Odd aperture problems with A lens on superA body

mwi13 · 10-30-2020, 01:47 PM

I've decided to revive my analog photography hobby, bought a bunch of stuff, including batteries, and almost immediately discovered a weird problem using my FA 77mm limited lens on my superA body. I'm wondering if anyone is familiar with these symptoms:

- with diaphragm ring off A, aperture indication is reversed in the viewfinder, and the aperture does not close
- with ring in A, viewfinder indication seems to work
- with ring off A, diaphragm does not close when actuating the shutter
- bulb mode displays a flashing 'E'??
- when slightly turning the lens in the mount (P indicator disappears), the diaphragm starts to close again when actuating the shutter!

I've owned this superA for years, but I think I never used it with an A lens before. Does anyone recognise the above? Are the electronics fried somehow? That would make me a bit sad!

Not a Number · 10-30-2020, 02:45 PM

The only thing I can think of is to check to see if the screws on the mount on both the lens and camera body are tightened down.

The lens is securely locked in the mount I take it.

stevebrot · 10-30-2020, 03:08 PM

Welcome to the Pentax Forums!

Does your Super A still work with non-A lenses?

Originally posted by mwi13

- with diaphragm ring off A, aperture indication is reversed in the viewfinder, and the aperture does not close

With the aperture ring off "A" and in "auto" or "125/X" mode, the viewfinder and top LCD should both display as if a non-A lens were mounted meaning nothing in the right-hand pane in the viewfinder and shutter speed only in the top LCD. I am not sure what you mean by "aperture indication is reversed".

RE: aperture not actuating. Does the lens stop down when DOF preview lever is depressed? If not, the lens is probably not fully rotated onto the mount --OR-- the actuator coupling in the body or on the lens is out of alignment or damaged. The coupler on the body should actuate even when no lens is mounted.

Originally posted by mwi13

bulb mode displays a flashing 'E'??

This is expected in B mode when the aperture ring is in the "A" position.

With any luck these questions will provide an answer!

Steve

stevebrot · 10-30-2020, 03:41 PM

BTW...If you don't already have one, there is a free download of the Super A manual at:

Pentax Manuals | Manual Focus Bodies

Error states and messages are on pages 30 and 31.

Steve

mwi13 · 10-31-2020, 01:20 AM

Originally posted by stevebrot

Welcome to the Pentax Forums!

Does your Super A still work with non-A lenses?

Thanks! Yes, using a non-A lens the diaphragm stops down fine. Also, all the screws etc are tight, and the A lens works as intended on my digital body.

Originally posted by stevebrot

With the aperture ring off "A" and in "auto" or "125/X" mode, the viewfinder and top LCD should both display as if a non-A lens were mounted meaning nothing in the right-hand pane in the viewfinder and shutter speed only in the top LCD. I am not sure what you mean by "aperture indication is reversed".

With the ring off A and the camera in auto, the viewfinder shows an aperture, but it does not match the aperture on the ring, and it is actually reversed! Thinking more about this, the camera must still be in program mode. Another look just now has confirmed this: the display keeps showing P. So this is just a weird combination of a manual aperture with P mode, making the camera pick odd aperture numbers to compensate ...

Originally posted by stevebrot

RE: aperture not actuating. Does the lens stop down when DOF preview lever is depressed? If not, the lens is probably not fully rotated onto the mount --OR-- the actuator coupling in the body or on the lens is out of alignment or damaged. The coupler on the body should actuate even when no lens is mounted.

This is expected in B mode when the aperture ring is in the "A" position.

With any luck these questions will provide an answer!

Steve

The DOF lever works fine. And, the E error is the final clue i think: even with the aperture ring not in the A position, this error shows. So, the camera never detects that the lens leaves A mode! Could this be caused by the lens being too new? It's the PENTAX-FA 77mm 1:1.8. I might have another A lens, some kind of kit zoom, will give that one a test, too.

mwi13 · 10-31-2020, 01:59 AM

So, tested with an old 28-70 AF zoom lens, and there I can switch in and out of P mode using the A setting on the aperture ring. So, does this mean that the 77mm doesn't support this? I bought this lens new (a few years ago), and I can't really believe that there's a defect in nit!

