Rant: Are automatic extension tubes really not made anymore?

Capslock118 · 11-02-2010, 12:49 PM

Staff note: This post may contain affiliate links, which means Pentax Forums may earn a small commission if a visitor clicks through and makes a purchase. If you would like to support the forum directly, you may also make a donation here.

I'm trying to understand this, maybe I am not searching well enough or plenty of folks here will agree with my frustrations.

why does it seem that automatic extension tubes are not in production by any manufacturer for pentax k mounts?

I have a handful of manual lenses, so I bought cheapo manual extension tubes off ebay.

But now i would really like it if I could use my DA lenses, or use the automatic aperture setting, and have automatic metering.

Come to find, there seems to be tubes out there but they are not made today, made years ago, and are extremely hard to find.

I don't care about auto focus - I do care about aperture control (as DA lenses obviously do not have an aperture ring), and while we are at it metering would be really nice too.

Is there really nothing out there other than to continually watch used item markets? Is this really a hard thing to ask for? Or is there only 3 people out there (myself included) that are looking for these types of tubes and anyone else who would want them already owns them?

drougge · 11-02-2010, 01:32 PM

There are plenty of "automatic extension tubes" for K mount, the problem is that they are what you call manual. (They allow open aperture viewing, but don't pass electronics through.) I don't know what the type you want are called, but I hope there is a separate name for them. (And they are scarce, yes.)

The cheapest way to get a tube with electronics is probably to make it yourself. Either from a crappy teleconverter where you remove the glass, or from one of the tubes you have by replacing the mounts and pulling cables through it. (A broken camera and lens with electronic contacts to take parts from should be pretty cheap, and plentiful.) If the tubes you have really are manual (don't pass the aperture lever through) you need to get new tubes, but that type isn't hard to get.

Also, on metering, last I checked all Pentax cameras would meter through anything.

Come to think of it, another possibility for using lenses without aperture rings on tubes would be to fix the aperture lever in some semi-open position, or if you want to make it hard, construct an aperture ring on the tube that moves the lever.

Nass · 11-02-2010, 01:52 PM

I was looking for this too. I moved onto other things, but it struck me that getting a Kenko Pz-AF Teleplus SHQ (1.5 TC which passes SDM) and drilling the glass out should do it, whilst still passing all the electronics through. Someone else might be able to confirm that this works.

GerryL · 11-02-2010, 01:57 PM

Back in the days when Pentax WAS king, a lot of third party manufacturers would make accessories for Pentax since they would be able to ride along with its popularity, thereby selling their accessories together with Pentax.
Now that Canon and Nikon are top of the hill, most third party accessories producers ride on their popularity to sell their wares.
Why in the world would they make accessories for Pentax when there are so few users compared to the tons that use Canon and Nikon.
We just hope that the the K-x, K-r and the K-5 would change those views of third party manufacturers and start making items for Pentax again.

**NaClH2O** · 11-02-2010, 02:03 PM

Patience grasshopper patience
They can be found you just have to have patience. I scored a 25mm Unitube plus in K mount on eek bay after looking for about 6-8 weeks and it just so happened that the guy was only about 10 miles away. I also scored a set(I wanted more than just 25mm) from someone here. Watch the forum here and have e-bay watch for you. They ARE out there. If you get a set of the rokunar 6 pin types you can scratch a mark in the mount for the 7th pin and they will work as well as any other auto tubes. Or do likedrougge suggested and make one from an old cheap TC.

NaCl(if you wait they will come)H2O

SOldBear · 11-02-2010, 02:08 PM

Originally posted by Nass

...getting a Kenko Pz-AF Teleplus SHQ (1.5 TC which passes SDM) and drilling the glass out should do it, whilst still passing all the electronics through. Someone else might be able to confirm that this works.

The Kenko will work. But IMHO it's too costly just for an extension tube. I'd buy a real macro lens before I have to multilate a good Kenko TC.

Check you local ads often. You may get lucky someday....

I have a few extension tubes (ex TCs) like the one on the right in this photo:

Capslock118 · 11-02-2010, 02:12 PM

Quote:

There are plenty of "automatic extension tubes" for K mount, the problem is that they are what you call manual. (They allow open aperture viewing, but don't pass electronics through.)

That's one part I don't understand about these tubes allowing for open aperture. What does that mean exactly if the camera cannot control the aperture via electrical contacts? or is that not how the lenses work? More to the point, do these 'automatic extension tubes' which allow open aperture mean that DA lenses can be used? and at different aperture levels? or just all open?

