Sigma stops K-Mount support

Mistral75 · 12-08-2019, 01:04 PM

Originally posted by y0chang

The problem with an AF adapter is that to be completely electronic it would have to be KAF4, and there are not a lot of Pentax Lenses that have that. (...)

Indeed, there are only two KAF4 lenses in Pentax's portfolio.

Originally posted by reh321

A KAF3 adapter wouldn't need the screw drive - but even KAF3 lenses are not particularly typical. (...)

No, it wouldn't, but it would still need a motor (an actuator, actually) to move the aperture lever.

**travelswsage** · 12-08-2019, 04:40 PM

So, if I am understanding correctly engineering wise Pentax has several different types of af lenses and it would be difficult to design an af adapter to work with all or even some them -- FA lenses, KAF4, KAF3 all would need a different type of adapter?

**mlt** · 12-08-2019, 04:44 PM

Originally posted by travelswsage

So, if I am understanding correctly engineering wise Pentax has several different types of af lenses and it would be difficult to design an af adapter to work with all or even some them -- FA lenses, KAF4, KAF3 all would need a different type of adapter?

Correct if you wish to maintain AF and aperture control across all mount variations.

reh321 · 12-08-2019, 04:58 PM - **1 Like**

Originally posted by travelswsage

So, if I am understanding correctly engineering wise Pentax has several different types of af lenses and it would be difficult to design an af adapter to work with all or even some them -- FA lenses, KAF4, KAF3 all would need a different type of adapter?

As far as I am aware, my KP can AF with any K-mount lens, so a properly designed adapter should be able to work with all AF lenses, but this would require that the adapter contain both an aperture 'actuator' and a focus motor, which would add complexity and weight to the design. Just as Pentax chose to use 'green button' metering instead of directly handling all K-mount lenses ever built, they might choose to correctly handle only some lenses.

**travelswsage** · 12-08-2019, 05:03 PM

Ah … got it. Sure sounds like I can cross this one off my wishlist ….

reh321 · 12-08-2019, 05:27 PM

Originally posted by travelswsage

Ah … got it. Sure sounds like I can cross this one off my wishlist ….

Not permanently. As Rondec correctly observed, the Nikon F-mount is very similar to K-mount, except, if I understand Nikon users correctly, the F-mount has more special cases. Despite being at a disadvantage, Nikon has developed a F-mount to Z-mount adapter which comes with some MILC kits. Similarly, someone could develop some form of adapter for the K-mount, but they would need some kind of real incentive to do so.

**mlt** · 12-08-2019, 06:19 PM

The Nikon F to Z converter does not work with screw drive lenses or control the aperture on non-af lenses, so basically it is for their AF-4 type lenses (af and aperture electronically controlled). To include mechanical actuations for both would involve micro-motors and either an on adapter power source or someway to pass power from the body, along with the in-body coding to recognize what is attached and how to use it.

sculptor666 · 12-08-2019, 06:19 PM

kenko(and perhaps others) make a teleconverter that works with all pentax af/aperture control systems, so it's not that hard:
Kenko 1.5X Pz-AF Teleconverter (Pentax Mount) - PentaxForums.com

**mlt** · 12-08-2019, 06:27 PM - **1 Like**

The af on that converter is strictly a pass-through from the body, including the screw-drive - the af is not a function of the adapter.

y0chang · 12-08-2019, 06:33 PM

Originally posted by mlt

The Nikon F to Z converter does not work with screw drive lenses or control the aperture on non-af lenses, so basically it is for their AF-4 type lenses (af and aperture electronically controlled). To include mechanical actuations for both would involve micro-motors and either an on adapter power source or someway to pass power from the body, along with the in-body coding to recognize what is attached and how to use it.

This is a really good point. The biggest issue is the pass through of electrical contacts, I am pretty sure every contact right now is used on the pentax mount for some use. You would not only need data but power to those motors. Not saying it isnt possible, but its got to be really really hard.

reh321 · 12-08-2019, 07:37 PM

Originally posted by y0chang

This is a really good point. The biggest issue is the pass through of electrical contacts, I am pretty sure every contact right now is used on the pentax mount for some use. You would not only need data but power to those motors. Not saying it isnt possible, but its got to be really really hard.

The K-mount standard of today does include electrical contacts. It was added at one point to power zoom-lenses, but it is used today to power lenses such as the DC and PLM lenses, both of which have AF motors in the lens. A KAF3-KAF4 adapter would simply have to pass through this contact; a KAF4-KAF3-KAF2 adapter would have to tap the power to run a tiny motor powering a tiny screw_drive when appropriate.

**mlt** · 12-08-2019, 08:22 PM

Or just simplify things, build a true mirrorless body with all the K-AF3 hardware in the body and sell it with a small adapter tube with all the needed connections to mount dslr K mount lenses at the proper registration distance. As an added bonus, the adapter could double as a full af extension tube on dslr’s.

Ian Stuart Forsyth · 12-08-2019, 09:05 PM

Originally posted by Rondec

My point was only that the "technical difficulties" that Sigma faces in dealing with the K mount are similar to those faced when dealing with the F mount. They are not insurmountable if Sigma sells enough lenses to warrant the effort.

