[spystyle]

Regarding automatic tubes - couldn't a person add wires to a tube without contacts - making contacts? Wires that extend from the bottom to the top?

It seems like it would be pretty easy. If it had to be flush you could use a dremel to cut a little channel in the extension tube, then solder the wire so it's flush.

Do you see what I'm saying ?

[Hypocorism]

Regarding automatic tubes - couldn't a person add wires to a tube without contacts - making contacts? Wires that extend from the bottom to the top?

It seems like it would be pretty easy. If it had to be flush you could use a dremel to cut a little channel in the extension tube, then solder the wire so it's flush.

Do you see what I'm saying ?

Sure do, good idea but is it worth the $ saving for the hours, materials and effort you'd put in?

And what does one start with? The USD10 eBay tubes are no way any comparison to serious quality made tubes that cost minimum 10 times as much and are now like hen's teeth to acquire second hand.

Also the modular-screwed mfgr/assembly method, good for economy, used in the cheap eBay manual types excludes them from easy independent separation and reconnect if wired.

I have a set (of the better ones too) but still shudder after reading horror stories of them pin-locking to camera bodies.
Luckily ? picked up a s/h set of Asahi-A tubes and use them -- only when desperate though, aperture only is no substitute for full control that my modern cameras are made to do, and quite capably.

So how about designing and marketing an affordable DIY adaption to your concept, one that will fit cheap and readily available K-mount ETs?
Or you could sell the ready-to-go Tubes set.

You can put me on your list of buyers if it's affordable and works, is easy to use and doesn't damage cameras or lenses.

.R.

[Steve Beswick]

...
I have a set (of the better ones too) but still shudder after reading horror stories of them pin-locking to camera bodies.
...

So unscrew the rear mount and pull out the Ricoh pin. It shouldn't take more than 5 minutes per tube.

[Hypocorism]

So unscrew the rear mount and pull out the Ricoh pin. It shouldn't take more than 5 minutes per tube.

???
I don't understand. ? What is there to "unscrew" with quick-twist-lock K-mount?

There is no "pin" to pull out in the rear K-mount piece of these tubes sets. Nor is there access to the in-camera mounted pin - the body mount lens-release one that apparently locks to the tube's rear mount piece, when the rear mount piece supplied with the tubes set is fitted to the camera body.

And Ricoh? Nope, these are generic 3rd party tubes made and sold for Pentax K-mount cameras and lenses. There was no mention of them also fitting Ricoh, or any other brand camera.

Can you pls explain further what you mean with this "5 minutes per tube" ?? process that addresses this potential lock-on problem, that others claim to be a machining job?

.R.

---

Last edited by Hypocorism; 02-05-2011 at 01:37 AM.

[Steve Beswick]

???
I don't understand. ? What is there to "unscrew" with quick-twist-lock K-mount?

There is no "pin" to pull out in the rear K-mount piece of these tubes sets. Nor is there access to the in-camera mounted pin - the body mount lens-release one that apparently locks to the tube's rear mount piece, when the rear mount piece supplied with the tubes set is fitted to the camera body.

And Ricoh? Nope, these are generic 3rd party tubes made and sold for Pentax K-mount cameras and lenses. There was no mention of them also fitting Ricoh, or any other brand camera.

Can you pls explain further what you mean with this "5 minutes per tube" ?? process that addresses this potential lock-on problem, that others claim to be a machining job?

.R.

If an extension tube, teleconverter, or lens is "pin locked" on any autofocus Pentax body, 99.9% of the time that means that the Ricoh pin on said lens is jammed in the AF drive mechanism hole on the body.

This link should explain it pretty well:
Sears 60-300(auto aperture, push pull zoom): Pentax SLR Talk Forum: Digital Photography Review

[Hypocorism]

If an extension tube, teleconverter, or lens is "pin locked" on any autofocus Pentax body, 99.9% of the time that means that the Ricoh pin on said lens is jammed in the AF drive mechanism hole on the body.

