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**cdw2000** · 04-23-2021, 09:20 AM

I own the venerable DA* 300mm F/4 which I purchased used from a forum member. The SDM appears to work ok, but the focus time seems very slow, especially when compared to my HD Pentax-DA 55-300mm F4.5-6.3 ED PLM WR RE.

For those who own the DA* 300mm F/4 SDM, is this your experience as well? Or is the SDM on my lens maybe on it's way out?

In either case, for those that have done the conversion to camera focus drive, have you found that the lens focuses faster? Even compared to a fully working SDM version?

Thanks, Chris

**bwgv001** · 04-23-2021, 09:25 AM

I observed the same thing, did the conversion and can't be any happier. From my experience I highly recommend. If you follow the procedure posted in the forum -did mine with a K200D- then you will be done in 5 minutes.

**jatrax** · 04-23-2021, 10:11 AM

DA*300 is not noted as a fast focusing lens. Mine is noticeably slower than my DA 55-300. I think that is normal and not a sign that the SDM is failing.

jddwoods · 04-23-2021, 11:20 AM

I have both the DA* 200 & DA*300 and the 55-300 PLM. SDM is fine on both DA* lenses. Simply put, the PLM is much faster than either of them.

11GTCS · 04-23-2021, 12:20 PM

I’ve got the 300 (one I bought new this year), and the focus is fine to me, even for birding. Aside from occasionally hunting, I haven’t noticed any issue with focus performance, even when birding.

**ramseybuckeye** · 04-23-2021, 01:07 PM

I have the DA* and the PLM, the PLM is much faster focusing. I'm probably crazy but it seems faster on the DA 1.4TC. I've used it a lot lately so my technique is probably just better. Although today I went to my car and got the PLM to try to catch barn swallows in flight. Did not help, it's not the lens, I'm too slow to track them.

shyrsio · 04-23-2021, 02:35 PM

The sdm motor could be dropping in performance after time of use. Try to see a YouTube video of the outofocus and see if it matches.

gatorguy · 04-23-2021, 03:11 PM

Originally posted by ramseybuckeye

I have the DA* and the PLM, the PLM is much faster focusing. I'm probably crazy but it seems faster on the DA 1.4TC. I've used it a lot lately so my technique is probably just better. Although today I went to my car and got the PLM to try to catch barn swallows in flight. Did not help, it's not the lens, I'm too slow to track them.

I have the PLM and keep forgetting to give it a serious go. I was out an hour ago with the new K3 III and a *300 when I probably should have mounted the 55-300PLM

Kwong · 04-23-2021, 03:31 PM

Originally posted by cdw2000

I own the venerable DA* 300mm F/4 which I purchased used from a forum member. The SDM appears to work ok, but the focus time seems very slow, especially when compared to my HD Pentax-DA 55-300mm F4.5-6.3 ED PLM WR RE.

For those who own the DA* 300mm F/4 SDM, is this your experience as well? Or is the SDM on my lens maybe on it's way out?

In either case, for those that have done the conversion to camera focus drive, have you found that the lens focuses faster? Even compared to a fully working SDM version?

Thanks, Chris

Yes I have both and the 55-300 is definitely faster but I don’t think I’ll convert it anytime soon unless the sdm starts dying. No issues for the 8 yrs I’ve had it

**ramseybuckeye** · 04-23-2021, 04:27 PM

Originally posted by Kwong

Yes I have both and the 55-300 is definitely faster but I don’t think I’ll convert it anytime soon unless the sdm starts dying. No issues for the 8 yrs I’ve had it

Same here, it's not broke, don't fix it. But it's nice to have a lens with a "plan B".

Billk · 04-23-2021, 04:39 PM

It focuses much faster on my K1 than it did on the K3 or K7.

What you really need is a K3iii : )

**K-Three** · 04-23-2021, 06:01 PM

Originally posted by 11GTCS

Aside from occasionally hunting, I haven’t noticed any issue with focus performance, even when birding.

