Honeywell Pentax H1a

pamphoto · 2025-08-10T16:20:25-0400

I received a Honeywell Pentax from a friend the other day, and it works. The issue is the mirror gets locked up most of the time. It has two lenses with it, but they are the screw on mount. I have a friend with the Pentax K1000 I was thinking of gifting the two lenses to her.
My question is, what adaptor would she need to use these lenses, or is that even worth it? I tried googling, but am unsure which adapter would be best. The costs were all over the place from $12-$100.

Thank you

Hunter_Compton · 2025-08-10T17:31:18-0400

It's an M42 lens to a Pentax K-Mount adapter. They're pretty common, Pentax made one for the K1000 originally. Keep in mind that you will not have open aperture metering, nor auto-diaphragming with these lenses on the K1000 since it has nothing to trip the stop down pin on the back of the lens mount. The lenses you have would need to have an auto-manual switch to be used at anything other than wide open.

F4U · 2025-08-10T19:29:00-0400

Locking up is a very common problem with this Pentax design, from the H1a/H3V's all the way up to the ESII's and everything in between. Especially when the weather cools. I suspect this problem carried over to the K mounts, as I suspect Pentax kept the same basic body design, but can't speak with first hand knowledge on the K's. Whether a CLA on it can cure this nuisance problem, I don't know, as I switched over to Nikon after years of putting up with that nonsense. If yours does that you can take off the bottom cover and fiddle around with the works under there and get it unjammed, but it will just do it again, especially when the weather cools off. Maddening.

Paul Howell · 2025-08-10T19:45:45-0400

I think the lower cost adapters will work just as well as the more expensive. Have a Pentax M42 to K, just machined metal, the following is $14 on Amazon and looks to be same as the Pentax branded

Fotodiox Pro Lens Mount Adapter - M42 Screw Mount SLR Lens to Pentax K (PK) Mount

Jbennett68 · 2025-08-10T19:48:34-0400

The H1A is a great camera worth fixing.

John Wiegerink · 2025-08-10T19:59:56-0400

pamphoto, look at your mirror and see if there is any residue on the very bottom edge. If so, it could be that the foam bumper/damper stop up near the focus screen is old and has become sticking. If so you can replace it with new foam and it should then run for years without hanging up. Worth a look anyway. I love the old Pentax screw mount M42 cameras and they are usually very, very reliable even today.

Steve Roberts · 2025-08-10T20:06:09-0400

A CLA should cure the problem. As F4U says, it's well known with Pentaxes of that era. They aren't difficult to work on and a half decent repair man (or woman!) should be able to go straight to the problems. It might be worth looking into before giving away the two lenses, especially if the camera is otherwise in good condition.
Steve

Steve Roberts · 2025-08-10T20:07:37-0400

+1 to Jbennet68's comment!

pamphoto · 2025-08-10T20:23:37-0400

John Wiegerink said:
pamphoto, look at your mirror and see if there is any residue on the very bottom edge. If so, it could be that the foam bumper/damper stop up near the focus screen is old and has become sticking. If so you can replace it with new foam and it should then run for years without hanging up. Worth a look anyway. I love the old Pentax screw mount M42 cameras and they are usually very, very reliable even today.

Thank you John, I will take a look and see if that is the issue.

pamphoto · 2025-08-10T20:24:36-0400

Paul Howell said:
I think the lower cost adapters will work just as well as the more expensive. Have a Pentax M42 to K, just machined metal, the following is $14 on Amazon and looks to be same as the Pentax branded

Fotodiox Pro Lens Mount Adapter - M42 Screw Mount SLR Lens to Pentax K (PK) Mount

Thank you Paul, That is good to know! It's hard to tell these days what is cheap and what is real.

pamphoto · 2025-08-10T20:26:21-0400

F4U said:
Locking up is a very common problem with this Pentax design, from the H1a/H3V's all the way up to the ESII's and everything in between. Especially when the weather cools. I suspect this problem carried over to the K mounts, as I suspect Pentax kept the same basic body design, but can't speak with first hand knowledge on the K's. Whether a CLA on it can cure this nuisance problem, I don't know, as I switched over to Nikon after years of putting up with that nonsense. If yours does that you can take off the bottom cover and fiddle around with the works under there and get it unjammed, but it will just do it again, especially when the weather cools off. Maddening.

Interesting. I have several Nikons and haven't had used a Pentax in decades. I'll see if I can fiddle around with the mirror. I might have a friend who knows a little more about cameras than I do look at it.

pamphoto · 2025-08-10T20:26:55-0400

Jbennett68 said:
The H1A is a great camera worth fixing.

