K_50 aperture block issues / 55-300 PLM lens

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zmem Forum Member • Posts: 88
K_50 aperture block issues / 55-300 PLM lens

Thankfully my K-50  still has no  aperture block issues .  The 55-300 PLM lens is my favorite lens and  other glass works fine.   It’s my understanding that a PLM lens works on a different principle.  Questions:  Would a PLM lens still work on a camera with aperture issues . Has anyone with a K-70 or K-50 tried this as a  way to keep the camera usable ?

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Pentax K-50 Pentax 55-300mm F4.5-6.3 ED PLM WR RE +1 more
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DougOB
DougOB Senior Member • Posts: 1,611
Re: K_50 aperture block issues / 55-300 PLM lens

zmem wrote:

Thankfully my K-50 still has no aperture block issues . The 55-300 PLM lens is my favorite lens and other glass works fine. It’s my understanding that a PLM lens works on a different principle. Questions: Would a PLM lens still work on a camera with aperture issues . Has anyone with a K-70 or K-50 tried this as a way to keep the camera usable ?

If I am not mistaken the oldest camera that works with PLM is the K-3 with firmware updates.  Or is it the K-3ii?  In either case, after the K-50.

Doug

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Benoz
Benoz Veteran Member • Posts: 6,343
Re: K_50 aperture block issues / 55-300 PLM lens

Haven't had any problem with my K-70 + 55-300 PLM

Ben

Ps. I have been using the PLM on the KP and K 70 and it seems to work much the same with both cameras...maybe a little quicker focusing on the KP.

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Kobie M-C
Kobie M-C Junior Member • Posts: 42
Re: K_50 aperture block issues / 55-300 PLM lens
1

The K-50 is actually the oldest camera that will work with PLM lenses. I because I've done the hackware to get my K-30 onto K-50 Firmware and my 55-300 PLM works fine on it.

From what I've read across the internet, since the PLM uses an electromagnetic aperture system, there's no mechanical lever in use so the can't be aperture block failure since it doesn't use the mechanical aperture mechanism inside the camera. People with aperture block failures have reported that they've had no issues using the 55-300 PLM.

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I am not a Pentax insider. I just have a unique way of gaining insight.

 Kobie M-C's gear list:Kobie M-C's gear list
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drummercam Senior Member • Posts: 1,510
Re: K_50 aperture block issues / 55-300 PLM lens
1

Kobie M-C wrote:

The K-50 is actually the oldest camera that will work with PLM lenses. I because I've done the hackware to get my K-30 onto K-50 Firmware and my 55-300 PLM works fine on it.

From what I've read across the internet, since the PLM uses an electromagnetic aperture system, there's no mechanical lever in use so the can't be aperture block failure since it doesn't use the mechanical aperture mechanism inside the camera. People with aperture block failures have reported that they've had no issues using the 55-300 PLM.

Kobie is correct.  My K-S2, before I fixed it, worked with the 55-300 RE.  I think Kobie hacked a K-30 to work with the PLM (?).   The oldest camera Pentax officially issued PLM s/w for was the original K-3.  I don't think they included the k-50.

I'm shooting my K-S2 all the time covering BLM in DC.  Self repair of block fail (filing method) has been successful.

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The Squirrel Mafia
The Squirrel Mafia Contributing Member • Posts: 564
Re: K_50 aperture block issues / 55-300 PLM lens

The oldest KAF4 compatible camera is the K-50 & like already stated, even if the aperture block on the K-50 or K-70 fails, the KAF4 type lens will still work fine on it since the lens doesn't rely on the body's mechanical lever. All KAF4 lenses have their own electronic aperture control mechanism inside the lens. It relies on the body's ability to communicate with that control, hence the firmware updates. The 55-300 PLM works fine with the K-50 that has the latest firmware, but not sure if the new DFA* 50 or 85 work with the K-50. I  think they will, but I could be wrong.

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Pentax K-50 Pentax smc DA 18-55mm F3.5-5.6 AL WR Pentax smc DA 35mm F2.4 AL Pentax smc DA 50mm F1.8 Pentax smc DA 50-200mm F4-5.6 ED WR +1 more
DougOB
DougOB Senior Member • Posts: 1,611
Re: K_50 aperture block issues / 55-300 PLM lens

Kobie M-C wrote:

The K-50 is actually the oldest camera that will work with PLM lenses. I because I've done the hackware to get my K-30 onto K-50 Firmware and my 55-300 PLM works fine on it.

I stand corrected.  Thanks for the info.

Doug

From what I've read across the internet, since the PLM uses an electromagnetic aperture system, there's no mechanical lever in use so the can't be aperture block failure since it doesn't use the mechanical aperture mechanism inside the camera. People with aperture block failures have reported that they've had no issues using the 55-300 PLM.

