Pentax SDM to Screwdrive Autofocus Test

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Hey! In this video I tested whether the SDM or screwdrive autofocus system is faster at achieving focus confirmation from both maximum to minimum and minimum to maximum focusing distances and with the K-70 and the K-3 III.
TL;DR: Converting to screwdrive improves focusing speed on average by 11.5%.
How to convert your lens: • Pentax SDM to Screwdri...
To be clear: this is only the old SDM micro-AF motors for some lenses capable of making this conversion. The new SDM ring-type designs will obviously be substantially improved.
List of similar SDM designs:
smc PENTAX-DA* 16-50mm f/2.8 ED AL [IF] SDM
smc PENTAX-DA* 50-135mm f/2.8 ED [IF] SDM
smc PENTAX DA* 60-250mm f/4 ED [IF] SDM
smc PENTAX-DA* 200mm f/2.8 ED [IF] SDM
smc PENTAX-DA* 300mm f/4 ED [IF] SDM
Let me know what you think!
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Stephen Foster
PO Box 99900 WU 227 122
RPO Meadowbrook
Edmonton AB T6T 0W4

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Опубликовано:

5 сен 2021

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Комментарии : 16

@Orion795 2 года назад

Thank you, this channel is a must

@sakatabg 2 года назад

Great test!! Great algorithm, logic and analyse!!!

@shassan5287 2 года назад

Exactly the video I was looking for since getting the K3iii :)

Год назад

thanks for the tests

@jackcieslawski1076 2 года назад

thank you , very informative

@doncoombez 2 года назад

Love it!

@coolcat23 2 года назад

Nice. Would have been good to accompany this with a sharpness analysis, i.e., check whether the screw-drive AF results are as good as the SDM results.

@seanc8054 2 года назад

id like to have known what the hell a screw drive is, cuz ive no idea wtf this entire video is supposed to be doing? i just bought a pentax K-5 and was looking for videos on it, and ran across this one, dunno why i clicke don it, i dunno anything about cameras right now, i just am starting to get into it. sometimes i think smart need to pretend they are dumb right before they do a video like this because half of everyone that watches it will be dumb, 486 views, and 29 thumbs up from smart people the rest were like me, wtf is happening :(

@HarisF1 2 года назад

@@seanc8054 A quick Google search would fix that for you. Stop being lazy.

@n_3719 11 месяцев назад

@@seanc8054 late but i hope this information is still useful. screw drive is a type of af motor. its integrated into the body while sdm is inside the lens. the sdm motor is prone to failure but you could "convert" the lens to screw drive when it fails

@allthelux 2 года назад

Can this be generalized to all SDM -> Screwdrive conversions, or just the lens and body combinations you tested?

@PentaxTips 2 года назад

Although I would love to extrapolate, since I only have the one lens, my sample size is an n of 1. However, knowing the similar technology employed on the earlier SDM lenses (the ones capable of converting) I am reasonably confident in saying "yes - the screwdrive operates faster and more reliably than their SDM autofocus".

@allthelux 2 года назад

@@PentaxTips That's very surprising, as I thought SDM technology was a step up from the screwdrive. Thank you for a great video and test!

@PentaxTips 2 года назад

@@allthelux I guess it all depends on what you want to get out of the lens. Speed or silence!

@coolcat23 2 года назад

@@allthelux As PentaxTips said, it is about priorities, but also note that Pentax use the "SDM" moniker for a wide range of AF implementations. There are really slow ones using micro-AF motors and really fast ones using big ring motors.

@HarisF1 2 года назад

@@coolcat23 When people talk about the slow SDM they're usually discussing the system used in the older DA* lenses as well as the DA 17-70. This one is more prone to failure than other types of focusing motor they've used in their 'SDM' lenses.