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02-05-2014, 01:09 AM   #16
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I'm going to try a Tamron 70-200 this weekend to really compare it in action with my Sigma 70-200 DG HSM, I'm not satisfied with the image quality and AF reliability of the Sigma :-(
I'm shooting dogs (sighthounds) too...

02-05-2014, 01:54 AM   #17
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QuoteOriginally posted by awaldram Quote
Screwdrive is in general a total waste of time for Sport shorting the screw latency reduces tracking ability below both SDM and HSM for all but the most 'sport' tuned glass are better.
Do you have more evidence on this (either qualitative or quantitative)?

This doesn't mesh with my experience, or with some comments I've read from others (e.g. F*300 or FA*300/4.5 focus faster than DA*300).


Of course, the specific camera model's important when comparing screw-drive on Pentax, with the latest models being better.
02-05-2014, 03:18 AM   #18
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I find that my Tamron 70-200 and the K-3 is very snappy compared to my K-5. Also sharp as a razor. It is just a little noisy which is not an issue at sports but can be a problem shooting wildlife. I have cammo taped it which gives ok noise reduction.
02-05-2014, 03:30 AM   #19
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Just received it, I can't wait to shoot. I've struggled with the Sigma since day 1 and learned a lot since then, front and back focussing, focus plane shifting, maximum aperture, etc... really interesting but I just to shoot without these problems haha...

02-05-2014, 06:23 AM   #20
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QuoteOriginally posted by kenyee Quote
Also look at Sigma's HSM lenses. E.g., the 70-200. Too bad they haven't released the latest version for Pentax..
From Sigma's website:

SIGMA 70-200mm F2.8 EX DG OS HSM - Telephoto Zoom Lenses - SigmaPhoto.com

Pentax is one of the available mounts.
02-05-2014, 06:35 AM   #21
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I think he meant the Tamron 70-200 2.8 VC USD (Model A009) ;-)
02-05-2014, 06:55 AM   #22
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QuoteOriginally posted by DSims Quote
Do you have more evidence on this (either qualitative or quantitative)?

This doesn't mesh with my experience, or with some comments I've read from others (e.g. F*300 or FA*300/4.5 focus faster than DA*300).


Of course, the specific camera model's important when comparing screw-drive on Pentax, with the latest models being better.
Well I own Sigma EX 70-200 ,Sigma EX DG 50 macro , da40 , Sigma 400 Telemacro , Sigma Bigma and multitude of cheap screw lens (28-80, 18-250, 70-300 etc etc)

In Sdm/HSM
I own da*16-50, da* 50-135 , da* 55 , da* 300 , Sigma ex DG OS HSM 70-200.

Models I have extensive experience of
k10d ,k20d,Kx, k5 and k3
I shoot an average 500+ sport images a week in low light varying from linear tracking to spot tracking.
I also have quite a lot of exposure to Canon / Nikon FF bodies with lens like Canon 200mm EF f2L

Don;t mistake focus 'speed' with tracking ability

High screw drive focus speed means low torque which in turn mean changing direction takes time....ie poor tracking ability

HSM (ring type) is moderately slow but because its direct drive and short throw makes it ideal for tracking.
The da* 300 suffers from too weak a motor needing ling throw and as such is a halfway house in performance.

as I said "all but the most 'sport' tuned glass are better."
So don't see that in conflict with "with some comments I've read from others (e.g. F*300 or FA*300/4.5 focus faster than DA*300)."

I don't know the fa300 but my Sigma 400 being short throw and rear focusing is fast (rear focus low weight and lower latency )

There is a reason screw is nothing but a legacy option dropped by most manufacturers , They didn't drop it because its better !

Last edited by awaldram; 02-05-2014 at 07:05 AM.
02-05-2014, 07:06 AM   #23
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Maybe because it was too expensive too? (to build a powerful reliable motor into a body)

02-05-2014, 07:14 AM   #24
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I believe that *part* of the equation is for manufacturers is to provide several justifications to charge a slightly higher price for a perceived improved value. CaNikon both went with VR and AF motors in lens, with the result that their lenses are bigger, heavier, and costlier. I applaud Pentax's conservative approach of using screw drive and in-body stabilization resulting in smaller, lighter, and cheaper lenses. This is further a benefit for them as the time-to-market is much shorter with a simpler lens. I hope they keep (and improve) the screw drive for years to come.

