[daacon]

I have a Pentax 1.7x TC where autofocus more or less works. I have found that on some lenses at some times I have to go MF to kind of kick start the AF - when I get close in MF I the AF usually starts to work. Almost like cranking an old motor.

Sometimes it goes back to not working after I change FL say from 200 to 70 and I have to go do the MF trick again. (The MF is usually done with a quick shift on the lens iteself).

So my question is do you think my TC is malfunctioning ? Is is suppose to work 100% all the time with no degradation in AF speed ?

Some non Pentax Lens I have to switch SR off before I turn on the camer (Thanks for that info Marc !!) otherwise it will ask my for FL. I think this is ok - it's more the auto focus that I am cocncerned about.

Edit: do I just need to give it a good cleaning perhaps ? If so how would I do that ?

[hinman]

I have a Pentax 1.7x TC where autofocus more or less works. I have found that on some lenses at some times I have to go MF to kind of kick start the AF - when I get close in MF I the AF usually starts to work. Almost like cranking an old motor.

Sometimes it goes back to not working after I change FL say from 200 to 70 and I have to go do the MF trick again. (The MF is usually done with a quick shift on the lens iteself).

So my question is do you think my TC is malfunctioning ? Is is suppose to work 100% all the time with no degradation in AF speed ?

Some non Pentax Lens I have to switch SR off before I turn on the camer (Thanks for that info Marc !!) otherwise it will ask my for FL. I think this is ok - it's more the auto focus that I am cocncerned about.

Edit: do I just need to give it a good cleaning perhaps ? If so how would I do that ?

As far as I know, that is the normal behavior in Pentax F-1.7x AF TC, you need to manual focus to close proximity to your target in order for the TC to engage in AF. It is as if the AF resides in the TC but the catch is that you need to move the focusing ring close to the position of your intended object. In a way, it is partial AF as you need to manual focus first to a close point.

Regarding the SR focal length, you can enter it by

1. power off, then on
2. menu button -> followed by one UP arrow

And I always count on the 2nd method on SR focal length when I am using a zoom lens. Perhaps, other can jump in with better explanation.

Thanks,
Hin

[daacon]

Thanks Hin - I don't use it often , good to know that is normal behaviour. Perhaps I need to buy a DA* 300 ummmmmmmmmmm