[MMVIII]

Even though the DA*300 wasn't badly impacted compared to other SDM lenses, I don't think Ricoh could or should release a refresh without replacing the old SDM AF motor somehow - just as we wouldn't want them to release another camera with the K-30 / K-50 aperture control mechanism and solenoid part...

Probably here ends the "small, quick and easy" part of this story. These lenses were dual AF, to allow focussing on older screw drive only cameras. Wouldn't a new version also better get rid of this, as this complex double system might have been one of the reasons for some failures...

[mlt]

Probably here ends the "small, quick and easy" part of this story. These lenses were dual AF, to allow focussing on older screw drive only cameras. Wouldn't a new version also better get rid of this, as this complex double system might have been one of the reasons for some failures...

Motor driven focus only, along with electronic aperture control (K-AF4) is obviously the way of the future. I would expect all new releases to go that way, with the exception of a few specific updates.

[BigMackCam]

Motor driven focus only, along with electronic aperture control (K-AF4) is obviously the way of the future. I would expect all new releases to go that way, with the exception of a few specific updates.

Sadly, where anything more than a cursory refresh (a la FA35/2) is concerned, I'd have to agree. As an owner and prolific user of pre-KAF4 bodies, I get a little twinge of pain when saying that... but we shouldn't stand in the way of progress.

Of course, without screw drive as a fall-back (even if it's via a hack), it's doubly important that the in-lens AF motors are bullet-proof

[Digitalis]

As for the Pentax-A* 135/1.8, I would expect a modern version to be at least a smidge bigger and maybe a bit lighter that the 80mm (D) x 98mm (L) at 865gm for that lens.

I wouldn't expect a modern revamp to be lighter, it would either be the same weight or heavier* due to the increased number of elements to correct the optical issues. It is true aspherics could make this lens lighter while remedying some of the optical issues but considering the modern inclination for "otus" clones with biting sharpness across the frame, be prepared to be disappointed if you were expecting anything with the compactness of the K 135mm f/3.5.


* And hopefully with an appropriate tripod collar. I think the omission of a tripod collar on the D-FA100mm f/2.8 was a lens design blooper.

[nocturnal]

Using moulded aspherical elements introduces a new problem of onion ring bokeh. Ground aspherical elements are better but very expensive to make. I think Sony have a new way of making aspherical elements but these are only used in expensive G-master lenses however I'm no expert on Sony gear.

[reh321]

Sadly, where anything more than a cursory refresh (a la FA35/2) is concerned, I'd have to agree. As an owner and prolific user of pre-KAF4 bodies, I get a little twinge of pain when saying that... but we shouldn't stand in the way of progress.

Of course, without screw drive as a fall-back (even if it's via a hack), it's doubly important that the in-lens AF motors are bullet-proof

After an exercise of going through lenses currently offered by Nikon, I have a much better idea of which of their lenses can be used by which of their bodies. If Pentax were to offer most new lenses with the KAF4 interface, they would limit use of these lenses by older cameras, but those cameras already have many options ...... and I believe the KAF4 interface is Pentax's entry to the future. I have only five lenses equipped with AF motors - and three of them are Q-mount lenses - but I have yet to experience a lens motor failure.

[Digitalis]

Ground aspherical elements are better but very expensive to make.

It depends on the size of the aspheric element, as I recall the Nikkor "Noct" 58mm f/1.2 had a 50mm ground aspheric at the front which was massive [even by today's consumer lens standards] and that element alone was said to account for nearly 50% of the production cost. The cheaper alternative being molded aspherics have the draw back of onion ring bokeh. The biggest element in the cost with ground aspherics is the amount of time it takes to make them* but I suppose a hybrid approach could be taken, with the molded glass being ground down slightly a lot of time could be shaved off by using the molding process to produce the more complex shaping of the glass with a final grinding being a refinement step to remove the concentric rings that appear in GMo aspherics before final optical coating. This process would be more labour intensive than producing standard GMo aspherics but would provide superior optical quality overall.