I have a feeling that this was an excuse from Sigma as to why the would no longer support K mount lens in their newer designs. After 2007 all Nikon bodies are able to use E (electronic aperture ) lenses. there are several lenses that Sigma has designed and still sell that use mechanical aperture control.
We first started seeing lenses that would be low volume sellers that Sigma no longer updated in K mount this really started around 2010 and the only updates that had K mount available are lenses that are higher volume sellers while the more specialized they stepped away.

We only started to see electronic aperture lenses from sigma after 2015

y0chang · 12-08-2019, 09:59 PM

Originally posted by mlt

Or just simplify things, build a true mirrorless body with all the K-AF3 hardware in the body and sell it with a small adapter tube with all the needed connections to mount dslr K mount lenses at the proper registration distance. As an added bonus, the adapter could double as a full af extension tube on dslr’s.

Well the mirrorless mount would have a vestigial screw mount and aperture connection? Guess they could do it like a DF does for the AI-s which it would either automatically or user-operated retract when unused.

Reed · 12-09-2019, 12:33 AM

Originally posted by Ian Stuart Forsyth

I have a feeling that this was an excuse from Sigma as to why the would no longer support K mount lens in their newer designs. After 2007 all Nikon bodies are able to use E (electronic aperture ) lenses. there are several lenses that Sigma has designed and still sell that use mechanical aperture control.
We first started seeing lenses that would be low volume sellers that Sigma no longer updated in K mount this really started around 2010 and the only updates that had K mount available are lenses that are higher volume sellers while the more specialized they stepped away.

We only started to see electronic aperture lenses from sigma after 2015

I have the same feeling on this. Sigma lenses are made in one standard, where you are able to separate optical and drive block from part with mount and control electronics board etc. In every mount, the front section is the same. They just switch the back and use proper firmware to drive it.

12-08-2019, 07:37 PM	#656
reh321 Pentaxian Join Date: Nov 2014 Location: South Bend, IN, USA Photos: Gallery \| Albums Posts: 23,181	Originally posted by y0chang This is a really good point. The biggest issue is the pass through of electrical contacts, I am pretty sure every contact right now is used on the pentax mount for some use. You would not only need data but power to those motors. Not saying it isnt possible, but its got to be really really hard. The K-mount standard of today does include electrical contacts. It was added at one point to power zoom-lenses, but it is used today to power lenses such as the DC and PLM lenses, both of which have AF motors in the lens. A KAF3-KAF4 adapter would simply have to pass through this contact; a KAF4-KAF3-KAF2 adapter would have to tap the power to run a tiny motor powering a tiny screw_drive when appropriate. Attached Images Last edited by reh321; 12-08-2019 at 07:43 PM.

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12-08-2019, 01:04 PM	#646
Mistral75 Pentaxian Join Date: Feb 2009 Location: Paris, France Posts: 7,527	Originally posted by y0chang The problem with an AF adapter is that to be completely electronic it would have to be KAF4, and there are not a lot of Pentax Lenses that have that. (...) Indeed, there are only two KAF4 lenses in Pentax's portfolio. Originally posted by reh321 A KAF3 adapter wouldn't need the screw drive - but even KAF3 lenses are not particularly typical. (...) No, it wouldn't, but it would still need a motor (an actuator, actually) to move the aperture lever.

12-08-2019, 04:40 PM	#647
travelswsage Site Supporter Join Date: Jun 2016 Posts: 385	So, if I am understanding correctly engineering wise Pentax has several different types of af lenses and it would be difficult to design an af adapter to work with all or even some them -- FA lenses, KAF4, KAF3 all would need a different type of adapter?

12-08-2019, 04:44 PM	#648
mlt Site Supporter Join Date: Dec 2007 Posts: 1,159	Originally posted by travelswsage So, if I am understanding correctly engineering wise Pentax has several different types of af lenses and it would be difficult to design an af adapter to work with all or even some them -- FA lenses, KAF4, KAF3 all would need a different type of adapter? Correct if you wish to maintain AF and aperture control across all mount variations.

12-08-2019, 04:58 PM - 1 Like	#649
reh321 Pentaxian Join Date: Nov 2014 Location: South Bend, IN, USA Photos: Gallery \| Albums Posts: 23,181	Originally posted by travelswsage So, if I am understanding correctly engineering wise Pentax has several different types of af lenses and it would be difficult to design an af adapter to work with all or even some them -- FA lenses, KAF4, KAF3 all would need a different type of adapter? As far as I am aware, my KP can AF with any K-mount lens, so a properly designed adapter should be able to work with all AF lenses, but this would require that the adapter contain both an aperture 'actuator' and a focus motor, which would add complexity and weight to the design. Just as Pentax chose to use 'green button' metering instead of directly handling all K-mount lenses ever built, they might choose to correctly handle only some lenses.

12-08-2019, 05:03 PM	#650
travelswsage Site Supporter Join Date: Jun 2016 Posts: 385	Ah … got it. Sure sounds like I can cross this one off my wishlist ….

