[Laurentiu Cristofor]

Interesting numbers on market share of mirrorless cameras:

CIPA starts to report growing mirrorless sales: Digital Photography Review

They have most market share in Japan, least in Americas.

[illdefined]

Interesting numbers on market share of mirrorless cameras:

CIPA starts to report growing mirrorless sales: Digital Photography Review

They have most market share in Japan, least in Americas.

Japan is always ahead, its no coincidence that all these brands we talk about are Japanese.

Canon and Nikon will surely be the last to ditch the SLR, but I bet even then, they won't give up their mount. Just like Pentax

[Wheatfield]

That 1.46mm difference is large enough to impact what kind of M42 adapter you can build for the mount.

Originally posted by Wheatfield I think with Pentax the answer is simpler. They stayed with the M42 register distance to maintain backwards compatibility with their M42 lenses. That they didn't have to make any major changes inside the mirror box when they went from M42 to K mount would have been a definite bonus from a design and construction standpoint as well, and finally, they wouldn't have had to do much by way of optical redesigns on the early K mount lenses.
The early K mount cameras were little more than Spotmatics with a bayonet mount bolted onto the front.


As you are pointing out in the part I emphasized, the real answer was manufacturing convenience, not backward compatibility. By keeping the same flange distance they didn't had to make many changes to their designs and perhaps even to some other aspects of their production. But that means that pure convenience, not backward compatibility, guided that choice.

Today, Canon and Sony can claim backward compatibility with M42 mount just as easily as Pentax. Having a mount with same flange distance as M42 doesn't make you more compatible than having a mount with a shorter flange distance.

You are wrong regarding their reasoning.
I was working in the industry when the K-Mount came out. Pentax was adamant that they were not going to abandon their screw mount lens users, and render their Takumar lenses obsolete. The rest is, of course, a happy coincidence.
Pentax had, at the time, the best lenses available from any Japanese company, and they weren't willing to abandon those designs. In the 1970s, lens formulas were still calculated using abacuses, so a complete overhaul of a perfected lens line for no good reason would have been drooling stupid anyway.
There was no pressing reason in 1974 to change the register distance, and many, many very good reasons to leave it the same.
Today is not 1974, and while it is possible to mount all sorts of lenses via adapters to all sorts of cameras, it is, for the most part, kludges for masochists. I loaned a whole bunch of little used lenses to a friend for using on his Lumix a few years ago. He piddled around for a while before deciding that it just wasn't all that viable.
I'm not sure what the reasoning is for wanting Pentax to waste resources on yet another lens line when they have 3 lens lines already that need fleshing out. But this is what people are saying when they say they want a shorter registration distance.
Personally, I think it's just a stupid fetish.

[Laurentiu Cristofor]

There was no pressing reason in 1974 to change the register distance, and many, many very good reasons to leave it the same.

Many? Name just one that made sense for customers.

A shorter registration distance (1-2mm) mount would have actually made it easier to use M42 lenses by allowing the construction of adapters that would lock on the K-mount just like K lenses do. That would have allowed users to switch between M42 lenses and K lenses with the same ease that they could switch between K lenses. Instead of that, the solution they provided makes M42 lenses just as hard to use as they were on M42 cameras and fails to leverage the advantages of a bayonet mount.

Even in terms of lens design, they could have kept the same designs for a while and just add the extra 1-2mm into the lens mount piece. In time, as they designed new lenses, this would no longer be necessary.

Note that I am arguing from the perspective of providing better compatibility with M42 lenses, not with lenses for other mounts. I don't expect those 1-2mm to make a large difference in terms of the lens designs made possible, but it would have allowed them to build a better M42 adapter.

M42 lenses and backward compatibility should not even be mentioned together. The K mount is not backward compatible with M42 lenses. M42 lenses are adapted to K mount and they are adapted in a pretty poor fashion. Even sticking to K mount equipment, Pentax has botched their backward compatibility job by crippling their mounts. Pentax only looks good in comparison with other companies, not on an absolute scale.

