PK-A extension rings on a K10D

Hello all,

I have recently bought a set of PK-A extension rings to use on my Pentax K10D.

I have mounted the PK-A extension tubes on my camera then attached my PK-A lens to the front.

When I switch on the camera I get a message asking me to set the correct focal length. So I set it accordingly, then when I look at the LCD display on top of the camera the shutter speed / aperture settings flash. The camera does not allow me to manually set an aperture all I get is 'F___' and when I look through the view finder it is very dark (probably because I am unable to set the aperture).

Has anyone experienced these symptoms? and more importantly is there a cure so that I can use my Pentax FA-J and DA lenses with these extension rings on my Pentax K10D??

Best Regards,

Paul

For a start, with genuinely PK-A tubes, you should set the lens to A, just as you would without the tubes.

Now, the question arises, are the tubes genuinely PK-A, regardless of what they're labelled as.

Have a very close look at the contacts on the mount side.

How many are there - 6, or 7?

Thank you for both of your responses, the extension rings have six contacts and are made by Jessops. As you suggest I will scrape some paint off both sides of each extension rings.

Is it possible to add these extension rings to a macro lens to get even closer? or should they only be used with standard fixed lenses?

Another question the set contain 3 extension rings (13, 21 & 31) is each one for a set lens or magnification?

Your help and advice would be very gratefully received.

Best Regards,

Paul

Thanks for the suggestion of scrapping off the paint the image helped me easily understand what I needed to do. I have just done this and they work as I originally expected them to work. So thank you very much indeed.

As Mike says you can use them with almost any lens. It becomes a bit impractical
with lenses smaller than about 20mm because the subject becomes too close to the lens.

The magnification depends on how close the original lens can focus.

The sizes are probably arranged so that 21+31 = 52mm = 2 inches
The 13mm is half an inch.

52mm + 50mm lens should give about 1:1

There's loads of stuff on the web and probably videos on Youtube.

This threads quite good for calcs: link

Sure. A macro lens of a given focal length does its magnification by letting you get closer to the subject and still be able to focus, not by doing more magnification than any other lens of the same focal length.

Since the tubes just move the lens a bit further away from the camera, they just allow you to get even closer to the subject, and still be able to focus.

However, once you get the camera very close to the subject (you'll soon discover how close) , you run into practical issues concerning focusing and lighting. You need a lot of light (or very long exposures), and depth of field is almost non-existent, so accurate focusing is hard.

No, they're just the distance in mm that the lens is moved away from the body by using that tube.

You can use any combination of the three.