get autofocus capability for your manual lenses!

Adnan EROL · 04-26-2009, 12:48 PM

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Some ebay sellers (of Pentax SMC F 1.7X AF Adapter) declare that:

When mounted between an autofocus body and either a Pentax A type or M type lens, the adapter converts the lens into an autofocus lens.

The focusing mechanism is fast and snappy. no problem with Pentax SMC A 50mm f1.7 lens & Pentax SMC A 28mm f2.8 lens,

Is it possible? Anybody test it?

MrApollinax · 04-26-2009, 01:02 PM

There are a bunch of people on here that report that it will get you close to focus but you will need to manually lock it in.

Andi Lo · 04-26-2009, 01:04 PM

Yes, this is true. There's a thread discussing this somewhere not so long ago...

**Canada_Rockies** · 04-26-2009, 01:05 PM

I own one, and yes, it's true ... sort of. With a long lens, you have to manually focus somewhere near, then the converter will fine tune the focus for you. It even works in good light and high contrast with my M 400mm f/5.6. Anything less and it just hunts and gives up. As it is stated to work only with lenses f/4 and faster, I cannot complain. There is a thread where I posted my results on a wintry day.

https://www.pentaxforums.com/forums/pentax-slr-lens-discussion/56876-i-bored-m400-af1-7x.html

Last edited by Damn Brit; 04-28-2009 at 06:29 PM. Reason: Fixed Link

**fs999** · 04-26-2009, 02:28 PM

Page not found...

**Canada_Rockies** · 04-26-2009, 03:10 PM

Originally posted by fs999

Page not found...

I see that - I redid the link, but it still does not work. In lenses, look for "I was bored m400 + af1.7" in the threads.

ballgofar · 04-28-2009, 06:11 PM

Which ebay seller have this? I never seem to find these TC's when I look.

Damn Brit · 04-28-2009, 06:19 PM

Originally posted by Canada_Rockies

I see that - I redid the link, but it still does not work. In lenses, look for "I was bored m400 + af1.7" in the threads.

Albert,I took the liberty of fixing your link.

**G_Money** · 04-28-2009, 06:22 PM

eBay link

Says he has 10 of them.

**Lowell Goudge** · 04-28-2009, 06:51 PM

The SMC-F 1.7x AF TC is an excellent teleconverter. I use it quite a bit on my SMC 300mmF4. Note that while the instructions state it must be used with lenses F2 and faster, it works very well up to F4. F4.5 is reported to work, but I have no experinece at that apature with it. I know F5.6 just does not work except in bright sunlight.

I would be careful about " close focusing claims. while the adaptor clearly will be able to focus closer than your normal 50mm lens, it will only give about a 20% reduction in close focus distance on a 50mm lens, and the longer you go with prime lenses the smaller the reduction in close focus is. that is just optics. It is not meant to replace close upl lenses or extension tubes.

**Canada_Rockies** · 04-28-2009, 09:16 PM

Originally posted by Damn Brit

Albert,I took the liberty of fixing your link.

Thanks. What had I done wrong?

**Canada_Rockies** · 04-28-2009, 09:19 PM

Originally posted by Lowell Goudge

The SMC-F 1.7x AF TC is an excellent teleconverter. I use it quite a bit on my SMC 300mmF4. Note that while the instructions state it must be used with lenses F2 and faster, it works very well up to F4. F4.5 is reported to work, but I have no experinece at that apature with it. I know F5.6 just does not work except in bright sunlight.

I would be careful about " close focusing claims. while the adaptor clearly will be able to focus closer than your normal 50mm lens, it will only give about a 20% reduction in close focus distance on a 50mm lens, and the longer you go with prime lenses the smaller the reduction in close focus is. that is just optics. It is not meant to replace close upl lenses or extension tubes.

But it will crop the subject by 1.7, which might be what was meant. My next project will be to see how it works with my M 100 macro. It might just give me an edge. A 170mm f/6.8 macro lens, all Pentax glass.

