Rebel SL1 and Tamron 100-400mm F4.5.5-6.3 autofocus issue

i have a lady friend that just purchased a Tamron 100-400mm F4.5.5-6.3 lens for her SL1 and at 400mm it’s pretty soft.  I am wondering if the lens is auto focusing correctly. The camera spec sheet says auto focus up to 5.6 only. Looking for a little help here, she is going to Africa and is not having much luck with this new lens. I’m a Nikon and Olympus guy don’t know much about Canon products.

Any help would be appreciated Jack

I can't speak to the combination in question, but I can address this:

AlaskaAce wrote:

The camera spec sheet says auto focus up to 5.6 only.

If the aperture is too small, autofocus will simply fail. It's not a matter of how good the AF is, but rather whether AF functions at all.

With an f/6.3 lens, a typical f/5.6 AF point is losing about one stop of light compared to an f/5.6 lens, so it won't won't work as well in dim light. The center AF point is rated down to -0.5 Ev on the SL1, but at f/6.3 it'll be more like +0.5 or maybe even +1 Ev. But the AF should work fine in good light.

Hi Doug

I'll will pass the information to my friend. The lens does seem to focus but appears to be back focused a good bit, and her camera has no way to fine tune the lens. Maybe the Tamron Dock can correct the lens to her camera. Tried to get her to upgrade the camera, but she is on a tight budget.

Thanks

Jack

I shoot the 80D with this lens , and I think you are on the right track with needing some focus adjustments, of course guessing without seeing photos. But every Tamron or Sigma I mount on my 80D seems to need MFA. I just recently got the Sigma 18-35 and had to adjust +10, my Tamron 150-600 is -6 on the long end can't remember the shorter sides. My Tamron 100-400 wasn't horrible but did need a -3 on the long end. Also there was a firmware update released for the 100-400 last year maybe that lens doest have . I hope she gets it ironed out I love my 100-400 after I got it dialed in.

Thanks, poor lady is beside herself. Planned the trip saved her money and now is confused on this camera. She thought it was simple, if she only knew.

It’s definitely back focus issue. I think the only way it could work is with the Tap-in module.

Jack