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08-15-2009, 03:54 AM   #1
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AF on K10D with TC

Hi,

I have a Pentax K10D with a Sigma APO 100-300mm F4 EX DG lens and have bolted my new Sigma APO 1.4x DG AF on this morning, and am having trouble with the auot focus.

I've got it set on the "P" setting and AF.S, shake reduction is on.

On the lens I have autofocus set and the ring set to A.

When I hold the shutter button half way down all I get is a whirring sound...

Any ideas or advice?

Thanks.

08-15-2009, 08:54 AM   #2
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Sounds like a SIGnificant MAlfunction...
Sorry, don't pay me any heed, I just happen to think Sigma is crap.
I also don't like hockey, baseball and the Hamilton Tigercats.
Just so you know.

It does sound like the AF keys aren't coupling though. Does the camera AF with the lens alone? If so, have a look at the AF key on the lens as compared to the AF key on the teleconverter.
08-15-2009, 12:19 PM   #3
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Does all work fine without the TC, if so at least you can point the finger at the TC.

Is it new, if so maybe a trip back o the shop.
08-15-2009, 02:56 PM   #4
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Make sure that the TC and the lens are coupled completely 'coz it might not be twisted in all the way that the screw drive on the TC is being driven by the camera but is not coupled with the lens so the TC to lens screw is not connecting and driving.
I had one incident like this 'coz the F became F--..so, I said, what the heck!??
TC might not be working or not compatible, but after fiddling a bit, the lens didn't couple or sit completely with the TC.
The TC has a lot of contacts too that when you turn the lens to couple with it, you might as times think that it's already seated right but not totally in yet.
You just hear a lot of clicks as contact to contact rub against each other when you put them together.
Try removing it and coupling first the lens to the TC without attaching it to camera first.
When you are sure that they are really seated and connected to each other, connect both to the lens as a single unit.
Anyway, it just sounds like the screw dive of the TC might not be coupled with the lens screw drive too, that's why you only hear a whirring sound which is the camera turning or driving the TC screw drive but no contact with the lens.

08-17-2009, 02:03 AM   #5
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Is the"Sigma APO 100-300mm F4 EX DG lens" an old one from the film camera days? Is the teleconverted a dedicated Pentax unit for that lens? Not likely as the Sigma lens is not intended fot digital use?
Neverless it should function after a fashion. But is it worth the effort including the risk of colateral damage to the camera?
08-17-2009, 03:39 AM   #6
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It's a new lens, not one of the old film ones.

I've checked that the lens is compatible with the TC on the Sigma website and it is.

The AF on the lens itself without the TC is fine.

I'm wondering if it's a fault with the TC, or because of the focal length I am trying to focus on.
08-17-2009, 04:35 AM   #7
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Maybe try rotating the focus barrel just a bit? I had some problems when lens' autofocus didn't align with the shaft in the camera, and I had to rotate the focus ring just a bit to make them lock.
08-17-2009, 07:24 AM   #8
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QuoteOriginally posted by arniejrim Quote
It's a new lens, not one of the old film ones.

I've checked that the lens is compatible with the TC on the Sigma website and it is.

The AF on the lens itself without the TC is fine.

I'm wondering if it's a fault with the TC, or because of the focal length I am trying to focus on.
Is it HSM? if yes, your TC will not wotk. The Sigma teleconvertor only work on non HSM, screw type only lenses.

08-17-2009, 08:58 AM   #9
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QuoteOriginally posted by Denis Quote
Is it HSM? if yes, your TC will not wotk. The Sigma teleconvertor only work on non HSM, screw type only lenses.
No it's not a HSM one, it's the Sigma EX 100-300mm F4 APO DG (I didn't think they did HSM on a Pentax mount).
08-17-2009, 02:26 PM   #10
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QuoteOriginally posted by pbo Quote
Maybe try rotating the focus barrel just a bit? I had some problems when lens' autofocus didn't align with the shaft in the camera, and I had to rotate the focus ring just a bit to make them lock.
I already suggested this as the screw drive might not be aligning but I guess he doesn't want to try that if it is misaligned.
All he is looking at is once it's coupled, it is already ok as he replies to the other suggestions but not to ours.
Oh well..I already told what is happening and if he doesn't want to do some trial and error to find out then, it's best just to return the TC.
08-17-2009, 03:43 PM   #11
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Does the lens have a push/pull focus ring for engaging/disengaging MF on the lens? IOW, is the lens set to MF?
08-18-2009, 03:44 AM   #12
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QuoteOriginally posted by GerryL Quote
Make sure that the TC and the lens are coupled completely 'coz it might not be twisted in all the way that the screw drive on the TC is being driven by the camera but is not coupled with the lens so the TC to lens screw is not connecting and driving.
I had one incident like this 'coz the F became F--..so, I said, what the heck!??
TC might not be working or not compatible, but after fiddling a bit, the lens didn't couple or sit completely with the TC.
The TC has a lot of contacts too that when you turn the lens to couple with it, you might as times think that it's already seated right but not totally in yet.
You just hear a lot of clicks as contact to contact rub against each other when you put them together.
Try removing it and coupling first the lens to the TC without attaching it to camera first.
When you are sure that they are really seated and connected to each other, connect both to the lens as a single unit.
Anyway, it just sounds like the screw dive of the TC might not be coupled with the lens screw drive too, that's why you only hear a whirring sound which is the camera turning or driving the TC screw drive but no contact with the lens.
Sorry to not reply Gerry - just reading through the post now.

I am getting the F-- message you mentioned.
How do I check the TC and the lens are coupled completely? Is a case of connecting the lens to the TC, selecting MF on the lens and then rotating the barrel as pbo suggested?
08-18-2009, 06:38 AM   #13
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QuoteOriginally posted by arniejrim Quote
Sorry to not reply Gerry - just reading through the post now.

I am getting the F-- message you mentioned.
How do I check the TC and the lens are coupled completely? Is a case of connecting the lens to the TC, selecting MF on the lens and then rotating the barrel as pbo suggested?
If you are getting the F--, then it is definitely not coupled.
Make sure you turn it fully as when putting the lens on the camera.
The only thing is it is easier to put the lens on the camera as it is only the lens to camera contacts that has to align.
With the TC, once you put it on the camera and is already aligned with the contacts, when you attach the lens to the TC after, twist fully also as it is harder for the TC to lens contacts to align.
If you are getting the F--, then the lens to TC is not aligned (more likely) or TC to camera isn't aligned (less likely).
Just make sure you fully twist till you get the "F" to give you a reading and not F--.
'Coz if the contacts are not aligned, then more so that the screw drive is not aligned or not coupled also.
08-18-2009, 06:46 AM   #14
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If the lens has the MF switch then you should turn if off too as this might be preventing the coupling.
Once you get the "F3.5 (or whatever)" reading and not F--, you can switch back the lens switch to AF.
I never had a lens that had a MF/AF switch.
The only switch I'm aware of is the camera body switch for MF/AF and I didn't switch mine to MF for the lenses to couple or align.
You have misalignment of lens to TC so the contacts are not touching nor the screw drive engaging.
This is the reason why you get the F-- and just the screw drive whirrr...
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