16-50 DA* Focus broken

**smh2005** · 09-11-2018, 03:30 PM

My Pentax DA* 16-50 2.8 ED AL (IF) SDM suddenly stopped focusing. It was working fine. And then it wasn't. Now I can turn the focus ring and it doesn't stop. I can turn forever. The motor does not make a sound so it clearly is not engaging.

The estimated repair price from Precision Camera is $212. It's my favorite lens, but at 7 years old and, to be honest, more cell phone photography than SLR, I'm a little concerned that within a few more years I'll move to either a full-frame Pentax or let my SLR use atrophy.

I'm seeking opinions:
- is it likely that this repair estimate is accurate or more likely that they will charge more (or less) after seeing the lens?
- is it likely that a repair will return the lens to pristine condition?
- should I go ahead with the repair at this cost?

Sandy Hancock · 09-11-2018, 03:39 PM

You can convert it to screw drive for no cost if you have access to an appropriate camera body and some confidence with a computer. I managed it years ago with a mate's K10D.

Video instructions HERE

If not, send it to @UncleVanya and he'll do it for you for a nominal fee.

But if silent focus is important to you, the quoted fee sounds about right and I'd go for it.

**rogerstg** · 09-11-2018, 04:57 PM

It's too bad because that's a wonderful lens. Assuming it will focus manually (if the switch is set to MF), I've heard of people having success "exercising" the focus a bit, then re-engaging AF.

**smh2005** · 09-11-2018, 05:16 PM

Sandy,
So my problem is a failed SDM? My symptoms are consistent with that? I had no idea that there are multiple focus mechanisms, never mind that they are programmable! Thank you!!!!!
Steve

**UncleVanya** · 09-11-2018, 07:39 PM

Originally posted by smh2005

My Pentax DA* 16-50 2.8 ED AL (IF) SDM suddenly stopped focusing. It was working fine. And then it wasn't. Now I can turn the focus ring and it doesn't stop. I can turn forever. The motor does not make a sound so it clearly is not engaging.

The estimated repair price from Precision Camera is $212. It's my favorite lens, but at 7 years old and, to be honest, more cell phone photography than SLR, I'm a little concerned that within a few more years I'll move to either a full-frame Pentax or let my SLR use atrophy.

I'm seeking opinions:
- is it likely that this repair estimate is accurate or more likely that they will charge more (or less) after seeing the lens?
- is it likely that a repair will return the lens to pristine condition?
- should I go ahead with the repair at this cost?

Does the lens focus manually? Set the body to manual focus and the lens to manual focus and turn the focus ring. At some point it should come into focus. If it does then yes sdm likely died. If it doesn't then more may be wrong.

Conversion to screw drive is possible and isn't hard if you are technical and you have a sufficiently old camera. What DSLR bodies do you have? As Sandy mentioned I also offer a conversion service. I charge $30 plus you pay shipping both ways.

Let me know if you have questions my intent is to return these lenses to their glory rather than have them collecting dust.

Oh and turning forever without stopping is normal for that lens. That series of DA* lenses works that way due to the type of quickshift clutch it uses. It never hits a hard stop at either end as far as the focus ring is concerned.

DeadJohn · 09-11-2018, 07:46 PM

Originally posted by smh2005

...Now I can turn the focus ring and it doesn't stop. I can turn forever...

That part sounds like ordinary normal behavior. As you turn the ring it should move easily as the focus distance changes, until you reach infinity or close focus, then you should feel a light click and the resistance increases. You can keep turning forever at that increased resistance. Reverse direction and it should be easier to rotate again, until you hit the other end of focus and resistance increases.

Does manual focus work? Try it with the AF/MF switch in both positions.

Does the focus gauge move as you turn the focus ring?

steve_k · 09-12-2018, 03:51 AM

To replace the lens with a used one will cost you $400. If it’s your favorite then you should repair it or convert it. I would probably have it repaired as non screw drive lenses sell for more on the used market.

