K-X Problem with Extension Tubes

Lloyd · 02-13-2011, 03:06 AM

I recently bought a set of extension tubes from ebay. This set does not have the electrical contacts, but does have the levers required to operate the aperture. I understand that some functionallity will be lost.

So trying to use said tubes in manual mode on my k-x, I've come across a strange behaviour.

Using my 1.7 50mm from my old ME-Super, I can use the green button to have optical preview, and manually set aperture/speed. I hear, and see, the aperture shut down.

Putting one or more extension tubes on the same configuration, green button no longer works.

However, if I use live view, changing the aperture changes the image (but I can't work out how to meter in this mode).

And, if I take a couple of shots at different apertures, I get different exposures, so the aperture is being closed.

I get the same behaviour with my Sigma 28-135 lens.

Can anyone offer any suggestions on where I'm going wrong, or why the tubes are not fully compatible?

Thanks

Lloyd

**Lowell Goudge** · 02-13-2011, 06:32 AM

I will guess the tubes and mounts are black

You need to sand the paint off the mount where it touches the body contacts. I discovered this with my K7 also

Lloyd · 02-13-2011, 06:41 AM

That was the only difference I could see between the two. Do you know what the electrical contact is doing?

**Lowell Goudge** · 02-13-2011, 06:49 AM

Some pentax cameras want a connection to the lens mount on the last pin. Furthest away from the lens locking pin to confirm manual focus

Wombat · 02-13-2011, 09:06 PM

Lowell, you're amazing!

Lloyd · 02-15-2011, 12:16 PM

Thanks Lowell. Having attacked the mounts with some 180 grade emery, the green button is now stopping the lens down. I think it is the data pin that needs to be grounded, which is around 5 o'clock on the lens.

**Lowell Goudge** · 02-15-2011, 12:56 PM

Originally posted by Lloyd

Thanks Lowell. Having attacked the mounts with some 180 grade emery, the green button is now stopping the lens down. I think it is the data pin that needs to be grounded, which is around 5 o'clock on the lens.

correct, last pin from the lens locking pin.

Bit of a Pain really, the camera should figure out nothing is talking, but I guess it can't

Ira · 02-15-2011, 02:32 PM

Won't aluminum tape do the same thing?

8 bucks for a roll that will help modify about a thousand lenses.

spider510 · 07-05-2011, 10:46 AM

Thanks Lowell just tried with piece of aluminium foil works fine now need aluminium tape or conductive paint as my extinsion tube back plate is plastic.

manstanox · 09-01-2013, 09:11 AM

I have a similar problem but maybe not quite the same. I am trying to use a Vivitar Auto Extension Tube Set AT-22 with an M 50mm f1.7 mated onto a K-r. I have set the Green Button and the required permissions in the Settings menu and the M lens works perfectly as a manual lens should (nice lens - have had it since 1981). However, using the tube set the Green Button will not operate when I use the viewfinder to compose and shoot in the normal way. However, if I switch to Live View the Green Button does work. I can use LV to set the aperture and then switch to the viewfinder - but this seems cumbersome. The forward facing surface of each of the three tubes in the set is metal but each rear face is black painted - possibly metal or maybe plastic. Changing the order of the tubes doesn't make any difference. The tubes themselves seem sturdy and well-made and are in good condition.

So is this a case of conductivity again - or is it something different? I have searched the forum and this thread seems closest to my problem. I would love some advice - can anyone help?

**RKKS08** · 09-04-2013, 12:32 PM

Originally posted by manstanox

So is this a case of conductivity again

The behaviour you describe is exactly what one would expect if there is no conductivity - for the body it will mean "no lens attached".

