advantage of SDM lenses

Wulifou · 10-20-2008, 01:22 AM

Hi all,

I have a question for you all who own SDM lenses. I want to acquire a wide zoom and am hesitating between the DA* 16-50 and the Tamron 17-50 F2.8. My local reseller says I should take the Tamron, since for approx. 300$ less, I would have similar if not better IQ. For my uses the weathersealing alone would not justify spending more money on the Pentax lense, but since I do a lot of low light, noisy and endless AF hunting would be a real issue.
So here is my question : in your experience, is there really such a big difference in speed and noise when using SDM lenses ? (I cannot compare, because prior to my K20D, I only owned a all-metall-all-manual Praktika SLR and a bridge camera ...)

thx for your input

soccerjoe5 · 10-20-2008, 02:00 AM

Hmm

1. weathersealing
2. silent AF (very good to have in stage performances like in theatres)
3. AF override anytime

My 16-50 is virtually silent. When I first got it I had to put my ear on it to check if the AF was working hahaha.

Wulifou · 10-20-2008, 02:05 AM

did you also notice any AF speed differences ? In other terms, is SDM "only" silent or is there also less AF hunting than with screw drive ?

Spex · 10-20-2008, 02:29 AM

Originally Posted by soccerjoe5

Hmm

1. weathersealing
.

17-70/4 SDM is not weathersealed

Wulifou · 10-20-2008, 02:40 AM

Originally Posted by Spex

17-70/4 SDM is not weathersealed

that's right Spex, but since my hesitation is between DA*16-50 and Tamron 17-50, I think soccerjoe5 points are quite pertinent

soccerjoe5 · 10-20-2008, 02:41 AM

Originally Posted by Spex

17-70/4 SDM is not weathersealed

I was referring to the 16-50 since he's deciding between the 16-50 and tammy 17-50

Spex · 10-20-2008, 02:48 AM

Ahaaa... Ok

10-20-2008, 04:10 AM

Originally Posted by Wulifou

Hi all,

I have a question for you all who own SDM lenses. I want to acquire a wide zoom and am hesitating between the DA* 16-50 and the Tamron 17-50 F2.8. My local reseller says I should take the Tamron, since for approx. 300$ less, I would have similar if not better IQ. For my uses the weathersealing alone would not justify spending more money on the Pentax lense, but since I do a lot of low light, noisy and endless AF hunting would be a real issue.
So here is my question : in your experience, is there really such a big difference in speed and noise when using SDM lenses ? (I cannot compare, because prior to my K20D, I only owned a all-metall-all-manual Praktika SLR and a bridge camera ...)

thx for your input

Bonjour, Wulifou!

I saw in your profile that you have the same camera as I do so my experience applies and hopefully will help you to choose. The Tamron is a nice lens from what I saw but my choice was largely based on the weather sealing factor and secondly on the SDM. I was also a bit worried reading all the stories about bad copies of the DA* and did a lot of research. My conclusions:

- as a combo with K20D this lens has tremendous less chances to be a bad focuser (compared to K10D). I really don't know why but the K10D+DA* is the bulk of troubles associated with this lens. Also the CA (PF) is way less on the new sensor;
- about the focus hunting in low light in my experience it happens especially when the target is a low contrast one (and I think most of the problem is from the AF module not the lens) and I saw it become more intense when the battery starts to deplete. I often use quick-shift (another great feature the Tamron don't have, btw) to roughly position the lens close to focus and it does the rest from there;
- the noise as you've been told already is almost not-existent and I suggest you keep the "confirmation beep" to realise when the focus is achieved;
- in good light my lens focuses "normal" that means not instantaneous but fairly quick. I don't think there are any speed benefits resulting from SDM compared to screw drive or at least not visible ones. The lens has a lot of glass in it and probably a ring motor with more torque would of speed things up more significantly;
- the esential part is the optical quality. I honnestly say that this is my most versatile lens and the last I would part away but of course it's a matter of taste. It constantly underexposes a bit so you may want to keep that in mind when shooting in low light. IMO it is very, very sharp and renders colors beautifuly with superb microcontrast. You can make your own opinion about it from the pictures.

Anyway I have absolutely no regrets for buying this lens whatsoever.

Hope it helps,
Radu

Wulifou · 10-20-2008, 06:25 AM

Originally Posted by RaduA

Bonjour, Wulifou!

