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Old Oct 2, 2008, 9:17 PM   #1
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re Pentax 1.7 AF adapter.

I am waiting for the one I have bought to arrive and have been reading up on use of the autofocus adapter with manual lenses.

The Pentax instruction sheet says it does not work with M42 (screw mount) lenses even when fitted with the appropriate adapter. However comments on-line says it will work with the contacts shorted, one comment said only the contact nearest the 6 o'clock position needs to be shorted which is weird as that contact sticks up and would always make contact with the lens mount.

Does anyone know? Otherwise I will just experiment when I get it in my hand.





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Old Oct 14, 2008, 10:11 PM   #2
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At last! My 1.7x AF Adapter has arrived and I tried it on my Takumar 300mm f1:4.

This is on my *ist DS and the Takumar has been fitted with a ring that locks the M42/PK adapter in place and also contacts all the contacts on the front of the adapter.



WWWWeeeeeeeellllllll, it seems to work, sort of, the camera drives the internals of the adapter and it does change the focus though the camera seems very reluctant to give focus confirmation even in bright light. This is with the camera set to AF and the program set to green 'Auto Pict'. More experimenting required before I give this the thumbs up.:roll:
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Old Oct 15, 2008, 4:37 AM   #3
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John Hill wrote:
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re Pentax 1.7 AF adapter.

I am waiting for the one I have bought to arrive and have been reading up on use of the autofocus adapter with manual lenses.

The Pentax instruction sheet says it does not work with M42 (screw mount) lenses even when fitted with the appropriate adapter. However comments on-line says it will work with the contacts shorted, one comment said only the contact nearest the 6 o'clock position needs to be shorted which is weird as that contact sticks up and would always make contact with the lens mount.

Does anyone know? Otherwise I will just experiment when I get it in my hand.




Hi John,

No readyinfo re. the 1.7 adaptor, but with M42 lenses to work in focus trap, I'd no success until I made foil rings that shorted the camera body contacts.

( Gumnuts Idea originally) I can't think where, but I've asneaky feeling thatI've read somewhere that this is also required with the 1.7 AF adaptor. ... Jack
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Old Oct 15, 2008, 8:24 AM   #4
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John Hill wrote:
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At last!¬* My 1.7x AF Adapter¬* has arrived and I tried it on my Takumar 300mm f1:4.¬*

This is on my *ist DS and the Takumar has been fitted with a ring that locks the M42/PK adapter in place and also contacts all the contacts on the front of the adapter.

¬*

WWWWeeeeeeeellllllll,¬* it¬* seems to work, sort of, the camera drives the internals of the adapter and it does change the focus though the camera seems very reluctant to give focus confirmation even in bright light.¬*¬* This is with the camera set to AF and the program set to green 'Auto Pict'.¬* More experimenting required before I give this the thumbs up.:roll:
Hi John,

You do realize that the AFA only has a limited range of focus? -- It's got enough range to cover a normal FL lens if it's set manually to infinity, but for most teles, you have to manually prefocus the lens somewhat to get it into the range of the AFA. This sounds more complicated than it really is. Once you have it in the AFA's range, focus lock should be pretty quick.

Scott
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Old Oct 15, 2008, 4:37 PM   #5
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John Hill wrote:
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the camera seems very reluctant to give focus confirmation even in bright light. This is with the camera set to AF and the program set to green 'Auto Pict'.
The camera doesn't give focus confirmation if there isn't good enough light. That is, a big enough largest aperture. My DS gives focus confirmation with my manual focus 600 mm f5.6 lens, but when I put the 2X converter on it doesn't. The AFA 1.7X works as a tele converter, but AF doesnt work either. Not even on a sunny day in a snowy landscape.

Pentax saysthe AFA 1.7Xworks with lenses with a largest aperture f2.8 or larger, but some of our members here use it successfully with A* 300 mm f4 or FA* 300 mm f4.5. I guess that's where the real limit is. It has nothing to do with either the converter or the settings of the camera, but with the capacity of the light metering sensor and the AF sensor in the camera body.

Kjell


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Old Oct 15, 2008, 5:59 PM   #6
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Maybe this was not my best purchase! I doubt that I could justify buying a long lens (which is my interest) of 2.8 or faster.:roll:

I did get a few focus locks with a300 f4 but no good images using basically hand held on my 'photo sniper' bracket.

However I have not given up on it yet and will try to refine my techniques a little to determine just what the limitations are.






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Old Oct 16, 2008, 12:40 AM   #7
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I don't think one should see the AFA as a tele converter that adds autofocus to a manual lens, but rather as a device that adds autofocus to a manual lens and when doing that also adds to focal length. I use it mainly with my 85 mm f1.4, thus getting a 145 mm lens f2.8. I also use it with a 200 mm lens f2.8 getting a 340 mm lens f4.5. Of course these lenses didn't come for free, but selling the AFA converter to get a F* or FA* 300 mm 4.5 and an A*135 mm f 1.8 wouldn't have been a cheap solution either.

Kjell
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Old Oct 16, 2008, 4:03 AM   #8
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I did manage to get a few almost reasonable shots today though it is rather a challenge hand held with an effective 510mm. I think the focus was OK on some of thembut increasing the shutter speed by increasing the ISO was I think overdone. If the weather is good tomorrow I will try some more and maybe get something worthy of posting!

I had to abandon using it on my "photo sniper" bracket due to fitting issues but this particular combination (*ist DS and Takumar1:4/300) might yet prove worthy of having its own photo sniper bracket made.

P.S. AF sure does .... the batteries dry!:roll:
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Old Oct 21, 2008, 6:18 PM   #9
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Still no chance to get out and about with this AF Adapter!I am really glad I bought it when I did though and since then I found water in the fuel tank of my vehicle will cost me a new fuel pump, new injectors, new filters, new fuel regulator and even new fuel lines, the cost will make what I paid for the AF Adapter rather trivial I am afraid!:roll:

Not to say I have not had the occasional play with the AF Adapter, at least enough to form a few conclusions. The first is that it will have limited practical use with the 300mm and up lenses that I have as the resultant combinations are just too long for use in the carry around style that I enjoy.
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Old Nov 20, 2008, 1:14 AM   #10
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Update on the Pentax 1.7 AF adapter.....

A few things to consider.........

I found I cannot get it to work without the pins being shorted, I know others have mentioned using foil to do this but I dont really like doing that, for various reasons.

Used with a lens that contact the pins it works fine, unfortunately not all my lenses do that!:roll:

The AF adapter does not work with an M42 lens using the Pentax M42/K adapter unless the lens body is shaped to make that contact.

Not only must the lens body contact the pins but it must be a conductive surface! So black lacquer and anodized aluminium are no go.

Now it just so happens the much despised wide-flange type M42/K adapters, the ones that loose infinity focus, have their use! They do contact the pins but once again there has to be a conductive surface so the nice black anodised one did not work but the stainless steel(?) one does. My Takumar 1:3.5/200 and 1:4/300 now work a treat! A treat that is except for loss of infinity focus.

Loss of infinity effect is very marked in both these lenses with a maximum focus range of little more than 30 metres/yards using these M42/K adapters but on the other hand I now have an effective 1:6.8/510mm autofocus combination that will focus to just about 2 metres/yards!:lol:

I just need to get out and about with these new combinations, maybe the zoo! Handholding 510mm will be a challenge though.:roll:



BTW, the anodised black M42/K adapter works with the AF adapter after just two minutes with a scrap of sandpaper.:G




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