[beholder3]

I understand it is actually more to do with internal focus than internal zoom, but I'm willing to be corrected.

Yes. Every lens which does not do focussing purely by extending the barrel has focus breathing, so pretty much all modern lenses have it other than select few macro lenses. The FA 77 mm princess is a surprising positive example with practically no focus breating. On the other side even expensive niche 200mm macros do have very visible focus breating.

All this doesnt stop a manufacturer from building a tube around the lens elements, so that tube doesnt seem to be extending from the outside and consumers then call it "internal".

[Serkevan]

It's relatively easy to replace an AF motor with another kind of AF motor, provided that the new one delivers at least as much torque as the former (you can't replace a ring SDM motor by a PLM motor, for instance).

It's more complicated, and not always possible, to add a focus motor to a manual focus lens. Sometimes, often, you have to modify the optical formula, e.g. if the manual focus lens's focusing method is front extension, thus needing to move all lens elements.

That was what I meant; if the 50/1.7 could get screwdrive AF without an optical formula change, maybe the 60-250 wouldn't need too much work either (although, of course, it is a tele zoom and thus a far more complicated design).

---------- Post added 10-10-19 at 04:46 AM ----------

The idea, I believe, is that such "minor changes" implying the redesign of the barrel gets you to the point where you'd better do new optics (if desirable). Not that you cannot reuse the old optics.
This is also something I've read in an older Pentax interview; once you change the barrel, there's no real cost saving not to update the optics as well: the cost is basically that of a new lens anyway.

About the DA* 60-250 - a lens which I had, very good (except it's slow AF) but unfortunately not FF without surgery - maybe they're going 70-200 f/4 instead in order to keep certain parameters (size, weight, price) under control; it doesn't make much sense to offer something too close to the D FA* 70-200 f/2.8, right?

I was hoping that the SDM substitution might allow for a DC motor (for example; obviously the PLM is out of the question and a ring-type SDM will probably require the barrel changes).

As I said before, considering the 60-250 is already a well-performing FF design with the baffle cutout (and that requires no changes to the lens construction itself), the 70-200/4 should be capable of substantially lowering the size and weight. And hopefully the price as well, although I would expect a 999€ launch price depending on optics/AF/etc.

[andelski]

I like my cope of 60-250, but it has 2 big issue: slow AF and very bad performing against light (flares). Hope new 70-200/4 will perform much better...

[Mistral75]

And the 70-200 RF is not even certain (okay, it's just too short to not extend so it's 99% it will extend, but we officially don't know yet right?)

Correct. We'll know for sure in less than a month.

Confirmation that the Canon RF 70-200mm f/2.8L IS USM extends when zooming came much earlier than that.



Source : RF F2.8 L Zoom Lens Series - YouTube

[Serkevan]

Hah, I hadn't seen that one. Well, that confirms what was almost certain.

[mlt]

IS (nor IBIS) will not help this guy

[thibs]

IS (nor IBIS) will not help this guy

LOL, no ideed.

[Rondec]

It's relatively easy to replace an AF motor with another kind of AF motor, provided that the new one delivers at least as much torque as the former (you can't replace a ring SDM motor by a PLM motor, for instance).

It's more complicated, and not always possible, to add a focus motor to a manual focus lens. Sometimes, often, you have to modify the optical formula, e.g. if the manual focus lens's focusing method is front extension, thus needing to move all lens elements.

I have to think it is a bit more complicated when you have lenses (like the 16-50, 50-135, and 60-250) with dual focus mechanisms. Surely if you update those lenses you would take away their ability to be screw driven auto focus? Seems as though that's a little more of a change.

Anyway, regardless of how easy it would be, Pentax is in the mood to sell new lenses to Pentaxians and they have decided they will sell more by making a new 70-200 f4 than by replacing the baffle and focus motor on the 60-250.

[Mistral75]

I have to think it is a bit more complicated when you have lenses (like the 16-50, 50-135, and 60-250) with dual focus mechanisms. Surely if you update those lenses you would take away their ability to be screw driven auto focus? Seems as though that's a little more of a change.

(...)

Why would it be more complicated? Either

1. You take away the lens's ability to be screw driven autofocus. All you have to do is remove the parts corresponding to the screw driven autofocus, including the clutch allowing the Quick-Shift focus system. In return you gain more freedom to design the new autofocus; or
2. You keep the screw driven autofocus ability. Then you have to replace the SDM motor and its reduction gear by a DC motor and another reduction gear that shall fit in the available space.

(...)

Anyway, regardless of how easy it would be, Pentax is in the mood to sell new lenses to Pentaxians and they have decided they will sell more by making a new 70-200 f4 than by replacing the baffle and focus motor on the 60-250.

Indeed.

[Rondec]

Why would it be more complicated? Either

1. You take away the lens's ability to be screw driven autofocus. All you have to do is remove the parts corresponding to the screw driven autofocus, including the clutch allowing the Quick-Shift focus system. In return you gain more freedom to design the new autofocus; or
2. You keep the screw driven autofocus ability. Then you have to replace the SDM motor and its reduction gear by a DC motor and another reduction gear that shall fit in the available space.

Indeed.

Well, clearly you are a lens designer and have a better feel for the whole process. I wouldn't have thought it was as simple as taking out SDM and screw driven parts and dropping in a DC motor. Sounds like a day's work for a lens designer, maybe a bit less, not? Spray on some HD coatings and call it a day!

[Mistral75]

Sarcasm and rhetorical exaggeration don't help the discussion.

It's definitely not 'a day's work for a lens designer': (i) it's not the job of a lens designer but that of a mechanical engineer and (ii) it's many days of work (the order of magnitude is a few man-months) but feasible nonetheless and much less expensive than designing a new lens from scratch (which, by the way, would definitely involve lens designers ).

[bxf]

Sarcasm...

Where?

...and rhetorical exaggeration...

Where, where???

[monochrome]

We should remember, the timing of new lens introductions is at least partly driven by the existing inventory of the lenses to be sunsetted, which at current volumes might well be not trivial.

[reh321]

Yes. Every lens which does not do focussing purely by extending the barrel has focus breathing, so pretty much all modern lenses have it other than select few macro lenses. The FA 77 mm princess is a surprising positive example with practically no focus breating. On the other side even expensive niche 200mm macros do have very visible focus breating.

All this doesnt stop a manufacturer from building a tube around the lens elements, so that tube doesnt seem to be extending from the outside and consumers then call it "internal".

This is where WR comes into play. If nothing external moves - if all movement is within the external tube - then the external tube's WR is all that matters, and from that pov the lens is considered to "internal".

[luftfluss]

There would be much ridicule of Pentax if they were to release a rehashed 60-250 as a new "FF" lens.

Also, the 1:7 max magnification is unacceptable and would be embarassing for a "new" lens. It might also be an impediment to new future technologies Pentax may introduce.