This link should explain it pretty well:
Sears 60-300(auto aperture, push pull zoom): Pentax SLR Talk Forum: Digital Photography Review

Thanks Steve, doesn't apply to these common eBay tubes that have no pin -- but at least I have another good reason now to avoid horrible old lenses like the plague.

.R.

[RioRico]

...I have another good reason now to avoid horrible old lenses like the plague.

Excellent! That leaves more for the rest of us!

[/me drools over collection of horrible old lenses, smiles, cackles ominously...]

[spystyle]

Which old lenses are horrible ?

I thought they were classic gems and mechanical marvels

[Steve Beswick]

Thanks Steve, doesn't apply to these common eBay tubes that have no pin -- but at least I have another good reason now to avoid horrible old lenses like the plague.

.R.

Old, not necessarily horrible.

[gp1806]

Which old lenses are horrible ?

I thought they were classic gems and mechanical marvels

I guess there could be some old horrible lenses out there, but of the few that I've got, no prime would I label even bad, much less horrible. Some of the first generation zooms were not very good, but old primes seem very usable at the least and can be really nice. Price does not seem to be the determining factor. I have an Assanuma 35mm f/2.8 M42 that I paid a whopping $9 for shipped, and that included an M42 to PK adapter that was stuck on the threads. It's quite usable and pretty sharp. Go try an old prime lens, you might like it.

[SOldBear]

If an extension tube, teleconverter, or lens is "pin locked" on any autofocus Pentax body, 99.9% of the time that means that the Ricoh pin on said lens is jammed in the AF drive mechanism hole on the body.

Not necessarily. Or maybe I'm just lucky....

One some Pentax p-KA/Ricoh lenses/TCs/ETs, the "Ricoh pin" is actually a ball, or a pin with round head. It does not get stuck in the AF drive hole at all.

I have a copy of "proper" ET (left in the photo below) and 3 copies of ex-TC ET (right in the photo). They all have the infamous "Ricoh pin." I use them as is on Pentax DSLRs, none of them get stuck.

You have a 12mm extension tube from the AT-23 set and the 2x TC converted to ET. Comparing the two, is there any difference in the exposure accuracy between the AT-23 ET and the TC-ET? If there is no difference, then simply grounding the pin is sufficient but if the AT-23 is more accurate then there is a seventh pin on the TC-ET located about 1cm left of the scratch mark point that can be moved to the grounding point. There is no contact at that location on the Pentax DSLR body, so I am assuming that the pin can be relocated without consequences.

I tested the 7-pin ET and the 6-pin ex-TC ET (7th pin is grounded). In terms of the exposure accuracy, I could not detect any difference. For the test, I used a K7 body and a DA Ltd. 70mm lens.

What about moving the seventh pin on the TC to the correct position? Your thoughts would be appreciated.

I did some more tests and found something I had never expected.

The bodies I used were K10D (firmware version 1.30) and K7 (firmware version 1.1). The result was the same with either body.

The lenses I used were DA* zoom lenses with SDM: 16-50, 50-135, and 60-250. The result was the same with any of them.

1. With a 6-pin ET, the operations were normal as expected: the camera treated the combo as if there were an A-lens attached.
   
2. With a 7-pin ET, things became interesting:
   
   • When I hit the "Menu" or "Info" button, the LCD screen flashed and then turned itself off. There was no way to view the info or change any setting in the menu. Even when the memory card was full, the message "Memory Card Full" flashed once on the LCD screen, then turned off.
   • With the body in AF-S and the lens in AF, pushing the shutter release button did not do anything. In other words, there was no way to release the shutter.
   • With the body in AF-C or MF, or the lens in MF, the shutter might or might not release, depending on the focusing of the lens. What was even more interesting was that the shutter could release when the photo was NOT in focus, but the shutter did not release when the photo was in focus.
   • There was no focus indicator (red LED) lighting up in viewfinder. There was no focus confirmation (green hexagon) in viewfinder display.

