extension tubes question....


scarr1

Link Posted 23/09/2016 - 11:44
when using an extension tube(s) (without contacts), on a macro lens, does the lens have to have an aperture ring?
I have the d-fa 100mm 2.8 macro, and was looking at some cheap extension tubes, but im not sure they would work, as this lens has no aperture ring.
would I need a macro with an aperture ring, or extension tubes with the electrical contacts.
confused!!

geordie01

Link Posted 23/09/2016 - 11:58
Yes you will need a lens with an aperture ring on the lens to manually stop the lens down if the tubes have no contacts.

bforbes

Link Posted 23/09/2016 - 12:05
I think you're right, either aperture ring or contacts. When I've tried no aperture ring Pentax lenses on a Fuji system I have to use an adapter that has it's own iris in. link like this one on ebay
Barrie
Too Old To Die Young

http://www.pentaxphotogallery.com/artists/barrieforbes

scarr1

Link Posted 23/09/2016 - 12:16
Thought so.
Are extension tubes available in pentax fit with contacts....just for aperture control.
I have seen some for sale on here which describes a "modificaton" to control aperture, but ive no idea what the "modification" is.

McGregNi

Link Posted 23/09/2016 - 12:29
It's a rare case of cheap can be best. The results can be superb from some really old glass. One extra point is that issue of the lens auto aperture control. A lot of 'Pentax K, M and A series type lenses would not be suitable, I presume, with contactless tubes .... ? This is because they are auto-aperture types and the aperture is held open until stopped down by the camera. You could only shoot wide open.

An old fully manual aperture lens would give that control, but couldn't be used ' normally' on the camera, The best of both worlds is provided by something like my old Tamron Adaptall 135mm F2.8 (from the early 1970's), which has an auto/manual switch.... This allows stop down metering control in the Auto position, but full manual control in the manual position, for those times with the contactless extension tubes.

It can be hard to see for focusing through a manual aperture lens when stopped down, say to F8 or smaller. Indoors I put my 'Pentax AF-540FGZII on the camera and shine it's LED light onto the subject while focusing.
My Guides to the Pentax Digital Camera Flash Lighting System : Download here from the PentaxForums Homepage Article .... link
Pentax K7 with BG-4 Grip / Samyang 14mm f2.8 ED AS IF UMC / DA18-55mm f3.5-5.6 AL WR / SMC A28mm f2.8 / D FA 28-105mm / SMC F35-70 f3.5-4.5 / SMC A50mm f1.7 / Tamron AF70-300mm f4-5.6 Di LD macro / SMC M75-150mm f4.0 / Tamron Adaptall (CT-135) 135mm f2.8 / Asahi Takumar-A 2X tele-converter / Pentax AF-540FGZ (I & II) Flashes / Cactus RF60/X Flashes & V6/V6II Transceiver
Last Edited by McGregNi on 23/09/2016 - 12:34

geordie01

Link Posted 23/09/2016 - 13:45
The modification is to scratch a bit of the black paint off the base of the tube if it has any to make a ground contact with the camera lens mount.
This explains it better

http://www.thepentaxforum.co.uk/viewtopic.php?f=15&t=3237
Last Edited by geordie01 on 23/09/2016 - 13:48

JAK

Link Posted 23/09/2016 - 13:46
scarr1 wrote:
I have the d-fa 100mm 2.8 macro, and was looking at some cheap extension tubes, but im not sure they would work, as this lens has no aperture ring.

Older ones do, my D-FA 100mm f2.8 macro has an aperture ring.
John K

JAK

Link Posted 23/09/2016 - 13:50
scarr1 wrote:
Thought so.
Are extension tubes available in pentax fit with contacts....just for aperture control.
I have seen some for sale on here which describes a "modificaton" to control aperture, but ive no idea what the "modification" is.