Not a Number · 10-31-2020, 07:14 AM

Look at the mount (back) of the 77mm. As you turn the aperture dial the settings linkage tab/lever should be seen moving in the slot opening on the mount. Check to see if the aperture lever is not bent.

The fact that you have rotational movement with the lens mounted and locked seems suspicious to me. On all my K-mount bodies and all my K-mount lenses the lenses will barely move at all - just the tiniest fraction of a millimeter if at all.

stevebrot · 10-31-2020, 10:03 AM

Originally posted by mwi13

Could this be caused by the lens being too new?

No...I tested my FA 77/1.8 on my Super Program before posting. Clean the mount contacts on your Super Program as well as on the lens and see if that helps. Something is definitely not right and I still wonder if the FA 77/1.8 is full seated in the mount (index line for focus at top?).

Steve

stevebrot · 10-31-2020, 10:08 AM

OK...I was able to reproduce with my camera/lens by not fully rotating the lens onto the mount.

Steve

mwi13 · 11-01-2020, 01:24 AM

Thanks for all your testing! I really appreciate the time you're taking

So, I checked seating of the 77mm on the superA, it's all perfectly tight, no problem there. Then I really started to doubt the 77mm instead of the superA, as the other A lens worked just fine. Putting the 77mm on my K3 in Av mode and turning the ring out of A left it in Av mode ... and doing this with the working A lens gave a reading of "F--"! So something is up with the 77mm, who would have thought that! I'm going to try cleaning the contacts etc, maybe that's enough. Not sure if I want to take a screw driver to that lens, it's not very cheap

don't want to "screw" it up (lol) ...

---------- Post added 11-01-20 at 02:00 AM ----------

Confirmed with a multi-meter, the '*' contact on the 77mm is always closed! On my other A lens, it's closed if the ring is on A, and open otherwise. Now, how to fix this ...

stevebrot · 11-01-2020, 04:47 AM

Originally posted by mwi13

Confirmed with a multi-meter, the '*' contact on the 77mm is always closed!

Hmmmm...That would account for the behavior on the K-3 and might account for the behavior on the Super A. I would leave this one to the experts as far as doing the repair. The Pentax Manuals site has the parts list with exploded diagram for the FA 77/1.8 that might be helpful.

Pentax Manuals | Service Manuals

Good luck!

Steve

mwi13 · 11-03-2020, 09:29 AM

Ohh, service manuals, just what I need. Also, my set of JIS screwdrivers came in the mail today, so I think I'll give it a (careful!!) go. The manuals will be very valuable to allow me to be prepared for various springamathingies trying to vanish into nowhere. I might make pictures, and I might even post some of them if I think they could be of help to other people. Many thanks for your excellent help and good questions enabling me to get at the actual problem!

stevebrot · 11-03-2020, 02:26 PM

Originally posted by mwi13

The manuals will be very valuable to allow me to be prepared for various springamathingies trying to vanish into nowhere.

Look at the resource I sent you before you pull the mount. There are a lot of springamathingies. The exploded diagram should provide clues as to possible cause and also show that a soldering iron will not likely be a help.

Steve

Not a Number · 11-03-2020, 05:11 PM

Will be looking forward to what the results are.

stevebrot · 11-03-2020, 08:25 PM

One other thing that may be helpful is a key to the expected pin encoding.* Note that all should remain constant except the pin for the "A" contact, which should toggle depending on whether the aperture ring is in the "A" position.

Features and Operation of the KA Mount | The K-Mount Page

Steve

* These determine the max/min values for display on non-AF bodies.

10-30-2020, 01:47 PM	#1
mwi13 New Member Join Date: Oct 2020 Posts: 5	Odd aperture problems with A lens on superA body I've decided to revive my analog photography hobby, bought a bunch of stuff, including batteries, and almost immediately discovered a weird problem using my FA 77mm limited lens on my superA body. I'm wondering if anyone is familiar with these symptoms: - with diaphragm ring off A, aperture indication is reversed in the viewfinder, and the aperture does not close - with ring in A, viewfinder indication seems to work - with ring off A, diaphragm does not close when actuating the shutter - bulb mode displays a flashing 'E'?? - when slightly turning the lens in the mount (P indicator disappears), the diaphragm starts to close again when actuating the shutter! I've owned this superA for years, but I think I never used it with an A lens before. Does anyone recognise the above? Are the electronics fried somehow? That would make me a bit sad!

