SDM 300 f4 concerns?

**DWS1** · 05-01-2021, 06:08 PM

Great lens. Had mine for 4 years now with no problems.

**UncleVanya** · 05-01-2021, 06:47 PM

Originally posted by caliscouser

Not sure anyone addressed this. But I believe the K100d can and the K-3 / KP can't.

Awesome lens by the way, image quality is absolutely top notch.

Correct. My favorite conversion body is a k100d.

**mikesbike** · 05-01-2021, 07:17 PM

This is interesting. I recall when the K100D Super came out, the primary upgrade was for using the new SDM lenses, while the K100D was said to be incompatible with these lenses. So many people thought the new lenses would not AF at all with the K100D- but now I guess they could, but via screw-driven instead of SDM.

**UncleVanya** · 05-01-2021, 07:41 PM

Originally posted by mikesbike

This is interesting. I recall when the K100D Super came out, the primary upgrade was for using the new SDM lenses, while the K100D was said to be incompatible with these lenses. So many people thought the new lenses would not AF at all with the K100D- but now I guess they could, but via screw-driven instead of SDM.

Only those five. The others that only have sdm fail to af. The k100d has the power zoom contacts so it isn’t clear precisely what hardware has differs from it to the super version.

5ks · 05-02-2021, 05:49 AM - **1 Like**

Originally posted by UncleVanya

5 DA* lenses were made to work on both screwdrive only and sdm cameras. They were setup to use with both systems but there wasn’t any way on the sdm cameras to tell them to NOT use sdm even if the sdm had failed. By programming the lens you can have it lie to the camera and trick it into thinking it is not sdm compatible at which point the camera uses screwdrive. Only four of the five lenses made specifically with screwdrive and sdm can be converted the da* 16-50, 50-135, 200, and 300. The 60-250 behaves weirdly and is unreliable if you attempt conversion.

Thank you for the additional info. Wonderful to see people having such knowledge.

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05-01-2021, 06:08 PM	#16
DWS1 Site Supporter Join Date: Aug 2018 Location: Arkansas, USA Posts: 1,169	Great lens. Had mine for 4 years now with no problems.

05-01-2021, 06:47 PM	#17
UncleVanya Loyal Site Supporter Join Date: Jul 2014 Photos: Gallery \| Albums Posts: 28,385	Originally posted by caliscouser Not sure anyone addressed this. But I believe the K100d can and the K-3 / KP can't. Awesome lens by the way, image quality is absolutely top notch. Correct. My favorite conversion body is a k100d.

05-01-2021, 07:17 PM	#18
mikesbike Site Supporter Join Date: Dec 2016 Location: Southeastern Michigan Posts: 4,547	This is interesting. I recall when the K100D Super came out, the primary upgrade was for using the new SDM lenses, while the K100D was said to be incompatible with these lenses. So many people thought the new lenses would not AF at all with the K100D- but now I guess they could, but via screw-driven instead of SDM.

05-01-2021, 07:41 PM	#19
UncleVanya Loyal Site Supporter Join Date: Jul 2014 Photos: Gallery \| Albums Posts: 28,385	Originally posted by mikesbike This is interesting. I recall when the K100D Super came out, the primary upgrade was for using the new SDM lenses, while the K100D was said to be incompatible with these lenses. So many people thought the new lenses would not AF at all with the K100D- but now I guess they could, but via screw-driven instead of SDM. Only those five. The others that only have sdm fail to af. The k100d has the power zoom contacts so it isn’t clear precisely what hardware has differs from it to the super version.

05-02-2021, 05:49 AM - 1 Like	#20
5ks Pentaxian Join Date: Feb 2011 Location: Southern Finland Posts: 681	Originally posted by UncleVanya 5 DA* lenses were made to work on both screwdrive only and sdm cameras. They were setup to use with both systems but there wasn’t any way on the sdm cameras to tell them to NOT use sdm even if the sdm had failed. By programming the lens you can have it lie to the camera and trick it into thinking it is not sdm compatible at which point the camera uses screwdrive. Only four of the five lenses made specifically with screwdrive and sdm can be converted the da* 16-50, 50-135, 200, and 300. The 60-250 behaves weirdly and is unreliable if you attempt conversion. Thank you for the additional info. Wonderful to see people having such knowledge.

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