SMC Pentax-FA 28-80 - broken power zoom switch

apaluch · 06-02-2021, 01:18 AM

Hi

I have lens with broken power zoom switch, as on photo...
Zoom ring doesn't work, is it expected with all contacts open? Is it issue of switch? If yes, which pads may be connected to make zoom ring works?

br
Andrzej

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pschlute · 06-02-2021, 01:34 AM

Originally posted by apaluch

I have lens with broken power zoom switch, as on photo..

That is a common issue with that series of lenses. Pull the zoom ring towards you and you can then zoom manually.

The best way to get a replacement switch is to buy another lens and swap it over, but I am not sure if the power zoom works on a modern DSLR.

Bertrand3000 · 06-02-2021, 03:38 AM

High end models can operate powerzoom like K3 and K1. KP cannot.

**Lowell Goudge** · 06-02-2021, 03:46 AM

Originally posted by Bertrand3000

High end models can operate powerzoom K3, K1. KP cannot.

What you say is contradictory, the K1 and K3 clearly are high end models.

For the record, the support for Power Zoom is limited to supplying power to the zoom motor, so you can zoom using the zoom ring, but nothing else, none of the functions such as zoom while shutter is open , image so PZ1 tracking don’t work

---------- Post added 06-02-21 at 06:47 AM ----------

Originally posted by apaluch

Hi

I have lens with broken power zoom switch, as on photo...
Zoom ring doesn't work, is it expected with all contacts open? Is it issue of switch? If yes, which pads may be connected to make zoom ring works?

br
Andrzej

I picked up one for $10 with the same issue. I filled the hole with epoxy, but I can’t recall whether the poser zoom worked or not, on my 28-105 I managed to find all the pieces and put it back in place with crazy glue

apaluch · 06-03-2021, 10:06 AM

Originally posted by pschlute

That is a common issue with that series of lenses. Pull the zoom ring towards you and you can then zoom manually...

Thank you for advice, worth to know that zoom ring can be pulled

but too late - I've just disassembled the lens... and interesting, zoom motor was broken (brushes was exhausted). After bending them to better contact to rotor, motor works (with 5V power supply)... but after assembly power zoom still don't work with K-x. Strange that power zoom is an issue for DSLRs, since it's just matter of delivering current to motor.

pschlute · 06-03-2021, 12:33 PM

Originally posted by apaluch

Strange that power zoom is an issue for DSLRs, since it's just matter of delivering current to motor.

Power zoom was a short lived feature of lenses of this period. Most people, myself included, turned the stupid thing off.

titrisol · 03-28-2022, 10:26 AM

Originally posted by pschlute

Power zoom was a short lived feature of lenses of this period. Most people, myself included, turned the stupid thing off.

what was the switch for???? I just one one of these attached to a Pz-20 at a yard sale

pschlute · 03-28-2022, 02:08 PM - **1 Like**

Originally posted by titrisol

what was the switch for???? I just one one of these attached to a Pz-20 at a yard sale

https://www.pentax-manuals.com/manuals/accessories/fa_lenses_91.pdf

Password is Pentax

Chefk0ch · 04-27-2022, 01:40 PM

Hello everybody,

same Lens here, same Switch Problem, but my copy of the lens shows no problem when its mounted on a Z10. Power Zoom and AF are fine and functional. Mounted on my K1II/K5/K20 im only able to use manul focus and manual zoom and the camera asks for the focal length, only the apeture can be controlled by the camera. Any Ideas how to solve the problem? Would be great if at least AF could be used.

Regards
Chefk0ch

**TwoUptons** · 04-28-2022, 05:52 PM

Originally posted by Chefk0ch

Hello everybody,

same Lens here, same Switch Problem, but my copy of the lens shows no problem when its mounted on a Z10. Power Zoom and AF are fine and functional. Mounted on my K1II/K5/K20 im only able to use manul focus and manual zoom and the camera asks for the focal length, only the apeture can be controlled by the camera. Any Ideas how to solve the problem? Would be great if at least AF could be used.

Regards
Chefk0ch

I'd clean the contacts on the lens and on the camera.

I used the very similar PZ 28-105 on my K1/ii for a while as my main lens, and it worked fine as a basic lens.
Autofocus and power zoom were both completely functional. Focal length was also fine.
As mentioned above, none of the fancy features worked, though.

I will note I have a nasty habit of switching the body to manual focus mode then wondering why my lenses don't focus...

-Eric

kypfer · 04-30-2022, 03:14 PM

I made a brief enquiry regarding these Power Zoom lenses on DSLRs a few months ago … conclusion was basically that the feature was only good for flattening batteries on modern cameras

The "trick" is that if you can read the lettering "Power Zoom" then manual zoom won't work, you need to pull the zoom ring towards the camera to engage manual zoom.
In that configuration it works just like any other "A" lens.

Chefk0ch · 05-01-2022, 01:22 PM

Contacts already cleaned a few times, makes no difference, all my other lenses are ok without any problem.

Sometimes the lens is fine, tested today again, got it functional two times: pulled the power zoom ring to manual zoom mode, K1II to MF, switched the Camera on, switched to AF and the lens does what it should. Powered the Camera off, repeated the steps, lens functions again, no card in the camera, so Power off, insert card, Power on, camera asked for focal lenght.

Since then, no more AF.

I can really do without power zoom but AF would be great, for MF i´ve got many other lenses. Ok, for AF too, but thats not the point here. I like the colors out of this lens. Example posted in the FA unlimited Lens Club.