10-30-2020, 03:08 PM	#3
stevebrot Otis Memorial Pentaxian Join Date: Mar 2007 Location: Vancouver (USA) Photos: Gallery \| Albums Posts: 42,007	Welcome to the Pentax Forums! Does your Super A still work with non-A lenses? Originally posted by mwi13 - with diaphragm ring off A, aperture indication is reversed in the viewfinder, and the aperture does not close With the aperture ring off "A" and in "auto" or "125/X" mode, the viewfinder and top LCD should both display as if a non-A lens were mounted meaning nothing in the right-hand pane in the viewfinder and shutter speed only in the top LCD. I am not sure what you mean by "aperture indication is reversed". RE: aperture not actuating. Does the lens stop down when DOF preview lever is depressed? If not, the lens is probably not fully rotated onto the mount --OR-- the actuator coupling in the body or on the lens is out of alignment or damaged. The coupler on the body should actuate even when no lens is mounted. Originally posted by mwi13 bulb mode displays a flashing 'E'?? This is expected in B mode when the aperture ring is in the "A" position. With any luck these questions will provide an answer! Steve Last edited by stevebrot; 10-30-2020 at 03:36 PM.

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10-30-2020, 02:45 PM	#2
Not a Number Moderator Join Date: Mar 2012 Location: Venice, CA Posts: 10,526	The only thing I can think of is to check to see if the screws on the mount on both the lens and camera body are tightened down. The lens is securely locked in the mount I take it.

10-30-2020, 03:41 PM	#4
stevebrot Otis Memorial Pentaxian Join Date: Mar 2007 Location: Vancouver (USA) Photos: Gallery \| Albums Posts: 42,007	BTW...If you don't already have one, there is a free download of the Super A manual at: Pentax Manuals \| Manual Focus Bodies Error states and messages are on pages 30 and 31. Steve

10-31-2020, 01:20 AM	#5
mwi13 New Member Join Date: Oct 2020 Posts: 5 Original Poster	Originally posted by stevebrot Welcome to the Pentax Forums! Does your Super A still work with non-A lenses? Thanks! Yes, using a non-A lens the diaphragm stops down fine. Also, all the screws etc are tight, and the A lens works as intended on my digital body. Originally posted by stevebrot With the aperture ring off "A" and in "auto" or "125/X" mode, the viewfinder and top LCD should both display as if a non-A lens were mounted meaning nothing in the right-hand pane in the viewfinder and shutter speed only in the top LCD. I am not sure what you mean by "aperture indication is reversed". With the ring off A and the camera in auto, the viewfinder shows an aperture, but it does not match the aperture on the ring, and it is actually reversed! Thinking more about this, the camera must still be in program mode. Another look just now has confirmed this: the display keeps showing P. So this is just a weird combination of a manual aperture with P mode, making the camera pick odd aperture numbers to compensate ... Originally posted by stevebrot RE: aperture not actuating. Does the lens stop down when DOF preview lever is depressed? If not, the lens is probably not fully rotated onto the mount --OR-- the actuator coupling in the body or on the lens is out of alignment or damaged. The coupler on the body should actuate even when no lens is mounted. This is expected in B mode when the aperture ring is in the "A" position. With any luck these questions will provide an answer! Steve The DOF lever works fine. And, the E error is the final clue i think: even with the aperture ring not in the A position, this error shows. So, the camera never detects that the lens leaves A mode! Could this be caused by the lens being too new? It's the PENTAX-FA 77mm 1:1.8. I might have another A lens, some kind of kit zoom, will give that one a test, too.

10-31-2020, 01:59 AM	#6
mwi13 New Member Join Date: Oct 2020 Posts: 5 Original Poster	So, tested with an old 28-70 AF zoom lens, and there I can switch in and out of P mode using the A setting on the aperture ring. So, does this mean that the 77mm doesn't support this? I bought this lens new (a few years ago), and I can't really believe that there's a defect in nit!

10-31-2020, 07:14 AM	#7
Not a Number Moderator Join Date: Mar 2012 Location: Venice, CA Posts: 10,526	Look at the mount (back) of the 77mm. As you turn the aperture dial the settings linkage tab/lever should be seen moving in the slot opening on the mount. Check to see if the aperture lever is not bent. The fact that you have rotational movement with the lens mounted and locked seems suspicious to me. On all my K-mount bodies and all my K-mount lenses the lenses will barely move at all - just the tiniest fraction of a millimeter if at all.

