Re: Sigma HSM lenses for Pentax KAF mount
Inner Focus wrote: Yes, interesting posts by the engineer who started that thread. The conclusion is that ultrasonic motors CAN be faster, it's just that Pentax have chosen a poor implementation (SDM) which doesn't make full use of the technology, and thus it's results are far from optimal (they should have chosen a ring-type motor instead of a micromotor). I've always suspected, and still suspect, that the focus motor speed is not really the limiting factor on the Pentax AF system. Or to be more blunt, It's always seemed to me that the logic that goes my AF is slow, so the motor must be made faster is an example of narrow-minded thinking. Remember that there's a lot more involved in an AF system than just a motor. I've also suspected (or experienced) that the Pentax AF isn't really as slow as some would have it, or not slow at all in relative terms if you compare fairly (as Mr Robb points out), but that's a different issue. - T -- PDML Pentax-Discuss Mail List PDML@pdml.net http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions.
Re: Sigma HSM lenses for Pentax KAF mount
[ ... ] OK, I also have a question: what's the advantage of ultrasonic motors? I'm interested in AF speed, since I've had a lot of trouble with my camera and it's kit lens (annoying AF hunting or even impossible AF in not-so-low :( light). It's sort of been pointed out by myself and others already, but if AF hunting or inability to focus is the problem, an ultrasonic motor won't help a lot. HSM/SDM merely means that a different kind of motor that moves the focusing ring to the place it needs to be. When you experience hunting or missed focus, the camera doesn't really know where that place is, so how it was going to get there makes little difference. Or maybe it might hunt faster or quieter with a different motor, but what you really need is better AF sensors. Or a faster lens... About ultrasonic motors (technical article): http://en.wikipedia.org/wiki/Ultrasonic_motor PS: is HTML formatting of emails allowed on this list? A.M. -- PDML Pentax-Discuss Mail List PDML@pdml.net http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions.
Re: Sigma HSM lenses for Pentax KAF mount
- Original Message - From: Toralf Lund Subject: Re: Sigma HSM lenses for Pentax KAF mount I've also suspected (or experienced) that the Pentax AF isn't really as slow as some would have it, or not slow at all in relative terms if you compare fairly (as Mr Robb points out), but that's a different issue. It was pointed out to me in an offlist post that the cameras that Pentax AF can keep up with are entry level cameras from the other manufacturers, as these are the ones in the same price league. It would be nice if they would set their sights a bit higher, but a Pentax that would compete with a high end Canon would probably cost the end user 2-3 times what the Canon would cost due to the economies of scale. We can't expect the company to underwrite our hobby, if we want the good stuff we have to be willing to pay for it. William Robb -- PDML Pentax-Discuss Mail List PDML@pdml.net http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions.
Re: Sigma HSM lenses for Pentax KAF mount / focus speed
On Nov 26, 2007, at 2:58, Toralf Lund wrote: I've also suspected (or experienced) that the Pentax AF isn't really as slow as some would have it, or not slow at all in relative terms if you compare fairly (as Mr Robb points out), but that's a different issue. I was at a family function a couple days ago.. spent about half an hour shooting with the DS with and without flash (but mostly with) and used manual focus almost exclusively as it was dark and... well... the focus is stinky in dim light. This was with the Tamron 28-75 f2.8 lens. Then I noticed a camera sitting lonely on the counter - a Nikon D70 with the 18-whatever kit lens. I figured it belonged to one of my cousins and that he'd appreciate having someone take a few snaps with it. So (first time with a Nikon in my hands) after orienting myself with some of the controls, I walked around and took a bunch of photos with it. And I have to say - the response of that camera (both in terms of how quickly it focused and how quickly the shutter/mirror combo went THWAP the instant you pressed the shutter) was very very impressive. And this is a camera of the same vintage as my DS. (Same sensor too, is it not?). The interface was a bit to get used to - but the SPEED was something else. I would LOVE to have a camera with the image quality of my DS but with the raw SPEED of the Nikon. I was impressed. Yes, the DS focus speed is slow. Maybe you're right and it isn't as slow as some would have it but the difference was immediately noticeable (and annoying). -Charles -- Charles Robinson - [EMAIL PROTECTED] Minneapolis, MN http://charles.robinsontwins.org -- PDML Pentax-Discuss Mail List PDML@pdml.net http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions.
