Showcase Pentax 70mm f/2.8 auto 110

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Dec 10, 2020
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Ottawa, Ontario, Canada
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Karen McBride
hmmm, a C-mount adapter on its own has some thickness and that will leave you with very little room to work with...
Is there a reason not to start with a M39 adapter (thread mount common of so many old lenses)?
In my case I had to do very little cutting/shaving to create the room for the diaphragm, and then some JB-Weld.

Unless, if I understand you correctly, you want an interchangeable adapter where you can swap and mount all the Pentax-110 lenses?
In that case you have indeed 7.75mm to play with
I had a good look at what you did with the m39 adapter and that makes sense. Did you use a c-M39 adapter to glue to each lens? Something that looks like this below?

If you have time can you let me know the outside diameter of the iris that you bought or the inside measurement for the m39-m4/3 adapter and then I can order everything at once.
Thanks
K
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gnarlydog australia

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Damiano Visocnik
I had a good look at what you did with the m39 adapter and that makes sense. Did you use a c-M39 adapter to glue to each lens? Something that looks like this below?

If you have time can you let me know the outside diameter of the iris that you bought or the inside measurement for the m39-m4/3 adapter and then I can order everything at once.
Thanks
K
View attachment 869201
I don't currently have the lens as is on loan to my niece, and god knows when I will see it again :crying:

On the notion of having an adapter like you show to then thread each Pentax-110 lens onto the common MFT to M39 adapter.... I rather go a different route.
I like to swap lenses as the conditions/subjects dictate and out in the field futzing with threaded adapters... is slow and cumbersome.
To have the same experience as I have with a native lens all of my vintage glass has a dedicated adapter; they are just too cheap to be messing around with one shared with many lenses.
So, on evilBay I source a generic MFT to M39 adapter, glue the "silver" ring to the lens (a tiny bit of spacing needed between the two surfaces) and then screw the "silver" ring into position in the adapter.
To me having infinity on the lens marking is somehow important and that way I can assure decent registration on each lens.

Happy tinkering :)
 
Joined
Dec 10, 2020
Messages
19
Location
Ottawa, Ontario, Canada
Real Name
Karen McBride
I don't currently have the lens as is on loan to my niece, and god knows when I will see it again :crying:

On the notion of having an adapter like you show to then thread each Pentax-110 lens onto the common MFT to M39 adapter.... I rather go a different route.
I like to swap lenses as the conditions/subjects dictate and out in the field futzing with threaded adapters... is slow and cumbersome.
To have the same experience as I have with a native lens all of my vintage glass has a dedicated adapter; they are just too cheap to be messing around with one shared with many lenses.
So, on evilBay I source a generic MFT to M39 adapter, glue the "silver" ring to the lens (a tiny bit of spacing needed between the two surfaces) and then screw the "silver" ring into position in the adapter.
To me having infinity on the lens marking is somehow important and that way I can assure decent registration on each lens.

Happy tinkering :)
Thanks. I will make an adapter for each lens. I will buy a bunch of m39 adapters and play with the lenses a bit using a standard adapter and then add irises to my preferred lenses. This is my first go at making an adapter so there is lots to learn for sure.
K
 
Last edited:

gnarlydog australia

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Damiano Visocnik
Thanks. I will make an adapter for each lens. I will buy a bunch of m39 adapters and play with the lenses a bit using a standard adapter and then add irises to my preferred lenses. This is my first go at making an adapter so there is lots to learn for sure.
K
hmmm, the M39 adapter will work well for the 70mm and the 50mm but for the smaller ones I think a C-mount base and then some C-mount macro rings (or even PVC plumbing tube) might be a more elegant solution since the lenses are so tiny. Here shown is the 70mm and the 24mm

Pentax-110 70mm and 24mm_c by gnarlydog, on Flickr
 

Mike Wingate

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Mike Wingate
I am pleased with my inexpensive Roxsen mount. No evidence of light leakage, quick to change lenses. Love the 70mm and have taken a liking to the 18mm. Still tempted to buy a P20.
 
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