02-13-2011, 03:06 AM	#1
Lloyd New Member Join Date: Sep 2010 Location: Bedfordshire Posts: 11	K-X Problem with Extension Tubes I recently bought a set of extension tubes from ebay. This set does not have the electrical contacts, but does have the levers required to operate the aperture. I understand that some functionallity will be lost. So trying to use said tubes in manual mode on my k-x, I've come across a strange behaviour. Using my 1.7 50mm from my old ME-Super, I can use the green button to have optical preview, and manually set aperture/speed. I hear, and see, the aperture shut down. Putting one or more extension tubes on the same configuration, green button no longer works. However, if I use live view, changing the aperture changes the image (but I can't work out how to meter in this mode). And, if I take a couple of shots at different apertures, I get different exposures, so the aperture is being closed. I get the same behaviour with my Sigma 28-135 lens. Can anyone offer any suggestions on where I'm going wrong, or why the tubes are not fully compatible? Thanks Lloyd

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02-13-2011, 06:32 AM	#2
Lowell Goudge Site Supporter Join Date: Jan 2007 Location: Toronto Photos: Gallery \| Albums Posts: 17,892	I will guess the tubes and mounts are black You need to sand the paint off the mount where it touches the body contacts. I discovered this with my K7 also

02-13-2011, 06:41 AM	#3
Lloyd New Member Join Date: Sep 2010 Location: Bedfordshire Posts: 11 Original Poster	That was the only difference I could see between the two. Do you know what the electrical contact is doing?

02-13-2011, 06:49 AM	#4
Lowell Goudge Site Supporter Join Date: Jan 2007 Location: Toronto Photos: Gallery \| Albums Posts: 17,892	Some pentax cameras want a connection to the lens mount on the last pin. Furthest away from the lens locking pin to confirm manual focus

02-13-2011, 09:06 PM	#5
Wombat Veteran Member Join Date: May 2008 Location: South Australia Photos: Gallery \| Albums Posts: 901	Lowell, you're amazing!

02-15-2011, 12:16 PM	#6
Lloyd New Member Join Date: Sep 2010 Location: Bedfordshire Posts: 11 Original Poster	Thanks Lowell. Having attacked the mounts with some 180 grade emery, the green button is now stopping the lens down. I think it is the data pin that needs to be grounded, which is around 5 o'clock on the lens.

02-15-2011, 12:56 PM	#7
Lowell Goudge Site Supporter Join Date: Jan 2007 Location: Toronto Photos: Gallery \| Albums Posts: 17,892	Originally posted by Lloyd Thanks Lowell. Having attacked the mounts with some 180 grade emery, the green button is now stopping the lens down. I think it is the data pin that needs to be grounded, which is around 5 o'clock on the lens. correct, last pin from the lens locking pin. Bit of a Pain really, the camera should figure out nothing is talking, but I guess it can't

02-15-2011, 02:32 PM	#8
Ira Inactive Account Join Date: Mar 2009 Location: Coral Springs, FL Photos: Gallery \| Albums Posts: 5,216	Won't aluminum tape do the same thing? 8 bucks for a roll that will help modify about a thousand lenses.

07-05-2011, 10:46 AM	#9
spider510 New Member Join Date: Jul 2011 Location: North Wales Posts: 2	Thanks Lowell just tried with piece of aluminium foil works fine now need aluminium tape or conductive paint as my extinsion tube back plate is plastic.

09-01-2013, 09:11 AM	#10
manstanox Junior Member Join Date: Oct 2012 Location: High Wycombe Photos: Gallery Posts: 35	I have a similar problem but maybe not quite the same. I am trying to use a Vivitar Auto Extension Tube Set AT-22 with an M 50mm f1.7 mated onto a K-r. I have set the Green Button and the required permissions in the Settings menu and the M lens works perfectly as a manual lens should (nice lens - have had it since 1981). However, using the tube set the Green Button will not operate when I use the viewfinder to compose and shoot in the normal way. However, if I switch to Live View the Green Button does work. I can use LV to set the aperture and then switch to the viewfinder - but this seems cumbersome. The forward facing surface of each of the three tubes in the set is metal but each rear face is black painted - possibly metal or maybe plastic. Changing the order of the tubes doesn't make any difference. The tubes themselves seem sturdy and well-made and are in good condition. So is this a case of conductivity again - or is it something different? I have searched the forum and this thread seems closest to my problem. I would love some advice - can anyone help?

09-04-2013, 12:32 PM	#11
RKKS08 Site Supporter Join Date: Mar 2010 Location: Frankfurt am Main Posts: 1,241	Originally posted by manstanox So is this a case of conductivity again The behaviour you describe is exactly what one would expect if there is no conductivity - for the body it will mean "no lens attached".