Exposure issues with 5D MK IV and Tamron 150-600

[SSipple]

I seem to be experiencing e posture issues with my 5D MK IV when using my Tamron 150-600.    I did send the Tamron for the latest firmware update.   I took the camera and lens on a trip and was shooting with auto ISO and shutter priority.   All of a sudden, the exposures were dark.    I switched to my Canon 24-105, and then everything was dark.  Called Canon and they had me reset the camera settings.  Appears to have corrected the 24-105 issues.    For the most part, the 150-600 is working, but at the 150 range appears to randomly underexposed.   I looked and the auto ISO is being set to a very low ISO.    I was using evaluative metering.

called Canon and they basically told me I was using an inferior lens and that was the problem.   This has been working fine until now.  Not sure whether to send the camera to Canon, he lens to Tamron.   I used partial spot metering and the exposures seemed better.

[TTMartin]

 f/stop penalty and IQ loss are nice push button catch phrases when it comes to teleconverters.

But here is the reality, the Canon EF 100-400 L IS II with a teleconverter is still sharper than the Tamron 150-600 without a teleconverter. That really says something about the superb image quality of the EF 100-400 L IS II. 

As for the f/stop penalty Tamron already has a 1/3 stop 'penalty' since it is a f/6.3 lens at the long end. So the real f/stop penalty of using a teleconverter on the Canon EF 100-400 L IS II is 2/3 of a stop (f/6.3 vs f/8).

I'm not sure how the Tamron 150-600 G2 compares to the Canon EF 100-400 L IS II, but, I do know if the original Tamron 150-600 lived up to all its hype, Tamron would not have replaced it after only 3 years with a G2.

[TTMartin]

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@SSipple wrote:

TTMartin, that is a very nice image, but it is no better than what I have shot with the Tamron 150-600.   I see absolutely no reason to purchase the Canon lens to replace what is an already excellent lens.  There is an issue with either the camera or lens that needs to be addressed and then everything will be fine.   The below image was shot while on a moving vehicle. 

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Nice shot. That is a big if though. If the issue is with the lens are you willing to wait for Tamron to come out with a firmware fix, if they ever do.

These were also shot from a vehicle using the EF 100-400 L IS II and 1.4X TC III

edit: You can see the reflection of the vehicle in the Ostrich's eye.

[SSipple]

I am not quite sure what you are trying to prove here.    I shoot professionally for a local concert venue and have relied on my Tamron for years.   My shots will compare with anyone out there.     I don't think it is appropriate for you to continue to make comments to the effect that the lens is a piece of junk.    You like Canon...that is wonderful and I respect that.  It seems that you should respect that I have been very pleased with Tamron and the quality of my shots.   The shot I displayed of the elephant stands up against any shot out there.    

I came to this forum to see if by any chance anyone knew of any issues and an 'easy' fix that I was unaware of.    My camera is currently with Canon and the lens is with Tamron.     I am confident that both companies will do right by me in the end.

[ebiggs1]

"It seems that you should respect that I have been very pleased with Tamron and the quality of my shots."

Don't hold you breath on that guy.  He is always like that.  You are on the right path and I am sure the issue will be resolved.

It seems Canon can upgrade their lenses but Tamron can't!  Right?  I would love to be able to give you the answer but I don't have that problem with my Tamron(s).  I owned the first 100-400mm and sold it after I got the first Tamron 150-600mm.  I tried the second version of the 100-400mm and was not sufficiently impressed with it either. Some folks like it and more power to'em.  Beside that fact it isn't 500mm or 600mm long.  Who wants to mess with a tele converter at all.  Let alone spending two grand on the lens and another $450 on the converter.

If were are not careful there is probably an MTF chart in our future.  

[SSipple]

Update:  

I got the camera back from Canon, and low and behold.....there was a problem with the camera!   They found that the adjustment of the ae assembly was incorrect and causing unevennuess in exposure!   I guess it is a good thing that I followed my instincts and sent the camera back as well as the lens!  

[ebiggs1]

"I followed my instincts and sent the camera back as well as the lens!"

Bingo!    Good to hear. I was kinda leaning that way, too.