SDM lens manual focus question

ianinbc · 01-19-2021, 06:31 PM

Hello, I have just acquired my first SDM lens (16-50mm f2.8) and the manual focus feels very "rough". It travels through the whole focus range, it's just not smooth at all. To clarify, I have the lens but I don't currently have camera body to mount it on and test the SDM. I know it won't be smooth like a manual focus lens, but I wasn't expecting it to feel so awful. What is the typical feel of an SDM lens when manual focusing?
Thanks

Not a Number · 01-19-2021, 06:53 PM

Have you switched the lens to MF?

Adam · 01-19-2021, 11:01 PM

It should be nice and smooth, and considerably better than film-era autofocus lenses. Sounds like there might be an issue with the lens.

**UncleVanya** · 01-19-2021, 11:30 PM

Maybe if possible post a video? Different people perceive the da* lenses focus rings differently. They have a clutch that interacts with the focus ring that you can feel. It isn’t “rough” like a bad manual focus lens but it has a grittiness to it. It has no real resistance - less than a typical K or M or A series lens, but it isn’t buttery smooth.

ianinbc · 01-24-2021, 08:20 PM

Hi, I just saw these replies now. It seems exactly the same in AF or MF mode (on the lens). Here is the video, but I think I already know the answer. Definitely rougher than my FA lenses when manual focusing.

Youtu.be

**UncleVanya** · 01-24-2021, 09:39 PM

Originally posted by ianinbc

Hi, I just saw these replies now. It seems exactly the same in AF or MF mode (on the lens). Here is the video, but I think I already know the answer. Definitely rougher than my FA lenses when manual focusing.
https://youtu.be/3zDztGXR-js

That’s hard to assess. Mine sounds similar but much less loud. It could be microphone and gain causing the confusion. I can try recreating your video with my lens.

**UncleVanya** · 01-25-2021, 10:38 PM

Sound of DA* 16-50 manual focus by -vanya_42nd-

As promised.

**UncleVanya** · 01-25-2021, 10:39 PM

Listening to both I’m stumped. I can’t tell if the differences are real or just mic related.

01-19-2021, 06:31 PM	#1
ianinbc Forum Member Join Date: Aug 2009 Location: Ottawa, ON Posts: 69	SDM lens manual focus question Hello, I have just acquired my first SDM lens (16-50mm f2.8) and the manual focus feels very "rough". It travels through the whole focus range, it's just not smooth at all. To clarify, I have the lens but I don't currently have camera body to mount it on and test the SDM. I know it won't be smooth like a manual focus lens, but I wasn't expecting it to feel so awful. What is the typical feel of an SDM lens when manual focusing? Thanks

01-19-2021, 11:01 PM	#3
Adam Administrator Site Webmaster Join Date: Sep 2006 Location: Arizona Photos: Gallery \| Albums Posts: 51,608	It should be nice and smooth, and considerably better than film-era autofocus lenses. Sounds like there might be an issue with the lens. 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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01-19-2021, 06:53 PM	#2
Not a Number Moderator Join Date: Mar 2012 Location: Venice, CA Posts: 10,526	Have you switched the lens to MF?

01-19-2021, 11:30 PM	#4
UncleVanya Loyal Site Supporter Join Date: Jul 2014 Photos: Gallery \| Albums Posts: 28,472	Maybe if possible post a video? Different people perceive the da* lenses focus rings differently. They have a clutch that interacts with the focus ring that you can feel. It isn’t “rough” like a bad manual focus lens but it has a grittiness to it. It has no real resistance - less than a typical K or M or A series lens, but it isn’t buttery smooth.

01-24-2021, 09:39 PM	#6
UncleVanya Loyal Site Supporter Join Date: Jul 2014 Photos: Gallery \| Albums Posts: 28,472	Originally posted by ianinbc Hi, I just saw these replies now. It seems exactly the same in AF or MF mode (on the lens). Here is the video, but I think I already know the answer. Definitely rougher than my FA lenses when manual focusing. https://youtu.be/3zDztGXR-js That’s hard to assess. Mine sounds similar but much less loud. It could be microphone and gain causing the confusion. I can try recreating your video with my lens.

01-25-2021, 10:38 PM	#7
UncleVanya Loyal Site Supporter Join Date: Jul 2014 Photos: Gallery \| Albums Posts: 28,472	Sound of DA* 16-50 manual focus by -vanya_42nd- As promised.

01-25-2021, 10:39 PM	#8
UncleVanya Loyal Site Supporter Join Date: Jul 2014 Photos: Gallery \| Albums Posts: 28,472	Listening to both I’m stumped. I can’t tell if the differences are real or just mic related.