Re: Some Pentax sales spotted, including 70-200/2.8
And yes the tamron are ring type ultrasonic motors similar to what canon uses. I hope that clears some confusion. The DC motor in my 20-40 is a little poky but it feels solid and reliable. I can't say the same about my 60-250 -- 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: Some Pentax sales spotted, including 70-200/2.8
You won't see another lens use the SDM motor that was in the 17-70, 60-250,50-135, 16-50, etc ever again. They revived the branding for the tamron lenses, which frankly was a serious mistake and has led to a lot of confusion. The motors are built by tamron in those lenses and are comparable to the DC motors pentax is using now. On Wed, Jul 27, 2016 at 6:21 PM, Gonz wrote: > Hmmm nice deal. Is this lens one of the ones that has the unreliable > SDM focusing mechanism I heard about with the 60-250 or such? > > > > On Wed, Jul 27, 2016 at 5:05 PM, Igor PDML-StR wrote: >> >> Hi All, >> >> Just in case someone is shopping for lenses... >> B&H has some sale on Pentax items. I don't know how good all the prices are, >> - but D FA* 70-200mm/2.8 is only $1696, which is $100 lower than what is was >> going for (1800). >> Adorama has the same price for this lens. >> >> Here are other sale items: >> http://www.bhphotovideo.com/c/buy/items/ci/32002/ipp/48/N/3638625979/view/GRID >> >> HTH, >> >> Igor >> >> >> >> -- >> 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. > > > > -- > -- Reduce your Government Footprint > > -- > 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. -- 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: Some Pentax sales spotted, including 70-200/2.8
Stan, You raised an interesting question. The thought of the ultrasound being heard by some animals/birds had crossed my mind before. I had not got to read about that actual design of the motor until your post nudged me. Prior to that I was somewhat dismissing "ultrasonic" assuming it could've been just a marketing term that has nothing to do with the original meaning of the word (as "Nano" i-Pod :-) ). But no, it looks like the motor indeed may be using vibration at ultrasonic frequencies (above 20 kHz). I'd be curious to know which frequencies they actually use. I have never been exposed to any work with ultrasound (short of ultrasonic cleaners and patient side of ultrasound imaging). From the general principles, I'd say it should be easy to damp those vibrations to avoid "leakage" to the outside, but I don't know if anybody cared about that. In principle, the body of the lens should attenuate the ultrasound drastically. But only a careful measurement could tell for sure. Or you can watch how a bat reacts when you activate AF in your SDM lens. :-) I'll try to do that next time I am at a zoo with bats (although they are usually behind the glass, so it is not a "clean" experiment). Got a barn with bats? ;-) Or, if you have a friend who is an ultrasound imaging technician, bring your camera with the lens, and activate AF near the imaging "probe". If you see some distortions of the image (AF on vs. AF off), you have leakage. If you don't, - it's inconclusive: it might be that the frequency ranges are too different, and the imaging instrument is not sensitive to the SDM's frequency. Cheers, Igor Stanley Halpin Thu, 28 Jul 2016 06:06:36 -0700 wrote: I went to Wikipedia to see if they could tell me what an ultrasonic motor is, how it works, and whether it can be heard. That last point was my first question actually. Seeing the term “ultrasonic” triggered the thought that the sonic may be “ultra” with respect to human hearing, but maybe birds and other animals can hear and be alerted by the ultrasound? I suspect probably not, but Wikipedia did not address this. The Wikipedia article is written for someone with a technical background and I found it unintelligible. However, they do include a list of common application of this technology, autofocus lenses, pioneered by Canon. With several other companies now using the technology under various names including Sigma HSM, Tamron USD, PZD, Nikon SWM, Olympus SWD, and Pentax SDM. stan -- 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: Some Pentax sales spotted, including 70-200/2.8 (SDM question)
