Here is my answer to this member's question:
A: Dear eBay Member,
I must respond by telling you that I have had serious compatibly problems with Sigma and several other "third party" lenses. I use quite a few EOS cameras and it is extremely important to me that all of my lenses will work with ALL of my EOS bodies.
I only have one Sigma lens now, a long 400mm prime telephoto. When I try to use it on my EOS Elan 7e or my wife's old EOS D30, the auto-focusing mechanism works fine, but the aperture fails to respond. It still works perfectly on my old EOS 620. On my newer Digital SLRs, it will not work at all, no AF and no aperture control.
This has happened to me many times. As soon as I buy a new camera, most of my "3rd party" lenses stop working! However, EVERY ONE OF MY CANON BRAND EF SERIES LENSES STILL WORKS PERFECTLY ON EVERY EOS CAMERA THAT I HAVE EVER OWNED!
Consequently, I have gotten rid of every lens that will not work properly with all of my camera bodies. The Sigma 400mm is the only 3rd party lens I have kept. It is a really fine lens, but it won't work on any of the cameras that I prefer to use it with. I know that this may not affect someone with just one camera (until they buy a new one), but I still have to avoid them for myself. Those lenses are not "bad", the performance is often quite respectable, it is just the compatibility issues that have driven me away.
I must recommend that you ALWAYS buy third party lenses from a local store, so that you can physically check for compatibility before buying. Only buy the lens that actually works on YOUR camera! Don't accept a "fresh" one from the stock room, buy the one that you tested on your camera. If you plan to keep the lens and the camera for a very long time, you may be very pleased with your purchase (and the savings too).
Please understand, I really appreciate your excellent question. I wish I could give you "good news" about the very affordable Sigma lenses. Unfortunately, my experiences with that company has caused me some serious disappointments. I know that there are several other very fine companies that produce some highly competitive lenses for the Canon EOS camera line.
These manufacturers had to use a special process called "reverse engineering" to create their operating software, in order to make their lenses work properly with Canon cameras. Canon is not required to give "trade secrets" away to these companies, if fact that is totally forbidden by international laws. When Canon introduces a brand new EOS camera model, the 3rd party companies must scramble to reverse engineer a brand new software "chip" for all of their current lenses. That means that all of the previous lenses that they have manufactured may be incompatible with the newest Canon EOS cameras. Most of these corporations will "re-chip" the incompatible lenses that are still under warranty, for free, but all of the previous models are permanently left unable to work with any newer EOS camera bodies.
I have tried desperately to get my Sigma 400mm lens "re-chipped", but to no avail. I was told that it was too old to be updated. There are no chips available that can make this lens work with all of my cameras. It is very frustrating, but I am "stuck" with a wonderful lens that is nearly useless to me. I could accept the loss of auto-focus, I often use manual focusing on long lenses anyway, but no aperture control completely destroys the lens's usability.
I am very sorry that I couldn't give you a much more encouraging answer. As things stand now, the only way to be absolutely certain that your lenses will continue to work properly whenever you upgrade your camera is to buy genuine Canon brand EF series lenses exclusively. If you are not concerned about future upgrades, just be sure to confirm that your 3rd party lens works perfectly with your current camera, before you purchase it.
Introduction To The Q & A Guide Series:
I have been answering potential bidder's questions about the items that I have listed on eBay for several years. One kind person suggested that there may be other members who have wondered about the same subject, but may have been too shy to contact me directly. He suggested that it could be useful to post his question, and my answer, for others to see. He recommended that it could be done in the form of an eBay Guide.
This is the fith in a series of Q & A "Guides" that will be posted.
This series of eBay Guides is based on real questions that were asked of me through eBay Messages, using the "Ask The Seller A Question" feature on my listings. Hopefully, these Guides, based on my actual responses, might provide useful answers to some of your questions too.
If you have found this Guide to be informative or at least interesting, please let me know by clicking on the "YES" button below. Your vote is completely anonymous. However, your comments and criticisms are always welcomed. I am more than happy hear about ways to improve my reviews and guides so that more people can find more useful information in them. Your "helpfulness" votes are the only compensation that eBay reviews and Guides authors receive for their efforts. Your votes are used exclusively to determine writer's rankings. Encourage us with your votes and we will return the favour by supplying you with a lot more informative Buyer's Guides and honest Reviews.
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