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06-19-2017, 04:15 AM   #1
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Auto teleconverter not passing aperture control.

Sorry if this is in the wrong place. I was looking for a set of extension tubes for macro work, but couldn't find any with auto aperture. I found a forum post which suggested that the best way to get around this is to gut an auto teleconverter with the contacts, to leave a single extension tube, with no optics in it. So, I bought a "Ranger auto 2x teleconverter (PKA)". It has the apature lever, for stop down metering, and six electrical contacts. These contacts pass straight through and, I believe, have no electronics in the way.

When I connected the teleconverter to my K-1 it asked for the focal length of the lens - which made sense I suppose - but then continued to not register the aperture, just like if you connect a lens without the contacts. On pressing the metering button, it stops down to the minimum F-number, and it also only takes photos at the minimum F-number. I believe this is the expected behaviour of a lens without the electrical contacts to the camera, but with the lever.

The lens I tested this with was the 100mm macro (I just wanted to get a little bit closer), and I didn't do anything to the teleconverter.

There are only three things I can think of as to why it doesn't work, that the contacts are in a slightly different place/missing one contact or something - I now realise that the converter has some of the contacts in slightly different places, but most of them line up. That the contacts might not be making good electrical contact with either the camera or the lens. Or that there is some option in the menus which needs to be enabled.

I don't know if anyone else has had this problem. I'll try to find the original thread which suggested this. If someone has any other ideas for how to get auto aperture extension tubes or any teleconverters that are known to work that would be great. The ones that people suggest (I think the Vivitar AT-23 seem to be very hard to find).

Thanks

06-19-2017, 04:23 AM   #2
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I'm thinking aloud here. What camera setting did you use (e.g. green mode, P, M???). This might be a factor to consider.
06-19-2017, 04:36 AM   #3
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QuoteOriginally posted by Wild Mark Quote
I'm thinking aloud here. What camera setting did you use (e.g. green mode, P, M???). This might be a factor to consider.
I quickly tried it in P and in Manual. It didn't work in either. The stop down metering was with the green button. It did stop down, but it would only stop down to the minimum aperture.
06-19-2017, 04:58 AM   #4
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This might help...
Teleconverter Aperture Control Issues - PentaxForums.com

06-19-2017, 05:15 AM   #5
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QuoteOriginally posted by joshuamcateer Quote
I quickly tried it in P and in Manual. It didn't work in either. The stop down metering was with the green button. It did stop down, but it would only stop down to the minimum aperture.
hmmm ok. Have you enabled aperture ring in the settings?
06-19-2017, 06:45 AM   #6
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I tried as many of those fixes as possible, such as cleaning the contacts and checking continuity. But none of those things fixed this issue. It behaves in exactly the same way as it did before, like a manual lens.

I think the problem might be Imgur: The most awesome images on the Internet related to the location of the pins and the number of them. When I bought the teleconverter I bought the one which had the most contacts (6), although they don't match up with all of the pins on the lens. Although, I thought that it should still work, as it would be like connecting the lens to an older camera, or the camera to an older lens. This article The Evolution of the Pentax K-mount - Articles and Tips | PentaxForums.com suggests that the teleconverter is a KA mount, but also suggests that it should meter.

I'm not sure quite what you mean
QuoteOriginally posted by Wild Mark Quote
hmmm ok. Have you enabled aperture ring in the settings?
. The lens doesn't have an aperture ring.
06-19-2017, 07:17 AM - 1 Like   #7
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QuoteOriginally posted by joshuamcateer Quote
When I connected the teleconverter to my K-1 it asked for the focal length of the lens - which made sense I suppose - but then continued to not register the aperture, just like if you connect a lens without the contacts.
Yes, the camera will always ask for focal length for non-AF lenses.

