I had an opportunity to buy one a great price. I just worried about it hanging with me and nothing else.

J. R.

burkphoto Loc: High Point, NC

Those are my conclusions after personal testing of equipment on loan from Canon Professional Services and Tamron stock in my former employer's inventory. The newest 70-200 smokes the 24-105 from 70-105, at f/2.8 and f/4. It has faster and more reliable low-light AF, with better contrast, better color definition, and better viewfinder visibility. Its drawback is weight.

The 24-105 is fine in good light, but if you want the better bokeh and shallower depth of field you get at f/2.8, you need f/2.8. The 70-200 is a spectacular and versatile portrait lens, engineered to be used at wider apertures, and it is used by some of the best photographers in the business. It's also great for low light sports.

On the other side, I liked the Tamron 28-75 f/2.8 better than the 24-105, again for its f2.8 bokeh, faster AF, macro zoom feature, low cost/high performance, lighter weight, compactness, and reliability. Other than not having a longer focal length, it is a wonderful lens.

burkphoto Loc: High Point, NC

There are primes shorter than 10mm. Most are a bit wonky for my taste, too. I wish there were a 6mm to 18mm true wide angle zoom for APS-C, but the cost and physics of that probably don't work.

Gifted One Loc: S. E. Idaho

I have yet to even see a Sig 8-16. But it was on my short shop list. The 10-22 just came in when it did.

It's funny to do a lens loan for a few minutes to someone that doesn't have or vision an UWA. Long shadows, feet how to be creative. I hope my model is available tomorrow to do a UWA portrait. Now that is ballsy.

Mr. K Loc: VA

First, thank you for the outpouring of input to help me in making a very important lens decision. I have been very pleased with my Tamron 28-75 and my Canon 70-200 (wow-what a beast). I think researching something in the 17-70mm or 15-85mm range would a good fit for me. In reading each post in this topic I realize that you guys have given me an enormous amount of needed information that I will not take lightly. I'm humbled. I will do my due diligence and let you know which lens I decide to purchase. Thanks again and may the Lord bless you abundantly.