Cannon EF lens on Pentax K70

gasood · 11-15-2020, 12:53 AM

Hey Experts,

This is Gaurav and i have recently got Pentax K70. I have been using CannonT7 for quite sometime. I have got few Cannon and Sigma lenses which i am using on CannonT7. So, i am wondering if it's possible to use the same lenses on Pentax K70 by using some kind of adapter mount.

Thank you
Gaurav

Not a Number · 11-15-2020, 02:06 AM - **1 Like**

I haven't found an EF to K-mount adapter. Depending on the model of the Sigma lens you may be able to send it back to Sigma for a mount conversion. Again it depends on the model of lens and if K-mount is available for that lens.

Mount Conversion Service | Lenses | SIGMA Corporation

**PJ1** · 11-15-2020, 03:23 AM - **1 Like**

The Canon EF mount has a shorter registration than Pentax K mount (44 mm vs 45.46 mm). Because of this, you would require an adapter with an extra element to adapt the EF lens on a K mount. It is not really feasible (I don't know if anyone makes one. But you could use a reversing ring and use a Canon lens for macro). Other than that, if you have a Sigma lens that is worth paying the money to have converted, there may be that option. I think Sigma offer it for lenses that were originally offered in K mount as well as Canon, etc.

**Serkevan** · 11-15-2020, 03:24 AM

The EF mount's flange distance is 44 mm, and the K mount's is 45.46... you'd need to insert the lenses 1.5mm inside the K-70's mount for it to work (or have an adapter with glass which would degrade image quality somewhat on top of being bulky).

For the Sigma lenses, maybe they'll be able to help as Not a Number just said, for Canon originals I'm afraid it's a resounding "no".

Edit: and PJ1 overtakes me out of nowhere!

One other thing is that, if you let us know which lenses you own, we'll be happy to point you at Pentax equivalents

Thagomizer · 11-15-2020, 11:46 AM

Another thing to consider is that Canon EF lenses have no aperture rings and no mechanical control for the diaphragm. I don't know about Sigma made lenses for EF, but Canon made EF lenses are strictly electronic control.

ecostigny · 11-15-2020, 12:40 PM

Since Sigma has gotten out of manufacturing K-mount lenses, you certainly cannot hope to convert a recent EF mount lens to K mount. Their exit from Pentaxland also might be limiting what conversions they are willing to perform. Their Mount Conversion Service page says that Pentax conversions may be "subject to mount, parts, and service availability" and that "Not all products are available in Pentax and/or Sony Mounts."

Mount Conversion Service | SIGMA America

gasood · 11-15-2020, 01:54 PM

Thank you all for the valuable responses. I believe then i should start exploring Tamron as a next option.

**clackers** · 11-15-2020, 08:45 PM

Originally posted by gasood

Thank you all for the valuable responses. I believe then i should start exploring Tamron as a next option.

Same problem, Gaurav.

No EF mount lens can work, whether Canon, Sigma or Tamron.

You can't control the aperture, autofocus won't work, and you would need some adapter with limiting glass in it compromising the image quality.

11-15-2020, 12:53 AM	#1
gasood New Member Join Date: Nov 2020 Posts: 2	Cannon EF lens on Pentax K70 Hey Experts, This is Gaurav and i have recently got Pentax K70. I have been using CannonT7 for quite sometime. I have got few Cannon and Sigma lenses which i am using on CannonT7. So, i am wondering if it's possible to use the same lenses on Pentax K70 by using some kind of adapter mount. Thank you Gaurav

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11-15-2020, 02:06 AM - 1 Like	#2
Not a Number Moderator Join Date: Mar 2012 Location: Venice, CA Posts: 10,526	I haven't found an EF to K-mount adapter. Depending on the model of the Sigma lens you may be able to send it back to Sigma for a mount conversion. Again it depends on the model of lens and if K-mount is available for that lens. Mount Conversion Service \| Lenses \| SIGMA Corporation

11-15-2020, 03:23 AM - 1 Like	#3
PJ1 Loyal Site Supporter Join Date: Jul 2012 Location: Toowoomba, Australia Photos: Gallery \| Albums Posts: 5,486	The Canon EF mount has a shorter registration than Pentax K mount (44 mm vs 45.46 mm). Because of this, you would require an adapter with an extra element to adapt the EF lens on a K mount. It is not really feasible (I don't know if anyone makes one. But you could use a reversing ring and use a Canon lens for macro). Other than that, if you have a Sigma lens that is worth paying the money to have converted, there may be that option. I think Sigma offer it for lenses that were originally offered in K mount as well as Canon, etc.

11-15-2020, 03:24 AM	#4
Serkevan Site Supporter Join Date: May 2019 Photos: Albums Posts: 5,976	The EF mount's flange distance is 44 mm, and the K mount's is 45.46... you'd need to insert the lenses 1.5mm inside the K-70's mount for it to work (or have an adapter with glass which would degrade image quality somewhat on top of being bulky). For the Sigma lenses, maybe they'll be able to help as Not a Number just said, for Canon originals I'm afraid it's a resounding "no". Edit: and PJ1 overtakes me out of nowhere! One other thing is that, if you let us know which lenses you own, we'll be happy to point you at Pentax equivalents

11-15-2020, 11:46 AM	#5
Thagomizer Pentaxian Join Date: Jun 2014 Location: London Ontario Posts: 2,068	Another thing to consider is that Canon EF lenses have no aperture rings and no mechanical control for the diaphragm. I don't know about Sigma made lenses for EF, but Canon made EF lenses are strictly electronic control.

11-15-2020, 12:40 PM	#6
ecostigny Pentaxian Join Date: Nov 2017 Location: Branford, CT Posts: 561	Since Sigma has gotten out of manufacturing K-mount lenses, you certainly cannot hope to convert a recent EF mount lens to K mount. Their exit from Pentaxland also might be limiting what conversions they are willing to perform. Their Mount Conversion Service page says that Pentax conversions may be "subject to mount, parts, and service availability" and that "Not all products are available in Pentax and/or Sony Mounts." Mount Conversion Service \| SIGMA America

11-15-2020, 01:54 PM	#7
gasood New Member Join Date: Nov 2020 Posts: 2 Original Poster	Thank you all for the valuable responses. I believe then i should start exploring Tamron as a next option.

11-15-2020, 08:45 PM	#8
clackers Otis Memorial Pentaxian Join Date: Jul 2013 Location: Melbourne Photos: Albums Posts: 16,397	Originally posted by gasood Thank you all for the valuable responses. I believe then i should start exploring Tamron as a next option. Same problem, Gaurav. No EF mount lens can work, whether Canon, Sigma or Tamron. You can't control the aperture, autofocus won't work, and you would need some adapter with limiting glass in it compromising the image quality.