Good to know! It seems like a nice camera if the mirror would cooperate.

pamphoto · 2025-08-10T20:29:39-0400

John Wiegerink said:
pamphoto, look at your mirror and see if there is any residue on the very bottom edge. If so, it could be that the foam bumper/damper stop up near the focus screen is old and has become sticking. If so you can replace it with new foam and it should then run for years without hanging up. Worth a look anyway. I love the old Pentax screw mount M42 cameras and they are usually very, very reliable even today.

I don't see anything or feel any sticky, but then, I am not quite sure what I'm looking for. It seems nice and I like the weight of it. If we can get the mirror to work I think it would be a nice camera

pamphoto · 2025-08-10T20:34:49-0400

Steve Roberts said:
A CLA should cure the problem. As F4U says, it's well known with Pentaxes of that era. They aren't difficult to work on and a half decent repair man (or woman!) should be able to go straight to the problems. It might be worth looking into before giving away the two lenses, especially if the camera is otherwise in good condition.
Steve

I'll have to see if there is a repair person in our area. I am going to give these to my friend regardless as I have too many 35mm cameras and don't really need another one!

Jbennett68 · 2025-08-10T21:29:13-0400

pamphoto said:
Good to know! It seems like a nice camera if the mirror would cooperate.

The design of the bodies Stratton g with the ap are in my opinion the best looking slr’s ever and they really influenced the design and layout of most cameras that came after. One you get to spotmatics they got too big for my taste.

Jbennett68 · 2025-08-10T21:30:09-0400

pamphoto said:
I'll have to see if there is a repair person in our area. I am going to give these to my friend regardless as I have too many 35mm cameras and don't really need another one!

Eric Hendrickson is the go to guy for Pentax. Very reasonable and decent turn around times.

pamphoto · 2025-08-10T21:34:16-0400

Jbennett68 said:
Eric Hendrickson is the go to guy for Pentax. Very reasonable and decent turn around times.

OK! Thank you.

randyB · 2025-08-10T21:36:17-0400

Paul Howell said:
I think the lower cost adapters will work just as well as the more expensive. Have a Pentax M42 to K, just machined metal, the following is $14 on Amazon and looks to be same as the Pentax branded

Fotodiox Pro Lens Mount Adapter - M42 Screw Mount SLR Lens to Pentax K (PK) Mount

View attachment 405033

Generally, this type of adapter will not allow infinity focus with the M42 lenses, it is too thick. The adapters that fit inside the PK mount, flush with the surface will allow infinity focus with many M42 lenses. They are the ones you want.

Here is an example:
https://www.kentfaith.com/KF06.278_...wX753j_4ed1ZpVaWzNqQbyxRkvGgEWoxoCHaoQAvD_BwE

runswithsizzers · 2025-08-10T21:36:48-0400

F4U said:
Locking up is a very common problem with this Pentax design, from the H1a/H3V's all the way up to the ESII's and everything in between. Especially when the weather cools.

I remember one of my Pentax Spotmatics worked fine in the summer in southwest Missouri, but when I took it to Colorado in the fall, the mirror would fail to return almost every time.

F4U said:
I suspect this problem carried over to the K mounts, as I suspect Pentax kept the same basic body design, but can't speak with first hand knowledge on the K's. Whether a CLA on it can cure this nuisance problem, I don't know

One of my Pentax MX cameras did suffer from the stuck-up mirror in cool weather. A CLA done by Eric Hendrickson did resolve that issue for me.

pamphoto said:
I'll have to see if there is a repair person in our area.

If you can't find someone locally, I second the recommendation by @Jbennett68 to send it to Eric Hendrickson!

pamphoto · 2025-08-10T21:43:20-0400

runswithsizzers said:
I remember one of my Pentax Spotmatics worked fine in the summer in southwest Missouri, but when I took it to Colorado in the fall, the mirror would fail to return almost every time.

One of my Pentax MX cameras did suffer from the stuck-up mirror in cool weather. A CLA done by Eric Hendrickson did resolve that issue for me.

If you can't find someone locally, I second the recommendation by @Jbennett68 to send it to Eric Hendrickson!

Thank you!
It's almost 100 here, so it's not a cold weather issue. I'll send Erik an email to see if this is worth investigating and let my friend know if it is an option or not.

pamphoto · 2025-08-10T21:44:08-0400

randyB said:
Generally, this type of adapter will not allow infinity focus with the M42 lenses, it is too thick. The adapters that fit inside the PK mount, flush with the surface will allow infinity focus with many M42 lenses. They are the ones you want.