If the top and rear LCD display F--- for aperture, that is an indication that the lens is not being detected as supported aperture control by the body. Reasons include:
  • Lens lacks the "A" contacts
  • Aperture ring not on the "A" position
  • The "A" contact is not functional (defective or damaged wiring) or is misaligned. You can check the contacts on your TC with a continuity checker (ohmmeter).

QuoteOriginally posted by joshuamcateer Quote
On pressing the metering button, it stops down to the minimum F-number, and it also only takes photos at the minimum F-number. I believe this is the expected behaviour of a lens without the electrical contacts to the camera, but with the lever.
Ummm...sort of...

Lenses without contacts all have aperture rings. The lens should stop down to the aperture set on the ring if contacts are not present or if the aperture ring is off the "A" position. If that is the case, what you describe is a lens that lacks a functioning aperture actuator. Are you able to control the lens aperture with the TC/lens assembly off-camera? If you flick the lever on the TC, the aperture on the lens should respond in a snappy manner at all settings.

QuoteOriginally posted by joshuamcateer Quote
When I bought the teleconverter I bought the one which had the most contacts (6), although they don't match up with all of the pins on the lens.
?????

Here are summary points:
  • All "A" contact lenses and accessories will have at minimum the "A" contact plus one other (see diagram below)
  • All manual focus TCs and extension tubes having contacts will have all 6 contacts
  • Auto-focus TCs and extension tubes will have 7 contacts (the 6 regular contacts plus an additional for data transmission)
  • Combo Pentax/Ricoh-P mounts will have Pentax contacts plus the Ricoh pin on the opposite side of the mount*
If they don't match up with the pins on the lens, the first question would be whether the lens is fully engaged to the TC. The second is whether the lens and/or TC has been damaged by accident, modification, or botched repair attempt.

KA body mount detail The "A" contact is indicated by the "*".

Image courtesy of Dimitrov's K-mount page (LINK)


Steve

* The Ricoh "pin" (if present) can be problematic (may foul AF pawl and jam lens to camera) and is something to be aware of with manual focus K-mount lenses and accessories. Google "Ricoh Pin" for resources.

Last edited by stevebrot; 06-19-2017 at 07:28 AM.
06-19-2017, 07:29 AM   #8
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Steve got in while I was typing - detailed and accurate as usual...

OK I take it the top pic is of the lens mount. The pin arrangement on that is designed to communicate the lens min/max apertures according to the contact code. Actually if this is a more modern lens with a 7th data contact - looks like it is - then am I right in thinking the chip communicates that info on a dslr? In any case I don't think the non- conformity of the lens mount contacts with the standard array of 6 contacts (no data contact on older tc's) on the tc is the issue.
If the f number is not registering on the top (and maybe the rear) lcd, then the lens isn't being recognised as a PKA. The first line of inquiry is to check that the the contact that transmits this info is working. Thats the 3rd contact down on the tc, and the third one down, at approx 25mins of with a flat head (on my K5), on the camera. On most "A" series lenses, this contact mechanically engages only when the aperture ring is clicked into "A" position.
Test the lens first, then the tc.

06-19-2017, 07:32 AM   #9
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I think @Stevebrot covered things far better than I could so I will only add that the first thing I would do is check the continuity of the contacts through the TC. I have purchased several over the years that looked just fine but the wires or springs inside had come loose and there was no continuity from one side of the TC to the other. Without knowing for sure the TC is functional you can chase your tail trying different suggestions and nothing will help.
06-19-2017, 07:40 AM   #10
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A few questions for clarification:

1) You say the lens has no aperture ring and is a 100mm macro. Is this ithe DFA 100 WR?
2) Is the mount on this Teleconverter Black as opposed to chrome?
3) Does the lens work correctly without the Teleconverter mounted?
4) When you said the pins don't match - I assume the 6 that are there line up correctly but the 7th pin on the lens is not aligned with a pin?

