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02-10-2011, 08:44 AM   #1
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Why No Inexpensive SDM?

Although I've been a Pentaxian for a couple of years I'm not really committed too much since I only have a K-x and 3 lenses. So I took a look at Nikon out of curiosity when at the LCS the other day. Even the most basic cameras have the equivalent of SDM on the kit lenses. I've never used an SDM lens but when I picked up the D90 I was impressed by the quick focus and silent operation. If nikon can make their cheapest lenses SDM why can't we at least get a couple of affordable and reliable SDM lenses from Pentax?

I'm not here to get, 'Don't let the door hit you in the arse' comments but I'm considering the switch. It's looking like the price savings by going pentax that existed when I became a pentaxian are going away. Even Sigma and Tamron do other lenses in SDM equivalent and not for Pentax. Why is that?

(DUCKING and waiting for flying shoes)

02-10-2011, 08:49 AM   #2
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good question, not sure i'd buy one myself given the sdm history as it sits though. Mind you most of the time i shoot with legacy primes now so even AF is a treat when i use it
02-10-2011, 08:56 AM   #3
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Nikon's cheapest lenses have SWM (not ring type), but they aren't very good.

Pentax used to be a great value brand (and can still be with the right choices, such as the 16-45). They are moving away from that. But they are still a great choice for quality stabilized primes, which for the most part cannot be bought on Nikon for any price.

Because Canikon sell bodies without motors, they have to put the motors in the cheap lenses. There is no screwdrive option for the type of kits that include these lenses. I think they pass the cost on to the customer. The 18-55 lens, for example, resells used for about $100, whereas the Pentax 18-55 AL-II resells for about $60. Similarly, the Nikon 50-200 resells for about $170, where the Pentax 50-200 can be found for less than $100.

I think Pentax is smart to use cheaper construction techniques where it doesn't matter much and instead putting it toward things like non-rotating front elements, finger windows for the hoods, sometimes metal mounts, and sometimes WR. Canikon cannot use screw drive. Pentax can.

/rambling
02-10-2011, 09:02 AM   #4
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Even if SDM were reliable to start with, AF performance would be still behind Nikon. If you are opened to any option, I think it would be a waste of time waiting for Pentax to get serious. If you like Limited lenses, go get them. Otherwise, there is not much attraction.

02-10-2011, 09:18 AM   #5
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All of Sigma's lenses that have "SDM" have it in the pentax mount versions...
02-10-2011, 09:21 AM   #6
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QuoteOriginally posted by Ubuntu_user Quote
All of Sigma's lenses that have "SDM" have it in the pentax mount versions...
OK, HSM for sigma.

I don't think the 50 1.4 does. And I think that the 10-20 F4-5.6 is also HSM for Nikon..
02-10-2011, 09:32 AM   #7
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I'm sure they could do it, and to some extent have (17-70, 18-135), but why put a motor in the lens when you already have a perfectly good one in the body? The reason Nikon have a motor in their kit lenses is because the low end Nikon bodies don't have a screwdrive.

Focusing speed is also heavily dependent on the focusing throw. Some lenses have to turn over 180 to go from one end to the other of the focusing scale while others barely have to turn at all. One approach is better for AF while the other is better for MF.
02-10-2011, 09:36 AM   #8
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QuoteOriginally posted by joakimfors Quote
I'm sure they could do it, and to some extent have (17-70, 18-135), but why put a motor in the lens when you already have a perfectly good one in the body? The reason Nikon have a motor in their kit lenses is because the low end Nikon bodies don't have a screwdrive.

Focusing speed is also heavily dependent on the focusing throw. Some lenses have to turn over 180 to go from one end to the other of the focusing scale while others barely have to turn at all. One approach is better for AF while the other is better for MF.
True, but the internal motors seem SO much quieter and smoother. My 16-45 sounds like it's going to bind up at any moment. And the 17-70 and 18-135 are still 500+ dollar lenses compared to the more inexpensive Nikons.

And if pentax comes out with an EVIL that takes K mount lenses, they'll really need the SDM unless they want it to have a large bulky camera.

