Lens Adapters

Wolfestone · 10-02-2020, 06:03 AM

Hello all, i was wondering if i could use my old Sigma SA 300 lenses ( 28 - 200mm & 70 - 210mm ) on my Pentax K100D and Pentax K100D Super ..
Are there any mount adapters available to accommodate this please ??

thank you.

35mmfilmfan · 10-02-2020, 06:19 AM

When you say Sigma lenses, do you mean lenses with a specific Sigma mount ? Many Sigma lenses are / were available in K-mount, so these will need no adapter.

**boriscleto** · 10-02-2020, 06:22 AM - **1 Like**

No. There is no SA mount adapter for K-mount. But there is a SA mount adapter for Sony E mount, but it isn't cheap, so kind of pointless for consumer zooms.

Topsy · 10-02-2020, 06:24 AM - **1 Like**

The SA mount/lenses have a shorter registration distance than the K mount and thus can't be adapted. You wouldn't be able to reach infinity.

Though apparently the SA mount sort of fits loosely in the K bayonet.
I'm not sure if these lenses have any electronics, if not you maybe could mess around with the mount, shim it to fit snuggly or even replace the mount, but it's probably not worth it.

Fogel70 · 10-02-2020, 07:11 AM

As I understand Sigma SA mount has the same electrical interface and flange distance as Canon EF mount, but the mount itself is similar to Pentax K-mount.
So it may be easier to modify the lenses to fit on a Canon EF camera.

But I'm not sure it is worth the effort for these lenses.

Another major problem adapting Sigma SA mount lenses to K-mount is that aperture is controlled electronically on these lenses, so you would not be able to control aperture if mounting them on a Pentax camera.

Breakfastographer · 10-02-2020, 09:27 AM

Originally posted by Fogel70

As I understand Sigma SA mount has the same electrical interface and flange distance as Canon EF mount, but the mount itself is similar to Pentax K-mount.
So it may be easier to modify the lenses to fit on a Canon EF camera.

But I'm not sure it is worth the effort for these lenses.

Another major problem adapting Sigma SA mount lenses to K-mount is that aperture is controlled electronically on these lenses, so you would not be able to control aperture if mounting them on a Pentax camera.

From my current knowledge, that seems a strong statement. KAF4 allows for electromagnetic actuation of aperture. Is this known to be incompatible with how it works on SA mount? The location of the pins should not matter if one is making a major modification of the entire mount of the lens - you'd just have to reconnect the pins as needed as part of your modification. Again, assuming the underlying protocol is compatible, but the EF mount is old and Ricoh not generally known for over-engineering. Looking across at what Yongnuo is doing with old EF lens patents, I can't help but wonder what the status of the EF mount patent currently is.

Fogel70 · 10-03-2020, 04:52 AM

Originally posted by Breakfastographer

From my current knowledge, that seems a strong statement. KAF4 allows for electromagnetic actuation of aperture. Is this known to be incompatible with how it works on SA mount? The location of the pins should not matter if one is making a major modification of the entire mount of the lens - you'd just have to reconnect the pins as needed as part of your modification. Again, assuming the underlying protocol is compatible, but the EF mount is old and Ricoh not generally known for over-engineering. Looking across at what Yongnuo is doing with old EF lens patents, I can't help but wonder what the status of the EF mount patent currently is.

I think it is safe to assume that Canon EF/Sigma SA and Pentax K mount is not electrnically compatible.

Pentax K-mount have electronically evolved in several steps and that KAF4 version have become the same as Canon EF is not very likely.

Breakfastographer · 10-03-2020, 01:51 PM

Originally posted by Fogel70

I think it is safe to assume that Canon EF/Sigma SA and Pentax K mount is not electrnically compatible.

Pentax K-mount have electronically evolved in several steps and that KAF4 version have become the same as Canon EF is not very likely.

We're only talking about aperture, likely to be just one pin but this is presumably public information so could be checked.

