[red5isalive]

Hi guys,

I've been offered a DA* 50-135mm f2.8 SDM and money for my FA* 200mm f2.8 that recently put for sale on the spanish forum as I did not managed to make it work for races, and since I own a Sigma 100-300mm F4 I decided to sell it.

The thing is that the Pentax sounds good for its focal length (it does cover a focal I don't have covered as I use both Sigma 17-50mm f2.8 and 100-300mm f4, and two Pentax 50mm but as you can see there is a gap in between), but I've heard the AF is quite slow. I have also read about how to convert the lens to Screw Drive instead of SDM and that this helps to increase the AF speed.

But my biggest fear is, does that solve the AF issues? Would it be a champion and work on racing environments? I use to do racetrack and rally photography, and accuracy on AF its important to me. I use a K3 and have a nice K5 as a second body.

I have also read that from 90mm on to 135mm the quality on images can be a bit lower? Is it any true?

Thank you very much for your help, I am quite comfused with that lens as if.

Regards,

[aslyfox]

i have no personal experience with this lens

have you seen the In Depth Review on that lens

Pentax-DA* 50-135mm F2.8 Review
Pentax-DA* 50-135mm F2.8 Review - Introduction | PentaxForums.com Reviews



AF Verdict

The autofocus speed of the Pentax 50-135mm is perhaps its weakest point. Many will plan to use this lens for sports, and for this purpose the 50-135mm simply does not deliver. On the other hand, for other applications you will probably find its autofocus to be sufficient.

One interesting observation we made is that there's some latency between the time that the user activates the AF and the time that the SDM motor actually starts to move, which might account for some of the perceived sluggishness.
The fact that this lens has silent autofocus to begin with, and that it supports quick-shift reduces the overall severity of the slow AF speed in our eyes, though it's still something that sports shooters should consider when deciding between this lens and other options, such as the Sigma 70-200mm OS HSM, which boasts much faster AF.


Read more at: https://www.pentaxforums.com/reviews/pentax-da-star-50-135mm-f28-lens/autofo...#ixzz5AJGZJG00


Disabling SDM to use Screwdrive
If the SDM in your 50-135mm fails, it is possible to deactivate it and force the camera to use the screwdrive mechanism. However, if your SDM has not failed, then we do not recommend disabling it. The screwdrive AF system is much more noisy than SDM, and user reports have shown that it is not faster in practice.


Read more at: https://www.pentaxforums.com/reviews/pentax-da-star-50-135mm-f28-lens/autofo...#ixzz5AJGSevIu

[john5100]

I've used this lens for motorsports for a long time and it works fine.


Historic Sports Car Races by John Rudolph, on Flickr


Ford GT40 by John Rudolph, on Flickr


Sprint Boat Racing by John Rudolph, on Flickr

DA 18-250mm not fast either


NHRA Drags by John Rudolph, on Flickr

[aslyfox]

that is the difference between real world experience and knowing how to take action photos

and testing

since I don't have the lens, I couldn't give that real world experience

great photos

it is a long way away from your home but if you do end up in Wisconsin during the right time of the year I recommend Road America - 4 mile road circuit

Welcome to Road America Elkhart Lake's Road America, Inc.

[red5isalive]

I've used this lens for motorsports for a long time and it works fine.


Historic Sports Car Races by John Rudolph, on Flickr


Ford GT40 by John Rudolph, on Flickr


Sprint Boat Racing by John Rudolph, on Flickr

DA 18-250mm not fast either


NHRA Drags by John Rudolph, on Flickr

i have no personal experience with this lens

have you seen the In Depth Review on that lens

Pentax-DA* 50-135mm F2.8 Review
Pentax-DA* 50-135mm F2.8 Review - Introduction | PentaxForums.com Reviews



AF Verdict

The autofocus speed of the Pentax 50-135mm is perhaps its weakest point. Many will plan to use this lens for sports, and for this purpose the 50-135mm simply does not deliver. On the other hand, for other applications you will probably find its autofocus to be sufficient.