Assuming the answers to all of these is YES. Then the black painted mount may be an issue. There have been issues with this with modern Pentax cameras. I have a black painted deglassed TC I use with my K-3 that sometimes fails to work. I have checked the pins and all are conducting correctly but my guess is that the mount is not fully conductive and that occasionally I get an less reliable connection. Over time it has gotten better. There are articles about using foil tape to simulate the conductivity you need or you can try sanding the mount to expose the bare metal. It is also entirely possible this is NOT the problem.
06-19-2017, 08:07 AM   #11
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QuoteOriginally posted by marcusBMG Quote
Steve got in while I was typing - detailed and accurate as usual...

OK I take it the top pic is of the lens mount. The pin arrangement on that is designed to communicate the lens min/max apertures according to the contact code. Actually if this is a more modern lens with a 7th data contact - looks like it is - then am I right in thinking the chip communicates that info on a dslr? In any case I don't think the non- conformity of the lens mount contacts with the standard array of 6 contacts (no data contact on older tc's) on the tc is the issue.
If the f number is not registering on the top (and maybe the rear) lcd, then the lens isn't being recognised as a PKA. The first line of inquiry is to check that the the contact that transmits this info is working. Thats the 3rd contact down on the tc, and the third one down, at approx 25mins of with a flat head (on my K5), on the camera. On most "A" series lenses, this contact mechanically engages only when the aperture ring is clicked into "A" position.
Test the lens first, then the tc.
Yes, the top picture is the mount of the lens. I have read that the 7th pin does this. The f-number is not registering on either of the screens, displaying the "f - -" just like Steve said. I've checked all of the pins on the teleconverter with a multimeter and they all conduct all of the way through the teleconverter.

However, I'm not sure how to test the contact in the camera, although it's quite new and looks clean. The lens I tested it with is a D-series lens, the DFA 100mm macro, which doesn't have an aperture ring. However, I tested it on an F-series lens (a 70-200), which does have an aperture ring. The camera still doesn't recognise the lens even with it set to "A", displaying "F - -" on the screen. I'm not sure how to test my lens. I don't have an A-series lent to test it with.

---------- Post added 06-19-17 at 08:19 AM ----------

QuoteOriginally posted by UncleVanya Quote
A few questions for clarification:

1) You say the lens has no aperture ring and is a 100mm macro. Is this ithe DFA 100 WR?
2) Is the mount on this Teleconverter Black as opposed to chrome?
3) Does the lens work correctly without the Teleconverter mounted?
4) When you said the pins don't match - I assume the 6 that are there line up correctly but the 7th pin on the lens is not aligned with a pin?

Assuming the answers to all of these is YES. Then the black painted mount may be an issue. There have been issues with this with modern Pentax cameras. I have a black painted deglassed TC I use with my K-3 that sometimes fails to work. I have checked the pins and all are conducting correctly but my guess is that the mount is not fully conductive and that occasionally I get an less reliable connection. Over time it has gotten better. There are articles about using foil tape to simulate the conductivity you need or you can try sanding the mount to expose the bare metal. It is also entirely possible this is NOT the problem.
To answer your questions:
1) yes
2) no, it is bare metal
3) yes, perfectly, bought new in a shop and it has never been an issue
4) Some of the pins match. I've tried to align the images and flick between them Imgur: The most awesome images on the Internet and several of the pins are in different places.

to expand on 2) I believe that the metal lens mount is the ground for the electrical contacts. I checked the continuity between the two sides of it and it seems pretty dodgy but still makes contact. I thought that since the surface area is quite large the contact would be good enough. There is definitely continuity between then, as I also checked the polished metal screws. The screws on the opposite sides of the mount (lens and camera sides) make very good contact, so I thought that they should also make good contact with the surrounding metal mount. I could try polishing the mount.
06-19-2017, 08:35 AM   #12
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Those pins look aligned to me. The flat plastic button on the lens is there on purpose it prevents that pin from shorting and signals the max aperture if I recall correctly.