**boriscleto** · 10-03-2020, 02:23 PM

Originally posted by Breakfastographer

We're only talking about aperture, likely to be just one pin but this is presumably public information so could be checked.

It's proprietary information and is not public. I don't recall anyone mentioning a patent filing anyway. Information would be passed through the data pin, and no one has ever publicly disclosed the data pin protocol. Power would be from the PZ/SDM contacts.

Fogel70 · 10-03-2020, 09:00 PM

Originally posted by Breakfastographer

We're only talking about aperture, likely to be just one pin but this is presumably public information so could be checked.

It is not just the aperture than must works. For it to work the camera must first identify the lens as having KAF4 mount.
If the comminication between the camera and lens is not properly set up the camera will most likely use the default mechanical aperture control.

Breakfastographer · 10-03-2020, 11:57 PM

Originally posted by boriscleto

It's proprietary information and is not public. I don't recall anyone mentioning a patent filing anyway. Information would be passed through the data pin, and no one has ever publicly disclosed the data pin protocol. Power would be from the PZ/SDM contacts.

Please list me as a skeptic regarding aperture control being done via the data pin, but I haven't looked at this in any detail. It just seems like a really, really weird/poor choice. Especially where the data pin is concerned, there seems to me to be a risk of overloading it with too many duties.

**boriscleto** · 10-04-2020, 06:01 AM

Originally posted by Breakfastographer

Please list me as a skeptic regarding aperture control being done via the data pin, but I haven't looked at this in any detail. It just seems like a really, really weird/poor choice. Especially where the data pin is concerned, there seems to me to be a risk of overloading it with too many duties.

So what pin are they using? There are seven pins plus the power contacts. Six of the pins are passive.

**loyalt** · 11-16-2023, 10:07 AM

I am wondering if anyone has used adapters to get a longer "sports-able" lens from another maker to work on the K-3 Mark III. I would love to have the ability to use a 400mm lens in my sports photography and wonder if that is at all worth the trouble. I am hoping a 300mm f2.8 Pentax lens will come out, and I do have the 300mm f4, but would like to have the choice of a longer lens ability for my sports photography business. Any advice on those who have tried adapters with non-K mount lenses would be useful. Thank you!

**pepperberry farm** · 11-16-2023, 10:14 AM

Originally posted by loyalt

I am wondering if anyone has used adapters to get a longer "sports-able" lens from another maker to work on the K-3 Mark III. I would love to have the ability to use a 400mm lens in my sports photography and wonder if that is at all worth the trouble. I am hoping a 300mm f2.8 Pentax lens will come out, and I do have the 300mm f4, but would like to have the choice of a longer lens ability for my sports photography business. Any advice on those who have tried adapters with non-K mount lenses would be useful. Thank you!

have you tried the FA* 400/5.6 or DA 560/5.6?

**loyalt** · 11-16-2023, 09:32 PM

Originally posted by pepperberry farm

have you tried the FA* 400/5.6 or DA 560/5.6?

No...since I am frequently in low light, the lowest apperture, the better, so f2.8-f4 are my preferred. Thank you!

10-02-2020, 06:03 AM	#1
Wolfestone New Member Join Date: Sep 2020 Posts: 7	Lens Adapters Hello all, i was wondering if i could use my old Sigma SA 300 lenses ( 28 - 200mm & 70 - 210mm ) on my Pentax K100D and Pentax K100D Super .. Are there any mount adapters available to accommodate this please ?? thank you.

10-02-2020, 07:11 AM	#5
Fogel70 Pentaxian Join Date: Sep 2009 Location: Stockholm, Sweden Photos: Albums Posts: 3,062	As I understand Sigma SA mount has the same electrical interface and flange distance as Canon EF mount, but the mount itself is similar to Pentax K-mount. So it may be easier to modify the lenses to fit on a Canon EF camera. But I'm not sure it is worth the effort for these lenses. Another major problem adapting Sigma SA mount lenses to K-mount is that aperture is controlled electronically on these lenses, so you would not be able to control aperture if mounting them on a Pentax camera. Last edited by Fogel70; 10-02-2020 at 07:18 AM.