Quote:

The cheapest way to get a tube with electronics is probably to make it yourself. Either from a crappy teleconverter where you remove the glass, or from one of the tubes you have by replacing the mounts and pulling cables through it. (A broken camera and lens with electronic contacts to take parts from should be pretty cheap, and plentiful.) If the tubes you have really are manual (don't pass the aperture lever through) you need to get new tubes, but that type isn't hard to get.

Well this is my point though. Why isnt this product being manufactured? Is there that little of demand? I like DIYing stuff but with cameras and lenses being so expensive, do I really want to just scape together a couple of wires, splice them up and call it a day? Nah, I'd rather a product made for this purpose.

Quote:

Also, on metering, last I checked all Pentax cameras would meter through anything

Maybe I'm not recalling correctly right now but I'm pretty sure my exposure is not displayed on M lenses unless I hold down the depth of field button passed the 'on' position.

Quote:

I moved onto other things, but it struck me that getting a Kenko Pz-AF Teleplus SHQ (1.5 TC which passes SDM) and drilling the glass out should do it, whilst still passing all the electronics through.

I'm considering that. Actually I would prefer to find some screws and dismantle the glass out versus drilling them out, still. We're going back to DIY while I am more apt to doing this than splicing some wires together, i still don't get why these products are not longer being made.

Quote:

Patience grasshopper patience
They can be found you just have to have patience. I scored a 25mm Unitube plus in K mount on eek bay after looking for about 6-8 weeks and it just so happened that the guy was only about 10 miles away.

That's what I'm doing for sure, I have no other option

Ira · 11-02-2010, 02:48 PM

If you're setting up for serious macro work with tubes, auto is a pretty moot point.

Why do you think you need or want that for proper exposure, especially since center weighted and spot manual metering works so perfectly for macro type shots?

That's why you don't find them. It's an unnecessarily expensive accessory.

drougge · 11-02-2010, 03:26 PM

Originally posted by Capslock118

That's one part I don't understand about these tubes allowing for open aperture. What does that mean exactly if the camera cannot control the aperture via electrical contacts? or is that not how the lenses work? More to the point, do these 'automatic extension tubes' which allow open aperture mean that DA lenses can be used? and at different aperture levels? or just all open?

Sorry, no. DA-lenses can be used, but only at their most closed aperture.

All pre-SDM lenses are controlled completely mechanically, the electronics are only for telling the camera things about the lens. (And with SDM the camera talks to the lens for focusing, but aperture is still mechanically controlled. M lenses (and some of the cameras) are completely mechanical, they still allow open aperture viewing.)

Auto tubes pass this mechanical linkage (and the other one, that tells the camera what relative aperture you set on the ring, though "modern" cameras no longer listen to this.)

I'm sure there are a million explanations already if you want to know exactly how it works. But just play with the lever on an unmounted lens and it should be easy enough to understand.

SOldBear · 11-02-2010, 03:40 PM

Originally posted by Ira

If you're setting up for serious macro work with tubes, auto is a pretty moot point.

Why do you think you need or want that for proper exposure, especially since center weighted and spot manual metering works so perfectly for macro type shots?

That's why you don't find them. It's an unnecessarily expensive accessory.

(.... scratching my head, not sure what Ira means, Tuesday must be one of my slow days....)

I'm not sure why an extension tubes with electrical contacts is "an unnecessarily expensive accessory."

To me, these are either necessary or at least, very convenient to have:

- The tube can be used with any lens that normally fits a Pentax body, including lens without aperture ring.

- The camera can control the aperture of the combo (tube + lens) just like it does the aperture of the lens alone.

- You can have full-aperture focusing, a feature very much needed because focusing is critical and has to be done manually. The dim viewfinder (due to the tube) makes this even more important.

- You can have p-TTL flash metering.

**Lowell Goudge** · 11-02-2010, 03:47 PM

Except for P-TTL flash I see no value in manual focus extension tubes having aperture contacts

Any Kmount auto tubes support open aperture focusing and will stop down the lens when shooting

Metering with green button works the same and with macro and manual focus I dint see any other issue. Flash would be the biggie

drougge · 11-02-2010, 04:01 PM

And if you really want P-TTL flash with cheap tubes, get the fully manual ones, put some foil in the mount so the camera thinks it's an A-lens, set the camera to whatever aperture it believes to be wide open (it won't affect the lens since the tubes are fully manual), and P-TTL works well enough.

