KAF4 is more than a good idea

stevebrot · 02-15-2020, 06:53 PM

Originally posted by Kunzite

I'm not saying it's bad; just that perhaps the difference from well-made KAF4 lenses isn't that big. In reliability, because in other aspects...

Yes, it would be reasonable to expect that in-lens aperture control would be as reliable as in-body aperture control* and that in-lens focus motor general reliability would continue according to historic patterns**.

I'm not saying its bad, but probably no worse than similar miniaturized assemblies in small appliances, personal care, office automation, and automotive. Too bad we have such a short time line to assess the KAF4 aperture control tech.

Steve

* Aperture control failure anyone?

** Has any established maker avoided a failure-prone in-lens AF motor series?

Last edited by stevebrot; 02-15-2020 at 08:38 PM.

**BigMackCam** · 02-16-2020, 06:36 AM

Originally posted by stevebrot

** Has any established maker avoided a failure-prone in-lens AF motor series?

So far as I can tell, Canon's USM and STM motors appear to have been generally reliable. Tamron's USD motors seem dependable too... which isn't to say either manufacturer hasn't had failures; only that this doesn't seem to be a general weakness. I've read of quite a few Nikon SWM failures, but this seems to be on earlier examples and nothing like the scale and early-onset with Pentax' older SDM efforts. From what I've read casually, it seems the Nikon folks have an expectation of 10+ years reliability...

stevebrot · 02-16-2020, 10:12 AM

Originally posted by BigMackCam

So far as I can tell, Canon's USM and STM motors appear to have been generally reliable. Tamron's USD motors seem dependable too... which isn't to say either manufacturer hasn't had failures; only that this doesn't seem to be a general weakness. I've read of quite a few Nikon SWM failures, but this seems to be on earlier examples and nothing like the scale and early-onset with Pentax' older SDM efforts. From what I've read casually, it seems the Nikon folks have an expectation of 10+ years reliability...

Sigma had a serious problem for a couple of years too.

I am not saying that the tech is prone to troubles. Today's everything-in-the-lens approach results in product that is at least as reliable as today's camera bodies. Aye, but there's the rub. Conventional wisdom has been that lenses are forever purchases and that bodies come and go. The new paradigm is that nothing lasts.

While thinking about this thread, I gave some thought to the people I know in the local photographic community and it occurred to me that the active shooters churn through their gear (lenses and bodies) fairly quickly will often sell their main lenses when they do a body upgrade. Pentax users, OTOH, tend to hang on to their stuff, particularly lenses.

Steve

**Serkevan** · 02-16-2020, 11:48 AM

Originally posted by BigMackCam

So far as I can tell, Canon's USM and STM motors appear to have been generally reliable. Tamron's USD motors seem dependable too... which isn't to say either manufacturer hasn't had failures; only that this doesn't seem to be a general weakness. I've read of quite a few Nikon SWM failures, but this seems to be on earlier examples and nothing like the scale and early-onset with Pentax' older SDM efforts. From what I've read casually, it seems the Nikon folks have an expectation of 10+ years reliability...

We have at home a Canon EF 28-135/3.5-5.6 IS USM that still works. The lens is probably my age and it has survived half a year of trekking all around South America with its previous owner, plus apparently a bunch of falls and some banging here and there. The EF 70-200/4L USM (non-IS) works like the first day. The painting is scratched, you can barely read some of the labels, and that's it. I would say they can last, yeah

angerdan · 02-16-2020, 11:55 AM

Originally posted by Kunzite

Of course, proper in-lens AF motors are also a better solution - at least regarding speed and precision.

Only with tele lenses. short focal lengths or slow lenses (few and light glass elements) can be faster with screw-drive.
Se the FA and DA limiteds.

Kunzite · 02-16-2020, 12:56 PM

Originally posted by angerdan

Only with tele lenses. short focal lengths or slow lenses (few and light glass elements) can be faster with screw-drive.
Se the FA and DA limiteds.

For lenses with light focus groups, the PLM is the fastest solution.

02-16-2020, 06:36 AM	#32
BigMackCam Digitiser of Film Join Date: Mar 2010 Location: North East of England Posts: 20,695	Originally posted by stevebrot ** Has any established maker avoided a failure-prone in-lens AF motor series? So far as I can tell, Canon's USM and STM motors appear to have been generally reliable. Tamron's USD motors seem dependable too... which isn't to say either manufacturer hasn't had failures; only that this doesn't seem to be a general weakness. I've read of quite a few Nikon SWM failures, but this seems to be on earlier examples and nothing like the scale and early-onset with Pentax' older SDM efforts. From what I've read casually, it seems the Nikon folks have an expectation of 10+ years reliability... Last edited by BigMackCam; 02-16-2020 at 06:49 AM.

