[lacror2]

Hello,

After purchasing a Pentax-DA 55-300 ED PLM WR RE lens, I upgraded the firmware on my K-50 to version 1.10 as required to use the new lens on the camera. The new lens works great on the K-50, but I recently tried my 18-55 kit lenses on the K-50 (I have a couple of these - one that came with the K-50 and one from an old Kx), and these do not expose properly - all photos are dark to the point of being only black. I get the same result with my old 5-200mm kit lenses. I know it is not a lens defect - all four lenses could not have the same defect!

Pentax's notes on v1.10 firmware state:

>>Corresponded to [KAF4 lens mount] that is equipped with an electromagnetic diaphragm control system.
Enable new lens HD PENTAX-DA 55-300mmF4.5-6.3ED PLM WR RE to shoot stable by updating firmware.

Does the v1.10 firmware render the older lenses, with the mechanical aperture stop down lever, incompatible with the camera?

Thank you,

Ray LaCroix
Thompson's Station, TN

[Sandy Hancock]

Welcome to the Forums!

It sounds like your K-50 might have the dreaded aperture block failure. I suspect it is not related to the firmware update.

[lacror2]

Welcome to the Forums!

It sounds like your K-50 might have the dreaded aperture block failure. I suspect it is not related to the firmware update.

Thank you Sandy. Would this failure just happen with the older lenses, and not on the new lens with the KAF4 mount?
Where can I find more info on the aperture block failure?

[Sandy Hancock]

Would this failure just happen with the older lenses, and not on the new lens with the KAF4 mount?

Precisely.

Where can I find more info on the aperture block failure?

Type it into the search window at the top of this page. Or Google it. It's a very well known problem with the K-50 and other bodies which used the inferior green solenoid in the aperture block. It's repairable.

[photolady95]

I'll make it easier for you.

Dark exposure problems on K-30 or K-50? Discussion Thread - PentaxForums.com

[lacror2]

Thank you. I will test more, then decide what to do. It is interesting that the Pentax-DA 55-300 ED PLM WR RE lens works just fine - but not the other lenses.

[The Squirrel Mafia]

^ The 55-300mm PLM lens has the aperture motor inside the lens. It doesn't rely on the aperture motor in the K-50 body, hence no issues with that lens.

[DWS1]

The Pentax DA 55-300mm ED PLM WR RE works differently than all other lenses. It bypasses the aperture control module in the camera and controls the aperture electronically from within the lens itself. That's why it works on a camera with the aperture control block failure, which I believe you have. If you have a lens with the aperture ring, it should work also, but have to set it manually on the lens and enable aperture ring use in the menu settings.

[ramseybuckeye]

What the others said is correct, and I can also vouch that the firmware update does not affect older lenses, I have a K-50 and have done the update. If you look at the back (mount) of the PLM lens, you'll notice it does not have the aperture lever sticking out like your other lenses do. Instead of the camera mechanically moving the lever to change the aperture in the lens, it sends an electronic signal and the lens performs the aperture change. I'm afraid your camera will need a repair to work with the other lenses.

[Not a Number]

See this post to help diagnose the aperture problem:

Dark exposure problems on K-30 or K-50? Read me first! - PentaxForums.com

[lacror2]

Thank you all for your responses and the information. Since the only lens that will work on a camera with the aperture block failure is one with a KAF4 mount, I was wondering if a wide-angle prime or zoom was available with this mount - or is the Pentax-DA 55-300 ED PLM WR RE lens the only lens manufactured with the KAF4 mount? Looking at the Pentax lens catalog (http://www.ricoh-imaging.co.jp/english/support/pdf/pentax_acc.pdf), it appears that this is the only lens manufactured with the KAF4 mount. Is this the case?

[photogem]

Thank you all for your responses and the information. Since the only lens that will work on a camera with the aperture block failure is one with a KAF4 mount, I was wondering if a wide-angle prime or zoom was available with this mount - or is the Pentax-DA 55-300 ED PLM WR RE lens the only lens manufactured with the KAF4 mount? Looking at the Pentax lens catalog (http://www.ricoh-imaging.co.jp/english/support/pdf/pentax_acc.pdf), it appears that this is the only lens manufactured with the KAF4 mount. Is this the case?

The HD Pentax-D FA* 50mm/f1,4 SDM AW is the other one with its electromagnetic diaphragm control
But you are not going to buy this one for a K-50 with aperture problem, this is a lens for the K-1, maybe K3 and KP.

To large and heavy for the K-70 I'd say.

First get your K-50 repaired and enjoy the lenses you have.


For a proper test this is very simple: Use any lens with an A-Ring or any modern lens such as your Kitlens, DA50, DA35 etc.:
Set your K50 to AV and take a picture wide open (DA50 = f1,8) This will be dark if the solenoid is stuck, i.e. with aperture control failure!

Then same setting AV but closed such as f22 or whatever the max. value of your given lens is: This photo will be fine!