I went to Wikipedia to see if they could tell me what an ultrasonic motor is, how it works, and whether it can be heard. That last point was my first question actually. Seeing the term “ultrasonic” triggered the thought that the sonic may be “ultra” with respect to human hearing, but maybe birds and other animals can hear and be alerted by the ultrasound? I suspect probably not, but Wikipedia did not address this. The Wikipedia article is written for someone with a technical background and I found it unintelligible. However, they do include a list of common application of this technology, autofocus lenses, pioneered by Canon. With several other companies now using the technology under various names including Sigma HSM, Tamron USD, PZD, Nikon SWM, Olympus SWD, and Pentax SDM. stan > On Jul 27, 2016, at 7:17 PM, Alex Sarbu wrote: > > The HD Pentax D FA* 70-200mmF2.8 ED DC AW doesn't use the same type of > SDM micromotors as the DA*-series lenses. Actually it doesn't use SDM > at all - but DC motors. Fast, reliable. > > Last Pentax lens with these SDM micromotors was announced in 2008. > Since then we had 3 K-mount "SDM" lenses, all using Tamron's > "ultrasonic"-type motors (in case of the D FA 24-70 and 15-30, > ring-type "ultrasonic" motors). > > Alex > > On Thu, Jul 28, 2016 at 1:21 AM, Gonz wrote: >> Hmmm nice deal. Is this lens one of the ones that has the unreliable >> SDM focusing mechanism I heard about with the 60-250 or such? >> >> >> >> On Wed, Jul 27, 2016 at 5:05 PM, Igor PDML-StR wrote: >>> >>> Hi All, >>> >>> Just in case someone is shopping for lenses... >>> B&H has some sale on Pentax items. I don't know how good all the prices are, >>> - but D FA* 70-200mm/2.8 is only $1696, which is $100 lower than what is was >>> going for (1800). >>> Adorama has the same price for this lens. >>> >>> Here are other sale items: >>> http://www.bhphotovideo.com/c/buy/items/ci/32002/ipp/48/N/3638625979/view/GRID >>> >>> HTH, >>> >>> Igor >>> >>> >>> >>> -- >>> 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. >> >> >> >> -- >> -- Reduce your Government Footprint >> >> -- >> 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. > > -- > 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. -- 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: Some Pentax sales spotted, including 70-200/2.8
The HD Pentax D FA* 70-200mmF2.8 ED DC AW doesn't use the same type of SDM micromotors as the DA*-series lenses. Actually it doesn't use SDM at all - but DC motors. Fast, reliable. Last Pentax lens with these SDM micromotors was announced in 2008. Since then we had 3 K-mount "SDM" lenses, all using Tamron's "ultrasonic"-type motors (in case of the D FA 24-70 and 15-30, ring-type "ultrasonic" motors). Alex On Thu, Jul 28, 2016 at 1:21 AM, Gonz wrote: > Hmmm nice deal. Is this lens one of the ones that has the unreliable > SDM focusing mechanism I heard about with the 60-250 or such? > > > > On Wed, Jul 27, 2016 at 5:05 PM, Igor PDML-StR wrote: >> >> Hi All, >> >> Just in case someone is shopping for lenses... >> B&H has some sale on Pentax items. I don't know how good all the prices are, >> - but D FA* 70-200mm/2.8 is only $1696, which is $100 lower than what is was >> going for (1800). >> Adorama has the same price for this lens. >> >> Here are other sale items: >> http://www.bhphotovideo.com/c/buy/items/ci/32002/ipp/48/N/3638625979/view/GRID >> >> HTH, >> >> Igor >> >> >> >> -- >> 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. > > > > -- > -- Reduce your Government Footprint > > -- > 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. -- 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: Some Pentax sales spotted, including 70-200/2.8
Hmmm nice deal. Is this lens one of the ones that has the unreliable SDM focusing mechanism I heard about with the 60-250 or such? On Wed, Jul 27, 2016 at 5:05 PM, Igor PDML-StR wrote: > > Hi All, > > Just in case someone is shopping for lenses... > B&H has some sale on Pentax items. I don't know how good all the prices are, > - but D FA* 70-200mm/2.8 is only $1696, which is $100 lower than what is was > going for (1800). > Adorama has the same price for this lens. > > Here are other sale items: > http://www.bhphotovideo.com/c/buy/items/ci/32002/ipp/48/N/3638625979/view/GRID > > HTH, > > Igor > > > > -- > 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. -- -- Reduce your Government Footprint -- 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.