Sony did a PR release a while ago stating they had developed a molding technique that eliminated the onion ring effect by simply polishing the interior of the aspheric molds - that is certainly a viable step, and unlikely to be subject to patent.

* also the lapidary machinery used to create them is rather specialized, and costly.

[stevebrot]

Using moulded aspherical elements introduces a new problem of onion ring bokeh. Ground aspherical elements are better but very expensive to make. I think Sony have a new way of making aspherical elements but these are only used in expensive G-master lenses however I'm no expert on Sony gear.

Well, that is a shock. I am totally dismayed that the vast majority of the work I've done in the last decade has been flawed due to molded aspheric elements in my go-to lenses...each ruined by bad bokeh. I can't even browse through my Flickr stream without cringing. I am literally sick to my stomach.

Of course, the above is in gest. I did take a tour through my Flickr stream and probably 90% of the photos there were taken with lenses having aspheric elements, but strangely enough, there was only one shot with one ugly onion ring bokeh ball and even on that one, it had to be viewed at full resolution in order to tell.

I guess I just must be living right, eh?


Steve

[stevebrot]

but I suppose a hybrid approach could be taken

Perhaps like in my FA 35/2.0 AL which totally fails the onion ring bokeh test with 0.0% incidence and has a hybrid aspheric element?


Steve

(...Sigma 17-70/2.8-4.0 |C is similarly resistant...)

[robiles]

The Tamron lens has Quick Shift (just not named that way), SDM = USD here and the seals are positioned at the same places in both versions.

Tamron

Pentax

It seems the Tamron (blue) has one extra seal. Or is the extra seal in the pentax not visible due to perspective?

[Mistral75]

It seems the Tamron (blue) has one extra seal. Or is the extra seal in the pentax not visible due to perspective?

It's a perspective effect. The last one is on the mount and can be seen from the outside.

[superdave]

I think they'd have to ditch the old SDM too and go with a newer / better equivalent, no?

I Agree, bigest problem with 300/4 is slow and not precise focusing (especially with TC) due to old SDM. As this is the only long prime in the lineup (except 560), that should be a priority to upgrade it... (or to keep it and release a DFA* 300/2.8). The unsharp/sharp images ratio difference was crazy when I compared my k3ii/300 and Canon 6Dii/100-400II, not speaking about focusing speed...

[Rondec]

I think they'd have to ditch the old SDM too and go with a newer / better equivalent, no?

I think if they are going to redesign the DA * lenses they had best just do it from the ground up. The newest Nikon 300mm f4 has a weight of 755 grams compared to the DA *300 which is 1.1 kg in size. And the Nikon has considerably faster auto focus. My understanding is that this has to do with fresnel elements in the lens design, but if there is a way to keep image quality while shrinking the size of the lens, I'm pretty much in favor of it.

As others have said, I would go ahead and get rid of the dual drive system. These lenses don't have aperture rings and probably are seldom used on pre-K 10 cameras. If someone needs a DA *300 and is still shooting with a *ist D or K100, they'll just have to use the old version. Unfortunately the new DFA *300 won't work on those. But the K10 came out in 2006 and is 12 years old now and anything newer than that would be able to drive these lenses.

[WorksAsIntended]

I also think that there are not a lot of old DSLRs left that cannot make use of sdm or equivalent technology. Even if, those are propably not the customers that buy a lot of new lenses.


About usage of fresnel lenses: Using fresnel lenses allows for less mass and volume but you get diffraction issues at the lenses costing you optical resolution. I am not completly up to date with industrial progress against this and maybe the diffraction limits are rather low with current products, but it stays tradeoff for more comact design against a sharper image for sure.

[reh321]

I also think that there are not a lot of old DSLRs left that cannot make use of sdm or equivalent technology. Even if, those are propably not the customers that buy a lot of new lenses.

I understand it to be more the interface rather than the technology inside. The KAF4 lenses, which have electronic control of aperture inside the lens {instead of the old mechanical system begun with the KA mount nearly forty years ago} will not work with older cameras, although there is a firmware update for cameras as old as the K-50.