topic 5D Mark 3 auto focus problem. in EF & RF Lenses

5D Mark 3 auto focus problem.

w15938713330 — Fri, 03 Apr 2020 02:20:06 GMT

I probably shudl post my question on lens section but i cant find the section anywhere.

Here is the thing , I bought a used 24-70 2.8L USM online, tne seller claimed that he tested the functionality and no problem upon mailing the lens.

However I run into some issuses.

1)When I use AF, the lens is consistently focusing in front and back without actually taking the picture.Pictures shot by MF is normal and working normally.
2) The eyecup vision is extremely dark through the lens.I can barely see the object through the eyecup.

I tried with different lens(24-105mm) but non of the problem occurred(Using exact camera setting). Since i am a beginner , is this issue about my camear, or i should try to fix the lens. How can i reslove those two problems.

Re: 5D Mark 3 auto focus problem.

rs-eos — Fri, 03 Apr 2020 02:41:40 GMT

Sounds like the lens is bad, unfortunately. Especially since you tried a different lens and it was a-ok on your camera.

Re: 5D Mark 3 auto focus problem.

RobertTheFat — Fri, 03 Apr 2020 03:47:04 GMT

@w15938713330 wrote:
I probably shudl post my question on lens section but i cant find the section anywhere.

Here is the thing , I bought a used 24-70 2.8L USM online, tne seller claimed that he tested the functionality and no problem upon mailing the lens.
However I run into some issuses.
1)When I use AF, the lens is consistently focusing in front and back without actually taking the picture.Pictures shot by MF is normal and working normally.
2) The eyecup vision is extremely dark through the lens.I can barely see the object through the eyecup.

I tried with different lens(24-105mm) but non of the problem occurred(Using exact camera setting). Since i am a beginner , is this issue about my camear, or i should try to fix the lens. How can i reslove those two problems.

The lens should stay at maximum aperture until you press the shutter button, at which time it should automatically stop down to the desired aperture to take the picture. This allows the camera to use the lens's maximum aperture for previewing and focusing. It sounds like that's not working in your lens. Both the inconsistent focusing and the dim viewfinder point to that as the problem.

I'm afraid you've learned a possibly expensive, but ultimately valuable, lesson: A beginner should never buy a used lens.

Re: 5D Mark 3 auto focus problem.

w15938713330 — Fri, 03 Apr 2020 03:55:29 GMT

so it's not my camaera or setting ?

Re: 5D Mark 3 auto focus problem.

w15938713330 — Fri, 03 Apr 2020 03:56:51 GMT

Fair point, thanks for the informative and professional reply !

May I ask , in your opinon, is this worth to fix it ? should i just return the lens?

Re: 5D Mark 3 auto focus problem.

Waddizzle — Fri, 03 Apr 2020 08:57:22 GMT

@w15938713330 wrote:
Fair point, thanks for the informative and professional reply !

May I ask , in your opinon, is this worth to fix it ? should i just return the lens?

Return it, ASAP. While there is still time.

Re: 5D Mark 3 auto focus problem.

rs-eos — Fri, 03 Apr 2020 08:58:37 GMT

I would recommend returning it. Especially if you're able to get a full refund.

Re: 5D Mark 3 auto focus problem.

wq9nsc — Fri, 03 Apr 2020 13:48:36 GMT

Definitely return it and make sure you follow all of the "rules" if this is from ebay or another online auction site to avoid problems. Although the aperture petals MAY have gotten stuck during shipping, it is likely this problem was known before it was sold so don't expect the seller to necessarily be gracious in accepting the return. A stuck aperture is not uncommon on a lens that has been left to sit for a very long period of time but once it happens the only way to be confident it won't be an ongoing issue is to have it properly serviced and since this is far from a "rare" lens it would be best to return it and get a good working copy.

Rodger

Re: 5D Mark 3 auto focus problem.

