S-M-C A Series Lens On Mirrorless Camera Operation

**RazzleBas** · 11-07-2021, 03:04 AM

How would a Pentax S-M-C A Series lens perform on a mirrorless camera with an adapter? Having no digital connection, would it not have to be operated in the same stopped down manual or aperture preferred manner as M42 Takumars?

Last edited by RazzleBas; 11-07-2021 at 03:11 AM.

Adam · 11-07-2021, 03:16 AM

It's the same as M lenses, and the adapter should automatically be able to stop them down to the selected aperture.

**pepperberry farm** · 11-07-2021, 04:19 AM

you lose the functionality of the 'A' setting on the aperture ring - it becomes a fully manual lens...

**UncleVanya** · 11-07-2021, 06:06 AM

If you get a DA compatible adapter you can use it like a preset or m42 with auto/manual switch: set the aperture ring, focus with the lens wide open, turn the control ring on the adapter to stop down the lens, take the shot, turn the control ring to open the lens back up… repeat.

**RazzleBas** · 11-07-2021, 06:37 AM

Originally posted by UncleVanya

If you get a DA compatible adapter you can use it like a preset or m42 with auto/manual switch: set the aperture ring, focus with the lens wide open, turn the control ring on the adapter to stop down the lens, take the shot, turn the control ring to open the lens back up… repeat.

Yes, I've got a couple of pre-set Taks for just that practical purpose (55 f2.2, 135 f3.5, & 50mm 1:1 Macro so far), best of all the M42 Takumars in that all important way (wish my Zebra was a pre-set). Not worth using the A series if they don't offer the digital connection benefits that sets them apart from the other manual focus series..... I'll stick to my incomparable screwy Taks.

**UncleVanya** · 11-07-2021, 06:47 AM

Originally posted by RazzleBas

Not worth using the A series if they don't offer the digital connection benefits that sets them apart from the other manual focus series..... I'll stick to my incomparable M42s.

The A series lenses typically don’t actively communicate anything. They are coded to passively convey wide open aperture and to have calibrated aperture actuation levers to make aperture automation function. Some modern lenses that are manual focus add the digital communication pin to allow more info to be conveyed but those are all 3rd party.

In theory an adapter could be created to use these lenses. Something like the monster la-ke1 could be made to work with these lenses, but today it isn’t planned to work that way.

11-07-2021, 03:04 AM	#1
RazzleBas Site Supporter Join Date: Mar 2021 Posts: 32	S-M-C A Series Lens On Mirrorless Camera Operation How would a Pentax S-M-C A Series lens perform on a mirrorless camera with an adapter? Having no digital connection, would it not have to be operated in the same stopped down manual or aperture preferred manner as M42 Takumars? Last edited by RazzleBas; 11-07-2021 at 03:11 AM.

11-07-2021, 03:16 AM	#2
Adam Administrator Site Webmaster Join Date: Sep 2006 Location: Arizona Photos: Gallery \| Albums Posts: 51,593	It's the same as M lenses, and the adapter should automatically be able to stop them down to the selected aperture. Adam PentaxForums.com Webmaster (Site Usage Guide \| Site Help \| My Photography) PentaxForums.com server and development costs are user-supported. You can help cover these costs by donating or purchasing one of our Pentax eBooks. Or, buy your photo gear from our affiliates, Adorama, B&H Photo, KEH, or Topaz Labs, and get FREE Marketplace access - click here to see how! Trusted Pentax retailers:

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11-07-2021, 04:19 AM	#3
pepperberry farm amateur dirt farmer Join Date: Dec 2014 Location: probably out in a field somewhere... Photos: Gallery \| Albums Posts: 41,625	you lose the functionality of the 'A' setting on the aperture ring - it becomes a fully manual lens...

11-07-2021, 06:06 AM	#4
UncleVanya Loyal Site Supporter Join Date: Jul 2014 Photos: Gallery \| Albums Posts: 28,381	If you get a DA compatible adapter you can use it like a preset or m42 with auto/manual switch: set the aperture ring, focus with the lens wide open, turn the control ring on the adapter to stop down the lens, take the shot, turn the control ring to open the lens back up… repeat.

11-07-2021, 06:37 AM	#5
RazzleBas Site Supporter Join Date: Mar 2021 Posts: 32 Original Poster	Originally posted by UncleVanya If you get a DA compatible adapter you can use it like a preset or m42 with auto/manual switch: set the aperture ring, focus with the lens wide open, turn the control ring on the adapter to stop down the lens, take the shot, turn the control ring to open the lens back up… repeat. Yes, I've got a couple of pre-set Taks for just that practical purpose (55 f2.2, 135 f3.5, & 50mm 1:1 Macro so far), best of all the M42 Takumars in that all important way (wish my Zebra was a pre-set). Not worth using the A series if they don't offer the digital connection benefits that sets them apart from the other manual focus series..... I'll stick to my incomparable screwy Taks.

11-07-2021, 06:47 AM	#6
UncleVanya Loyal Site Supporter Join Date: Jul 2014 Photos: Gallery \| Albums Posts: 28,381	Originally posted by RazzleBas Not worth using the A series if they don't offer the digital connection benefits that sets them apart from the other manual focus series..... I'll stick to my incomparable M42s. The A series lenses typically don’t actively communicate anything. They are coded to passively convey wide open aperture and to have calibrated aperture actuation levers to make aperture automation function. Some modern lenses that are manual focus add the digital communication pin to allow more info to be conveyed but those are all 3rd party. In theory an adapter could be created to use these lenses. Something like the monster la-ke1 could be made to work with these lenses, but today it isn’t planned to work that way.

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