Yes. The modification sometimes necessary is to scrape some paint off to allow all the contacts to work (though that normally refers to adapting some teleconverters.)
There's a photo of Vivitar tubes with contacts and the converter mod in a thread on the US forum:
http://www.pentaxforums.com/forums/58-troubleshooting-beginner-help/146065-about...
John K
Last Edited by JAK on 23/09/2016 - 14:00

bforbes

Link Posted 23/09/2016 - 13:56
just having a rethink.

I thought the idea of a longer macro lens was to move the camera back from the subject. Whereas the idea of the tubes is to bring you closer.

Could you just use an old standard short focal length lens, maybe with the tubes, to achieve what you want?
Barrie
Too Old To Die Young

http://www.pentaxphotogallery.com/artists/barrieforbes

LennyBloke

Link Posted 23/09/2016 - 14:04
JAK wrote:
scarr1 wrote:
Thought so.
Are extension tubes available in pentax fit with contacts....just for aperture control.
I have seen some for sale on here which describes a "modificaton" to control aperture, but ive no idea what the "modification" is.

Yes. The modification sometimes necessary is to scrape some paint off to allow all the contacts to work.

In essence that is what the modification is, but if you do it yourself you will need to ensure you make a nice clean job of it - the debris produced may be very fine but it can interfere with camera functions if you're not careful (speaking from experience ).

There certainly are tubes with the full set of contacts (except for AF), you can pick up a set of 3 for around 125 new. I have a partial set of 2 Teleplus full contact tubes for sale if you're interested (apologies for the plug - but it does seem relevant)
LennyBloke

petrochemist

Link Posted 23/09/2016 - 14:57
bforbes wrote:
just having a rethink.

I thought the idea of a longer macro lens was to move the camera back from the subject. Whereas the idea of the tubes is to bring you closer.

Could you just use an old standard short focal length lens, maybe with the tubes, to achieve what you want?

A long focal length macro lens will give 1:1 from a greater distance than a short one. In either case extension tubes will make the point of focus closer, and so the magnification greater. The degree of extension needed for an magnification is a function of the lenses focal length, so short focal lengths are easier to get high magnifications with by adding extension, but the working distances can be impractical - especially for insects!
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

davidstorm

Link Posted 23/09/2016 - 22:29
It's not too difficult to acquire tubes with the aperture contacts, they come up sometimes on here and also on ebay. Expect to pay around 50 for a decent set in good condition. I would have a look on ebay and if you can find some your DFA 2.8 macro will work just fine with them, with the exception of 'no AF', but that isn't a factor with macro photography.

Regards
David
My Website http://imagesbydavidstorm.foliopic.com

Flickr

Some cameras, some lenses, some bits 'n' bobs

JAK

Link Posted 23/09/2016 - 22:45
davidstorm wrote:
... your DFA 2.8 macro will work just fine with them, with the exception of 'no AF', but that isn't a factor with macro photography.

Regards
David

It won't if it's one of the new HD ones as the aperture ring has been abolished for some strange reason.
While the aperture can be set from the camera if the tubes have the electrical contacts, it can't be set with tubes where these are not present.
Ricoh weren't thinking straight when they redesigned this lens.
It may be worth obtaining an old manual setting macro lens or the older style Pentax one which has an aperture ring, or of course, extension tubes which have the electrical contacts.
John K
Last Edited by JAK on 23/09/2016 - 22:51

petrochemist

Link Posted 24/09/2016 - 08:14
JAK wrote:
It won't if it's one of the new HD ones as the aperture ring has been abolished for some strange reason.h tubes where these are not present.

You obviously missed the first art of Davids post, where he specified tubes with contacts! The contacts allow the camera to adjust the aperture when there's no ring.
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

JAK

Link Posted 24/09/2016 - 20:18
petrochemist wrote:
JAK wrote:
It won't if it's one of the new HD ones as the aperture ring has been abolished for some strange reason.h tubes where these are not present.

You obviously missed the first art of Davids post, where he specified tubes with contacts! The contacts allow the camera to adjust the aperture when there's no ring.

My intention was to suggest the alternatives, of which David's was but one!
John K
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