11-16-2023, 10:07 AM	#13
loyalt Loyal Site Supporter Join Date: Jul 2017 Location: Minnesota Photos: Albums Posts: 261	How well do adapters really work? I am wondering if anyone has used adapters to get a longer "sports-able" lens from another maker to work on the K-3 Mark III. I would love to have the ability to use a 400mm lens in my sports photography and wonder if that is at all worth the trouble. I am hoping a 300mm f2.8 Pentax lens will come out, and I do have the 300mm f4, but would like to have the choice of a longer lens ability for my sports photography business. Any advice on those who have tried adapters with non-K mount lenses would be useful. Thank you!

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10-02-2020, 06:19 AM	#2
35mmfilmfan Pentaxian Join Date: Oct 2016 Location: Norfolk, UK Posts: 4,329	When you say Sigma lenses, do you mean lenses with a specific Sigma mount ? Many Sigma lenses are / were available in K-mount, so these will need no adapter.

10-02-2020, 06:22 AM - 1 Like	#3
boriscleto Loyal Site Supporter Join Date: Dec 2009 Location: North Syracuse, NY Photos: Gallery Posts: 16,475	No. There is no SA mount adapter for K-mount. But there is a SA mount adapter for Sony E mount, but it isn't cheap, so kind of pointless for consumer zooms.

10-02-2020, 06:24 AM - 1 Like	#4
Topsy Veteran Member Join Date: Feb 2014 Photos: Gallery \| Albums Posts: 625	The SA mount/lenses have a shorter registration distance than the K mount and thus can't be adapted. You wouldn't be able to reach infinity. Though apparently the SA mount sort of fits loosely in the K bayonet. I'm not sure if these lenses have any electronics, if not you maybe could mess around with the mount, shim it to fit snuggly or even replace the mount, but it's probably not worth it.

10-02-2020, 09:27 AM	#6
Breakfastographer Pentaxian Join Date: Nov 2018 Posts: 673	Originally posted by Fogel70 As I understand Sigma SA mount has the same electrical interface and flange distance as Canon EF mount, but the mount itself is similar to Pentax K-mount. So it may be easier to modify the lenses to fit on a Canon EF camera. But I'm not sure it is worth the effort for these lenses. Another major problem adapting Sigma SA mount lenses to K-mount is that aperture is controlled electronically on these lenses, so you would not be able to control aperture if mounting them on a Pentax camera. From my current knowledge, that seems a strong statement. KAF4 allows for electromagnetic actuation of aperture. Is this known to be incompatible with how it works on SA mount? The location of the pins should not matter if one is making a major modification of the entire mount of the lens - you'd just have to reconnect the pins as needed as part of your modification. Again, assuming the underlying protocol is compatible, but the EF mount is old and Ricoh not generally known for over-engineering. Looking across at what Yongnuo is doing with old EF lens patents, I can't help but wonder what the status of the EF mount patent currently is.

10-03-2020, 04:52 AM	#7
Fogel70 Pentaxian Join Date: Sep 2009 Location: Stockholm, Sweden Photos: Albums Posts: 3,062	Originally posted by Breakfastographer From my current knowledge, that seems a strong statement. KAF4 allows for electromagnetic actuation of aperture. Is this known to be incompatible with how it works on SA mount? The location of the pins should not matter if one is making a major modification of the entire mount of the lens - you'd just have to reconnect the pins as needed as part of your modification. Again, assuming the underlying protocol is compatible, but the EF mount is old and Ricoh not generally known for over-engineering. Looking across at what Yongnuo is doing with old EF lens patents, I can't help but wonder what the status of the EF mount patent currently is. I think it is safe to assume that Canon EF/Sigma SA and Pentax K mount is not electrnically compatible. Pentax K-mount have electronically evolved in several steps and that KAF4 version have become the same as Canon EF is not very likely.

