extension tubes

Hi
Not sure if this is the right forum for this question.But can someone please confirm or otherwise that these are indeed NOT auto focus or exposure ( i bought them from ebay described as auto extension tubes it also says so on the box "Jessops auto extension tubes for pentax k fit) so i have emailed the seller waiting for an answer as perhaps he was mis-sold them in the first place,,but thought i would get more "expert" advice on them.There are no electrical contacts at all on them.Also what would they be worth if not...i paid £30 inc p and p.
Roy




edited for "exposure"

I think they were correctly described, I'm afraid. 'Auto' here refers to automatic diaphragm. There are others around here much more knowledgable than me about things macro but I'm sure auto focus extension tubes dont exist and the reason for the absent contacts is that these tubes are designed for the (film) K and M series lenses and bodies. No idea as to price.

Ken

They were correctly described. Auto as in diaphram. to my knowledge, only kenko had an af (screw drive) extension tube for pentax. Buy yourself a pentax af 1.7 teleconverter, and stack the converter, then the smaller auto tube and then a 50mm lens, for a decent (if slow) af macro set-up.....

I made the same mistake as you, this week actually, mine arrived 2 days ago - they are exactly the same as those in the pic.

For some reason I haven't been able to take a picture with them - or rather every image just comes out black even though everything looks ok through the viewfinder (I'm attempting to use my SMC-A 50mm). Have you managed anything with yours yet? I will keep trying with them (at least I'm having fun!) - I'm sure there is something obvious I'm missing

I paid around £20 with p&p for mine but don't think they are in as good condition as yours. The most annoying thing about mine is that the picture on the ebay is obviously a newer model as it had different clips and generally just looked a little more modern.

Sorry for the daft question - but what do you mean by auto-diaphragm, mine doesn't seem to do anything automatically?

edited due to dodgy spelling

see the spring attached to the lever inside the mount?
that pull your lens aperture wide open to let in as much light as possible (when viewing/focussing), and when the shutter fires it AUTOmatically stops the lens down to your chosen aperture.

Thanks Don - I'd flicked that spring and assumed it must do something but couldn't see what.

Woodworm
My images to came out black,but with flash it does work.I want to use mine with my tamron 90mm macro to get even closer.
I think we will have to adjust tv value to let more light in.
Oh well another learning curve
Roy

Although they are correctly described as Auto tubes (auto diaphragm), you'll have to set everything to manual (M exposure mode) to get any sense out of them.

Here are two examples with very similar tubes and a Pentax M 1.7. The lens was at its widest and manual focus, but I can't rememeber the no. of tubes I used. They are hand held in the garden with a breeze blowing - probably a lesson in how NOT to take macro and will make the experts cringe. :blushBut one has to start somewhere)

[IMG]http://i83.photobucket.com/albums/j311/Tinywales/garden/spider_1.jpg[/IMG]

and

[IMG]http://i83.photobucket.com/albums/j311/Tinywales/garden/spider_2.jpg[/IMG]


Howard

Pentax A compatible tubes are worthwhile, but AF? I don't think they are at all necessary as most macro shots require MF.

FWIW, I have a set of Kenko tubes marked as Pentax AF compatible. They are that, but only in MF mode because they lack the screw drive coupling.

Confused? You will be.

The genuine Pentax Auto Extension tubes have exactly the same - aperture levers, but no metering contacts.

I have some "Triplus" tubes that do have the contacts. Very helpful (but not AF - which they don't need to be).

So there are some out there...
Matt

I brought mine thinking they were AF, they are Kenko brand with "for P/AF" stamped on the side. But it was obvious when i looked at them that they don't have the AF screw drive
So what does the AF stand for if not auto focus.

I may have been wrong about the kenko having af coupling....but they definately have a 25mm with electrical contacts for metering, with the a, and af lenses.

There does seem to be a lot of different versions of the Jessops tubes, mine cost £60 IIRC off ebay, but they do have all 7 electric contacts in place.

Yep those were the ones i thought i was getting.
Too late now but i will learn how to use the ones i have.
Roy