**Lowell Goudge** · 04-29-2009, 02:34 AM

Originally posted by Canada_Rockies

But it will crop the subject by 1.7, which might be what was meant. My next project will be to see how it works with my M 100 macro. It might just give me an edge. A 170mm f/6.8 macro lens, all Pentax glass.

of course it crops by 1.7x after all it is a teleconverter, to my knowledge there is no 1:1 autofocusing adaptor for any camera. It needs to have magnification because im the adaptor changes the mount to focusing plane distance.

as for the SMC-M100 F4, it works just fine, I have one.

simico · 04-29-2009, 03:13 AM

I don't understand this... a pure MF lens doesn't have any built-in mechanics for AF, the only way to focus is to turn the focusing ring with your hand. How can a TC make it AF??

Or is it that the TC have some moving optical element used for focusing?
Enlighten me please

Adnan EROL · 04-29-2009, 03:40 AM

Originally posted by simico

I don't understand this... a pure MF lens doesn't have any built-in mechanics for AF, the only way to focus is to turn the focusing ring with your hand. How can a TC make it AF??

Or is it that the TC have some moving optical element used for focusing?
Enlighten me please

one more question:
Does it work for instance with a M42 lens?

04-26-2009, 12:48 PM	#1
Adnan EROL Senior Member Join Date: Oct 2007 Photos: Gallery Posts: 120	get autofocus capability for your manual lenses! Staff note: This post may contain affiliate links, which means Pentax Forums may earn a small commission if a visitor clicks through and makes a purchase. If you would like to support the forum directly, you may also make a donation here. Some ebay sellers (of Pentax SMC F 1.7X AF Adapter) declare that: When mounted between an autofocus body and either a Pentax A type or M type lens, the adapter converts the lens into an autofocus lens. The focusing mechanism is fast and snappy. no problem with Pentax SMC A 50mm f1.7 lens & Pentax SMC A 28mm f2.8 lens, Is it possible? Anybody test it?

04-28-2009, 06:19 PM	#8
Damn Brit Guest	Originally posted by Canada_Rockies I see that - I redid the link, but it still does not work. In lenses, look for "I was bored m400 + af1.7" in the threads. Albert,I took the liberty of fixing your link. Last edited by Damn Brit; 04-28-2009 at 06:30 PM.

04-28-2009, 06:22 PM	#9
G_Money Site Supporter Join Date: Jul 2007 Location: London, Ontario, Canada Posts: 598	eBay link Says he has 10 of them. Last edited by G_Money; 04-28-2009 at 06:28 PM.

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04-26-2009, 01:02 PM	#2
MrApollinax Veteran Member Join Date: Apr 2008 Location: Minnesota Photos: Gallery Posts: 1,529	There are a bunch of people on here that report that it will get you close to focus but you will need to manually lock it in.

04-26-2009, 01:04 PM	#3
Andi Lo Veteran Member Join Date: Jul 2008 Location: Halifax, Nova Scotia Posts: 2,924	Yes, this is true. There's a thread discussing this somewhere not so long ago...

04-26-2009, 01:05 PM	#4
Canada_Rockies Loyal Site Supporter Join Date: Nov 2007 Location: Sparwood, BC, Canada Photos: Gallery \| Albums Posts: 12,385	I own one, and yes, it's true ... sort of. With a long lens, you have to manually focus somewhere near, then the converter will fine tune the focus for you. It even works in good light and high contrast with my M 400mm f/5.6. Anything less and it just hunts and gives up. As it is stated to work only with lenses f/4 and faster, I cannot complain. There is a thread where I posted my results on a wintry day. https://www.pentaxforums.com/forums/pentax-slr-lens-discussion/56876-i-bored-m400-af1-7x.html Last edited by Damn Brit; 04-28-2009 at 06:29 PM. Reason: Fixed Link

04-26-2009, 02:28 PM	#5
fs999 Loyal Site Supporter Join Date: Jul 2008 Location: Luxembourg Photos: Gallery Posts: 8,638	Page not found...