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flektogon
flektogon Veteran Member • Posts: 4,351
Re: K_50 aperture block issues / 55-300 PLM lens

The Squirrel Mafia wrote:

The oldest KAF4 compatible camera is the K-50 & like already stated, even if the aperture block on the K-50 or K-70 fails, the KAF4 type lens will still work fine on it since the lens doesn't rely on the body's mechanical lever. All KAF4 lenses have their own electronic aperture control mechanism inside the lens. It relies on the body's ability to communicate with that control, hence the firmware updates. The 55-300 PLM works fine with the K-50 that has the latest firmware, but not sure if the new DFA* 50 or 85 work with the K-50. I think they will, but I could be wrong.

So, how many KAF4 lenses has Pentax made so far? Only those thee? What about other manufacturers' lenses, which have built-in aperture activator? With a suitable adapter they could work on (newer) Pentax bodies. Oh, very unlikely, because of a different communication protocol .

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Regards,
Peter

The Squirrel Mafia
The Squirrel Mafia Contributing Member • Posts: 564
Re: K_50 aperture block issues / 55-300 PLM lens

^ Those 3 & I believe the upcoming DA* 16-50mm PLM lens will be KAF4 too. More will eventually come. When? Who knows.

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Pentax K-50 Pentax smc DA 18-55mm F3.5-5.6 AL WR Pentax smc DA 35mm F2.4 AL Pentax smc DA 50mm F1.8 Pentax smc DA 50-200mm F4-5.6 ED WR +1 more
altis Contributing Member • Posts: 984
Re: K_50 aperture block issues / 55-300 PLM lens
4

I have a K50 with a failed aperture solenoid and the 55-300 PLM works fine with it.

Kobie M-C
Kobie M-C Junior Member • Posts: 42
Re: K_50 aperture block issues / 55-300 PLM lens

altis wrote:

I have a K50 with a failed aperture solenoid and the 55-300 PLM works fine with it.

I wish I had the aperture block failure on my K-30. I have a complete phase detect AF failure

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I am not a Pentax insider. I just have a unique way of gaining insight.

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karoly7603
karoly7603 Regular Member • Posts: 233
Re: K_50 aperture block issues / 55-300 PLM lens

My Pentax 55-300 PLM has strange aperture behaviour between 98mm-200mm roughly. I set to f4.5 but when I dial it immediately jump to f5.6 I cannot set to f5.0. Below 98mm doesn't have any issue. Does somebody has similar problem? Is it normal?
Thanks.

drummercam Senior Member • Posts: 1,510
Re: K_50 aperture block issues / 55-300 PLM lens

It's variable aperture changes according to focal length.

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karoly7603
karoly7603 Regular Member • Posts: 233
Re: K_50 aperture block issues / 55-300 PLM lens

drummercam wrote:

It's variable aperture changes according to focal length.

I understand this, but why exist f4.5 over 98mm and not f5.0? This is the issue. I can shoot with either f4.5 or f5.6 but cannot go to f5.0.

DougOB
DougOB Senior Member • Posts: 1,611
Re: K_50 aperture block issues / 55-300 PLM lens

karoly7603 wrote:

My Pentax 55-300 PLM has strange aperture behaviour between 98mm-200mm roughly. I set to f4.5 but when I dial it immediately jump to f5.6 I cannot set to f5.0. Below 98mm doesn't have any issue. Does somebody has similar problem? Is it normal?
Thanks.

Uhh.... I think I remember this, it came up a few years ago but I can't remember what it was (I haven't had my coffee yet).  I remember testing it though...

What camera body or is it multiple bodies?  What shooting mode?  Auto ISO?

Let me try to engage my brain/memory...

Doug

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DougOB
DougOB Senior Member • Posts: 1,611
Re: K_50 aperture block issues / 55-300 PLM lens

karoly7603 wrote:

My Pentax 55-300 PLM has strange aperture behaviour between 98mm-200mm roughly. I set to f4.5 but when I dial it immediately jump to f5.6 I cannot set to f5.0. Below 98mm doesn't have any issue. Does somebody has similar problem? Is it normal?
Thanks.

What Program Line are you using?  MTF?

Doug

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grcolts Veteran Member • Posts: 3,272
Re: K_50 aperture block issues / 55-300 PLM lens

Kobie M-C wrote:

The K-50 is actually the oldest camera that will work with PLM lenses. I because I've done the hackware to get my K-30 onto K-50 Firmware and my 55-300 PLM works fine on it.

From what I've read across the internet, since the PLM uses an electromagnetic aperture system, there's no mechanical lever in use so the can't be aperture block failure since it doesn't use the mechanical aperture mechanism inside the camera. People with aperture block failures have reported that they've had no issues using the 55-300 PLM.