One lens I wish had a focus range limiter on it, Though It does not focus that close, it's a nuisance for it to go all the way to the close stop when it does miss. Especially w/BIF

**DWS1** · 04-23-2021, 06:20 PM - **1 Like**

Originally posted by K-Three

One lens I wish had a focus range limiter on it, Though It does not focus that close, it's a nuisance for it to go all the way to the close stop when it does miss. Especially w/BIF

This is my only complaint with this lens. I've found it focuses about the same as the older DA 55-300 but nowhere near as fast as the plm version. Few lenses do.

11GTCS · 04-24-2021, 01:48 PM

Originally posted by K-Three

One lens I wish had a focus range limiter on it, Though It does not focus that close, it's a nuisance for it to go all the way to the close stop when it does miss. Especially w/BIF

Concur, that’s really my only issue. Not that it’s too slow, just that without a limiter it has to move the glass a long way to get a shot. I’ve just learned to prefocus at “infinity” lock (actually past infinity, but you know). That forces it to start there and work back, which usually results in a practically instant lock.

**cdw2000** · 04-26-2021, 06:09 AM

Thanks for all the helpful replies. It sounds like my lens is working normally based on all the responses.

04-23-2021, 09:20 AM	#1
cdw2000 Site Supporter Join Date: Aug 2020 Location: New Hampshire Photos: Albums Posts: 244	*Pentax DA 300mm F/4 - Would focus be quicker if SDM de-activated?** I own the venerable DA* 300mm F/4 which I purchased used from a forum member. The SDM appears to work ok, but the focus time seems very slow, especially when compared to my HD Pentax-DA 55-300mm F4.5-6.3 ED PLM WR RE. For those who own the DA* 300mm F/4 SDM, is this your experience as well? Or is the SDM on my lens maybe on it's way out? In either case, for those that have done the conversion to camera focus drive, have you found that the lens focuses faster? Even compared to a fully working SDM version? Thanks, Chris

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04-23-2021, 09:25 AM	#2
bwgv001 Site Supporter Join Date: Aug 2015 Location: Alabama Photos: Gallery Posts: 698	I observed the same thing, did the conversion and can't be any happier. From my experience I highly recommend. If you follow the procedure posted in the forum -did mine with a K200D- then you will be done in 5 minutes.

04-23-2021, 10:11 AM	#3
jatrax Site Supporter Join Date: May 2010 Location: Washington Cascades Photos: Gallery \| Albums Posts: 12,992	DA*300 is not noted as a fast focusing lens. Mine is noticeably slower than my DA 55-300. I think that is normal and not a sign that the SDM is failing.

04-23-2021, 11:20 AM	#4
jddwoods Pentaxian Join Date: Nov 2012 Location: Newark, Delaware Posts: 1,035	I have both the DA* 200 & DA300 and the 55-300 PLM. SDM is fine on both DA lenses. Simply put, the PLM is much faster than either of them.

04-23-2021, 12:20 PM	#5
11GTCS Forum Member Join Date: Feb 2021 Posts: 98	I’ve got the 300 (one I bought new this year), and the focus is fine to me, even for birding. Aside from occasionally hunting, I haven’t noticed any issue with focus performance, even when birding.

04-23-2021, 01:07 PM	#6
ramseybuckeye Site Supporter Join Date: Apr 2009 Location: Hampstead, NC Photos: Gallery Posts: 17,296	I have the DA* and the PLM, the PLM is much faster focusing. I'm probably crazy but it seems faster on the DA 1.4TC. I've used it a lot lately so my technique is probably just better. Although today I went to my car and got the PLM to try to catch barn swallows in flight. Did not help, it's not the lens, I'm too slow to track them.

04-23-2021, 02:35 PM	#7
shyrsio Pentaxian Join Date: Apr 2016 Location: Tirana Posts: 780	The sdm motor could be dropping in performance after time of use. Try to see a YouTube video of the outofocus and see if it matches.