YMMV

Michael
02-05-2014, 09:03 AM   #25
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QuoteOriginally posted by awaldram Quote
Well I own Sigma EX 70-200 ,Sigma EX DG 50 macro , da40 , Sigma 400 Telemacro , Sigma Bigma and multitude of cheap screw lens (28-80, 18-250, 70-300 etc etc)

In Sdm/HSM
I own da*16-50, da* 50-135 , da* 55 , da* 300 , Sigma ex DG OS HSM 70-200.

Models I have extensive experience of
k10d ,k20d,Kx, k5 and k3
I shoot an average 500+ sport images a week in low light varying from linear tracking to spot tracking.
I also have quite a lot of exposure to Canon / Nikon FF bodies with lens like Canon 200mm EF f2L

Don;t mistake focus 'speed' with tracking ability

High screw drive focus speed means low torque which in turn mean changing direction takes time....ie poor tracking ability

HSM (ring type) is moderately slow but because its direct drive and short throw makes it ideal for tracking.
The da* 300 suffers from too weak a motor needing ling throw and as such is a halfway house in performance.

as I said "all but the most 'sport' tuned glass are better."
So don't see that in conflict with "with some comments I've read from others (e.g. F*300 or FA*300/4.5 focus faster than DA*300)."

I don't know the fa300 but my Sigma 400 being short throw and rear focusing is fast (rear focus low weight and lower latency )

There is a reason screw is nothing but a legacy option dropped by most manufacturers , They didn't drop it because its better !
So what can you recommend for photographing running dogs? I am willing to purchase something just for this photo shoot coming up, within my budget ($1,000). Whats most important to me is fast focusing/tracking, 2.8 fast aperture, and sharp high quality images.
02-05-2014, 09:25 AM   #26
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Don't let anyone fool you, both Tamron and Sigma are not sharp at 2.8, do some research and read several reviews
Why is 2.8 important, do you shoot at night? With the available lenses for Pentax you won't get the crisp sharp image you probably want, trust me, been there, done that...

Check (for example):
http://www.phodograf.com/photosets/event/Coursing_2013-10-19-20_Ronostrand

Last edited by wpompen; 02-05-2014 at 09:33 AM.
02-05-2014, 10:18 AM   #27
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QuoteOriginally posted by wpompen Quote
Don't let anyone fool you, both Tamron and Sigma are not sharp at 2.8, do some research and read several reviews
Why is 2.8 important, do you shoot at night? With the available lenses for Pentax you won't get the crisp sharp image you probably want, trust me, been there, done that...

Check (for example):
PhoDOGraf: Photography, Image Retouch & Manipulation - Coursing -20 Ronostrand
The Tamron 70-200 is really soft @ 2.8 but crisp @ 3.2.
02-05-2014, 11:39 AM   #28
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the Sigma F4.0<
02-05-2014, 11:51 AM   #29
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QuoteOriginally posted by Tjompen1968 Quote
The Tamron 70-200 is really soft @ 2.8 but crisp @ 3.2.
I like fast lenses for shallow depth of field. And to keep the ISO down. But for action I doubt I would shoot at 2.8, but living in Seattle sometimes there is not enough light for running dogs and open aperture is needed.
02-05-2014, 01:41 PM   #30
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QuoteOriginally posted by SashasMom Quote
I like fast lenses for shallow depth of field. And to keep the ISO down. But for action I doubt I would shoot at 2.8, but living in Seattle sometimes there is not enough light for running dogs and open aperture is needed.
But of course an appropriately shallow DOF can be just as attractive in action shots as in portraits. It can make the image.

Sometimes people will show examples of how they have no trouble with AF using an inexpensive lens or a P&S camera. But often the DOF is so great that they could hardly miss. Maintaining a shallower DOF is the reason AF performance becomes so critical for action shots.
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