Third party lens compatibility with Canon

[Magog]

Good day all.

When I first went digital in 2007, my EOS400D came in a bundle with a Tamron 70-300mm lens. When I moved to a 450D in 2009, I kept the Tamron lens. (My wife took over the 400D, with a new Canon 70-300mm)

Earlier this year I moved to a 60D, still with the Tamron as my "long iron". However, whilst on an organised wildlife photo-shoot a couple of months ago, the Tamron lens lost AF and metering functionality. The guy leading the shoot (an ex-director of Canon UK) commented that as Canon (or any other manufacturer) release successive generations of camera, third party lenses may sometimes have problems as they don't have the forwards compatibility path. This sounds plausible to me.

Since then I've tried the lens a couple of times and it's worked OK, but I've lost a bit of faith in it's reliability to deliver at the crucial moment.

What do other folks think?

As an aside, I finished the shoot by borrowing a Canon 70-200mm L f4 and 1.4 teleconverter, and was absolutely delighted with the results.
My wife, of course, thinks all this is all a plot by me to get a new toy.....

[DanK]

John,

I've read that forward compatibility problems have affected some Sigma lenses in the past, requiring that the lenses be sent in to be rechipped. I have never heard of this with Tamron lenses, but that is not to say that it hasn't happened. Others may know.

However, what you describe does not sound like a compatibility problem to me. The fact that the lens usually works fine suggests an intermittent electrical problem, such as bad or dirty contacts or an internal connection that is beginning to work lose. I believe Tamron has a 6 year warranty, so if you have had the lens less than that long, you could send it in to be checked. On the other hand, intermittent electrical problems are extremely hard to find.

Re the 70-200 f/4: if you mean the IS version, I have had one for several years, and it is a wonderful lens. I have version II of the 1.4x, not the newer version III, and I find that there seems to be slight but sometimes noticeable degradation of IQ with the converter on, but not enough to lead me to avoid using it. And on a crop sensor, that is a very nice length.

Dan

[Magog]

Thanks Dan; I did get the blower brush out when the lens "failed", but didn't make any attempt to clean the contacts with a cloth or similar. I also did the obvious demount/remount, camera off/on and AF off/on fiddling as well.

This was the first really serious workout the lens had on the 60D; I'd taken a few isolated shots (a couple here and there), but on the shoot it ceased functioning after about 20 shots.

[Manfred M]

Third party lens makers end up reverse engineering the connections / communications to the camera processor, so any time the camera manufacturer updates that camera's firmware, there is a chance that the third party lenses will no longer function properly with the camera.

The camera manufacturer will test their own lenses prior to the firmware updates, so they will continue to work.

[RustBeltRaw]

As far as I know, only Sigma offers anything that lets users update the lens firmware. But as others have suggested, intermittent performance makes dirty contacts a more likely candidate.

[Bobobird]

I tend to agree with the dirty/loose contacts theory.

It is doubtful that Canon would mess with the main camera/lens communications system as that would break every out of production EOS lens every made. Even if they did, they would have to retain compatibility with the old stuff. I recently tested a 1988 lens with the 1Dx and everything worked just fine.

[ajohnw]

Canon do maintain a data base of their lenses in their cameras. I don't think anyone is sure exactly why they do this. They also log the last lens that was used. For instance last time I had my 5D serviced it showed that their 50mm F1.4 had been used on it. In practice this was actually an AF confirm adapter that pretends to be this lens that I had used on a microscope. The AF confirm wont work on these cameras unless the tiny chip on the adapter pretends to be a lens and communicate with the camera. The sort of thing they might store in the lens or the camera is suitable AF focusing rates. Or even distortion and colour correction factors as per Panasonic. It's also possible to have completely different over all communication standards between different lenses.

The 50mm 1.4 might be a 1.2 can't remember but believe it was chosen to try and get the most precise focusing what ever lens is adapted to the camera.

I would guess dirty contacts too. 3 options on cleaning them. A hard ball point pen type eraser or one of those pencil like brush thingies that take either a fibre glass or brass brush insert. Those being in the order of severity. Little blocks are also available that are used for cleaning pcb tracks etc. These are fairly mild in action as well.

John
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[rpcrowe]

I have not had problems with my one Tamron lens (90mm f/2.8 SP AF) but, have experienced problems trying to use an older Sigma with a newer Canon camera. However, this showed up from the start and did not appear as an intermittent problem. Intermittent camera problems are like strange occasional noises in one's vehicle. They are difficult to isolate and to fix.

I would be sure to clean the contacts and whenever I have a camera problem that seems to be of electrical origin, I remove the lens (replacing it wit the body cap and shut off the camera. I then remove both batteries and leave them out for a short time. This has helped for other problems.

I can definitely recommend the 70-200mm f/4L (especially the IS model) as a great general purpose telephoto that I use for nearly half of my shooting... It is a great portrait lens, super for shooting pets and works quite decently with the Canon 1.4x TC. I have the original, Mk.I version of the TC and it works fine for my needs, both on my 70-200mm f/4L IS and my 300mm f/4L IS lenses.

BTW: The IS version is quite a bit more expensive than the non-IS 70-200mm f/4L lens. However, I can use my IS version 4-5 times more often than I ever used the non-IS version I had previously. It has slightly better IQ, better weather sealing and more pleasing bokeh due to its round aperture blades. However, the main reason I use the IS lens so frequently is that I am no longer a slave to bright light as I was with the non-IS lens...

[Magog]

Thanks for the comments folks. I will give the contacts a clean (not sure about the fibreglass pencil, John - IIRC they shed quite a lot of dust/strands of fibreglass).

Richard, you're pushing against an open door extolling the virtues of the Canon lens - I'm sold. I think I need to earn a lot more "brownie points" before I could get that one past the Domestic Manager, tho'.