04-26-2009, 03:10 PM	#6
Canada_Rockies Loyal Site Supporter Join Date: Nov 2007 Location: Sparwood, BC, Canada Photos: Gallery \| Albums Posts: 12,385	Originally posted by fs999 Page not found... I see that - I redid the link, but it still does not work. In lenses, look for "I was bored m400 + af1.7" in the threads.

04-28-2009, 06:11 PM	#7
ballgofar Forum Member Join Date: Jan 2008 Location: Rochester, NY Posts: 87	Which ebay seller have this? I never seem to find these TC's when I look.

04-28-2009, 06:51 PM	#10
Lowell Goudge Site Supporter Join Date: Jan 2007 Location: Toronto Photos: Gallery \| Albums Posts: 17,887	The SMC-F 1.7x AF TC is an excellent teleconverter. I use it quite a bit on my SMC 300mmF4. Note that while the instructions state it must be used with lenses F2 and faster, it works very well up to F4. F4.5 is reported to work, but I have no experinece at that apature with it. I know F5.6 just does not work except in bright sunlight. I would be careful about " close focusing claims. while the adaptor clearly will be able to focus closer than your normal 50mm lens, it will only give about a 20% reduction in close focus distance on a 50mm lens, and the longer you go with prime lenses the smaller the reduction in close focus is. that is just optics. It is not meant to replace close upl lenses or extension tubes.

04-28-2009, 09:16 PM	#11
Canada_Rockies Loyal Site Supporter Join Date: Nov 2007 Location: Sparwood, BC, Canada Photos: Gallery \| Albums Posts: 12,385	Originally posted by Damn Brit Albert,I took the liberty of fixing your link. Thanks. What had I done wrong?

04-28-2009, 09:19 PM	#12
Canada_Rockies Loyal Site Supporter Join Date: Nov 2007 Location: Sparwood, BC, Canada Photos: Gallery \| Albums Posts: 12,385	Originally posted by Lowell Goudge The SMC-F 1.7x AF TC is an excellent teleconverter. I use it quite a bit on my SMC 300mmF4. Note that while the instructions state it must be used with lenses F2 and faster, it works very well up to F4. F4.5 is reported to work, but I have no experinece at that apature with it. I know F5.6 just does not work except in bright sunlight. I would be careful about " close focusing claims. while the adaptor clearly will be able to focus closer than your normal 50mm lens, it will only give about a 20% reduction in close focus distance on a 50mm lens, and the longer you go with prime lenses the smaller the reduction in close focus is. that is just optics. It is not meant to replace close upl lenses or extension tubes. But it will crop the subject by 1.7, which might be what was meant. My next project will be to see how it works with my M 100 macro. It might just give me an edge. A 170mm f/6.8 macro lens, all Pentax glass.

04-29-2009, 02:34 AM	#13
Lowell Goudge Site Supporter Join Date: Jan 2007 Location: Toronto Photos: Gallery \| Albums Posts: 17,887	Originally posted by Canada_Rockies But it will crop the subject by 1.7, which might be what was meant. My next project will be to see how it works with my M 100 macro. It might just give me an edge. A 170mm f/6.8 macro lens, all Pentax glass. of course it crops by 1.7x after all it is a teleconverter, to my knowledge there is no 1:1 autofocusing adaptor for any camera. It needs to have magnification because im the adaptor changes the mount to focusing plane distance. as for the SMC-M100 F4, it works just fine, I have one.

04-29-2009, 03:13 AM	#14
simico Veteran Member Join Date: Jan 2009 Location: Budapest Posts: 821	I don't understand this... a pure MF lens doesn't have any built-in mechanics for AF, the only way to focus is to turn the focusing ring with your hand. How can a TC make it AF?? Or is it that the TC have some moving optical element used for focusing? Enlighten me please

04-29-2009, 03:40 AM	#15
Adnan EROL Senior Member Join Date: Oct 2007 Photos: Gallery Posts: 120 Original Poster	Originally posted by simico I don't understand this... a pure MF lens doesn't have any built-in mechanics for AF, the only way to focus is to turn the focusing ring with your hand. How can a TC make it AF?? Or is it that the TC have some moving optical element used for focusing? Enlighten me please one more question: Does it work for instance with a M42 lens?