Re: Sigma HSM lenses for Pentax KAF mount / focus speed
Charles Robinson wrote: On Nov 26, 2007, at 2:58, Toralf Lund wrote: I've also suspected (or experienced) that the Pentax AF isn't really as slow as some would have it, or not slow at all in relative terms if you compare fairly (as Mr Robb points out), but that's a different issue. I was at a family function a couple days ago.. spent about half an hour shooting with the DS with and without flash (but mostly with) and used manual focus almost exclusively as it was dark and... well... the focus is stinky in dim light. This was with the Tamron 28-75 f2.8 lens. [ ... ] And this is a camera of the same vintage as my DS. (Same sensor too, is it not?). Maybe the DS may be seen as a slightly more low end, or perhaps not... [ ... ] The interface was a bit to get used to - but the SPEED was something else. I would LOVE to have a camera with the image quality of my DS but with the raw SPEED of the Nikon. I was impressed. Yes, the DS focus speed is slow. Maybe you're right and it isn't as slow as some would have it but the difference was immediately noticeable (and annoying). I have never tried the DS, so I wouldn't know how fast it is. I tried a D70 once, and the AF didn't strike me as faster than what I was used to (from Pentax film bodies), but I didn't do a side-by-side comparison. Anyhow, my main point was that a different focus motor is hardly the solution to the low light focusing issues mentioned earlier, that you say you too have experienced. And I think one might argue that you didn't really test the focusing speed of the two cameras in the situation you mentioned. You compared the low-light performance of the AF systems, which is not exactly the same thing. - Toralf -- PDML Pentax-Discuss Mail List PDML@pdml.net http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions.
Re: Sigma HSM lenses for Pentax KAF mount
Yes, interesting posts by the engineer who started that thread. The conclusion is that ultrasonic motors CAN be faster, it's just that Pentax have chosen a poor implementation (SDM) which doesn't make full use of the technology, and thus it's results are far from optimal (they should have chosen a ring-type motor instead of a micromotor). A. M. - Original Message From: Joseph Tainter [EMAIL PROTECTED] To: pdml@pdml.net Sent: Saturday, November 24, 2007 8:06:11 PM Subject: Re: Sigma HSM lenses for Pentax KAF mount Bill wrote: OK, I also have a question: what's the advantage of ultrasonic motors? I'm interested in AF speed, since I've had a lot of trouble with my camera and it's kit lens (annoying AF hunting or even impossible AF in not-so-low :( light). Interesting discussion here: http://forums.dpreview.com/forums/read.asp?forum=1036message=25727826 Get easy, one-click access to your favorites. Make Yahoo! your homepage. http://www.yahoo.com/r/hs -- PDML Pentax-Discuss Mail List PDML@pdml.net http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions.
Re: Sigma HSM lenses for Pentax KAF mount
- Original Message - From: Inner Focus Subject: Re: Sigma HSM lenses for Pentax KAF mount Yes, interesting posts by the engineer who started that thread. The conclusion is that ultrasonic motors CAN be faster, it's just that Pentax have chosen a poor implementation (SDM) which doesn't make full use of the technology, and thus it's results are far from optimal (they should have chosen a ring-type motor instead of a micromotor). As far as I can ascertain, USM and SWM motors cannot be used in lenses with both in-lens and in-body drive systems, that's why Pentax uses the small ultrasonic motor similar to the competitions Micro-USM motors. Whether this is poor implementation from a couple of decades ago or not is the question. Unfortunately, twenty five years ago when auto focus technology was being developed, Pentax was floating rather aimlessly in the marketplace, and was giving the general impression of not having an RD department. Anyway, what you were describing as a problem can be mostly fixed by turfing the cheap and slow lenses and buying better ones. I mostly use prime lenses, and really don't experience many problems with AF, with the major exception of when my dogs are running more or less straight at me. Pentax AF is pretty much on par with the AF from cameras in the same price league from the other manufacturers. William Robb -- PDML Pentax-Discuss Mail List PDML@pdml.net http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions.
