Any Pentax users here?
Nov 30, 2017 20:24:07 #
Chris T wrote:
M42? ...
Why question that?? In the days of M42, Super Takumar were highly respected.
Nov 30, 2017 20:49:17 #
rehess wrote:
Why question that?? In the days of M42, Super Takumar were highly respected.
Okay ... ya got me, RE ... what IS M42?
Nov 30, 2017 21:09:28 #
Chris T wrote:
Okay ... ya got me, RE ... what IS M42?
Before Pentax developed the K-mount in 1975, they used the {generic} M42-mount. The M42-mount is a true threaded screw - you have to twist the lens perhaps 800 degrees {over two turns}; you should be able to see that the back {top in this picture} portion of this lens is actually threaded. The K-mount is a bayonet - you turn the lens just 60 degrees. The K-mount was intentionally designed so that a simple ring adapter {bayonet mount on the outside, threaded on the inside} would allow new cameras to use the old lenses.
Nov 30, 2017 22:32:37 #
rehess wrote:
Before Pentax developed the K-mount in 1975, they ... (show quote)
Yes, I remember ... I have the Pentax screw thread mount on my Zenit E ... I just didn't realize it had a letter and number designation ...
For a moment, RE ... I had to take a look at my K-50 to see if it had a screw thread inside the bayonet ... but this adapter you have pictured there - actually attaches via the K-Mount bayonet, right? ... And the screw thread is inside the adapter, it doesn't look nearly big enough for more than 2 turns.
So the M designation means manual ... and the 42 is the diameter of the thread, in millimeters, right?
Nov 30, 2017 22:42:55 #
Chris T wrote:
Yes, I remember ... I have the Pentax screw thread mount on my Zenit E ... I just didn't realize it had a letter and number designation ...
Yes, that is why I called it a "generic" mount. Praktica, Zenit, and Pentax all used it.
Chris T wrote:
For a moment, RE ... I had to take a look at my K-50 to see if it had a screw thread inside the bayonet ... but this adapter you have pictured there - actually attaches via the K-Mount bayonet, right? ... And the screw thread is inside the adapter, it doesn't look nearly big enough for more than 2 turns.
You put the pictured adapter into a K-mount camera, your K-50 for example, and it becomes a primitive M42-mount camera {the camera doesn't have the ability to open or close down the aperature
Chris T wrote:
There are several Mnn mounts; I'm thinking that the "M" stands for "millimeter" or "metric".So the M designation means manual ... and the 42 is the diameter of the thread, in millimeters, right?
Nov 30, 2017 22:52:27 #
rehess wrote:
There are several Mnn mounts; I'm thinking that the "M" stands for "millimeter" or "metric".
Well, in that case - it should've been the other way around .... 42M - no?
Nov 30, 2017 23:20:26 #
Chris T wrote:
Well, in that case - it should've been the other way around .... 42M - no?
It is more accurately known as the M42 × 1 mm standard, which means that it is a metric screw thread of 42 mm diameter and 1 mm thread pitch
similarly there are M39 lenses which can have an M42 Adapter ring , more likely to be adapted on an enlarger than a camera.
just having the thread isn't enough , you also need the registration distance with Pentax this was exactly the same as the k mount with canon a slightly shorter registration distance means a thin flange to hold the lens out far enough to get infinity focus. Nikon has a slightly longer registration distance which makes for problems getting infinity focus. There are some great M42 lenses around the russians made some with 15 even 21 aperture blades.
Nov 30, 2017 23:28:25 #
blackest wrote:
It is more accurately known as the M42 × 1 mm stan... (show quote)
Right ... the Helios series - it went on their Zenit E ... why on earth would they make one with 21 aperture blades? .... The more the merrier?
Nov 30, 2017 23:53:53 #
Chris T wrote:
Right ... the Helios series - it went on their Zenit E ... why on earth would they make one with 21 aperture blades? .... The more the merrier?
The more blades the rounder the bokeh and you can stop down without it becoming ugly.
https://www.shutterbug.com/content/how-capture-%E2%80%9Cbokeh-madness%E2%80%9D-video
sorry chris its a video again i grabbed a couple of stills from it. This was shot on a sony with a tilt shift adapter and the jupiter 9 f2 85mm
as it happens i have this lens and tilt adapter for m43 i'm tempted to go play :)
Dec 1, 2017 00:41:41 #
blackest wrote:
The more blades the rounder the bokeh and you can stop down without it becoming ugly.
https://www.shutterbug.com/content/how-capture-%E2%80%9Cbokeh-madness%E2%80%9D-video
sorry chris its a video again i grabbed a couple of stills from it. This was shot on a sony with a tilt shift adapter and the jupiter 9 f2 85mm
as it happens i have this lens and tilt adapter for m43 i'm tempted to go play :)
https://www.shutterbug.com/content/how-capture-%E2%80%9Cbokeh-madness%E2%80%9D-video
sorry chris its a video again i grabbed a couple of stills from it. This was shot on a sony with a tilt shift adapter and the jupiter 9 f2 85mm
as it happens i have this lens and tilt adapter for m43 i'm tempted to go play :)
Nice!!!
Well, go on, then ...
Don't let ME stop you, Blackest ....
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