DA-star and problems with extension tubes

I've just bought one of these lights and thought I'd have another go at macro with the DA* lenses.

The problem is that the Teleplus (sorry: Teleplus) tubes I have - which have the electrical contacts - seem to freak out the K5. Now, it did it with the K7 and IIRC the K20D as well. It's almost like the camera is confused, knowing that the lens should be SDM focused, but not able to communicate.

Now, I'm not one to take this without a fight

So, first thing: switch the lens or body to the MF setting. When the lens is on AF, the "MF" sign flashes madly in the viewfinder. (But I've lost focus confirmation ability!) With that, I can take shots through the viewfinder...

...but, odd things are going on. Holding a button down doesn't auto-repeat anymore (unless you slightly dismount the lens). Oh, and Live View doesn't work - the camera just opens and closes the shutter. Pah


I did manage to get it to work by holding the lens release tab and slightly rotating the lens.... but it's not working all the time

It's such a shame that Pentax can't update the firmware to allow for this situation. But, I admit it's low down on their priority - supporting a third-party extension tube!

My only other option is to modify the tubes to mask out one of the contacts - so the body thinks it's got an unidentified lens attached that still supports "A" aperture.

Will keep you posted

Matt

I have some Kenko tubes that have the contacts. I'll give them a try. From what you describe, I'd say it was a tolerence issue between the spacings/height/depth of the contacts.

Which particular lens were you using Matt?

Peter - I've tried both the DA*16-50 and DA*50-135
I reckon it's not tolerance, but down to the body expecting SDM communication from a lens that it knows is SDM

If I put an SMC-A 50/2 on the end of the same tubes then everything works absolutely perfectly

That's why I'm hoping I can get the body to see the DA* as an SMC-A style lens... maybe! (Better still would be a firmware update!)

Matt

I have a set of auto Hoya tubes, without the electrical contacts, that work fine on my istDS and K10D, i.e they allow the lens to stop down during exposure.

For some reason this doesn't work on my K7, it stays wide open, no matter what f-stop I have chosen.

Anyway, thanks to your idea of starting to remove the lens/tube, I can get it to at least operate at my chosen f-stop.

Not exactly what you were trying to do, but has got me out of a hole, thanks.

John.

John,
Do your tubes have the aperture 'finger'?

Pentax produced manual tubes, and 'auto' tubes. The manual ones were just a tube, and the auto ones have the mechanical linkage for the aperture lever.

AFAIK, only third party ones have electrical contacts, and there is only one (very rare) Kenko 25mm tube that has PZ contacts (i.e. the SDM contacts).

Wouldn't mind trying the Kenko ones
Matt

A bit of Googling for the "rarer than hen's teeth" Kenko Uniplus 25DG came up with this thread:


So there may be hope...
Matt

Hi Matt, yes they do have the aperture 'finger', and as I say they work with all my other cameras as expected, but not with the K7.

It's funny if I take the M 50mm f1.7 lens off the tube, and put it on the K7, it works ok.

I've tried the tubes with a few lenses, and they all work ok on the other cameras, but not on the K7.

Must be the tubes They are Hoya, but made and purchased before the 'take-over'

I've tested my Kenko tubes (labelled: KENKO EXTENSION TUBE FOR P/AF, which is a bit of a misnoma because they lack both SDM contacts and the AF screw) as per Matt's configuration, but only with the DA* 16-50mm lens.

They behave exactly as Matt has described, identically to his Teleplus tubes.

I've not gone any further with this because my macro lenses, which is what I would use anyway, perform as expected and give me focus confirmation when the body is in MF mode.

It shouldn't be beyond Pentax's expertise to allow us to choose which AF drive method we prefer, especially when some DA* lenses have both SDM & screw methods for focussing.

It'd be interesting to know what happens when a pre-SDM body is used. I guess it'll work fine.

You're not suffering this problem (link) are you?

Wow !!!

Exactly the same problem

Might start scraping.

Tried a little tin foil and this works too

.

I can now 'stop-down'

A50mm f1.2 @ f1.2 on three tubes on the K7





A50mm f1.2 @ f16 on three tubes on the K7




Sorry for hijacking your thread Matt, but I'm a happy bunny now.

Matt is wonderful

Liking the macros of the watch.

Excuse me but, whilst I agree that Matt is wonderful, check out this thread . . . from 4 years earlier.

Peter, you're a star and Matt is wonderful