10-03-2020, 01:51 PM	#8
Breakfastographer Pentaxian Join Date: Nov 2018 Posts: 673	Originally posted by Fogel70 I think it is safe to assume that Canon EF/Sigma SA and Pentax K mount is not electrnically compatible. Pentax K-mount have electronically evolved in several steps and that KAF4 version have become the same as Canon EF is not very likely. We're only talking about aperture, likely to be just one pin but this is presumably public information so could be checked.

10-03-2020, 02:23 PM	#9
boriscleto Loyal Site Supporter Join Date: Dec 2009 Location: North Syracuse, NY Photos: Gallery Posts: 16,475	Originally posted by Breakfastographer We're only talking about aperture, likely to be just one pin but this is presumably public information so could be checked. It's proprietary information and is not public. I don't recall anyone mentioning a patent filing anyway. Information would be passed through the data pin, and no one has ever publicly disclosed the data pin protocol. Power would be from the PZ/SDM contacts.

10-03-2020, 09:00 PM	#10
Fogel70 Pentaxian Join Date: Sep 2009 Location: Stockholm, Sweden Photos: Albums Posts: 3,062	Originally posted by Breakfastographer We're only talking about aperture, likely to be just one pin but this is presumably public information so could be checked. It is not just the aperture than must works. For it to work the camera must first identify the lens as having KAF4 mount. If the comminication between the camera and lens is not properly set up the camera will most likely use the default mechanical aperture control.

10-03-2020, 11:57 PM	#11
Breakfastographer Pentaxian Join Date: Nov 2018 Posts: 673	Originally posted by boriscleto It's proprietary information and is not public. I don't recall anyone mentioning a patent filing anyway. Information would be passed through the data pin, and no one has ever publicly disclosed the data pin protocol. Power would be from the PZ/SDM contacts. Please list me as a skeptic regarding aperture control being done via the data pin, but I haven't looked at this in any detail. It just seems like a really, really weird/poor choice. Especially where the data pin is concerned, there seems to me to be a risk of overloading it with too many duties.

10-04-2020, 06:01 AM	#12
boriscleto Loyal Site Supporter Join Date: Dec 2009 Location: North Syracuse, NY Photos: Gallery Posts: 16,475	Originally posted by Breakfastographer Please list me as a skeptic regarding aperture control being done via the data pin, but I haven't looked at this in any detail. It just seems like a really, really weird/poor choice. Especially where the data pin is concerned, there seems to me to be a risk of overloading it with too many duties. So what pin are they using? There are seven pins plus the power contacts. Six of the pins are passive.

11-16-2023, 10:14 AM	#14
pepperberry farm amateur dirt farmer Join Date: Dec 2014 Location: probably out in a field somewhere... Photos: Gallery \| Albums Posts: 41,679	Originally posted by loyalt I am wondering if anyone has used adapters to get a longer "sports-able" lens from another maker to work on the K-3 Mark III. I would love to have the ability to use a 400mm lens in my sports photography and wonder if that is at all worth the trouble. I am hoping a 300mm f2.8 Pentax lens will come out, and I do have the 300mm f4, but would like to have the choice of a longer lens ability for my sports photography business. Any advice on those who have tried adapters with non-K mount lenses would be useful. Thank you! have you tried the FA* 400/5.6 or DA 560/5.6?

11-16-2023, 09:32 PM	#15
loyalt Loyal Site Supporter Join Date: Jul 2017 Location: Minnesota Photos: Albums Posts: 261	Originally posted by pepperberry farm have you tried the FA* 400/5.6 or DA 560/5.6? No...since I am frequently in low light, the lowest apperture, the better, so f2.8-f4 are my preferred. Thank you!