10-31-2020, 10:03 AM	#8
stevebrot Otis Memorial Pentaxian Join Date: Mar 2007 Location: Vancouver (USA) Photos: Gallery \| Albums Posts: 42,007	Originally posted by mwi13 Could this be caused by the lens being too new? No...I tested my FA 77/1.8 on my Super Program before posting. Clean the mount contacts on your Super Program as well as on the lens and see if that helps. Something is definitely not right and I still wonder if the FA 77/1.8 is full seated in the mount (index line for focus at top?). Steve

10-31-2020, 10:08 AM	#9
stevebrot Otis Memorial Pentaxian Join Date: Mar 2007 Location: Vancouver (USA) Photos: Gallery \| Albums Posts: 42,007	OK...I was able to reproduce with my camera/lens by not fully rotating the lens onto the mount. Steve

11-01-2020, 01:24 AM	#10
mwi13 New Member Join Date: Oct 2020 Posts: 5 Original Poster	Thanks for all your testing! I really appreciate the time you're taking So, I checked seating of the 77mm on the superA, it's all perfectly tight, no problem there. Then I really started to doubt the 77mm instead of the superA, as the other A lens worked just fine. Putting the 77mm on my K3 in Av mode and turning the ring out of A left it in Av mode ... and doing this with the working A lens gave a reading of "F--"! So something is up with the 77mm, who would have thought that! I'm going to try cleaning the contacts etc, maybe that's enough. Not sure if I want to take a screw driver to that lens, it's not very cheap don't want to "screw" it up (lol) ... ---------- Post added 11-01-20 at 02:00 AM ---------- Confirmed with a multi-meter, the '*' contact on the 77mm is always closed! On my other A lens, it's closed if the ring is on A, and open otherwise. Now, how to fix this ...

11-01-2020, 04:47 AM	#11
stevebrot Otis Memorial Pentaxian Join Date: Mar 2007 Location: Vancouver (USA) Photos: Gallery \| Albums Posts: 42,007	Originally posted by mwi13 Confirmed with a multi-meter, the '*' contact on the 77mm is always closed! Hmmmm...That would account for the behavior on the K-3 and might account for the behavior on the Super A. I would leave this one to the experts as far as doing the repair. The Pentax Manuals site has the parts list with exploded diagram for the FA 77/1.8 that might be helpful. Pentax Manuals \| Service Manuals Good luck! Steve

11-03-2020, 09:29 AM	#12
mwi13 New Member Join Date: Oct 2020 Posts: 5 Original Poster	Ohh, service manuals, just what I need. Also, my set of JIS screwdrivers came in the mail today, so I think I'll give it a (careful!!) go. The manuals will be very valuable to allow me to be prepared for various springamathingies trying to vanish into nowhere. I might make pictures, and I might even post some of them if I think they could be of help to other people. Many thanks for your excellent help and good questions enabling me to get at the actual problem!

11-03-2020, 02:26 PM	#13
stevebrot Otis Memorial Pentaxian Join Date: Mar 2007 Location: Vancouver (USA) Photos: Gallery \| Albums Posts: 42,007	Originally posted by mwi13 The manuals will be very valuable to allow me to be prepared for various springamathingies trying to vanish into nowhere. Look at the resource I sent you before you pull the mount. There are a lot of springamathingies. The exploded diagram should provide clues as to possible cause and also show that a soldering iron will not likely be a help. Steve

11-03-2020, 05:11 PM	#14
Not a Number Moderator Join Date: Mar 2012 Location: Venice, CA Posts: 10,526	Will be looking forward to what the results are.

11-03-2020, 08:25 PM	#15
stevebrot Otis Memorial Pentaxian Join Date: Mar 2007 Location: Vancouver (USA) Photos: Gallery \| Albums Posts: 42,007	One other thing that may be helpful is a key to the expected pin encoding.* Note that all should remain constant except the pin for the "A" contact, which should toggle depending on whether the aperture ring is in the "A" position. Features and Operation of the KA Mount \| The K-Mount Page Steve * These determine the max/min values for display on non-AF bodies.