[Wheatfield]

I've never tried to define the expression backward compatibility since I reckon if a lens fits and works 99%, that's fine, and so it is if one fits, but works in a limited way.
The desertion of previously loyal users with a complete change of mount however is a big no-no to me. But I DON'T expect the most modern lenses to be 100% compatible with earlier bodies, but at least give the opportunity to use the earlier lens in part. The aperture side is a minor issue since there are work-arounds I've found. But if an AF lens has no manual control ring, that IS an issue! If the AF lens is a scrapper, then it can be modified, but if the AF lens is fully-working, especially if it is a non-screw drive lens, then there is little chance of adapting it. This, of course, refers to Pentax lenses-any lens that relies 100% on electronics such as the Canon is a different story.

In reality you can't expect manufacturers to still cater for camera models some 40+ years old, and the fact that Pentax has done so , at least in part, for most of that time, is to their credit, as is the ability to use the older lenses on new bodies as you said, albeit with some limitations.

Pentax signaled what backwards compatability meant to them in 1975 when it became relatively impossible to use the new K-mount lenses on screw mount bodies but very possible to use older screw mount lenses on K-mount bodies.

[martin42mm]

Pentax signaled what backwards compatability meant to them in 1975 when it became relatively impossible to use the new K-mount lenses on screw mount bodies but very possible to use older screw mount lenses on K-mount bodies.

No-one has right to expect newer lenses to fit older cameras, no matter what the make. It is to Pentax's credit that so many of the bayonet lenses can be used, with at least a degree of compatibility on a wide range of K-mount cameras from all eras no matter what age the lenses.
However I think we are getting slightly side-tracked here. It is not so much Canon's change of mount as their deterrance of 3rd-party manufacturers from making lenses to fit their cameras. Protection of intellectual property is one thing, reducing consumer choice is quite another. One would have hoped Canon could have found a middle path-although we clearly don't know all of the story, so it is difficult to be judgmental without all the facts. If it is a case of stopping 3rd-party manufacture even if that company is willing to pay a suitable licence fee, then consumer backlash is justified.

[UncleVanya]

No-one has right to expect newer lenses to fit older cameras, no matter what the make. It is to Pentax's credit that so many of the bayonet lenses can be used, with at least a degree of compatibility on a wide range of K-mount cameras from all eras no matter what age the lenses.
However I think we are getting slightly side-tracked here. It is not so much Canon's change of mount as their deterrance of 3rd-party manufacturers from making lenses to fit their cameras. Protection of intellectual property is one thing, reducing consumer choice is quite another. One would have hoped Canon could have found a middle path-although we clearly don't know all of the story, so it is difficult to be judgmental without all the facts. If it is a case of stopping 3rd-party manufacture even if that company is willing to pay a suitable licence fee, then consumer backlash is justified.

The license fee could seem reasonable to Canon and onerous to Viltrox - or they may never have even been offered that option. It's really easy to couch-QB these decisions but we aren't in the thick of it. I personally don't like this - but like some others in the thread I don't think this is anti-customer per say. It would have been helpful if Canon had started the new mount with an honest statement, "We do not intend to permit 3rd party from licensing this mount and if they reverse engineer the electronics side of the mount we will take legal action." This would have been a clear message to consumers. By tolerating Viltrox early on they setup consumers for disappointment.

As for FD - if the EF mount had been LONGER not shorter - OR if it was the same flange focal length - a method of adapting the existing lenses might have been possible without damaging the optical quality. The mount might have needed to be wider - and perhaps a more innovative task for the day than it would be today. Via the act of making it shorter than FD, EF was forever made incompatible - and that is what Pentax did NOT do with m42 to K.

---------- Post added 09-08-22 at 04:31 PM ----------

Just to expand - Using old lenses that you have invested in on new bodies is reasonable. Using NEW lenses on old bodies is a luxury and shouldn't be expected. However when it is possible (such as the K-50 and K-3 getting KAF4 compatibility) that's a nice surprise and very customer friendly action.

[martin42mm]

The license fee could seem reasonable to Canon and onerous to Viltrox - or they may never have even been offered that option. It's really easy to couch-QB these decisions but we aren't in the thick of it. I personally don't like this - but like some others in the thread I don't think this is anti-customer per say. It would have been helpful if Canon had started the new mount with an honest statement, "We do not intend to permit 3rd party from licensing this mount and if they reverse engineer the electronics side of the mount we will take legal action." This would have been a clear message to consumers. By tolerating Viltrox early on they setup consumers for disappointment.

As for FD - if the EF mount had been LONGER not shorter - OR if it was the same flange focal length - a method of adapting the existing lenses might have been possible without damaging the optical quality. The mount might have needed to be wider - and perhaps a more innovative task for the day than it would be today. Via the act of making it shorter than FD, EF was forever made incompatible - and that is what Pentax did NOT do with m42 to K.

