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helicoid extension tube

davem
Posted 03/01/2014 - 11:41 Link
I have seen a helicoid extension tube on ebay and wondered what is it and what does it do?

Can anybody help?

Dave
bforbes
Posted 03/01/2014 - 11:47 Link
Helicoil inserts are used to repair or strengthen threads in "soft" materials. link
Algernon
Posted 03/01/2014 - 11:53 Link
A helicopter is a type of rotorcraft in which lift and thrust are supplied by rotors.

http://en.wikipedia.org/wiki/Helicopter
Half Man... Half Pentax ... Half Cucumber

Pentax K-1 + K-5 and some other stuff

Algi
Edited by Algernon: 03/01/2014 - 11:53
Algernon
Posted 03/01/2014 - 11:56 Link
davem wrote:
I have seen a helicoid extension tube on ebay and wondered what is it and what does it do?

Can anybody help?

Dave

Best variable extension tube ever. Length varies as you twist it.
Good for slide copying etc. The Pentax Slide Copier K actually
has one built in.

--
Half Man... Half Pentax ... Half Cucumber

Pentax K-1 + K-5 and some other stuff

Algi
Edited by Algernon: 03/01/2014 - 11:58
pentaxian450
Posted 03/01/2014 - 12:48 Link
Algernon wrote:
A helicopter is a type of rotorcraft in which lift and thrust are supplied by rotors.

http://en.wikipedia.org/wiki/Helicopter

Are you drunk again?
Yves (another one of those crazy Canucks)
Algernon
Posted 03/01/2014 - 13:03 Link
Barrie's been hacked
Half Man... Half Pentax ... Half Cucumber

Pentax K-1 + K-5 and some other stuff

Algi
jamieallan
Posted 03/01/2014 - 14:18 Link
davem wrote:
I have seen a helicoid extension tube on ebay and wondered what is it and what does it do?

Can anybody help?

Dave

Dave,
This might help

http://www.google.co.uk/url?sa=t&rct=j&q=&esrc=s&source=web&cd=4&ved=0CD8QFjAD&u...

Funnily enough I've been looking at the same. The helicoid is effectively the screw thread that allows the two parts of the tube to expand/contract in length with a high degree of tolerance and no light leakage I'd suspect.
Jamie
Edited by jamieallan: 03/01/2014 - 14:21
Algernon
Posted 03/01/2014 - 14:47 Link
Shown here.....

http://www.bdimitrov.de/kmp/misc/macro/ext_helicoid.jpg

They usually go for £50 - £100...... Very handy piece of kit.
I bought mine new from Park Cameras in the 80's

--
Half Man... Half Pentax ... Half Cucumber

Pentax K-1 + K-5 and some other stuff

Algi
davem
Posted 03/01/2014 - 23:09 Link
These look interesting. The only ones I can see at the moment are m42. As you say Algi there is a k and I think an m. presumably the M42 is completely manual whereas the k and m will allow the aperture to be set.

What do you think that the best lens would be in conjunction with one of these and the K5?

Dave
jamieallan
Posted 03/01/2014 - 23:25 Link
davem wrote:
These look interesting. The only ones I can see at the moment are m42. As you say Algi there is a k and I think an m. presumably the M42 is completely manual whereas the k and m will allow the aperture to be set.

What do you think that the best lens would be in conjunction with one of these and the K5?

Dave

Dave,
The M42 is a completely different lens mount so unless you buy a K to M42 adaptor and an M42 to K adaptor these will not work. You will not be able to fit your extension tubes to your K series camera and you wont be able to fit your k series lens to the extension tubes.
Jamie
petrochemist
Posted 04/01/2014 - 08:51 Link
jamieallan wrote:

The M42 is a completely different lens mount so unless you buy a K to M42 adaptor and an M42 to K adaptor these will not work. You will not be able to fit your extension tubes to your K series camera and you wont be able to fit your k series lens to the extension tubes.

Unfortunately nobody seems to make an adapter to mount k bayonet lenses on m42 threads. Mounting m42 to PK is very common and has been done since the k mount first came out, so if you have some m42 lenses it's a great device for macro. M42 helicoids are cheap and easily available in a range of different lengths, K mount ones are rather rare
Mike
.
Pentax:K5ii, K7, K100D, DA18-55, DA10-17, DA55-300, DA50-200, F100-300, F50, DA35 AL, 4* M50, 2* M135, Helicoid extension, Tak 300 f4 (& 6 film bodies)
3rd Party: Bigmos (Sigma 150-500mm OS HSM),2* 28mm, 100mm macro, 28-200 zoom, 35-80 zoom, 80-200 zoom, 80-210 zoom, 300mm M42, 600 mirror, 1000-4000 scope, 50mm M42, enlarger lenses, Sony & micro 4/3 cameras with various PK mounts, Zenit E...
Far to many tele-converters, adapters, project parts & extension tubes etc.

.[size=11:].Flickr• WPF• Panoramio
Algernon
Posted 04/01/2014 - 10:27 Link
davem wrote:
These look interesting. The only ones I can see at the moment are m42. As you say Algi there is a k and I think an m. presumably the M42 is completely manual whereas the k and m will allow the aperture to be set.

What do you think that the best lens would be in conjunction with one of these and the K5?

Dave

Non of the Pentax K Tubes have 'A' contacts. I've never found that a problem with the Helicoid because I normally use it on mash-ups where a full sized tube won't work, such as slide copying etc. Sometimes the lens is reversed so the contacts wouldn't work anyway.

Olympus also did one and they sell for a lot more than the Pentax ones.

A K bayonet lens to M42 adapter can be cobbled up from an extension tube and an M42 T2 mount.

--
Half Man... Half Pentax ... Half Cucumber

Pentax K-1 + K-5 and some other stuff

Algi
Peter Elgar
Posted 04/01/2014 - 11:16 Link
years ago I WON a Asahi Pentax Helicoid Extension tube in ' Pentax Club Magazine' when it was run by Ron Spillman -- had £25-00 of Pentax gear of my choice so I got that and some pentax Club filters for my £25-00 prize.
been a member of Pentax Club since the Ron Spillman era! Got COMPUTERISED at last - DIGITISED? Taken the PLUNGE - BUT FILM STILL RULES !!!
gartmore
Posted 04/01/2014 - 11:41 Link
I got an M42 one on ebay to use as a focussing mechanism for an old lens mounted to the Q, I think it was about £15 and remarkably well engineered
Ken
“We must avoid however, snapping away, shooting quickly and without thought, overloading ourselves with unnecessary images that clutter our memory and diminish the clarity of the whole.” - Henri Cartier-Bresson -
davem
Posted 04/01/2014 - 19:41 Link
Thanks everyone, especially Barry for being so quick off the mark

Please bear with me whilst I sum up my options

1. Use an M42 lens with M42 helicoid tube and mount the assembly onto any k mount camera (including the K5) using an M42 k mount adaptor. Set the aperture on the lens

2. use the above on the Q with an additional adaptor for mounting k lens to the camera. Set the aperture on the lens.

3. Use an old k lens with an M42 T mount to connect to the helicoid. Mount the assembly onto the camera using an M42 k mount adaptor

Have I got it right or am I missing something.

Don't you just love working these things out.

Sometimes I think that pentax or a third party should reintroduce helicoids, extension tubes,bellows etc. as it would make life easier

Dave

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