Since tubes like these are so cheap you can get them just for this, and use better tubes for most stuff. (This is useful even if you have tubes with electrical contacts, since you might want to use an older lens.)

Lowell: I also see the value for someone who wants to use a DA lens. Which is a perfectly reasonable thing to want.

SOldBear · 11-02-2010, 04:02 PM

Originally posted by Lowell Goudge

Any Kmount auto tubes support open aperture focusing and will stop down the lens when shooting

How do you do that when the lens does not have an aperture ring (e.g. DA Ltd. lenses)?

Originally posted by Lowell Goudge

Metering with green button works the same and with macro and manual focus I dint see any other issue.

We know that at least for the KxxD and KxxxD bodies, the green button metering does not work consistently with manual lenses, and does not work consistently with A-lenses when the aperture ring is not at A position.

**Lowell Goudge** · 11-02-2010, 05:58 PM

SOldBear

I had not considered a DA or FA-J lens when you discuss manual focusing

As for metering I do not consider the flaws that serious because again in manual focus you have time to check the histogram and shoot again

**Douglas_of_Sweden** · 11-03-2010, 07:33 AM

Originally posted by Capslock118

I'm trying to understand this, maybe I am not searching well enough or plenty of folks here will agree with my frustrations.

why does it seem that automatic extension tubes are not in production by any manufacturer for pentax k mounts?

I have a handful of manual lenses, so I bought cheapo manual extension tubes off ebay.

But now i would really like it if I could use my DA lenses, or use the automatic aperture setting, and have automatic metering.

Come to find, there seems to be tubes out there but they are not made today, made years ago, and are extremely hard to find.

I don't care about auto focus - I do care about aperture control (as DA lenses obviously do not have an aperture ring), and while we are at it metering would be really nice too.

Is there really nothing out there other than to continually watch used item markets? Is this really a hard thing to ask for? Or is there only 3 people out there (myself included) that are looking for these types of tubes and anyone else who would want them already owns them?

German company Dörr is making a set with 13, 21 and 31 mm exension tubes with KA contacts for Pentax.

http://www.doerrfoto.de

The photo is for the Nikon version, but I have seen the Pentax version in real life with contacts.

Here they are for 109 Euro Foto Palme Online Shop - Dörr Zwischenringsatz 13/21/31 mm für Pentax
Technikguenstiger.de Online-Shop - Dörr Zwischenringsatz 13/21/31 mm für Pentax

Amazon wants 159 Euro
Dörr - Zwischenringsatz für Makro Fotografie - passend: Amazon.de: Elektronik

You can also get them from Cyberphoto in Sweden
Mellanringar systemkameror Dörr Mellanringsats 13/21/31mm till Pentax

A Korean company named Pro Optic also makes (made?) a set, that adorama was selling, but they now say out of stock.

Again the photo (at adorama) is not of a Pentax version, but someone posted a photo of what they got when ordering it at another forum
Re: Extension Tubes: Pentax SLR Talk Forum: Digital Photography Review

And yes, KA tubes are usefull. Bugs wont always kindly wait while you press the green button, shoot, correct exposure, and press two buttons again.
I have a set of Vivitar tubes with KA contacts. I've even got a tube with screw drive autofocus (made from a converter), which works just fine.

11-02-2010, 12:49 PM	#1
Capslock118 Senior Member Join Date: Apr 2010 Location: New Haven, CT Photos: Gallery Posts: 173	Rant: Are automatic extension tubes really not made anymore? Staff note: This post may contain affiliate links, which means Pentax Forums may earn a small commission if a visitor clicks through and makes a purchase. If you would like to support the forum directly, you may also make a donation here. I'm trying to understand this, maybe I am not searching well enough or plenty of folks here will agree with my frustrations. why does it seem that automatic extension tubes are not in production by any manufacturer for pentax k mounts? I have a handful of manual lenses, so I bought cheapo manual extension tubes off ebay. But now i would really like it if I could use my DA lenses, or use the automatic aperture setting, and have automatic metering. Come to find, there seems to be tubes out there but they are not made today, made years ago, and are extremely hard to find. I don't care about auto focus - I do care about aperture control (as DA lenses obviously do not have an aperture ring), and while we are at it metering would be really nice too. Is there really nothing out there other than to continually watch used item markets? Is this really a hard thing to ask for? Or is there only 3 people out there (myself included) that are looking for these types of tubes and anyone else who would want them already owns them?

