T7i focus shaking with EFS 17-55mm lens and with 70-300mm lens

[nimans]

I recently bought a (slightly used) EOS T7i to upgrade my previous T4i.  For some reason with the EFS 17-55mm lens and witht eh 70-300mm lens, the auto focus will shake and not finalize the focus.  I cannot take a picture because it's as if it's trying to find the focus point but shakes back and forth between focus points.  It also does this with the 70-300mm lens.  However it does not do this with the 18-135mm lens.  

I did not have this problem with the EOS T4i. I did check the lens metal contacts to make sure they are clean.  Can someone help figure out how to fix this? Thank you

[deebatman316]

Do all of these lenses work properly on your Rebel T4i. If so you should return the Rebel T7i. There are too many coincidences with this camera that is new to you (used) camera. Do you see a shaky image in the viewfinder with the affected lenses. Also can you post the full model name of 70-300mm and 18-135mm lenses. Canon has released 4 EF 70-300mm lenses. Canon has also released 3 EF-S 18-135mm lenses. The full model name of the lens can be found on the outer ring of the lens after you remove the lens cap. Or it will be on the outer ring. Two example lenses are shown below. On where you can find the full model name of the lens.

 

 

-Demetrius

Current Gear: EOS 5D Mark IV, EF 16-35mm F/2.8L III USM, EF 24-70mm F/2.8L II USM, EF 50 F/1.8 STM, EF 85mm F/1.8 USM, EF 70-200mm F/2.8L IS III USM, 470EX-AI & 600EX II-RT

Retired Gear: EOS 40D & Sigma 17-50mm F/2.8 EX DC OS HSM

[nimans]

Yes I see the shake in the viewfinder.  

The full model of the lens are Canon EF 70-300mm 1:4-5.6 IS USM and Canon Ef-S 17-55mm 1:2.8 IS USM.

On those two lenses, the camera struggles to find a final focus point.  It shakes back and forth between focus points without setting on a focus point.

My other lens is a Canon EF-S 18-135mm 1:3.5-5.6 IS STM lens.  The camera doesn't have a problem with this lens.

I do have a Canon  EOS T6 at work. I will take my lenses to work and try them on that camera to see if there is an issue with the lenses. But my feeling is the defect is in the T7i.

[deebatman316]

I'm suspicious of your used Rebel T7i. The focus ring on the EF-S 17-55mm will NOT TURN while it's autofocusing. There is a clutch on the focus ring to allow manual focus override. While the AF/MF switch is set to AF. Your EF-S 18-135mm 3.5-5.6 IS STM lens supports full time manual focus. STM and Nano USM lenses use an Electronic Focus Ring. The focus ring on STM and Nano USM lenses are not mechanically connected to the focus elements in the lens. To manually focus an STM or Nano USM lens you need to half press the shutter button and turn the focus ring. You can do this with the lens set to AF. Just like the EF-S 17-55mm the focus ring WILL NOT TURN while AF is in use. Your EF 70-300mm 4-5.6 IS USM lens DOES NOT SUPPORT full time manual focus. DO NOT turn the focus ring unless the the AF/MF switch on the lens is set to MF. Turning the focus ring on the lens with the AF/MF switch set to AF will cause damage to the lens. This lens doesn't support full time manual focus. 

-Demetrius

Current Gear: EOS 5D Mark IV, EF 16-35mm F/2.8L III USM, EF 24-70mm F/2.8L II USM, EF 50 F/1.8 STM, EF 85mm F/1.8 USM, EF 70-200mm F/2.8L IS III USM, 470EX-AI & 600EX II-RT

Retired Gear: EOS 40D & Sigma 17-50mm F/2.8 EX DC OS HSM

[nimans]

An update: I took my lenses to work to try them on the Canon EOS T6.  It turns out the problem happens with that camera as well which leads me to believe the problem is with the lenses not the camera.  I have a video from my Iphone but this website is not allowing uploading, or at least it's not working for me.  What are options to repair Canon EOS lenses?

[deebatman316]

Will the lenses do this in live view too or just in the viewfinder. Turn off IS (image Stabilization) on the lens to see if this stops happening. If it stops happening then the IS motors in the lens have failed. You can send your lenses to Canon for repair but get a quote first. Canon has discontinued the EF 70-300mm 4-5.6 IS USM lens. I don't believe Canon repairs this lens any longer. But you can check with Canon about this lens. If it can't be repaired you can send the lens to a 3rd party repair shop. Or you could replace the lens with the EF 70-300mm 4-5.6 IS II USM lens. If your budget allows you to replace the lens. Its best to avoid ANY of Canon's EF 75-300mm lenses. All of which have very poor optical quality.

-Demetrius

Current Gear: EOS 5D Mark IV, EF 16-35mm F/2.8L III USM, EF 24-70mm F/2.8L II USM, EF 50 F/1.8 STM, EF 85mm F/1.8 USM, EF 70-200mm F/2.8L IS III USM, 470EX-AI & 600EX II-RT

Retired Gear: EOS 40D & Sigma 17-50mm F/2.8 EX DC OS HSM

[nimans]

In liveview, it's definitely reduced or does not happen. The camera is able to pick a focus point better. 

[nimans]

Here are links to the videos showing the focus shake of both the 17-55mm lens and the 70-300mm lens. Pardon my attempting to hold my iphone and the camera at the same time.

Canon 17-55 Lens video:

https://www.dropbox.com/s/3g62i6tt8w78qui/lens%2017-55.MOV?dl=0

Canon 70-300mm lens video

https://www.dropbox.com/s/hozkt0sdllzkkpl/lens%2070-300.MOV?dl=0

[shadowsports]

First movie appears to be focus pulsing.  Second looks like an IS issue.

[nimans]

I think I'll have to replace to 70-300mm lens. Maybe get the 17-555 lens checked out for repair. 

Thank you everyone for your assistance.