I would try polishing the mount just in case on BOTH sides of the TC. The top and the bottom have to work reliably.
06-19-2017, 09:10 AM   #13
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QuoteOriginally posted by UncleVanya Quote
Those pins look aligned to me. The flat plastic button on the lens is there on purpose it prevents that pin from shorting and signals the max aperture if I recall correctly.

I would try polishing the mount just in case on BOTH sides of the TC. The top and the bottom have to work reliably.
I only make it four pins which are in the same location in each picture. I tried roughing up the surface with a nail file, trying to make the smallest possible difference to the teleconverter so that it wouldn't scratch then lens mount. I continued until there were faint scratches covering more than half of both the top and bottom of the teleconverter. I then cleaned it with isopropyl alcohol and tried it on the camera - it didn't work either. I then cleaned the lens mount of the camera and tried again, but to no avail.
06-19-2017, 09:11 AM   #14
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I can't really make it out from the photos but it looks to me as if the "A" pin is not protruding on the camera side of the TC Most TCs equipped with pins that I've seen the pin sticks out ever so slightly without an "A" lens mounted. If there is no continuity between the camera body and the "A" pin on the lens you will get the "F--". If the "F--" is flashing it means you haven't enabled the use aperture ring setting in the camera menu.

For a quick test try this:
  • Attach the lens set at "A" mode if it has a ring. If not a FA/DA/DFA should always be in "A" mode
  • Take a small strip of aluminum foil and cover the "A" pin on the camera. The "A" pin on the camera should be slightly recessed and you may have to make a small ball of aluminum foil to fill it in. Extreme care must be taken that the foil strip or ball doesn't fall into the mirror box.
  • Make the strip long enough that you can hold it in place either with a finger or some sticky tape beyond the silver mount ring.
  • Carefully mount the lens.
If the display no longer shows "F--" then either the "A" pin isn't connecting or the continuity otherwise is bad. The other pins have to do with the min and max aperture settings for the lens and should not affect the "F--" if they lack continuity. The camera would get erroneous information though as to what the speed of the lens is.
06-19-2017, 09:42 AM   #15
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QuoteOriginally posted by Not a Number Quote
I can't really make it out from the photos but it looks to me as if the "A" pin is not protruding on the camera side of the TC Most TCs equipped with pins that I've seen the pin sticks out ever so slightly without an "A" lens mounted. If there is no continuity between the camera body and the "A" pin on the lens you will get the "F--". If the "F--" is flashing it means you haven't enabled the use aperture ring setting in the camera menu.

For a quick test try this:
  • Attach the lens set at "A" mode if it has a ring. If not a FA/DA/DFA should always be in "A" mode
  • Take a small strip of aluminum foil and cover the "A" pin on the camera. The "A" pin on the camera should be slightly recessed and you may have to make a small ball of aluminum foil to fill it in. Extreme care must be taken that the foil strip or ball doesn't fall into the mirror box.
  • Make the strip long enough that you can hold it in place either with a finger or some sticky tape beyond the silver mount ring.
  • Carefully mount the lens.
If the display no longer shows "F--" then either the "A" pin isn't connecting or the continuity otherwise is bad. The other pins have to do with the min and max aperture settings for the lens and should not affect the "F--" if they lack continuity. The camera would get erroneous information though as to what the speed of the lens is.
I tried your aluminium foil suggestion, but I couldn't get the foil to stay in place. The TC fits too snugly with the camera mount and it just rips or drags the foil.

*Breaking news* tried to tape the aluminium foil into the pin hole. It didn't look like it was going to work, as the tape got dragged around as the lens mounted, but it did. I got aperture control and metering - perfect.

However, when I took the lens off the foil got dragged back and I'm not sure exactly where it was. I *think* that a tiny fleck of foil remained on the A pin, and that's what caused it. The only problem is that it's not really a permanent solution. I might try glueing some aluminium foil to the TC, although I'm not sure how best to do that.

Thanks so much. You've all been so helpful, I don't think I would have thought of any of those suggestions.
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