MikeSowsun — Fri, 03 Apr 2020 13:59:43 GMT

Yes, return the lens. Even if the aperture blades were damaged in shipping, it is not your fault and the lens should be returned for a full refund.

Often in cases like this, the seller will try and reach a compromise and offer you a partial refund if you keep the lens. Canon might be able to repair the lens, but it may cost anywhere from $200-$500, so keep that in mind if the seller offers a partial refund.

Re: 5D Mark 3 auto focus problem.

ebiggs1 — Fri, 03 Apr 2020 14:10:12 GMT

"Often in cases like this, the seller will try and reach a compromise and offer you a partial refund if you keep the lens."

This is not a bad idea. If you can get the price right, a trip to Canon would yield you almost a new lens. Canon will go completely through it and bring it back to new spec. Worth a try or offer.

Re: 5D Mark 3 auto focus problem.

kvbarkley — Fri, 03 Apr 2020 20:28:08 GMT

What a coincidence, the latest Lens Rentals Podcast #23 is about how to buy a used lens.

Re: 5D Mark 3 auto focus problem.

w15938713330 — Sat, 04 Apr 2020 02:13:21 GMT

I spent $650 for this lens guess i have to return it , thanks for the estimated price !

Re: 5D Mark 3 auto focus problem.

w15938713330 — Sat, 04 Apr 2020 02:16:37 GMT

I am taking your suggestion! already sent messege to the seller about return.

Re: 5D Mark 3 auto focus problem.

w15938713330 — Sat, 04 Apr 2020 02:17:38 GMT

Thanks for the extra information I have sarted the return process, hopefully it goes smoothly !!!! I love this commCommunity !!!so helpful !!

Re: 5D Mark 3 auto focus problem.

w15938713330 — Sat, 04 Apr 2020 02:18:40 GMT

Right now in los angeles all non essential business are closed. I am taking the easier way, which is return it for good.

Re: 5D Mark 3 auto focus problem.

w15938713330 — Sat, 04 Apr 2020 02:22:52 GMT

i did some reserch before purchsing . the apperacne of the lens was acutally perfect.It was really hard to notice some flaws without actually testing it

Re: 5D Mark 3 auto focus problem.

wq9nsc — Sat, 04 Apr 2020 02:45:35 GMT

I think returning it was the smart move. If you go the discount from seller followed by repair route it could potentially get more expensive than you expected and as you noted most repair places are closed. CPS sent out the notice earlier that only one Canon factory service center is still open in the U.S. (Newport News VA) and because of COVID they aren't accepting walk in customers.

I have purchased a couple of used lens over the years with good results but in addition to doing due diligence there is still a matter of luck involved-especially if purchasing from individuals.

Rodger

Re: 5D Mark 3 auto focus problem.

w15938713330 — Sat, 04 Apr 2020 02:51:14 GMT

it is my first time online shopping for used lens i am very disappointed. I just purchased a refurbished 24-70 2.8 2L from conon official website with $1500, hopefully the experience is better this time

Re: 5D Mark 3 auto focus problem.

RobertTheFat — Sat, 04 Apr 2020 03:12:03 GMT

@w15938713330 wrote:
it is my first time online shopping for used lens i am very disappointed. I just purchased a refurbished 24-70 2.8 2L from conon official website with $1500, hopefully the experience is better this time

The Canon refurb store has an excellent reputation. It's unlikely that you will be disappointed.

Re: 5D Mark 3 auto focus problem.

wq9nsc — Sat, 04 Apr 2020 11:39:33 GMT

I agree with Robert, the refurb section of Canon USA is excellent. It doesn't offer the steep discounts available through some of the auction sites but instead of coming with the risk of a misrepresented and malfunctioning product it is a properly checked out product with a warranty.

My only complaint about the refurb shop is very rarely do they have the specific item I am looking for but for the more popular items in the Canon line it is a great shopping location.

Enjoy the new lens when it arrives!

Rodger