02-10-2011, 09:45 AM   #9
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QuoteOriginally posted by VaughnA Quote
True, but the internal motors seem SO much quieter and smoother. My 16-45 sounds like it's going to bind up at any moment. And the 17-70 and 18-135 are still 500+ dollar lenses compared to the more inexpensive Nikons.

And if pentax comes out with an EVIL that takes K mount lenses, they'll really need the SDM unless they want it to have a large bulky camera.
I don't see any point in SDM in kit lens and the like. Screw drive keeps cost and size down on the lenses and there is no speed benefit to the SDM micro motors (there may be some speed benefit to the DC motors that are in the 18-135 lens). Lenses with motors in them have a much higher rate of failure compared to lenses that are screw driven. Even Canon and Nikon's silent wave motors, or whatever they call them fail much more often than screw driven lenses.

Where I would like to see improvement is in the upper end lenses, where hopefully faster motors would improve auto focus speed and tracking ability.
02-10-2011, 09:50 AM   #10
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I guess I'm enticed by the quiet of the SWM lenses. I can't count the number of times that someone has turned around when they hear the BRRRRT of the focus motor on my 16-45 or 55-300. I like the quiet of my manuals but the focus system on them is getting a bit flaky;-)
02-10-2011, 09:52 AM   #11
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It's cheaper for lens manufacturers to use a motor. Mechanical linkages require fine tolerances and careful hand assembly and adjustment. SDM should be cheaper but because it's new and quieter, lenses with this feature are being sold for more. It's kind of like power windows on cars. It's sold as an option on higher end cars but crank windows are more expensive to build and assemble. I guess it's all about profit. It appears Sigma is building all their new lenses with HSM motors. The seem to be phasing them out. It's much cheaper for them as one lens can be built for every camera with only a different mount. Whether a motor driven lens is better is open to debate. It adds size and weight to the lens. The Pentax Limiteds wouldn't be possible with SDM motors.
02-10-2011, 10:09 AM   #12
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QuoteOriginally posted by reeftool Quote
It's cheaper for lens manufacturers to use a motor. Mechanical linkages require fine tolerances and careful hand assembly and adjustment. SDM should be cheaper but because it's new and quieter, lenses with this feature are being sold for more. It's kind of like power windows on cars. It's sold as an option on higher end cars but crank windows are more expensive to build and assemble. I guess it's all about profit. It appears Sigma is building all their new lenses with HSM motors. The seem to be phasing them out. It's much cheaper for them as one lens can be built for every camera with only a different mount. Whether a motor driven lens is better is open to debate. It adds size and weight to the lens. The Pentax Limiteds wouldn't be possible with SDM motors.
This is true, except that it requires redesign of existing lenses. If you already have a lens plan (say a FA 50) and you have to redesign it to include a motor, the r and d costs will jump up compared to a lens where that was paid for long ago. Look at the Tamron 17-50 f2.8 (still sold with screw drive on Pentax) versus the in lens motor varieties sold in other mounts.

At the same time, most people do want silent, fast auto focus and Pentax has indicated that all future lenses (other than limiteds) will have in lens motors.
02-10-2011, 10:56 AM   #13
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Yes, they do have to redesign the lenses but in the long run, the manufacturing costs decline. This will be especially true for a company like Sigma that builds lenses for many camera bodies.
02-10-2011, 11:01 AM   #14
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QuoteOriginally posted by reeftool Quote
Yes, they do have to redesign the lenses but in the long run, the manufacturing costs decline. This will be especially true for a company like Sigma that builds lenses for many camera bodies.
Redesign does cost money, but no company takes the cost hit completely up front they factor r&d costs over a longer term. The biggest issue of course would be backwards compatability (not that i think they are overly concerned about that) to put out cheap entry level SDM, they would have to eliminate the screw drive to keep cost in line, then older cameras wouldn't be compatible. Of course they could put out a firmware for all the old cameras that don't have SDM support and then it would just be old film cameras without support. And i'm more than certain they don't care about that
02-10-2011, 11:14 AM   #15
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QuoteOriginally posted by eddie1960 Quote
Of course they could put out a firmware for all the old cameras that don't have SDM support and then it would just be old film cameras without support. And i'm more than certain they don't care about that
SDM is more than firmware. You have to have the electrical contacts in the mount.

All the cameras that can do SDM are able to.
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