04-23-2021, 03:11 PM	#8
gatorguy Moderator Join Date: Feb 2015 Location: Central Florida Photos: Gallery Posts: 6,094	Originally posted by ramseybuckeye I have the DA* and the PLM, the PLM is much faster focusing. I'm probably crazy but it seems faster on the DA 1.4TC. I've used it a lot lately so my technique is probably just better. Although today I went to my car and got the PLM to try to catch barn swallows in flight. Did not help, it's not the lens, I'm too slow to track them. I have the PLM and keep forgetting to give it a serious go. I was out an hour ago with the new K3 III and a *300 when I probably should have mounted the 55-300PLM

04-23-2021, 03:31 PM	#9
Kwong Senior Member Join Date: Feb 2013 Location: Canada Photos: Albums Posts: 198	Originally posted by cdw2000 I own the venerable DA* 300mm F/4 which I purchased used from a forum member. The SDM appears to work ok, but the focus time seems very slow, especially when compared to my HD Pentax-DA 55-300mm F4.5-6.3 ED PLM WR RE. For those who own the DA* 300mm F/4 SDM, is this your experience as well? Or is the SDM on my lens maybe on it's way out? In either case, for those that have done the conversion to camera focus drive, have you found that the lens focuses faster? Even compared to a fully working SDM version? Thanks, Chris Yes I have both and the 55-300 is definitely faster but I don’t think I’ll convert it anytime soon unless the sdm starts dying. No issues for the 8 yrs I’ve had it

04-23-2021, 04:27 PM	#10
ramseybuckeye Site Supporter Join Date: Apr 2009 Location: Hampstead, NC Photos: Gallery Posts: 17,296	Originally posted by Kwong Yes I have both and the 55-300 is definitely faster but I don’t think I’ll convert it anytime soon unless the sdm starts dying. No issues for the 8 yrs I’ve had it Same here, it's not broke, don't fix it. But it's nice to have a lens with a "plan B".

04-23-2021, 04:39 PM	#11
Billk Veteran Member Join Date: Jun 2012 Location: Melbourne, Victoria Posts: 349	It focuses much faster on my K1 than it did on the K3 or K7. What you really need is a K3iii : )

04-23-2021, 06:01 PM	#12
K-Three Loyal Site Supporter Join Date: May 2014 Location: Pugetopolis, WA Photos: Gallery Posts: 938	Originally posted by 11GTCS Aside from occasionally hunting, I haven’t noticed any issue with focus performance, even when birding. One lens I wish had a focus range limiter on it, Though It does not focus that close, it's a nuisance for it to go all the way to the close stop when it does miss. Especially w/BIF

04-23-2021, 06:20 PM - 1 Like	#13
DWS1 Site Supporter Join Date: Aug 2018 Location: Arkansas, USA Posts: 1,169	Originally posted by K-Three One lens I wish had a focus range limiter on it, Though It does not focus that close, it's a nuisance for it to go all the way to the close stop when it does miss. Especially w/BIF This is my only complaint with this lens. I've found it focuses about the same as the older DA 55-300 but nowhere near as fast as the plm version. Few lenses do.

04-24-2021, 01:48 PM	#14
11GTCS Forum Member Join Date: Feb 2021 Posts: 98	Originally posted by K-Three One lens I wish had a focus range limiter on it, Though It does not focus that close, it's a nuisance for it to go all the way to the close stop when it does miss. Especially w/BIF Concur, that’s really my only issue. Not that it’s too slow, just that without a limiter it has to move the glass a long way to get a shot. I’ve just learned to prefocus at “infinity” lock (actually past infinity, but you know). That forces it to start there and work back, which usually results in a practically instant lock.

04-26-2021, 06:09 AM	#15
cdw2000 Site Supporter Join Date: Aug 2020 Location: New Hampshire Photos: Albums Posts: 244 Original Poster	Thanks for all the helpful replies. It sounds like my lens is working normally based on all the responses.

Pentax DA* 300mm F/4 - Would focus be quicker if SDM de-activated?

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