Please note that this was not a case of equipment failure. The symptoms were the same for either camera body, any DA* lens. When I masked the 7th pin of the ET with a piece of aluminum tape (essentially grounding it), the ET operated like a 6-pin version.

Based on the result of my experiment, a 6-pin TC/ET is more desirable than a 7-pin version.

[Steve Beswick]

Not necessarily. Or maybe I'm just lucky....

One some Pentax p-KA/Ricoh lenses/TCs/ETs, the "Ricoh pin" is actually a ball, or a pin with round head. It does not get stuck in the AF drive hole at all.

...

I agree. I have had a few lenses with the rounded ball type "pin", and I have never had a problem. I was just saying if a lens is pin locked - not that all such lenses would.

[excanonfd]

I tested the 7-pin ET and the 6-pin ex-TC ET (7th pin is grounded). In terms of the exposure accuracy, I could not detect any difference. For the test, I used a K7 body and a DA Ltd. 70mm lens.

I did some more tests and found something I had never expected.

The bodies I used were K10D (firmware version 1.30) and K7 (firmware version 1.1). The result was the same with either body.

The lenses I used were DA* zoom lenses with SDM: 16-50, 50-135, and 60-250. The result was the same with any of them.

1. With a 6-pin ET, the operations were normal as expected: the camera treated the combo as if there were an A-lens attached.
   
2. With a 7-pin ET, things became interesting:
   
   • When I hit the "Menu" or "Info" button, the LCD screen flashed and then turned itself off. There was no way to view the info or change any setting in the menu. Even when the memory card was full, the message "Memory Card Full" flashed once on the LCD screen, then turned off.
   • With the body in AF-S and the lens in AF, pushing the shutter release button did not do anything. In other words, there was no way to release the shutter.
   • With the body in AF-C or MF, or the lens in MF, the shutter might or might not release, depending on the focusing of the lens. What was even more interesting was that the shutter could release when the photo was NOT in focus, but the shutter did not release when the photo was in focus.
   • There was no focus indicator (red LED) lighting up in viewfinder. There was no focus confirmation (green hexagon) in viewfinder display.

Please note that this was not a case of equipment failure. The symptoms were the same for either camera body, any DA* lens. When I masked the 7th pin of the ET with a piece of aluminum tape (essentially grounding it), the ET operated like a 6-pin version.

Based on the result of my experiment, a 6-pin TC/ET is more desirable than a 7-pin version.

Thanks SoldBear, for sharing your findings. I have tried to re-create your results just now and I agree that the exposure is unaffected whether the ET is 7 pin or 6.

I shot with Tamron SP 90mm f2.5, 52BB with both 6pin TC-ET and 12mm Vivitar AT-23 ET and K20D camera. I tried to follow your methodology to the letter and I found no difference in behaviour from either of the TC. I was able to trap focus with both TC in AF-S mode, Menu and Info buttons worked exactly as they should. I don't have many AF lenses, none fast enough to work with ETs under 2x13 watt CF light bulbs. I will see if SDM lenses cause 7 pin ET to malfunction during daylight hours with my lone SDM lens; DA 17-70.

Regards,

[blende8]

... [6-pin ... 7-pin tests] ...

I can confirm this behavior, same here.
Interesting!
It appears that the camera needs the SDM connection, too.
My Kenko SDM tube also has 7 pins and it works.

[excanonfd]

I can confirm this behavior, same here.
Interesting!
It appears that the camera needs the SDM connection, too.
My Kenko SDM tube also has 7 pins and it works.

Thanks blende8 for your input regarding SDM connection in the Kenko tubes, I have tried shooting with DA 17-70 + AT-23 ET and it behaves exactly as SoldBear has described it. Does the AF work at all with the Kenko tubes in macro mode, and to what degree - not that I see myself getting one anytime soon but I am curious about Kenko's own recommendation to use manual focus in macro mode.