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11-03-2020, 04:14 PM   #1
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QuickShift lenses with AF ring not moving during AF-motor operation

During a discussion in another forum, i discovered that most Pentax QS lenses have a turning focus ring during AF operation.
Like the DA 18-55mm or DA 12-24mm.
In the world of Canon, the QS feature is called FTM (Full Time Manual).

Especially QS screw-drive lenses did catch my interest, to see which lenses have a non turning focus ring during AF operation.
I did get the result, that only QS screwdrive lenses with a distance scale behind a transparent plastic-covered window offer this feature.

These are the eight ones:
  • DA 14mm 2.8
  • DA* 16-50mm 2.8
  • D FA 50mm 2.8 Macro
  • DA* 50-135mm 2.8
  • DA* 60-250mm 2.8
  • D FA 100mm 2.8 Macro
  • DA* 200mm
  • DA* 300mm
All other screw-drive AF lenses with QS have a turning focus ring during AF operation. No matter if they offer a separate distance scale or not.

So the interesting thing is that the D FA 100mm f2.8 Macro has a non-turning focus ring but the D FA 100mm f2.8 Macro WR has a turning focus ring.

the focus ring doesn't turn during AF operation with most of the 23 SDM/DC/PLM lenses offering QS.
Known Exceptions: DA 20-40mm Limited
Lenses with SDM/DC Autofocus | PentaxForums.com

But which are the ones with turning focus ring and which without?

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Last edited by angerdan; 02-27-2021 at 05:04 AM.
11-03-2020, 06:17 PM - 1 Like   #2
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Good post!
May find this to be of interest! https://www.bhphotovideo.com/explora/news/pentax-introduces-five-k-mount-lim...pdated-flashes

Last edited by SharkyCA; 11-03-2020 at 06:31 PM. Reason: Add link
11-03-2020, 06:31 PM   #3
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I feel like I now have to test this. Lol. Great info.
11-03-2020, 10:40 PM - 1 Like   #4
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QuoteOriginally posted by angerdan Quote
During a discussion in another forum, i discovered that most Pentax QS lenses have a turning focus ring during AF operation.
Like the DA 18-55mm or DA 12-24mm.


Especially QS screw-drive lenses did catch my interest, to see which lenses have a non turning focus ring during AF operation.
I did get the result, that only QS screwdrive lenses with a distance scale (also called depth-of-field scale on FA lenses) behind a transparent plastic-covered window offer this feature.

These are the eight ones:
  • DA 14mm 2.8
  • DA* 16-50mm 2.8
  • D FA 50mm 2.8 Macro
  • DA* 50-135mm 2.8
  • DA* 60-250mm 2.8
  • D FA 100mm 2.8 Macro
  • DA* 200mm
  • DA* 300mm
All other screw-drive AF lenses with QS have a turning focus ring during AF operation. No matter if they offer a separate distance scale or not.

So the interesting thing is that the D FA 100mm f2.8 Macro has a non-turning focus ring but the D FA 100mm f2.8 Macro WR has a turning focus ring.

With all 23 SDM/DC/PLM lenses offering QS the focus ring doesn't turn during AF operation.
Lenses with SDM/DC Autofocus | PentaxForums.com
Maybe I'm up too late and not understanding this fully but of the eight QS screw-drive lens that you list, most are not screw-drive, unless they have been converted because of a failed SDM. And then to say all 23 SDM/DC/PLM lenses offering QS the focus ring doesn't turn during AF operation is also incorrect, I tested one, the HD DA 20-40, and it turns. Without looking through all lenses I would get it has more to do with internal focusing.

11-04-2020, 08:03 AM - 1 Like   #5
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QuoteOriginally posted by angerdan Quote
screwdrive lenses with a distance scale (also called depth-of-field scale on FA lenses) behind a transparent plastic-covered window offer this feature.
You might want to edit your original post. The quoted sentence conflates distance scales and depth-of-field scales. They are not the same thing.
02-27-2021, 05:02 AM   #6
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QuoteOriginally posted by thibs Quote
The only thing annoying me with this lens (but it won't bother me since I won't buy it, my K5 would not run it properly anyway) is the absence of any distance scale on the barrel.
AFAIK this is because of PLM. I understand that but still a pity for a DA* lens (I would not care a dime of it was a consumer class lens).
QuoteOriginally posted by Serkevan Quote
I still think they could have put an LCD screen on it. Still, I seldom look at the distance scale, so it wouldn't be a big deal...
QuoteOriginally posted by TwoUptons Quote
I hadn't noticed the lack of a distance scale... that's a little weird...
It's just one of those things I'm used to seeing, and the old DA* 16-50 has one.
The DFA 28-105 doesn't have one, either, so it isn't just a PLM thing.
QuoteOriginally posted by pres589 Quote
A lot of Pentax zooms lost distance scales over the years. Some of them also lack hard stops at either end of the focusing range which is really awful. One of the few things I really don't like about my 18-135.
With PLM, a digital distance scale is possible. The distance measing is available since the first FA lens: AOHC - Asahi Optical Historical Club: Catalog

LCD/OLED displays on lenses already exists like with the Canon 70-300mm and Zeiss Batis.
Canon's New 70-300mm II is Its First with an LCD Info Display
Zeiss Batis: The First Ever Lenses with OLED Displays, Delivers FF Autofocus on Sony FE

Last edited by angerdan; 02-28-2021 at 05:58 AM. Reason: easier reading
02-28-2021, 04:16 AM   #7
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QuoteOriginally posted by angerdan Quote
With PLM, a digital distance scale is possible. The distance measing is available since the first FA lens.
AOHC - Asahi Optical Historical Club: Catalog
FA lenses have nothing to do with PLM. Wrong link ?
02-28-2021, 05:58 AM   #8
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QuoteOriginally posted by thibs Quote
Wrong link ?
The link and it's context are correct.
I now moved the link for easier reading.

02-28-2021, 06:45 AM   #9
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QuoteOriginally posted by angerdan Quote
The link and it's context are correct.
I now moved the link for easier reading.
OK, got what you meant. Distance infos from lenses to body, yes indeed, at least FA lenses (anf F for at least focal length).
Sure implementation in body is IMO cumbersome. They could implement screen on lenses but that would in the end cost more than doing it the proper way at first, no ?
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