Auto Focus is not functioning

[skid2964]

Just bought a used Pentax ZX-7 and separately bought a used Pentax SMC A 35-80 f4-5.6 lens.

The auto focus does not function, I have the white dot set to "A". The camera will sense when it is in focus but it will not focus automatically.

Does this sound like I have a malfunctioning lens? or is something like this commonly a problem within the camera body?

I have ordered a new Tamron lens but it has not arrived yet for me to test on this camera body.

 

[Steph]

I think the lens you bought is not designed for AF. It is an older lens for manual focus only.

 

[skid2964]

I think the lens you bought is not designed for AF. It is an older lens for manual focus only.

I just found the answer, like you suggest; the "A" Pentax lens is listed as compatible with the ZX-7.
But, everything works except the autofocus, even the snap focus works. Where you can pre-focus the camera and hold the shutter down and when something appears in the focus area, it will snap the picture for you.

 

[compur]

Pentax A-series lenses are manual focus regardless of which model camera
they're mounted on. These say "SMC Pentax-A" on them.

The F-series and FA-series are auto-focus.

 

[AndrewG]

I just found the answer, like you suggest; the "A" Pentax lens is listed as compatible with the ZX-7.
But, everything works except the autofocus, even the snap focus works. Where you can pre-focus the camera and hold the shutter down and when something appears in the focus area, it will snap the picture for you.

Nikon autofocus lenses are compatible with manual focus cameras and vice versa.
A Pentax SMC lens may use the same mount but it is not an autofocus lens.

 

[skid2964]

I have been educating myself on all the various Pentax lenses, past and present.

The "A" lens only has an aperture related automatic feature, not autofocus like the "F" and "FA" ... The "M" lens was completely manual.

And yes, they are all compatible with the latest DSLR's and vice versa with limited capabilities, like the Nikon.