I saw in your profile that you have the same camera as I do so my experience applies and hopefully will help you to choose. The Tamron is a nice lens from what I saw but my choice was largely based on the weather sealing factor and secondly on the SDM. I was also a bit worried reading all the stories about bad copies of the DA* and did a lot of research. My conclusions:

- as a combo with K20D this lens has tremendous less chances to be a bad focuser (compared to K10D). I really don't know why but the K10D+DA* is the bulk of troubles associated with this lens. Also the CA (PF) is way less on the new sensor;
- about the focus hunting in low light in my experience it happens especially when the target is a low contrast one (and I think most of the problem is from the AF module not the lens) and I saw it become more intense when the battery starts to deplete. I often use quick-shift (another great feature the Tamron don't have, btw) to roughly position the lens close to focus and it does the rest from there;
- the noise as you've been told already is almost not-existent and I suggest you keep the "confirmation beep" to realise when the focus is achieved;
- in good light my lens focuses "normal" that means not instantaneous but fairly quick. I don't think there are any speed benefits resulting from SDM compared to screw drive or at least not visible ones. The lens has a lot of glass in it and probably a ring motor with more torque would of speed things up more significantly;
- the esential part is the optical quality. I honnestly say that this is my most versatile lens and the last I would part away but of course it's a matter of taste. It constantly underexposes a bit so you may want to keep that in mind when shooting in low light. IMO it is very, very sharp and renders colors beautifuly with superb microcontrast. You can make your own opinion about it from the pictures.

Anyway I have absolutely no regrets for buying this lens whatsoever.

Hope it helps,
Radu

Radu,

thx a lot for sharing your experience. I really appreciate. So for me, the deal is settled : AF override, silence, weathersealing and excellent optical quality..... heading to the local reseller right now

10-20-2008, 06:57 AM

Originally Posted by Wulifou

Radu,

thx a lot for sharing your experience. I really appreciate. So for me, the deal is settled : AF override, silence, weathersealing and excellent optical quality..... heading to the local reseller right now

Wulifou,

I am glad that I could help you and I wish you a lot of beautiful pictures with your new lens (that is regardless of the weather and in silence

). Please post some comments after the purchase I am curious what you'll feel about it!

Regards,
Radu

sychen · 10-20-2008, 07:07 AM

I'm one of the happy few I guess with DA*16-50mm and K10D.
Focus was spot on with no issues at all.

Focus is nice and silent... but not faster.
I found that it focuses with less hunting than my Tamron 28-75mm. I know not the 17-50mm but don't have that lens.

But overall, I just love the colour/contrast and sharpness that it produces.

Cheers
Shang

deuces · 10-20-2008, 07:26 AM

Some other differences.

The DA* is huge and heavy, and takies 77mm filters.

Hm I was suprised that the Tamron 17-50 doesn't have an aperture ring either. I'm guessing neither are full frame?

Their minimum focus distances are also similar.

10-20-2008, 08:00 AM

Originally Posted by sychen

I'm one of the happy few I guess with DA*16-50mm and K10D.
Focus was spot on with no issues at all.

Focus is nice and silent... but not faster.
I found that it focuses with less hunting than my Tamron 28-75mm. I know not the 17-50mm but don't have that lens.

But overall, I just love the colour/contrast and sharpness that it produces.

Cheers
Shang

Hi, Shang!

I never said that K10D + DA* 16-50 is a problematic combo because I have no statistical data to think one way or another. I just say that from what I saw on different forums a very large part of people that complain about this lens tryied to use it on a K10D.

The poor record this lens has IMO has to do with commercial practice in the USA. In Europe a malfunctioning item (lens in this case) must be repaired or exchanged with a functional one during the warranty period. So it's more likely that most of the defective copies sold in Europe were repaired (with various degree of succes) or replaced with newer ones.
In the US a poor copy of this lens was shiped back and forth between the same dealer and multiple customers that asked for a refund and this added enormously to its bad reputation.

Regards,
Radu

BBear · 10-20-2008, 09:42 AM

i've had the 16-50 for a week and then bought the 50-135.. both SDM focus...

Like mentoned before, noise is inexistent... to the point you wonder if the AF is working!

Now, speed... hmmm.. hard to say it is faster... so that means is VERY similar to screw AF....

But one think i was always curious is about battery consumption. I started my collection with MF lenses and the battery would last THOUSANDS of clicks... (literally) and after getting the NOISY (but great) DA 55-300, i was surprised to see how faster the battery drained..

Now with the SDM, and less noise (thermodynamics, less noise could mean less wasted energy) i wonder if the AF is more energy efficient...

Anyone has ever read anything about that? Maybe not signficant?

Later

BB

Venturi · 10-20-2008, 10:09 AM

I own the Tamron 17-50. Bought it rather than the 16-50 largely due to the $300 difference. And I am very happy with it. I do a lot of indoor, marginal light, shooting (kids wee!) and have had zero problems with it hunting about noisily trying to AF.
I now also own the DA*50-135 and yes, the silent SDM motor is super cool and I absolutely love this lens. And I'm still glad I saved $300 on the wide zoom choice.
I'm sure the 16-50 is an equally good lens; for me though I can't believe it is $300 better.