06-02-2021, 03:38 AM	#3
Bertrand3000 Veteran Member Join Date: Feb 2019 Posts: 2,009	High end models can operate powerzoom like K3 and K1. KP cannot. Last edited by Bertrand3000; 06-02-2021 at 04:05 AM.

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06-02-2021, 01:34 AM	#2
pschlute Moderator Loyal Site Supporter Join Date: Mar 2007 Location: Surrey, UK Photos: Gallery Posts: 8,182	Originally posted by apaluch I have lens with broken power zoom switch, as on photo.. That is a common issue with that series of lenses. Pull the zoom ring towards you and you can then zoom manually. The best way to get a replacement switch is to buy another lens and swap it over, but I am not sure if the power zoom works on a modern DSLR.

06-02-2021, 03:46 AM	#4
Lowell Goudge Site Supporter Join Date: Jan 2007 Location: Toronto Photos: Gallery \| Albums Posts: 17,886	Originally posted by Bertrand3000 High end models can operate powerzoom K3, K1. KP cannot. What you say is contradictory, the K1 and K3 clearly are high end models. For the record, the support for Power Zoom is limited to supplying power to the zoom motor, so you can zoom using the zoom ring, but nothing else, none of the functions such as zoom while shutter is open , image so PZ1 tracking don’t work ---------- Post added 06-02-21 at 06:47 AM ---------- Originally posted by apaluch Hi I have lens with broken power zoom switch, as on photo... Zoom ring doesn't work, is it expected with all contacts open? Is it issue of switch? If yes, which pads may be connected to make zoom ring works? br Andrzej I picked up one for $10 with the same issue. I filled the hole with epoxy, but I can’t recall whether the poser zoom worked or not, on my 28-105 I managed to find all the pieces and put it back in place with crazy glue

06-03-2021, 10:06 AM	#5
apaluch New Member Join Date: Jun 2021 Photos: Gallery Posts: 4 Original Poster	Originally posted by pschlute That is a common issue with that series of lenses. Pull the zoom ring towards you and you can then zoom manually... Thank you for advice, worth to know that zoom ring can be pulled but too late - I've just disassembled the lens... and interesting, zoom motor was broken (brushes was exhausted). After bending them to better contact to rotor, motor works (with 5V power supply)... but after assembly power zoom still don't work with K-x. Strange that power zoom is an issue for DSLRs, since it's just matter of delivering current to motor.

06-03-2021, 12:33 PM	#6
pschlute Moderator Loyal Site Supporter Join Date: Mar 2007 Location: Surrey, UK Photos: Gallery Posts: 8,182	Originally posted by apaluch Strange that power zoom is an issue for DSLRs, since it's just matter of delivering current to motor. Power zoom was a short lived feature of lenses of this period. Most people, myself included, turned the stupid thing off.

03-28-2022, 10:26 AM	#7
titrisol Pentaxian Join Date: Dec 2007 Location: In the most populated state... state of denial Photos: Gallery \| Albums Posts: 1,851	Originally posted by pschlute Power zoom was a short lived feature of lenses of this period. Most people, myself included, turned the stupid thing off. what was the switch for???? I just one one of these attached to a Pz-20 at a yard sale

03-28-2022, 02:08 PM - 1 Like	#8
pschlute Moderator Loyal Site Supporter Join Date: Mar 2007 Location: Surrey, UK Photos: Gallery Posts: 8,182	Originally posted by titrisol what was the switch for???? I just one one of these attached to a Pz-20 at a yard sale https://www.pentax-manuals.com/manuals/accessories/fa_lenses_91.pdf Password is Pentax

04-28-2022, 05:52 PM	#10
TwoUptons Loyal Site Supporter Join Date: Nov 2015 Photos: Albums Posts: 4,207	Originally posted by Chefk0ch Hello everybody, same Lens here, same Switch Problem, but my copy of the lens shows no problem when its mounted on a Z10. Power Zoom and AF are fine and functional. Mounted on my K1II/K5/K20 im only able to use manul focus and manual zoom and the camera asks for the focal length, only the apeture can be controlled by the camera. Any Ideas how to solve the problem? Would be great if at least AF could be used. Regards Chefk0ch I'd clean the contacts on the lens and on the camera. I used the very similar PZ 28-105 on my K1/ii for a while as my main lens, and it worked fine as a basic lens. Autofocus and power zoom were both completely functional. Focal length was also fine. As mentioned above, none of the fancy features worked, though. I will note I have a nasty habit of switching the body to manual focus mode then wondering why my lenses don't focus... -Eric

04-30-2022, 03:14 PM	#11
kypfer Pentaxian Join Date: Jan 2018 Location: Jersey C.I. Posts: 3,588	I made a brief enquiry regarding these Power Zoom lenses on DSLRs a few months ago … conclusion was basically that the feature was only good for flattening batteries on modern cameras The "trick" is that if you can read the lettering "Power Zoom" then manual zoom won't work, you need to pull the zoom ring towards the camera to engage manual zoom. In that configuration it works just like any other "A" lens.

05-01-2022, 01:22 PM	#12
Chefk0ch New Member Join Date: Dec 2021 Posts: 4	Contacts already cleaned a few times, makes no difference, all my other lenses are ok without any problem. Sometimes the lens is fine, tested today again, got it functional two times: pulled the power zoom ring to manual zoom mode, K1II to MF, switched the Camera on, switched to AF and the lens does what it should. Powered the Camera off, repeated the steps, lens functions again, no card in the camera, so Power off, insert card, Power on, camera asked for focal lenght. Since then, no more AF. I can really do without power zoom but AF would be great, for MF i´ve got many other lenses. Ok, for AF too, but thats not the point here. I like the colors out of this lens. Example posted in the FA unlimited Lens Club.

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