11-02-2010, 04:02 PM	#13
SOldBear Veteran Member Join Date: Feb 2009 Location: Alameda, CA Posts: 3,206	Originally posted by Lowell Goudge Any Kmount auto tubes support open aperture focusing and will stop down the lens when shooting How do you do that when the lens does not have an aperture ring (e.g. DA Ltd. lenses)? Originally posted by Lowell Goudge Metering with green button works the same and with macro and manual focus I dint see any other issue. We know that at least for the KxxD and KxxxD bodies, the green button metering does not work consistently with manual lenses, and does not work consistently with A-lenses when the aperture ring is not at A position. Last edited by SOldBear; 11-02-2010 at 04:10 PM.

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
FUlly automatic extension tubes for K200D	hallenti	Ask B&H Photo!	3	05-27-2010 11:26 AM
AICO Automatic Extension tube set for pentax	yeatzee	Pentax SLR Lens Discussion	5	04-14-2010 11:29 AM
Extension tubes anyone?	max889	Pentax SLR Lens Discussion	13	03-01-2010 01:38 PM
extension tubes	keithbaran	Troubleshooting and Beginner Help	15	02-25-2010 10:48 PM

11-02-2010, 01:32 PM	#2
drougge Veteran Member Join Date: Jan 2010 Location: Malmö Photos: Gallery Posts: 787	There are plenty of "automatic extension tubes" for K mount, the problem is that they are what you call manual. (They allow open aperture viewing, but don't pass electronics through.) I don't know what the type you want are called, but I hope there is a separate name for them. (And they are scarce, yes.) The cheapest way to get a tube with electronics is probably to make it yourself. Either from a crappy teleconverter where you remove the glass, or from one of the tubes you have by replacing the mounts and pulling cables through it. (A broken camera and lens with electronic contacts to take parts from should be pretty cheap, and plentiful.) If the tubes you have really are manual (don't pass the aperture lever through) you need to get new tubes, but that type isn't hard to get. Also, on metering, last I checked all Pentax cameras would meter through anything. Come to think of it, another possibility for using lenses without aperture rings on tubes would be to fix the aperture lever in some semi-open position, or if you want to make it hard, construct an aperture ring on the tube that moves the lever.

11-02-2010, 01:52 PM	#3
Nass Veteran Member Join Date: Aug 2009 Location: The British Isles Photos: Gallery Posts: 2,402	I was looking for this too. I moved onto other things, but it struck me that getting a Kenko Pz-AF Teleplus SHQ (1.5 TC which passes SDM) and drilling the glass out should do it, whilst still passing all the electronics through. Someone else might be able to confirm that this works.

11-02-2010, 01:57 PM	#4
GerryL Veteran Member Join Date: Jan 2009 Location: CA Posts: 2,731	Back in the days when Pentax WAS king, a lot of third party manufacturers would make accessories for Pentax since they would be able to ride along with its popularity, thereby selling their accessories together with Pentax. Now that Canon and Nikon are top of the hill, most third party accessories producers ride on their popularity to sell their wares. Why in the world would they make accessories for Pentax when there are so few users compared to the tons that use Canon and Nikon. We just hope that the the K-x, K-r and the K-5 would change those views of third party manufacturers and start making items for Pentax again.

11-02-2010, 02:03 PM	#5
NaClH2O Site Supporter Join Date: Sep 2006 Location: Bronx NY Photos: Gallery \| Albums Posts: 5,631	Patience grasshopper patience They can be found you just have to have patience. I scored a 25mm Unitube plus in K mount on eek bay after looking for about 6-8 weeks and it just so happened that the guy was only about 10 miles away. I also scored a set(I wanted more than just 25mm) from someone here. Watch the forum here and have e-bay watch for you. They ARE out there. If you get a set of the rokunar 6 pin types you can scratch a mark in the mount for the 7th pin and they will work as well as any other auto tubes. Or do likedrougge suggested and make one from an old cheap TC. NaCl(if you wait they will come)H2O

