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04-24-2009, 11:41 AM   #1
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How do I maintain AF while imputing a custom SR setting when using a teleconverter

How do I maintain AF while imputing a custom SR setting when using a teleconverter?


Is there a pin I can short out? 510mm when it's actually registering 300mm really makes the SR less effective by at least a stop.

04-24-2009, 03:06 PM   #2
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QuoteOriginally posted by konraDarnok Quote
How do I maintain AF while imputing a custom SR setting when using a teleconverter?


Is there a pin I can short out? 510mm when it's actually registering 300mm really makes the SR less effective by at least a stop.
I'm not sure I understand the question. SR and AF don't have anything to do with each other. Can you describe the situation in detail?
If you are asking how to compose, focus, and then lower the camera to input the focal length that your lens is no set to so you can then raise the camera and still be focused the answer is to turn off "AF by press half way" and set the AF button to be used to focus. You didn't say what model camera, but for K10 or 20 the above will work.

Last edited by Parallax; 04-24-2009 at 03:16 PM.
04-24-2009, 03:15 PM   #3
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QuoteOriginally posted by Parallax Quote
I'm not sure I understand the question. SR and AF don't have anything to do with each other. Can you describe the situation in detail?
I understand the question. I just don't know the answer.

Here's the scenerio: I have a Tamron AF 90mm f/2.8. I want to use a Tamron 2X teleconverter with it.

The combination of the lens and a TC gives me an AF lens, with focal length of 180mm, and f/5.6 max aperture.

But electrically, the TC is just a pass-thru. The camera sees the combo as a lens with 90mm focal length and the SR will act accordingly. The action of SR is not sufficient for a lens of 180mm focal length.

Since the camera already has the focal length data (even though incorrect), it does not allow me to enter the actual focal length (as when I use a manual lens).

If I block the electrical connections that transfer focal length data (assuming I figure out what pins to block), chances are I will also block the AF connections.

The question is how do I NOT block the AF connections, yet trick the camera into allowing me to enter the focal length of the lens.
04-24-2009, 04:01 PM   #4
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QuoteOriginally posted by SOldBear Quote

The question is how do I NOT block the AF connections, yet trick the camera into allowing me to enter the focal length of the lens.

Yep.

May not be possible. But I've read threads where it seems like people claim to the contrary.

It should be a menu function.

04-24-2009, 04:11 PM   #5
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I think if you short out the 7th pin to the lens mount, therefore defeating the focal length and data transmission to the body, you also eliminate the focus data, You will get focus indication but not AF.

Youo can only achieve what you ask if you have the SMC-F 1.7x AF TC whihc requires you to focus close with the lens and then let the TC do the final adjustment. This works because the TC has its own moving elements.
04-24-2009, 04:40 PM   #6
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QuoteOriginally posted by Lowell Goudge Quote
I think if you short out the 7th pin to the lens mount, therefore defeating the focal length and data transmission to the body, you also eliminate the focus data, You will get focus indication but not AF.

Youo can only achieve what you ask if you have the SMC-F 1.7x AF TC whihc requires you to focus close with the lens and then let the TC do the final adjustment. This works because the TC has its own moving elements.
I know that the AF TC can do it. With the Tamron 60b, as you know, it weighed so much that you could focus and hold it by the palm grip with very satisfactory results -- SR wise.

This 300mm F* works great with the Promaster 1.7x, but I don't like it with the AF TC because it's so light it's hard to focus and keep steady.

If you "chicken wing" it with the Promaster, it works as good at the heavy 60b in palm.

But I know I could get a stop or more if I could get the camera to see it at the proper focal length.
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