Here is an example:
https://www.kentfaith.com/KF06.278_...wX753j_4ed1ZpVaWzNqQbyxRkvGgEWoxoCHaoQAvD_BwE

Perfect. Thank you!

F4U · 2025-08-10T22:11:47-0400

pamphoto said:
Thank you!
It's almost 100 here, so it's not a cold weather issue. I'll send Erik an email to see if this is worth investigating and let my friend know if it is an option or not.

You're right. It's not strictly a cold weather issue in the absolute sense. It's a nasty problem that rears its head with little rhyme or reason. But as soon as the weather cools off, it's an iron clad guarantee to happen repeatedly. Between that problem and the fact that the viewfinder shows only about 85% of the actual negative and is OFF-CENTER in both directions, I refuse to use a Pentax. Quite a turnabout from my youth when I preached the gospel of Pentax, claiming it to be the best. Now I wouldn't give 50 cents for a trainload of them.

Paul Howell · 2025-08-10T22:17:48-0400

randyB said:
Generally, this type of adapter will not allow infinity focus with the M42 lenses, it is too thick. The adapters that fit inside the PK mount, flush with the surface will allow infinity focus with many M42 lenses. They are the ones you want.

Here is an example:
https://www.kentfaith.com/KF06.278_...wX753j_4ed1ZpVaWzNqQbyxRkvGgEWoxoCHaoQAvD_BwE

Your right, my Pentax adapter fits inside the k mount, I assumed the Fotodiox did as well.

runswithsizzers · 2025-08-10T23:00:56-0400

F4U said:
...the fact that the viewfinder shows only about 85% of the actual negative and is OFF-CENTER in both directions, I refuse to use a Pentax.

I don't know about the older models, but the viewfinder coverage for my KX is 93% and for my MX it's 95%. The view through my MX is almost lifesize at 97x magnification (with 50mm lens). If there is any SLR with a viewfinder that is significantly bigger and brighter than the viewfinders on my MX cameras, I'd love to hear about it.

F4U · 2025-08-11T00:01:33-0400

runswithsizzers said:
I don't know about the older models, but the viewfinder coverage for my KX is 93% and for my MX it's 95%. The view through my MX is almost lifesize at 97x magnification (with 50mm lens). If there is any SLR with a viewfinder that is significantly bigger and brighter than the viewfinders on my MX cameras, I'd love to hear about it.

We're talking about the screw mount Pentaxes, a subject that I am quite versed on. The Spotmatic was the first Pentax with meter. To achieve this, they cut off that end of fthe viewfinder frame. Except for the small area where the needle opening shows, is cut off in the finder, yet appears on the negative. This is the left-right 36mm dimension. As or the up-down 24mm dimension, either the bottom or the top is also cut off in the finder, (can't remember which) but appears in the negative. This means that the viewfinder is off-center in both directions, for a total of 85% actual negative. I recall it being noted in a 1974 Modern Photography review of he Spotmatic F. This same situation exhibits in the ES and ESII models. In fact it dates back to 1964 when the original Spotmatic was introduced. And it is entirely unacceptable. Referring to the same tests, Modern Photography also published their lens testing chart on the 50mm 1.4 lens. It was found to be a very poor performer. The 1.8's and 2's were much better, as are many of the Super Multi coated Takumars. but we are discussing on this thread the H1a and H3v series which had no meter. Therefor, the viewfinder right side does not have this cut-off problem. But they DO have the up-down off-center problem.
In about 2004 I shot the storm photo of a lifetime on a Spotmatic IIa, and that damn Pentax RUINED my framing because of the off-center problem. I was already struggling with it's stupid mirror jam upwards problem. Never again. I use a Nikon FTN because it gives 100% exactly as I frame it and the camera is as dependable as an anvil.

Honeywell Pentax H1a

Fotodiox Pro Lens Mount Adapter - M42 Screw Mount SLR Lens to Pentax K (PK) Mount​

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Fotodiox Pro Lens Mount Adapter - M42 Screw Mount SLR Lens to Pentax K (PK) Mount​

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Fotodiox Pro Lens Mount Adapter - M42 Screw Mount SLR Lens to Pentax K (PK) Mount​

View attachment 405033​

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Privacy & Transparency

Fotodiox Pro Lens Mount Adapter - M42 Screw Mount SLR Lens to Pentax K (PK) Mount

Fotodiox Pro Lens Mount Adapter - M42 Screw Mount SLR Lens to Pentax K (PK) Mount

Fotodiox Pro Lens Mount Adapter - M42 Screw Mount SLR Lens to Pentax K (PK) Mount

View attachment 405033