BTW, as a reminder of where we started from: I brought up this point because I find it as puzzling to answer as the OP question.

[Stone G.]

You are wrong regarding their reasoning.
I was working in the industry when the K-Mount came out.
.
Pentax had, at the time, the best lenses available from any Japanese company, and they weren't willing to abandon those designs. In the 1970s, lens formulas were still calculated using abacuses, so a complete overhaul of a perfected lens line for no good reason would have been drooling stupid anyway.
.
.

Indeed, take a look at the optical designs of the SMC Takumars and the replacement SMC Pentax (K) lenses.

SMC Takumar designs were undisoutedly world-class and redesigning the fundamentals of the entire lens line would seem pointless at that time (as pointed out above without computer-adided design tools).

What would have been the point in making a shorter registration distance then??? Program automatics came later and AF was science fiction in 1975. No need to worry about electrical contacts at that time.

I bought my first Pentax SLR in 1982 and no one were complaining about Pentax registration distance even then.....

[zxaar]

In the 1970s, lens formulas were still calculated using abacuses,

you guys are not every well informed. And it is not you (general person) fault, it is difficult to know about the things not related to work field.

Between 1950 and 1970 we had our most important developments which are still the best methods to solve engineering problems in research field. Here are few very important ones:

1955-56 : Conjugate algorithm was developed (re-invented). krylov subspace methods are still backbone of optimization. By 1970 we had Bi conjugate gradient algorithm invented and working. Other methods were also in place. Not much has changed from that time.

1965: Cooley Tukey reinvented base 2 FFT algorithm and in 70s split radix was in place. Anyway FFT was available in 70s.

1969: Paul created generalized block cyclic reduction for direct solution of elliptical partial differential equations. Very useful and very much used algorithm when computers were not so good. (The idea cropped up because NASA's insistence for finding fast algorithms because computational power was not so good . Originally proposed in ~ 1956)

1967-70 : Numerical methods most used algorithm (in todays software) multigrids was already given. This is used in many many places related research. This is work horse of many many engineering softwares today.

By 1970: Fluid dynamics main algorithm SIMPLE was invented. Still most used algorithm in fluid dynamics.

List is long, but the point is most of the today's main used algorithms were invented by 1970. What we lacked was that our hardware was not so good. It was very poor compared to today but it was far far better than abacuses. I have read lots of papers from that time and engineers were very capable that time.

1950s was the time of abacuses. By 1970 we had a man on moon.



PS: sorry for technical jargon.

[Wheatfield]

Originally posted by Wheatfield There was no pressing reason in 1974 to change the register distance, and many, many very good reasons to leave it the same.

Many? Name just one that made sense for customers.

Backwards compatibility with lenses. This is so obvious, you'd have to be a brick not to get. Granted there is more than one way to skin a cat, but this is the way they chose.
Not having to completely re engineer their entire camera line would be a very compelling reason from a design perspective.
What is the advantage, from a 1974 perspective, of shortening the flange distance, thereby risking mirror vignetting on future lens designs?

[Laurentiu Cristofor]

Backwards compatibility with lenses. This is so obvious, you'd have to be a brick not to get. Granted there is more than one way to skin a cat, but this is the way they chose.
Not having to completely re engineer their entire camera line would be a very compelling reason from a design perspective.

What backward compatibility? Read my post again - backward compatibility with M42 lenses doesn't exist, unless you want to redefine the meaning of the words "backward compatibility".

What is the advantage, from a 1974 perspective, of shortening the flange distance, thereby risking mirror vignetting on future lens designs?

Like I already said - easier use of older M42 lenses. There is no vignetting issue either.

Here's my post again:

Many? Name just one that made sense for customers.

A shorter registration distance (1-2mm) mount would have actually made it easier to use M42 lenses by allowing the construction of adapters that would lock on the K-mount just like K lenses do. That would have allowed users to switch between M42 lenses and K lenses with the same ease that they could switch between K lenses. Instead of that, the solution they provided makes M42 lenses just as hard to use as they were on M42 cameras and fails to leverage the advantages of a bayonet mount.

