[Clavius]

I can get a really sweet deal on a DA* 55 1.4 SDM. The deal is so sweet because the current owner notes that the SDM makes a high pitch sound during auto focusing. Maybe "squeeking" is the wrong word to describe it. It's more like a chirp/whistle. I'm a sucker for deals like this. Maybe you guys can talk some sense into me. Or preferably, confirm that this will ok.

Is this one of the clear signs that the SDM is going some time soon? Or could it still go on for years?

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Last edited by Clavius; 06-16-2017 at 02:29 AM.

[Rondec]

It's hard to say. I can actually hear my 55 focus motor working if I listen carefully, just a high pitched whine and it has done that for years. On the other hand, a squeak would be concerning that there is something internally that is binding up and could make the tiny focus motor in it go out.

[Clavius]

Thanks for your reply, I thought as much.

I've also come to the conclusion that my assumption that the DA*55 1.4 would be an improvement over my FA 50 1.4 is false. According to Photozone it has worse IQ then the FA 50. That was not what I expected. Moreover the DA* 55 autofocus takes a full second longer to lock.

So, I'm just going to leave this offer alone.

[Rondec]

From a personal standpoint, I found the DA *55 significantly sharper than the FA 50 at apertures wider than f2.8. The biggest negative is (as you say) slowish auto focus. I think this lens has been plagued by poor as well as good copies and my guess is that Photozone got a not so good copy to test.

Here are two images at f1.4 on the K-1 with the DA *55.

[MrNPhoto]

Thanks for your reply, I thought as much.

I've also come to the conclusion that my assumption that the DA*55 1.4 would be an improvement over my FA 50 1.4 is false. According to Photozone it has worse IQ then the FA 50. That was not what I expected. Moreover the DA* 55 autofocus takes a full second longer to lock.

So, I'm just going to leave this offer alone.

I own both the FA 50 and DA55, and I greatly prefer the DA for anything from wide open f1.4 to f2.8. Also, for closer distances (<2m) it gives more pleasing results than the FA. Focus speed is slow compared to the FA. Mine was silent at purchase, but now has an audible high-pitched squeak as it focuses. One of my favorite lenses (on APS-C).

[slivo]

My DA 55 squeaks also. To me it seems more like a behaviour of this lens.

On the other hand, in my DA16-50 the SDM died, shortly after the warranty . It was working properly, not making any noises at all, or any other signs of upcoming failure - I just once put It on the camera and the sdm was dead. I think the reason was that I have not used this lens for couple of months.

[mattt]

The real sweetness is if the seller did not shoot with the lensregularly the squeek is most noticable, but through regular use it goes away... snap it up IMO

[Clavius]

DXO's scores seem to agree entirely with Photozone's:

Pentax smc DA Star 55mm F1.4 SDM mounted on Pentax K-3 : Tests and Reviews

Pentax smc FA 50mm F1.4 mounted on Pentax K-3 : Tests and Reviews

I realize fully that I'm letting steering way to much on numbers instead of actual performance. It just doesn't feel much like an upgrade. Going to look for another sweet deal.

[Rondec]

DXO's scores seem to agree entirely with Photozone's:

Pentax smc DA Star 55mm F1.4 SDM mounted on Pentax K-3 : Tests and Reviews

Pentax smc FA 50mm F1.4 mounted on Pentax K-3 : Tests and Reviews

I realize fully that I'm letting steering way to much on numbers instead of actual performance. It just doesn't feel much like an upgrade. Going to look for another sweet deal.

DxO Mark actually gave the DA *55 a score of 27 and the FA 50 a score of 21 and puts down that the sweet spot for the DA *55 is f2, while sharpness for the FA 50 begins at f2.8, which is (I think) what people on this thread have stated. In addition, chromatic aberration was significantly worse on the FA 50 than the DA *55.

But if you are happy with the FA 50, then it is reasonable to continue shooting with it.

[mee]

My 16-50mm's SDM squeeked like that for it's first year of life. Then one day, after sitting on a shelf for a couple of months, it apparently decided it was done.

Converting it to screwdrive fixed that though.

[jddwoods]

My DA* 200 sometimes has a slight squeaking sound, especially at the last moment when it locks focus. It is only audible in a quiet indoor setting. Outdoors it is inaudible. Occasionally my DA 17-17 also makes a slightly different squeaking sound. I do not think it is a problem with either lens. What is a concern with both lenses is if they sit around unused too long the SDM will stop working for a few minutes. The longer it sits, the longer it takes to start working. Others have observed this as well. My thought is if you are going to use this lens fairly frequently you should be fine. On the other hand, if you do not mind screwdrive autofocus noise, the FA 50's are sharp, lightweight and compact. When I decided I wanted a fast 50, I got an FA 50mm f1.7 used in like new condition and am perfectly happy with it.