---------- Post added 09-08-22 at 04:31 PM ----------

Just to expand - Using old lenses that you have invested in on new bodies is reasonable. Using NEW lenses on old bodies is a luxury and shouldn't be expected. However when it is possible (such as the K-50 and K-3 getting KAF4 compatibility) that's a nice surprise and very customer friendly action.

Agreed.

[reh321]

No-one has right to expect newer lenses to fit older cameras, no matter what the make. It is to Pentax's credit that so many of the bayonet lenses can be used, with at least a degree of compatibility on a wide range of K-mount cameras from all eras no matter what age the lenses.
However I think we are getting slightly side-tracked here. It is not so much Canon's change of mount as their deterrance of 3rd-party manufacturers from making lenses to fit their cameras. Protection of intellectual property is one thing, reducing consumer choice is quite another. One would have hoped Canon could have found a middle path-although we clearly don't know all of the story, so it is difficult to be judgmental without all the facts. If it is a case of stopping 3rd-party manufacture even if that company is willing to pay a suitable licence fee, then consumer backlash is justified.

I happily moved to Canon from Pentax - and put manual focus behind me - in 1995 when I happily embraced the usm/EF system. When I got a digital system, I got a Canon Rebel specifically because it was compatible with the EF lenses I already had. That was a mistake!! I had two Rebels die on me in the next seven plus years ….. then I came back to Pentax. I purchased a 18-135mm and a 55-300mm lens with the K-30 I got. I did use my old Pentax-A 50mm F/1.7 once before the lubrication dried and focusing became really impossible; I still hated manual focusing. I purchased a 20-40mm Ltd and a 55-300mm PLM together with the KP that followed. I have used the K-30+KP almost as much as I used the two Rebels; I still use both modern K-mount cameras - the K-30 admittedly with old film lenses because of ABF, but both Rebels are in the city dump. In general, I tend to purchase a group of lenses with a camera body now, use them as a set, then purchase another set. Punct.

[reh321]

No-one has right to expect newer lenses to fit older cameras, no matter what the make. It is to Pentax's credit that so many of the bayonet lenses can be used, with at least a degree of compatibility on a wide range of K-mount cameras from all eras no matter what age the lenses.
However I think we are getting slightly side-tracked here. It is not so much Canon's change of mount as their deterrance of 3rd-party manufacturers from making lenses to fit their cameras. Protection of intellectual property is one thing, reducing consumer choice is quite another. One would have hoped Canon could have found a middle path-although we clearly don't know all of the story, so it is difficult to be judgmental without all the facts. If it is a case of stopping 3rd-party manufacture even if that company is willing to pay a suitable licence fee, then consumer backlash is justified.

I do have a Sigma 10-20mm lens that I have used with both the K-30 and the KP. I was thrilled when I discovered it - I had used one with my Canon Rebels and had not expected to find a K- mount version. I would not have held the lack of one against Pentax and was unaware of it when I switched to Pentax. I evaluate only the lenses provided by the manufacturer when evaluating the system.

[Jonathan Mac]

There's a wonderful post in the comments thread on the DPREview site following this announcement. One Canon owner is so wedded to the Canon blurb that he says he has never, and never will, put 3rd party lenses on his camera, describing them as 'bottle glass'. It's his loss, choice-wise and financially, and there have been numerous less than subtle comments aimed at this blinkered attitude. It's his choice, of course, but why decry 3rd party manufacturers making lenses to fit a variety of cameras , and those that chose to use them? I doubt he's ever tried one, so isn't talking from experience , but prejudice. But as I said in an earlier post, this should free up third-party capacity for making lenses for Pentax if they have any sense-far simpler to make a lens that will be compatible with Pentax than many 'electronics-only' camera mounts.

Owning and using several very modern Viltrox and Sigma lenses I have to say they're some of the very best I've ever used. Sticking religiously to the brand of your camera for your lenses is a very blinkered outlook indeed.

[UncleVanya]

Owning and using several very modern Viltrox and Sigma lenses I have to say they're some of the very best I've ever used. Sticking religiously to the brand of your camera for your lenses is a very blinkered outlook indeed.

I agree that the third party glass today is quite different from the glass available long ago.

My dad was a skeptic until I put my Tamron 70-300 RXD on his a7RII. After seeing that for his use (telephoto landscapes from his car) it was comparable optically to his Sony FE 70-200/2.8 GM - he is a believer. In fact, due to his desire for a lighter kit, I now have the GM and a teleconverter and he has the Tamron and my FE 85/1.8 for his portrait needs. The GM offers me a more capable lens for use cases that differ from his - but at a weight premium.

[reh321]

Owning and using several very modern Viltrox and Sigma lenses I have to say they're some of the very best I've ever used. Sticking religiously to the brand of your camera for your lenses is a very blinkered outlook indeed.

I have a Sigma 10-20mm lens because nothing similar was available at anything similar in price.
I’m glad we still have such a collection of non-Pentax lenses available to us [/sarcasm]