11-02-2010, 02:08 PM	#6
SOldBear Veteran Member Join Date: Feb 2009 Location: Alameda, CA Posts: 3,206	Originally posted by Nass ...getting a Kenko Pz-AF Teleplus SHQ (1.5 TC which passes SDM) and drilling the glass out should do it, whilst still passing all the electronics through. Someone else might be able to confirm that this works. The Kenko will work. But IMHO it's too costly just for an extension tube. I'd buy a real macro lens before I have to multilate a good Kenko TC. Check you local ads often. You may get lucky someday.... I have a few extension tubes (ex TCs) like the one on the right in this photo:

11-02-2010, 02:12 PM	#7
Capslock118 Senior Member Join Date: Apr 2010 Location: New Haven, CT Photos: Gallery Posts: 173 Original Poster	Quote: There are plenty of "automatic extension tubes" for K mount, the problem is that they are what you call manual. (They allow open aperture viewing, but don't pass electronics through.) That's one part I don't understand about these tubes allowing for open aperture. What does that mean exactly if the camera cannot control the aperture via electrical contacts? or is that not how the lenses work? More to the point, do these 'automatic extension tubes' which allow open aperture mean that DA lenses can be used? and at different aperture levels? or just all open? Quote: The cheapest way to get a tube with electronics is probably to make it yourself. Either from a crappy teleconverter where you remove the glass, or from one of the tubes you have by replacing the mounts and pulling cables through it. (A broken camera and lens with electronic contacts to take parts from should be pretty cheap, and plentiful.) If the tubes you have really are manual (don't pass the aperture lever through) you need to get new tubes, but that type isn't hard to get. Well this is my point though. Why isnt this product being manufactured? Is there that little of demand? I like DIYing stuff but with cameras and lenses being so expensive, do I really want to just scape together a couple of wires, splice them up and call it a day? Nah, I'd rather a product made for this purpose. Quote: Also, on metering, last I checked all Pentax cameras would meter through anything Maybe I'm not recalling correctly right now but I'm pretty sure my exposure is not displayed on M lenses unless I hold down the depth of field button passed the 'on' position. Quote: I moved onto other things, but it struck me that getting a Kenko Pz-AF Teleplus SHQ (1.5 TC which passes SDM) and drilling the glass out should do it, whilst still passing all the electronics through. I'm considering that. Actually I would prefer to find some screws and dismantle the glass out versus drilling them out, still. We're going back to DIY while I am more apt to doing this than splicing some wires together, i still don't get why these products are not longer being made. Quote: Patience grasshopper patience They can be found you just have to have patience. I scored a 25mm Unitube plus in K mount on eek bay after looking for about 6-8 weeks and it just so happened that the guy was only about 10 miles away. That's what I'm doing for sure, I have no other option

11-02-2010, 02:48 PM	#8
Ira Inactive Account Join Date: Mar 2009 Location: Coral Springs, FL Photos: Gallery \| Albums Posts: 5,216	If you're setting up for serious macro work with tubes, auto is a pretty moot point. Why do you think you need or want that for proper exposure, especially since center weighted and spot manual metering works so perfectly for macro type shots? That's why you don't find them. It's an unnecessarily expensive accessory.

11-02-2010, 03:26 PM	#9
drougge Veteran Member Join Date: Jan 2010 Location: Malmö Photos: Gallery Posts: 787	Originally posted by Capslock118 That's one part I don't understand about these tubes allowing for open aperture. What does that mean exactly if the camera cannot control the aperture via electrical contacts? or is that not how the lenses work? More to the point, do these 'automatic extension tubes' which allow open aperture mean that DA lenses can be used? and at different aperture levels? or just all open? Sorry, no. DA-lenses can be used, but only at their most closed aperture. All pre-SDM lenses are controlled completely mechanically, the electronics are only for telling the camera things about the lens. (And with SDM the camera talks to the lens for focusing, but aperture is still mechanically controlled. M lenses (and some of the cameras) are completely mechanical, they still allow open aperture viewing.) Auto tubes pass this mechanical linkage (and the other one, that tells the camera what relative aperture you set on the ring, though "modern" cameras no longer listen to this.) I'm sure there are a million explanations already if you want to know exactly how it works. But just play with the lever on an unmounted lens and it should be easy enough to understand.

