Need help diagnosing an aperture issue - Tamron 150-600 G2

Hello. I could use some help diagnosing an issue I'm having with a recently acquired Tamron 150-600 G2 lens and also recently acquired 7D Mk II body. I purchased them both from members here. The 7D Mk II body arrived a few days ago, and I've been learning the features, making setting adjustments, and using it with my 100 2.8 Macro lens (the only lens I had at the time) to get familiar with it. Everything seemed to function just fine.

Yesterday, I received the clean, used 150-600 G2 Tamron. It looks like it's never been used - it's that clean. I also got the tap-in console with it.

Immediately I noticed focusing issues with it when zoomed to 600mm. It took me a while to realize what the problem was. Somewhere between 500 and 600 mm, the aperture changes from f/6.3 to (briefly) f/5, then straight from f/5 to f/9 just before 600 mm. It is consistent, and starts this right at 550-560mm. The reason I was having trouble focusing is because the body was reading f/9 at 600mm. I can shoot pictures at 600mm by manually focusing, but the widest aperture I can get the combo to register is f/9.

Has anyone else seen a problem like this? If so, how did you get it resolved?

I have another body I'll be able to test the lens on this weekend, so at least then I may learn whether it's a lens issue or a body issue. However, since the camera functions fine with the Canon Macro lens (although it's not a zoom) and the issue shows up very consistently at the same zoom range, I think it's probably a lens issue. Hopefully I know more this weekend, but I'd love to have some help if someone thinks they know how to work through this.

Thank you!

Whenever purchasing used photo equipment I suggest you download the OEM manuals and then find the appropriate section on how to set the body back to factory defaults and clear any custom functions. This will insure that the body behaves the way the manual says it should, not based on the setting of some other person who may or may not have preferences/settings like yours.

In the case of the Tamron lens, I also suggest you start with making sure it is up to date as far as firmware. There are two versions of that lens, A022 and I think A011, and the A022 has a firmware update from December 2018. See https://www.tamron.jp/​en/support/release_not​e.html. It appears that particular update addresses "Enable general operations on Canon EOS R with Mount Adapter EF-EOS R by the firmware updating" but it nevers hurts to be certain you are up to date by connecting the Tap-in console.

I did set the body back to factory settings. That's the first thing I did. I also updated the firmware last night, using the Tap-in-console.

But I admit I didn't get into photography 30 years ago because I wanted more technology in my life, so it could still be something I'm missing. I really hope it is.

Limbwalker wrote in post #19066180
Immediately I noticed focusing issues with it when zoomed to 600mm. It took me a while to realize what the problem was. Somewhere between 500 and 600 mm, the aperture changes from f/6.3 to (briefly) f/5, then straight from f/5 to f/9 just before 600 mm. It is consistent, and starts this right at 550-560mm. The reason I was having trouble focusing is because the body was reading f/9 at 600mm. I can shoot pictures at 600mm by manually focusing, but the widest aperture I can get the combo to register is f/9.

Since the aperture is changing significantly when goinf from 500 to 600mm, have you taken note of what the ISO is? Are you using a fixed ISO?

Yes, it does this with fixed ISO.

The fact that it drops from 6.3 to 5.0 (or 5.6) before jumping straight to f/9 tells me it's a not a settings issue. No settings would cause an aperture range to do that.

It is strange behaviour. Obviously it can't actually change from f6.3 to f5 as you increase focal length.
That has to be false reporting. I think almost no chance this is the body, rather a lens issue.

It should be reporting like this:
f5 150-212mm
f5.6 213-427mm
f6.3 428-600mm

I see no option other than sending for repair, or at least talking to repair shops.

Choderboy wrote in post #19066506
It is strange behaviour. Obviously it can't actually change from f6.3 to f5 as you increase focal length.
That has to be false reporting. I think almost no chance this is the body, rather a lens issue.

It should be reporting like this:
f5 150-212mm
f5.6 213-427mm
f6.3 428-600mm

I see no option other than sending for repair, or at least talking to repair shops.

Possible recourse with the seller?

Before doing a potential repair, you might run the serial number through the Tamron registration process. Tamron lenses have a 6-year warranty. Granted it states you need a receipt, but one never knows for sure until you try.