Sigma HSM lenses for Pentax KAF mount
Hello, I'm new on this list. Since I've seen some people curious about Sigma plans for the future, I decided to share the following with you. I was interested in buying a few Sigma lenses for my Samsung GX-1S, so I mailed the USA, UK and France Sigma representatives asking them if they plan to introduce HSM on Pentax lenses in the near future. The answers were the following: 1) USA: We are not working on that at this point in time. If any changes we will make an announcement on our website. 2) UK: At present we have no plans to produce our Pentax lenses with HSM. The majority of Pentax cameras cannot take the HSM system. Sigma may decide to produce Pentax HSM in the future. 3) FR: A ce jour, cela n'est pas prévu. (Translation: Sofar, this is not planned.) Comments are useless... :( OK, I also have a question: what's the advantage of ultrasonic motors? I'm interested in AF speed, since I've had a lot of trouble with my camera and it's kit lens (annoying AF hunting or even impossible AF in not-so-low :( light). About ultrasonic motors (technical article): http://en.wikipedia.org/wiki/Ultrasonic_motor PS: is HTML formatting of emails allowed on this list? A.M. Get easy, one-click access to your favorites. Make Yahoo! your homepage. http://www.yahoo.com/r/hs -- PDML Pentax-Discuss Mail List PDML@pdml.net http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions.
Re: Sigma HSM lenses for Pentax KAF mount
Inner Focus wrote: Hello, I'm new on this list. Since I've seen some people curious about Sigma plans for the future, I decided to share the following with you. I was interested in buying a few Sigma lenses for my Samsung GX-1S, so I mailed the USA, UK and France Sigma representatives asking them if they plan to introduce HSM on Pentax lenses in the near future. The answers were the following: 1) USA: We are not working on that at this point in time. If any changes we will make an announcement on our website. 2) UK: At present we have no plans to produce our Pentax lenses with HSM. The majority of Pentax cameras cannot take the HSM system. Sigma may decide to produce Pentax HSM in the future. 3) FR: A ce jour, cela n'est pas prévu. (Translation: Sofar, this is not planned.) Comments are useless... :( OK, I also have a question: what's the advantage of ultrasonic motors? I'm interested in AF speed, since I've had a lot of trouble with my camera and it's kit lens (annoying AF hunting or even impossible AF in not-so-low :( light). The advantage? Silence. Focus speed, (and hunting), is unchanged. However all the Pentax SSM, (same as USM AFAK), have wider apertures, which does make quite a big difference in focus speed and accuracy About ultrasonic motors (technical article): http://en.wikipedia.org/wiki/Ultrasonic_motor PS: is HTML formatting of emails allowed on this list? No. A.M. Get easy, one-click access to your favorites. Make Yahoo! your homepage. http://www.yahoo.com/r/hs -- The difference between individual intelligence and group intelligence is the difference between Harvard University and the Harvard University football team. -- P. J. O'Roark -- PDML Pentax-Discuss Mail List PDML@pdml.net http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions.
Re: Sigma HSM lenses for Pentax KAF mount
On Nov 24, 2007, at 6:42 AM, Inner Focus wrote: PS: is HTML formatting of emails allowed on this list? No, the list allows plain text only. Godfrey -- PDML Pentax-Discuss Mail List PDML@pdml.net http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions.
Re: Sigma HSM lenses for Pentax KAF mount
On 24/11/07, Inner Focus, discombobulated, unleashed: Hello, I'm new on this list. This may help. www.graywolfphoto.com/pentax/pdml-faq.html -- Cheers, Cotty ___/\__ || (O) | People, Places, Pastiche ||=|http://www.cottysnaps.com _ -- PDML Pentax-Discuss Mail List PDML@pdml.net http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions.
Re: Sigma HSM lenses for Pentax KAF mount
- Original Message - From: Inner Focus Subject: Sigma HSM lenses for Pentax KAF mount OK, I also have a question: what's the advantage of ultrasonic motors? I'm interested in AF speed, since I've had a lot of trouble with my camera and it's kit lens (annoying AF hunting or even impossible AF in not-so-low :( light). USM has the potential to be faster, but is not necessarily going to fix your problem. Kit zooms are pretty dim, and often rather low contrast lenses, so the AF doesn't get as much light to work with, and what it does get isn't as good quality, as AF is contrast sensitive. AF performance with an f5.6 lens is enormously compromised in surprisingly bright light. Try a better quality lens. Even an AF50/1.7, which isn't overly costly, will give an indication of what the kit zoom is costing you in performance. I think you'll find that if you are really interested in fast AF, you should be looking at the top end Canon or Nikons and their fast glass. Expensive, but really high performance, and they don't take Pentax lenses, which is a fatal flaw. William Robb -- PDML Pentax-Discuss Mail List PDML@pdml.net http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions.