12-08-2019, 05:27 PM	#651
reh321 Pentaxian Join Date: Nov 2014 Location: South Bend, IN, USA Photos: Gallery \| Albums Posts: 23,181	Originally posted by travelswsage Ah … got it. Sure sounds like I can cross this one off my wishlist …. Not permanently. As Rondec correctly observed, the Nikon F-mount is very similar to K-mount, except, if I understand Nikon users correctly, the F-mount has more special cases. Despite being at a disadvantage, Nikon has developed a F-mount to Z-mount adapter which comes with some MILC kits. Similarly, someone could develop some form of adapter for the K-mount, but they would need some kind of real incentive to do so.

12-08-2019, 06:19 PM	#652
mlt Site Supporter Join Date: Dec 2007 Posts: 1,159	The Nikon F to Z converter does not work with screw drive lenses or control the aperture on non-af lenses, so basically it is for their AF-4 type lenses (af and aperture electronically controlled). To include mechanical actuations for both would involve micro-motors and either an on adapter power source or someway to pass power from the body, along with the in-body coding to recognize what is attached and how to use it.

12-08-2019, 06:19 PM	#653
sculptor666 Pentaxian Join Date: Dec 2013 Location: PA Photos: Gallery Posts: 675	kenko(and perhaps others) make a teleconverter that works with all pentax af/aperture control systems, so it's not that hard: Kenko 1.5X Pz-AF Teleconverter (Pentax Mount) - PentaxForums.com

12-08-2019, 06:27 PM - 1 Like	#654
mlt Site Supporter Join Date: Dec 2007 Posts: 1,159	The af on that converter is strictly a pass-through from the body, including the screw-drive - the af is not a function of the adapter.

12-08-2019, 06:33 PM	#655
y0chang Veteran Member Join Date: Jan 2012 Location: United States Posts: 793	Originally posted by mlt The Nikon F to Z converter does not work with screw drive lenses or control the aperture on non-af lenses, so basically it is for their AF-4 type lenses (af and aperture electronically controlled). To include mechanical actuations for both would involve micro-motors and either an on adapter power source or someway to pass power from the body, along with the in-body coding to recognize what is attached and how to use it. This is a really good point. The biggest issue is the pass through of electrical contacts, I am pretty sure every contact right now is used on the pentax mount for some use. You would not only need data but power to those motors. Not saying it isnt possible, but its got to be really really hard.

12-08-2019, 08:22 PM	#657
mlt Site Supporter Join Date: Dec 2007 Posts: 1,159	Or just simplify things, build a true mirrorless body with all the K-AF3 hardware in the body and sell it with a small adapter tube with all the needed connections to mount dslr K mount lenses at the proper registration distance. As an added bonus, the adapter could double as a full af extension tube on dslr’s.

12-08-2019, 09:05 PM	#658
Ian Stuart Forsyth Pentaxian Join Date: May 2009 Location: Somewhere over the rainbow Photos: Gallery Posts: 1,531	Originally posted by Rondec My point was only that the "technical difficulties" that Sigma faces in dealing with the K mount are similar to those faced when dealing with the F mount. They are not insurmountable if Sigma sells enough lenses to warrant the effort. I have a feeling that this was an excuse from Sigma as to why the would no longer support K mount lens in their newer designs. After 2007 all Nikon bodies are able to use E (electronic aperture ) lenses. there are several lenses that Sigma has designed and still sell that use mechanical aperture control. We first started seeing lenses that would be low volume sellers that Sigma no longer updated in K mount this really started around 2010 and the only updates that had K mount available are lenses that are higher volume sellers while the more specialized they stepped away. We only started to see electronic aperture lenses from sigma after 2015

12-08-2019, 09:59 PM	#659
y0chang Veteran Member Join Date: Jan 2012 Location: United States Posts: 793	Originally posted by mlt Or just simplify things, build a true mirrorless body with all the K-AF3 hardware in the body and sell it with a small adapter tube with all the needed connections to mount dslr K mount lenses at the proper registration distance. As an added bonus, the adapter could double as a full af extension tube on dslr’s. Well the mirrorless mount would have a vestigial screw mount and aperture connection? Guess they could do it like a DF does for the AI-s which it would either automatically or user-operated retract when unused.

12-09-2019, 12:33 AM	#660
Reed Pentaxian Join Date: Mar 2015 Location: Warsaw Photos: Gallery Posts: 638	Originally posted by Ian Stuart Forsyth I have a feeling that this was an excuse from Sigma as to why the would no longer support K mount lens in their newer designs. After 2007 all Nikon bodies are able to use E (electronic aperture ) lenses. there are several lenses that Sigma has designed and still sell that use mechanical aperture control. We first started seeing lenses that would be low volume sellers that Sigma no longer updated in K mount this really started around 2010 and the only updates that had K mount available are lenses that are higher volume sellers while the more specialized they stepped away. We only started to see electronic aperture lenses from sigma after 2015 I have the same feeling on this. Sigma lenses are made in one standard, where you are able to separate optical and drive block from part with mount and control electronics board etc. In every mount, the front section is the same. They just switch the back and use proper firmware to drive it.