Yes, using the newest firmware for the K50 PLM lens work with it.

karoly7603
karoly7603 Regular Member • Posts: 233
Re: K_50 aperture block issues / 55-300 PLM lens

DougOB wrote:

karoly7603 wrote:

My Pentax 55-300 PLM has strange aperture behaviour between 98mm-200mm roughly. I set to f4.5 but when I dial it immediately jump to f5.6 I cannot set to f5.0. Below 98mm doesn't have any issue. Does somebody has similar problem? Is it normal?
Thanks.

Uhh.... I think I remember this, it came up a few years ago but I can't remember what it was (I haven't had my coffee yet). I remember testing it though...

What camera body or is it multiple bodies? What shooting mode? Auto ISO?

Let me try to engage my brain/memory...

Doug

Pentax K-70 and I use TAV mode with Auto Iso.

It means is it camera body or lens issue? Funny that I saw a Pentax K-70 photo with the same 55-300 PLM lens here on dpreview gallery at 108mm f5.0, but how is it possible?

DougOB
DougOB Senior Member • Posts: 1,611
Re: K_50 aperture block issues / 55-300 PLM lens

karoly7603 wrote:

DougOB wrote:

karoly7603 wrote:

My Pentax 55-300 PLM has strange aperture behaviour between 98mm-200mm roughly. I set to f4.5 but when I dial it immediately jump to f5.6 I cannot set to f5.0. Below 98mm doesn't have any issue. Does somebody has similar problem? Is it normal?
Thanks.

Uhh.... I think I remember this, it came up a few years ago but I can't remember what it was (I haven't had my coffee yet). I remember testing it though...

What camera body or is it multiple bodies? What shooting mode? Auto ISO?

Let me try to engage my brain/memory...

Doug

Pentax K-70 and I use TAV mode with Auto Iso.

It means is it camera body or lens issue? Funny that I saw a Pentax K-70 photo with the same 55-300 PLM lens here on dpreview gallery at 108mm f5.0, but how is it possible?

I found the old discussion I was thinking of, it was with a 55-300 PLM & KP and the buggy behaviour was when the camera had Program Line set to MTF.  Since the K-70 doesn't have this option I won't pursue that any further...

I tried my 55-300 PLM on my K-70, KP & K-3. I put it in Av mode and dialed down the aperture at different focal lengths. All 3 cameras are set to 1/3 EV stops. I tried it with both fixed ISO and Auto ISO. All cameras behaved exactly the same.

From 55mm to approx 100mm I could dial in 4.5, 5.0, 5.6, 6.3, ...

From approx 100mm to approx 150mm I could dial in 4.5, 5.6, 6.3, ...

From approx 150mm to ... something... I could dial in 5.6, 6.3, ...

I am guessing that between 100mm and 150mm the maximum aperture is (close to) 5.0 but it is displaying 4.5.  I didn't take any test pictures to see what was actually being recorded in the image file exif data.

Doug

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karoly7603
karoly7603 Regular Member • Posts: 233
Re: K_50 aperture block issues / 55-300 PLM lens

DougOB wrote:

karoly7603 wrote:

DougOB wrote:

karoly7603 wrote:

My Pentax 55-300 PLM has strange aperture behaviour between 98mm-200mm roughly. I set to f4.5 but when I dial it immediately jump to f5.6 I cannot set to f5.0. Below 98mm doesn't have any issue. Does somebody has similar problem? Is it normal?
Thanks.

Uhh.... I think I remember this, it came up a few years ago but I can't remember what it was (I haven't had my coffee yet). I remember testing it though...

What camera body or is it multiple bodies? What shooting mode? Auto ISO?

Let me try to engage my brain/memory...

Doug

Pentax K-70 and I use TAV mode with Auto Iso.

It means is it camera body or lens issue? Funny that I saw a Pentax K-70 photo with the same 55-300 PLM lens here on dpreview gallery at 108mm f5.0, but how is it possible?

I found the old discussion I was thinking of, it was with a 55-300 PLM & KP and the buggy behaviour was when the camera had Program Line set to MTF. Since the K-70 doesn't have this option I won't pursue that any further...

I tried my 55-300 PLM on my K-70, KP & K-3. I put it in Av mode and dialed down the aperture at different focal lengths. All 3 cameras are set to 1/3 EV stops. I tried it with both fixed ISO and Auto ISO. All cameras behaved exactly the same.

From 55mm to approx 100mm I could dial in 4.5, 5.0, 5.6, 6.3, ...

From approx 100mm to approx 150mm I could dial in 4.5, 5.6, 6.3, ...

From approx 150mm to ... something... I could dial in 5.6, 6.3, ...

I am guessing that between 100mm and 150mm the maximum aperture is (close to) 5.0 but it is displaying 4.5. I didn't take any test pictures to see what was actually being recorded in the image file exif data.

Doug

Hi Doug

Thank you for your efforts and comments on this, I appreciate it. So it means simply the display shows f4.5 instead of f5.0 I thaught there is a problem with my lens or something like that. Maybe Ricoh will solve this bug with the next firmware update.

Karoly

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