09-11-2018, 03:30 PM	#1
smh2005 Site Supporter Join Date: Apr 2010 Location: Connecticut Posts: 22	*16-50 DA Focus broken** My Pentax DA* 16-50 2.8 ED AL (IF) SDM suddenly stopped focusing. It was working fine. And then it wasn't. Now I can turn the focus ring and it doesn't stop. I can turn forever. The motor does not make a sound so it clearly is not engaging. The estimated repair price from Precision Camera is $212. It's my favorite lens, but at 7 years old and, to be honest, more cell phone photography than SLR, I'm a little concerned that within a few more years I'll move to either a full-frame Pentax or let my SLR use atrophy. I'm seeking opinions: - is it likely that this repair estimate is accurate or more likely that they will charge more (or less) after seeing the lens? - is it likely that a repair will return the lens to pristine condition? - should I go ahead with the repair at this cost?

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09-11-2018, 03:39 PM	#2
Sandy Hancock Moderator Site Supporter Join Date: Feb 2012 Location: Adelaide Hills, South Australia Photos: Gallery \| Albums Posts: 11,275	You can convert it to screw drive for no cost if you have access to an appropriate camera body and some confidence with a computer. I managed it years ago with a mate's K10D. Video instructions HERE If not, send it to @UncleVanya and he'll do it for you for a nominal fee. But if silent focus is important to you, the quoted fee sounds about right and I'd go for it.

09-11-2018, 04:57 PM	#3
rogerstg Loyal Site Supporter Join Date: Oct 2007 Location: Rhode Island Photos: Albums Posts: 1,168	It's too bad because that's a wonderful lens. Assuming it will focus manually (if the switch is set to MF), I've heard of people having success "exercising" the focus a bit, then re-engaging AF.

09-11-2018, 05:16 PM	#4
smh2005 Site Supporter Join Date: Apr 2010 Location: Connecticut Posts: 22 Original Poster	Sandy, So my problem is a failed SDM? My symptoms are consistent with that? I had no idea that there are multiple focus mechanisms, never mind that they are programmable! Thank you!!!!! Steve

09-11-2018, 07:39 PM	#5
UncleVanya Loyal Site Supporter Join Date: Jul 2014 Photos: Gallery \| Albums Posts: 28,468	Originally posted by smh2005 My Pentax DA* 16-50 2.8 ED AL (IF) SDM suddenly stopped focusing. It was working fine. And then it wasn't. Now I can turn the focus ring and it doesn't stop. I can turn forever. The motor does not make a sound so it clearly is not engaging. The estimated repair price from Precision Camera is $212. It's my favorite lens, but at 7 years old and, to be honest, more cell phone photography than SLR, I'm a little concerned that within a few more years I'll move to either a full-frame Pentax or let my SLR use atrophy. I'm seeking opinions: - is it likely that this repair estimate is accurate or more likely that they will charge more (or less) after seeing the lens? - is it likely that a repair will return the lens to pristine condition? - should I go ahead with the repair at this cost? Does the lens focus manually? Set the body to manual focus and the lens to manual focus and turn the focus ring. At some point it should come into focus. If it does then yes sdm likely died. If it doesn't then more may be wrong. Conversion to screw drive is possible and isn't hard if you are technical and you have a sufficiently old camera. What DSLR bodies do you have? As Sandy mentioned I also offer a conversion service. I charge $30 plus you pay shipping both ways. Let me know if you have questions my intent is to return these lenses to their glory rather than have them collecting dust. Oh and turning forever without stopping is normal for that lens. That series of DA* lenses works that way due to the type of quickshift clutch it uses. It never hits a hard stop at either end as far as the focus ring is concerned.

09-11-2018, 07:46 PM	#6
DeadJohn Pentaxian Join Date: Jan 2011 Location: New York Posts: 4,834	Originally posted by smh2005 ...Now I can turn the focus ring and it doesn't stop. I can turn forever... That part sounds like ordinary normal behavior. As you turn the ring it should move easily as the focus distance changes, until you reach infinity or close focus, then you should feel a light click and the resistance increases. You can keep turning forever at that increased resistance. Reverse direction and it should be easier to rotate again, until you hit the other end of focus and resistance increases. Does manual focus work? Try it with the AF/MF switch in both positions. Does the focus gauge move as you turn the focus ring?

09-12-2018, 03:51 AM	#7
steve_k Site Supporter Join Date: Dec 2016 Location: Shelton, CT Photos: Albums Posts: 708	To replace the lens with a used one will cost you $400. If it’s your favorite then you should repair it or convert it. I would probably have it repaired as non screw drive lenses sell for more on the used market.