Even in terms of lens design, they could have kept the same designs for a while and just add the extra 1-2mm into the lens mount piece. In time, as they designed new lenses, this would no longer be necessary.

Note that I am arguing from the perspective of providing better compatibility with M42 lenses, not with lenses for other mounts. I don't expect those 1-2mm to make a large difference in terms of the lens designs made possible, but it would have allowed them to build a better M42 adapter.

M42 lenses and backward compatibility should not even be mentioned together. The K mount is not backward compatible with M42 lenses. M42 lenses are adapted to K mount and they are adapted in a pretty poor fashion. Even sticking to K mount equipment, Pentax has botched their backward compatibility job by crippling their mounts. Pentax only looks good in comparison with other companies, not on an absolute scale.

BTW, as a reminder of where we started from: I brought up this point because I find it as puzzling to answer as the OP question.

[eddie1960]

sorry b ut wheat is correct. no electronic auto aperture in 1974 meant there was full backward compatibility. it would be several years before that issue cropped up. the MZ series of the 90's would have been the stuff of Science fiction never mind the cameras we use today
while i see your point, there was no reason to screw with what at that point was the most successful slr system. nikon was just taking the lead canon was an also ran at this point (and in fact it wasn't until they abandoned FD and went to EOS that they finally overtook nikon,

so hindsight is 20/0 yep they could have made some changes that would have allowed for some improved compatibility 40 years later, but it would have required reworking what was a succesful lens lineup from the ground up, in a market where they were doing very well so why would they

[WWWench]

The K-01 is a solid decision to move Pentax forward, we often forget film is obsolescent and the sensor is part of a computer system. I am sure when 35's replaced view and press cameras there were these same screams. Silliness !!

Pentax would make a big R&D mistake chasing viewfinders and a FF product. Adapt to technology.

[Laurentiu Cristofor]

no electronic auto aperture in 1974 meant there was full backward compatibility.

There couldn't be any full backward compatibility once an adapter was introduced. If you need any accessories to make it work, the camera is not backward compatible. But they could have at least made it easier to adapt M42 lenses. And they didn't. As for auto aperture (the mechanical one!), they didn't even bother to support that (this part is understandable). So what exactly are you calling backward compatible?

[Rondec]

There couldn't be any full backward compatibility once an adapter was introduced. If you need any accessories to make it work, the camera is not backward compatible. But they could have at least made it easier to adapt M42 lenses. And they didn't. As for auto aperture (the mechanical one!), they didn't even bother to support that (this part is understandable). So what exactly are you calling backward compatible?

The fact that you could screw your lens into an adapter and use it without any other adjustments?

You are acting like people knew where technology was headed years before it was even thought of. The K mount is pretty compatible with the electronic age any way. At this point Pentax offers all the things other companies do in their lenses through (a significantly modified) k mount. It really isn't the k mount and register difference that holds them back any more than the f mount hold back nikon.

[eddie1960]

The fact that you could screw your lens into an adapter and use it without any other adjustments?

You are acting like people knew where technology was headed years before it was even thought of. The K mount is pretty compatible with the electronic age any way. At this point Pentax offers all the things other companies do in their lenses through (a significantly modified) k mount. It really isn't the k mount and register difference that holds them back any more than the f mount hold back nikon.

Actually pre auto aperture lenses are more compliant on Pentax (K mount m42) than the f lenses on nikon. the Ai lenses like the a lenses are fully compliant (but in Nikon's case only on bodies they don't cripple intentionally)

[Wheatfield]

What backward compatibility? Read my post again - backward compatibility with M42 lenses doesn't exist, unless you want to redefine the meaning of the words "backward compatibility".

Ok, you are grasping at the proverbial straw now. Give it up, that dog don't hunt.

[illdefined]

another benefit to the thicker body is the same beefy battery as the K-5/7. shouldn't be any complaints about battery life.

so not only are you using the same lenses but the same batteries as well. Pentax is at least being efficient with this little experiment.