Extention Tubes

Hi All,

I've found a set of extention tubes which have the following as part of the description :-

"Auto Extension Macro tubes .
Pentax K bayonet mount ( K , PK , PK/M )

Full mechanical iris control of the lens is maintained with the SLR when these tubes are placed between lens and body "


From the included photograph there is no evidence of contacts around the flanges so :-

1. What would be their limitations when used with a K10D and say an 18-55mm kit lens
2. I can accept that I may well need to manually focus the lens.

There are probably a plethora of questions I should ask so any insights would be welcomed

regards
Bernard

To be of any use at all you will have to use them with a lens that has an aperture ring. From then on everything will be done in manual mode.

Thanks guys, I'll stay away from this set also.

I have a plane set of tubes on which I use a Pentax-M 1.7 50mm lens perfectly well but as this is the only K mount -M lens I have. I thought an update could be in order, and the price wasn't too bad either.

Ah well, sooner or later an ebay seller will come up with a reasonble price and at the same time I'll be the only one to notice.

regards
Bernard

I think there are quite a few people on the lookout for PKA tubes, their prices always seem to shoot up. You might be lucky & see a set miss described but with the contacts, but I've given up trying.

You can get a low quality PKA teleconverter & remove the glass, but they tend to be rather long IMO.
What I'd really like would be a PKA helicoid - but I don't think they were ever made. My M42 helicoid is great for enlarger lenses, but apertures on those are always fully manual anyway...

Have you ever noticed that it's always one step forward three steps back.

I've resorted to using M42 kit and a PK-M42 adapter, at least I already have the kit and it can't get any simpler, it's just frustrating when the best lenses I have are not suitable for one reason or another.


Bernard

I have a set of Automatic extention tubes for the K-mount. They have all the electronic contacts and the aperture lever, but not the Autofocus connection.
I suppose autofocus would not work to well with extention tubes.
The tubes are made by MARUMI of Japan and are mechanically of excelent quality.

Horst

Actually from trial and error (lots of error) the above isn't entirely correct.

Both fully manual (no aperture linkage/no electrical contacts) and 'auto' types (with the aperture linkage/no electrical contacts) will work happily with 'M' lenses with an aperture ring, but without the 'A' setting. I don't have an 'A' lens, but have read that these types won't actually work with it in the 'A' setting, but can't confirm that.

The difference between the two is this.

With the fully manual tubes (no aperture linkage) if you select f16, for example, on the aperture ring, the aperture on the lens will immediately close to f16 making the subject darker in the viewfinder and harder to compose/focus.

With the auto tubes (with aperture linkage), selecting f16 in the same way will leave the aperture wide open to make it easier to compose/focus and the aperture will only close to f16 when you take the shot.

I've seen auto types for sale that have the electrical contacts for aperture only (presumably can be used in AV mode for semi-auto metering) and a fourth type which has the full range of contacts for use with any lens as described above.

Hope this helps avoid some expensive mistakes. I only know this from trial and error buying a range of tubes and using them with a variety of lenses as I couldn't find any decent information about what the differences were.

Thanks Matt.

It's very confusing for what ought to be a straightforward subject.

I didn't mean to correct you - just wanted to help someone else avoid my mistakes.......

There seems to be pleny of people who buy these in ignorance or because of incorrect claims by Ebay sellers and who are then dissapointed and give up with tubes altogether.

Hello - I encountered the same problem with extension tubes.

Like other people I found out the hard way by using a set of auto extension tubes with a kit lens on my K10D. I couldn't adjust the aperture and hence all exposures were vastly long due to the lens being set at f/22.

I then bought an old PK-A lens to use on the extension tubes. For a few years I kept looking on auction websites and was out bidded. This year however I was more successful and managed to buy a set of Jessops extension tubes with electronic contacts for around £45.

Thanks to help from other members on here, I was advised to modify the set by scratching off a small section of paint to imitate the missing contact. Now I can use them with any of my lenses.

So these extension tubes are out there, I remember seeing used versions on the Mifsuds website a few times for around £135. So keep looking and you may be as lucky as I was.

Why not just buy a few cheap manual lenses (either fully manual or with the mechanical aperture linkage) and have some fun with extension tubes? It really is not that difficult to use the older lenses with tubes and I don't find it any disadvantage. I suspect most will want to shoot in manual anyway for this type of photography? Many of the old primes produce fabulous image quality on macro tubes.

Regards
David

I for one have sorted my problem. I've bought a set with contacts


Bernard