One interesting observation we made is that there's some latency between the time that the user activates the AF and the time that the SDM motor actually starts to move, which might account for some of the perceived sluggishness.
The fact that this lens has silent autofocus to begin with, and that it supports quick-shift reduces the overall severity of the slow AF speed in our eyes, though it's still something that sports shooters should consider when deciding between this lens and other options, such as the Sigma 70-200mm OS HSM, which boasts much faster AF.


Read more at: Pentax-DA* 50-135mm F2.8 Review - Autofocus Performance | PentaxForums.com Reviews


Disabling SDM to use Screwdrive
If the SDM in your 50-135mm fails, it is possible to deactivate it and force the camera to use the screwdrive mechanism. However, if your SDM has not failed, then we do not recommend disabling it. The screwdrive AF system is much more noisy than SDM, and user reports have shown that it is not faster in practice.


Read more at: Pentax-DA* 50-135mm F2.8 Review - Autofocus Performance | PentaxForums.com Reviews

Thank you to both!
Aslyfox i didn't knew this test, thank you! I've read a lot about it but seems that users can't find themselves with a unique opinion.

Thank you John, that shows up more than anything I can read around. Great images!

How hard do you find the lens to focus where you want compared to other lenses that you use (if it's the case) in comparison?
Do you pre-focus before taking the pictures? Or, let's say, in the case something unexpected happens you just focus and shoot? I mean, it is useful that way for me.

Thank you for your replies guys

[clackers]

Mine's converted to screw drive and is fast to focus.

[red5isalive]

Mine's converted to screw drive and is fast to focus.

Thank you clackers, that's always good to know also.

[UncleVanya]

The DA* 50-135 is superb at all focal lengths. The DA 18-135 is weaker from 70-135 and that may be getting mixed up in someone's messages about this lens. The 50-135 is just fantastic at all focal lengths - it is superb and one of the reasons to shoot Pentax. The speed of focusing isn't snappy - but as shown you can take stunning photos of moving objects using this lens. Technique will be involved more than it would be with some other systems and lenses.

[aslyfox]

. . . Technique will be involved more than it would be with some other systems and lenses.

despite advances in equipment


knowledge and technique remain very very important

if I am not mistaken, panning was used for the dragster, capturing the vehicle as if it was parked but with the speed shown by the blurred background

and recognizing location and predictability for the photo of the cars coming out of the S corners

and, at least to me, having multiple cars in that shot adds to the action and its attractiveness

[clackers]

Thank you clackers, that's always good to know also.

And remember, you can convert it back anytime, as long as you saved a copy of its original config file.

[red5isalive]

And remember, you can convert it back anytime, as long as you saved a copy of its original config file.

Yes I was watching the video on how to make it happen yesterday, the same a member of the forum posted here.
Just there is one thing I miss and it is that using MacOS the software downloaded I think is just running on Windows. A part from that, I think the process is quite simple if you do the steps correctly

[Rnovo]

Thank you clackers, that's always good to know also.

I've always had good results with mine, it's a matter of technique. I'm not sure I noticed any difference - after the SDM failed - in screw drive which I had done. Take the lens.

[UncleVanya]

Yes I was watching the video on how to make it happen yesterday, the same a member of the forum posted here.
Just there is one thing I miss and it is that using MacOS the software downloaded I think is just running on Windows. A part from that, I think the process is quite simple if you do the steps correctly

5 top ways to run Windows on a Mac | Computerworld

[red5isalive]

I've always had good results with mine, it's a matter of technique. I'm not sure I noticed any difference - after the SDM failed - in screw drive which I had done. Take the lens.

Thanks Rnovo

---------- Post added 03-20-18 at 04:05 PM ----------

5 top ways to run Windows on a Mac | Computerworld

Thank you!

[clackers]

Yes I was watching the video on how to make it happen yesterday, the same a member of the forum posted here.
Just there is one thing I miss and it is that using MacOS the software downloaded I think is just running on Windows. A part from that, I think the process is quite simple if you do the steps correctly

You don't use any software other than any straight forward text editor.

BTW, the 50-135 is just a beautiful lens that makes beautiful pictures of anything, not just racing cars. I really don't have a zoom like it on full frame.