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Updated list of KAF4 lenses	GregL65	Pentax SLR Lens Discussion	17	05-12-2021 03:42 AM
KAF3/KAF4 to E mount adapter?	amstel78	Pentax SLR Lens Discussion	6	08-26-2019 10:36 PM
KAF4 Lenses	cainmh	Pentax SLR Lens Discussion	56	03-17-2019 10:33 AM
Petition - Please allow KAF4 firmware for the K3, K5 series, and K50	VoiceOfReason	Pentax DSLR Discussion	227	12-28-2016 02:26 AM
K-3 firmware update: KAF4 mount support	ScooterMaxi Jim	Pentax K-3 & K-3 II	26	12-14-2016 08:22 PM

02-15-2020, 06:53 PM	#31
stevebrot Otis Memorial Pentaxian Join Date: Mar 2007 Location: Vancouver (USA) Photos: Gallery \| Albums Posts: 42,007	Originally posted by Kunzite I'm not saying it's bad; just that perhaps the difference from well-made KAF4 lenses isn't that big. In reliability, because in other aspects... Yes, it would be reasonable to expect that in-lens aperture control would be as reliable as in-body aperture control* and that in-lens focus motor general reliability would continue according to historic patterns*. I'm not saying its bad, but probably no worse than similar miniaturized assemblies in small appliances, personal care, office automation, and automotive. Too bad we have such a short time line to assess the KAF4 aperture control tech. Steve Aperture control failure anyone? ** Has any established maker avoided a failure-prone in-lens AF motor series? Last edited by stevebrot; 02-15-2020 at 08:38 PM.

02-16-2020, 10:12 AM	#33
stevebrot Otis Memorial Pentaxian Join Date: Mar 2007 Location: Vancouver (USA) Photos: Gallery \| Albums Posts: 42,007	Originally posted by BigMackCam So far as I can tell, Canon's USM and STM motors appear to have been generally reliable. Tamron's USD motors seem dependable too... which isn't to say either manufacturer hasn't had failures; only that this doesn't seem to be a general weakness. I've read of quite a few Nikon SWM failures, but this seems to be on earlier examples and nothing like the scale and early-onset with Pentax' older SDM efforts. From what I've read casually, it seems the Nikon folks have an expectation of 10+ years reliability... Sigma had a serious problem for a couple of years too. I am not saying that the tech is prone to troubles. Today's everything-in-the-lens approach results in product that is at least as reliable as today's camera bodies. Aye, but there's the rub. Conventional wisdom has been that lenses are forever purchases and that bodies come and go. The new paradigm is that nothing lasts. While thinking about this thread, I gave some thought to the people I know in the local photographic community and it occurred to me that the active shooters churn through their gear (lenses and bodies) fairly quickly will often sell their main lenses when they do a body upgrade. Pentax users, OTOH, tend to hang on to their stuff, particularly lenses. Steve

02-16-2020, 11:48 AM	#34
Serkevan Site Supporter Join Date: May 2019 Photos: Albums Posts: 5,976	Originally posted by BigMackCam So far as I can tell, Canon's USM and STM motors appear to have been generally reliable. Tamron's USD motors seem dependable too... which isn't to say either manufacturer hasn't had failures; only that this doesn't seem to be a general weakness. I've read of quite a few Nikon SWM failures, but this seems to be on earlier examples and nothing like the scale and early-onset with Pentax' older SDM efforts. From what I've read casually, it seems the Nikon folks have an expectation of 10+ years reliability... We have at home a Canon EF 28-135/3.5-5.6 IS USM that still works. The lens is probably my age and it has survived half a year of trekking all around South America with its previous owner, plus apparently a bunch of falls and some banging here and there. The EF 70-200/4L USM (non-IS) works like the first day. The painting is scratched, you can barely read some of the labels, and that's it. I would say they can last, yeah

02-16-2020, 11:55 AM	#35
angerdan Pentaxian Join Date: Feb 2015 Photos: Gallery \| Albums Posts: 2,643	Originally posted by Kunzite Of course, proper in-lens AF motors are also a better solution - at least regarding speed and precision. Only with tele lenses. short focal lengths or slow lenses (few and light glass elements) can be faster with screw-drive. Se the FA and DA limiteds.

02-16-2020, 12:56 PM	#36
Kunzite Pentaxian Join Date: Apr 2007 Location: Romania Posts: 15,132 Original Poster	Originally posted by angerdan Only with tele lenses. short focal lengths or slow lenses (few and light glass elements) can be faster with screw-drive. Se the FA and DA limiteds. For lenses with light focus groups, the PLM is the fastest solution.