See https://www.tamron-usa.com/reg/lens_regis​tration.html

I called Tamron today and the young lady was very polite and helpful, although now is not a good time to be sending anything to them, and for months they will have a deep backlog of repairs.

She agreed that it was probably a firmware issue and that they could reset it there and return it to me at minimal cost. Not sure about the warranty as I'm not the original owner. But I may ask the seller to take it back and send it in for warranty repair/replacement for me.

That may be a while though, due to their repair shop being down for a while, and a trip planned to Alaska this summer. I'm just going to use it out to 550 for now, until we return from our trip, and then I'll resolve the issue then. Even at 550 and f/6.3, it's still more lens for the money than anything else I can buy. Plus, these super zooms tend to be a hair sharper at 550 than 600 anyway. Annoying? Certainly. But I'm not going to throw a fit and act as if it is ruined. I am confident that between the Tamron and the seller, we'll get this worked out.

I should have a chance to put the lens on another Canon body tomorrow and see if it's still doing the same thing. I'll report back what I find. Thanks for all the suggestions so far.

I was getting a jump-start on microfocus adjustment with my 7D Mk II using this very cooperative dragonfly yesterday...

Image hosted by forum (1045949) © Limbwalker THIS IS A LOW QUALITY PREVIEW. Please log in to see the good quality stuff.

I have a Sigma 150-600 and have never used the Tamron but I do have the Sigma dock for doing firmware updates & customizing configurations. Does the Tamron Tap-in console allow for customizations as well as firmware updates? If so, the previous owner might have customized some lens settings that are causing this problem. The Sigma dock allows me to "reset to factory default settings" which is similar to buying a camera, have an issue, and choosing to reset to factory defaults because you don't know what settings the previous owner may have made.

If you can, reset the lens to factory default & see if the problem resolves itself. Good luck.

That was my first thought - that the last owner might have changed some settings. But #1 no settings would allow you to adjust the f stop to below the maximum at any focal length, and #2 why would anyone want f/9 when no body autofocuses at f/9?

I did run the updates through the tap in, and reset the lens to factory specs. but unfortunately nothing changed.

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Just keep in mind that for autofocus function, it doesn't matter what aperture the lens is set to. . All that matters is what the maximum opening is. . If it's an f6.3 lens, then it will AF just fine at f6.3 or at f11 or at f22 or any aperture at all (if the lens is working properly, which yours isn't).

I realize that you probably already know this, but thought I'd post it just in case.


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Tom Reichner wrote in post #19067404
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Just keep in mind that for autofocus function, it doesn't matter what aperture the lens is set to. . All that matters is what the maximum opening is. . If it's an f6.3 lens, then it will AF just fine at f6.3 or at f11 or at f22 or any aperture at all (if the lens is working properly, which yours isn't).

I realize that you probably already know this, but thought I'd post it just in case.


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Thanks. But I'm not sure that's entirely correct in this case. It seems as though the body is reading the max aperture and it's clearly affecting the AF function somehow. As soon as I dial the lens back to 550 (where it reads f/6.3) the AF functions perfectly, regardless of what aperture setting I have the body set to.

So I think it's definitely the lens.

I had the chance to try the lens on my daughter's Rebel body today and it does precisely the same thing on that body as it does on the 7D mk II I have.

But I guess that at least eliminates one variable.

Limbwalker wrote in post #19067810
Thanks. But I'm not sure that's entirely correct in this case. It seems as though the body is reading the max aperture and it's clearly affecting the AF function somehow. As soon as I dial the lens back to 550 (where it reads f/6.3) the AF functions perfectly, regardless of what aperture setting I have the body set to.

I think your unusual fault has shown that reported aperture will prevent a Canon body attempting to AF.
There's obviously two cases where aperture is reported. If working properly, your f6.3 lens reports f5.6 so that earlier bodies that only AF with f5.6 or faster will AF.
The EXIF info will show f6.3 however.

Now I'm curious, if you take a manually focused shot at 600mm, wide open, what does the EXIF say? f9 or f6.3?

It shows f/9

I'm sending the lens back to the original owner this week. I'll probably just buy a new copy from B&H, eat the $400 difference and save the aggravation. Seems to be the mode I'm in right now as I just did the exact same thing with a pair of Zeiss binoculars. Bought a used pair (from B&H) with focuser issues, returned them and just bought a new pair. When will I learn? LOL