TeleConvertor Query

Hello everyone

As always I have done a search for this, but I either get 100's of hits (that don't seem related) or nothing at all .....

Anyway, I've recently taken delivery of a Sigma 100-300mm f4 + 1.4TC.

When I'm using these together my K10D doesn't seem to realise there is a TC there - it still lets me select an apperture of f4 for example even though I know the minimum apperture is f5.6?

Is this normal behaviour?

It still lets me take pictures and everything else seems to respond as expected but I thought it would be clever enough to realise that the TC is there and restrict minimum apperture to f5.6?

Thanks

Lee

Yeah its normal behavour. Mine doesn't recognise it either (1.5xTC and 2xTC). Even in the image EXIF it will say that I took the shot at 300mm, rather than 600mm with the 2xTC....

Is it the Sigma 1.4TC?

That was a quick reply

Thank you

I have a Sigma 70-200mm f2.8 and both the 1.4x and 2x teleconverters and it does exactly the same.
I usually have to compensate by 1/2 stops on the exposure as well.

Yes!

Oh yeah, just saw your sig!!

Anyway, I was about to confirm that yes, it appears to be normal, and my k10d was the same with either sigma or kenko TC's, as was the K20d!

What do you think to the 100-300mm by the way?

The camera body will still display the aperture set on the lens, there is no electronic wizardry in the teleconverter (any make) that tells the camera a converter is fitted.

I changed my sig after posting the original message as it reminded me to update it!

Although I've had it a week I haven't really had much chance to have a play with it yet Hopefully this weekend!

Thanks to everyone for the replies

Having had my Tenko 1.5x apart i'm not surprised. The circuitry inside consisted of pins duplicating the connections on the front of the converter on the back. Any information taken from the lens would pass straight through with no change as if nothing where there.

I wonder how this impacts on the SR? How much difference does it make to SR if you have a 450mm lens but it thinks it is a 300mm?

I would imagine you would use a 400+mm lens on a tripod and therefore turn off SR anyway. But yes, I'm sure SR is incorrect in this situation.

Well i think going from 300mm to 450mm would increase the image shift on the censor, induced through shake, by 50%. So would the SR do only half a job.