11-02-2010, 03:40 PM	#10
SOldBear Veteran Member Join Date: Feb 2009 Location: Alameda, CA Posts: 3,206	Originally posted by Ira If you're setting up for serious macro work with tubes, auto is a pretty moot point. Why do you think you need or want that for proper exposure, especially since center weighted and spot manual metering works so perfectly for macro type shots? That's why you don't find them. It's an unnecessarily expensive accessory. (.... scratching my head, not sure what Ira means, Tuesday must be one of my slow days....) I'm not sure why an extension tubes with electrical contacts is "an unnecessarily expensive accessory." To me, these are either necessary or at least, very convenient to have: - The tube can be used with any lens that normally fits a Pentax body, including lens without aperture ring. - The camera can control the aperture of the combo (tube + lens) just like it does the aperture of the lens alone. - You can have full-aperture focusing, a feature very much needed because focusing is critical and has to be done manually. The dim viewfinder (due to the tube) makes this even more important. - You can have p-TTL flash metering.

11-02-2010, 03:47 PM	#11
Lowell Goudge Site Supporter Join Date: Jan 2007 Location: Toronto Photos: Gallery \| Albums Posts: 17,892	Except for P-TTL flash I see no value in manual focus extension tubes having aperture contacts Any Kmount auto tubes support open aperture focusing and will stop down the lens when shooting Metering with green button works the same and with macro and manual focus I dint see any other issue. Flash would be the biggie

11-02-2010, 04:01 PM	#12
drougge Veteran Member Join Date: Jan 2010 Location: Malmö Photos: Gallery Posts: 787	And if you really want P-TTL flash with cheap tubes, get the fully manual ones, put some foil in the mount so the camera thinks it's an A-lens, set the camera to whatever aperture it believes to be wide open (it won't affect the lens since the tubes are fully manual), and P-TTL works well enough. Since tubes like these are so cheap you can get them just for this, and use better tubes for most stuff. (This is useful even if you have tubes with electrical contacts, since you might want to use an older lens.) Lowell: I also see the value for someone who wants to use a DA lens. Which is a perfectly reasonable thing to want.

11-02-2010, 05:58 PM	#14
Lowell Goudge Site Supporter Join Date: Jan 2007 Location: Toronto Photos: Gallery \| Albums Posts: 17,892	SOldBear I had not considered a DA or FA-J lens when you discuss manual focusing As for metering I do not consider the flaws that serious because again in manual focus you have time to check the histogram and shoot again

11-03-2010, 07:33 AM	#15
Douglas_of_Sweden Site Supporter Join Date: Apr 2008 Location: Stockholm Photos: Gallery Posts: 3,374	Originally posted by Capslock118 I'm trying to understand this, maybe I am not searching well enough or plenty of folks here will agree with my frustrations. why does it seem that automatic extension tubes are not in production by any manufacturer for pentax k mounts? I have a handful of manual lenses, so I bought cheapo manual extension tubes off ebay. But now i would really like it if I could use my DA lenses, or use the automatic aperture setting, and have automatic metering. Come to find, there seems to be tubes out there but they are not made today, made years ago, and are extremely hard to find. I don't care about auto focus - I do care about aperture control (as DA lenses obviously do not have an aperture ring), and while we are at it metering would be really nice too. Is there really nothing out there other than to continually watch used item markets? Is this really a hard thing to ask for? Or is there only 3 people out there (myself included) that are looking for these types of tubes and anyone else who would want them already owns them? German company Dörr is making a set with 13, 21 and 31 mm exension tubes with KA contacts for Pentax. http://www.doerrfoto.de The photo is for the Nikon version, but I have seen the Pentax version in real life with contacts. Here they are for 109 Euro Foto Palme Online Shop - Dörr Zwischenringsatz 13/21/31 mm für Pentax Technikguenstiger.de Online-Shop - Dörr Zwischenringsatz 13/21/31 mm für Pentax Amazon wants 159 Euro Dörr - Zwischenringsatz für Makro Fotografie - passend: Amazon.de: Elektronik You can also get them from Cyberphoto in Sweden Mellanringar systemkameror Dörr Mellanringsats 13/21/31mm till Pentax A Korean company named Pro Optic also makes (made?) a set, that adorama was selling, but they now say out of stock. Again the photo (at adorama) is not of a Pentax version, but someone posted a photo of what they got when ordering it at another forum Re: Extension Tubes: Pentax SLR Talk Forum: Digital Photography Review And yes, KA tubes are usefull. Bugs wont always kindly wait while you press the green button, shoot, correct exposure, and press two buttons again. I have a set of Vivitar tubes with KA contacts. I've even got a tube with screw drive autofocus (made from a converter), which works just fine.