(you can use flash complete closed is difficult)


The other possibility:
Take a photo with liveview: Often those photos are still o.k. (but not always!)
Look into the front of your lens to see the iris (the blades)
When you switch your K50 into liveview the iris goes into f4 position!
This is still relativ open.
But if the iris closes completly, the solenoid is stuck.
It might still work because in Liveview the solenoid is used in a different way, switches twice and receives more milli-amperes because the mirror is up and when going down, there is an extra influx of energy.

You might be able to use your K50 for a while with Eneloop batteries (and the AA Adapter) but this won't last forever.
Only those who used Eneloops from the beginning and use the body very often (so high shuttercount) are sometimes lucky.

[Rob-48]

Hello,

After purchasing a Pentax-DA 55-300 ED PLM WR RE lens, I upgraded the firmware on my K-50 to version 1.10 as required to use the new lens on the camera. The new lens works great on the K-50, but I recently tried my 18-55 kit lenses on the K-50 (I have a couple of these - one that came with the K-50 and one from an old Kx), and these do not expose properly - all photos are dark to the point of being only black. I get the same result with my old 5-200mm kit lenses. I know it is not a lens defect - all four lenses could not have the same defect!

Pentax's notes on v1.10 firmware state:

>>Corresponded to [KAF4 lens mount] that is equipped with an electromagnetic diaphragm control system.
Enable new lens HD PENTAX-DA 55-300mmF4.5-6.3ED PLM WR RE to shoot stable by updating firmware.

Does the v1.10 firmware render the older lenses, with the mechanical aperture stop down lever, incompatible with the camera?

Thank you,

Ray LaCroix
Thompson's Station, TN

I had a (White) K-50, since mid-2016.
Running on AA batteries, it has been around Australia, NZ (several times), Noumea, Vanuatu, Hawaii, Tahiti, PNG's islands (twice), Dili, Bali (twice), Norfolk Island, AND it never missed a beat. I was lucky. I got a GOOD one (one of the later camera bodies to be assembled).
The v.1.10 update did, indeed, allow the use of PLM lens, AND had NO adverse reactions to ANY of my earlier lenses.
When COVID put a stop to travelling, i sold the camera (Stupid-Me).
I would suggest that the issues raised here would be indicative of other problems with the camera.

[photogem]

I had a (White) K-50, since mid-2016.
Running on AA batteries, it has been around Australia, NZ (several times), Noumea, Vanuatu, Hawaii, Tahiti, PNG's islands (twice), Dili, Bali (twice), Norfolk Island, AND it never missed a beat. I was lucky. I got a GOOD one (one of the later camera bodies to be assembled).

Well... a GOOD one is relative!
It had ABF and you had it repaired!

I would suggest that the issues raised here would be indicative of other problems with the camera.

Although this is a thread from 2019 and the TO never came back to report, he wrote, that he gets with all of his 4 "non KAF4 lenses" the very same symptoms:

.... all photos are dark to the point of being only black. I get the same result with my old 5-200mm kit lenses. I know it is not a lens defect - all four lenses could not have the same defect!

These symptoms are with 98% certainty ABF, i.e. a stuck solenoid and almost certainly no other problems with his camera.
That his DA55-300PLM worked fine just underlines that to almost 100% certainty.
It it had "other issues", it would have them with the PLMlens as well.

I have heard about this very situation twice from other people, i.e. Firmware update and then ABF,

it is sheer accident but:


A very possible reason:
When the camera hasn't been used ABF often loves "to creep in".
The reason is explained HERE

Sadly: Often people register, ask for help and then never come back to let us know.
So we possibly won't find out in this case either.

[Rob-48]

Well... a GOOD one is relative!
It had ABF and you had it repaired!


Although this is a thread from 2019 and the TO never came back to report, he wrote, that he gets with all of his 4 "non KAF4 lenses" the very same symptoms:

These symptoms are with 98% certainty ABF, i.e. a stuck solenoid and almost certainly no other problems with his camera.
That his DA55-300PLM worked fine just underlines that to almost 100% certainty.
It it had "other issues", it would have them with the PLMlens as well.

I have heard about this very situation twice from other people, i.e. Firmware update and then ABF,

it is sheer accident but:


A very possible reason:
When the camera hasn't been used ABF often loves "to creep in".
The reason is explained HERE

Sadly: Often people register, ask for help and then never come back to let us know.
So we possibly won't find out in this case either.

NO, sorry!
My White K-50, was purchased, Brand-New, from Camera House, in Lismore, NSW, Australia, when the K-70 was released (the K-50 was "on sale").
It NEVER had ABF, and it was NEVER repaired, or serviced.
.
The EARLIER post of mine that you refer to, was a USED K-50 (Red), purchased from B&H. It was DELIVERED to me, with ABF. CR Kennedy, in Melbourne, Australia, repaired thr Red (used) camera as a "Warranty" job. I immediately sold it on eBay.
.
Before you go off, half-cocked, on here, you may think of extending a simple courtesy, to other users, and PM them, to clarify "FACTS", before you state them as FACTS !!!!!