Re: Sigma HSM lenses for Pentax KAF mount
Correction: The original poster wrote that paragraph, not Bill. Joe - Bill wrote: OK, I also have a question: what's the advantage of ultrasonic motors? I'm interested in AF speed, since I've had a lot of trouble with my camera and it's kit lens (annoying AF hunting or even impossible AF in not-so-low :( light). Interesting discussion here: http://forums.dpreview.com/forums/read.asp?forum=1036message=25727826 I want Pentax to bring out a firmware option that will allow us to switch between shaft-drive and SDM AF. Reasons are: 1. Before getting the two DA* lenses, I had not realized how much I rely on audible feedback to know when an AF lens has locked focus. Now I know. In bright light I often can't see the focus indicator in the viewfinder. I would like to have the option of getting that audible feedback. And, no, I won't turn the focus confirmation beep back on. 2. In 10 or 15 years, when Pentax can't repair the SDM mechanism, I would like to be able to switch back to shaft drive. Overall I am not impressed with SDM. Perhaps it is useful for people who really need the quiet focusing. For me it is a big yawn, with some negatives. Pentax engineers hinted that SDM wouldn't focus faster. But even many people who read that interview were in denial about it. Other than this, I like the DA* lenses very much. Joe -- PDML Pentax-Discuss Mail List PDML@pdml.net http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions.
Re: Sigma HSM lenses for Pentax KAF mount
Bill wrote: OK, I also have a question: what's the advantage of ultrasonic motors? I'm interested in AF speed, since I've had a lot of trouble with my camera and it's kit lens (annoying AF hunting or even impossible AF in not-so-low :( light). Interesting discussion here: http://forums.dpreview.com/forums/read.asp?forum=1036message=25727826 I want Pentax to bring out a firmware option that will allow us to switch between shaft-drive and SDM AF. Reasons are: 1. Before getting the two DA* lenses, I had not realized how much I rely on audible feedback to know when an AF lens has locked focus. Now I know. In bright light I often can't see the focus indicator in the viewfinder. I would like to have the option of getting that audible feedback. And, no, I won't turn the focus confirmation beep back on. 2. In 10 or 15 years, when Pentax can't repair the SDM mechanism, I would like to be able to switch back to shaft drive. Overall I am not impressed with SDM. Perhaps it is useful for people who really need the quiet focusing. For me it is a big yawn, with some negatives. Pentax engineers hinted that SDM wouldn't focus faster. But even many people who read that interview were in denial about it. Other than this, I like the DA* lenses very much. Joe -- PDML Pentax-Discuss Mail List PDML@pdml.net http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions.
Re: Sigma HSM lenses for Pentax KAF mount
On Nov 24, 2007 8:07 PM, Joseph Tainter [EMAIL PROTECTED] wrote: I would like to have the option of getting that audible feedback. And, no, I won't turn the focus confirmation beep back on. Really? I wonder why... this is such an essential feature ... xD 2. In 10 or 15 years, when Pentax can't repair the SDM mechanism, I would like to be able to switch back to shaft drive. Why do sou specificaly fear 1/ That SDM motor will fail in that time 2/ That Pentax would not use the same SDM implementantion in 10-15 years? -- Thibault Massart aka Thibouille -- Photo: K10D,Z1,SuperA,KX,MX, P30t and KR-10x ;) ... Thinkpad: X23+UB,X60+UB Programing: D7 user (trying out D2007) -- PDML Pentax-Discuss Mail List PDML@pdml.net http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions.
Re: Sigma HSM lenses for Pentax KAF mount
On 11/24/07, Joseph Tainter [EMAIL PROTECTED] wrote: 1. Before getting the two DA* lenses, I had not realized how much I rely on audible feedback to know when an AF lens has locked focus. Now I know. In bright light I often can't see the focus indicator in the viewfinder. I would like to have the option of getting that audible feedback. And, no, I won't turn the focus confirmation beep back on. The camera's that i have, that have the beep are always turned on. I shoot with my right eye, as i'm sure most of us do, and i have somefloaties in my right eye that seem to gather right in the front. It interfers with eye focus as well as camera focus. I sometimes have to ime to move and clear it, but sometimes at the horse shows its now or never , and i have to rely on the beep or at least the green lights. Humm i remember saying that in the 60's. Hey man, look at the colours.:-) Dave Equine Photography www.caughtinmotion.com http://brooksinthecountry.blogspot.com/ Ontario Canada -- PDML Pentax-Discuss Mail List PDML@pdml.net http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions.
