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05-10-2019, 06:30 PM   #1
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any danger using M42 that has a 'fixed' bayonet?

I have a hand full of M42 lenses none of them have what I am guessing is a fixed bayonet....of course the tiny push pin for 'auto aperture' is present on a few of them...….

recently come into possession of a fortron 'auto zoom' 1:4.5 85-210mm that is M42 but has this 'fixed bayonet' ...it does not move whereas most other lenses it moves quite freely.....it has no 'a' / 'm' switch reckon its just 'auto'


curious of the dangers (if any) mounting with a K-mount adapter? (it fits on smoothly) may present no problem on my K-50 since it has the block failure but do not want to mess it up any more than it is or my other K-mount bodies

thanks

btw the fortron came with a yashica tl-electro-x (m42 mount) and looking forward to running a few rolls through it and prolly use the fortron for a few shots


Last edited by Aaron28; 05-10-2019 at 07:55 PM.
05-10-2019, 07:12 PM   #2
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Can you post a picture? Technically there shouldn't be a bayonet, just the screw threads... otherwise it is not m42...

DO you mean the m42 auto pin that sticks out? the TL-Electro-X is indeed an M42 camera. I just do not understand what do you mean by fixed bayonet... M42 and bayonet are seldom together synonymously within the same sentence.
05-10-2019, 07:53 PM   #3
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QuoteOriginally posted by edom31 Quote
M42 and bayonet are seldom together synonymously within the same sentence.
that's my thought so why I am asking.......currently cannot post pic.....but the tiny 'auto pin' would be at 6 o'clock (when mounted) and this fixed bayonet would sit around 10-11 o'clock.....there is also a little square bump out at 3:30.....failed to mention there is no 'a' or 'm' switch......which makes it an 'auto' lens only just like the yashinon-ds 50/1.7 mounted on the electro-x....the m42 to k- adapter fits great

found one on ebay..... 85-210MM 85-210/4.5 FORTRON IN ES-SPECIFIC M42 SCREWMOUNT (HAZE)/209473 | eBay
05-10-2019, 08:07 PM   #4
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That lens is an ES-Specific M42 Mount lens:

ES-specific screw mount? - PentaxForums.com

I've never used one myself... but with this info, you should be able to seek you answer.

05-10-2019, 08:15 PM   #5
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QuoteOriginally posted by edom31 Quote
but with this info, you should be able to seek you answer.
thank you edom! you have been very helpful with this and other film camera questions I have had recently
much appreciated!

that es thread does not really address any dangers of being mounted on a 'K' body tho…..
05-10-2019, 09:56 PM - 1 Like   #6
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QuoteOriginally posted by Aaron28 Quote
thank you edom! you have been very helpful with this and other film camera questions I have had recently
much appreciated!

that es thread does not really address any dangers of being mounted on a 'K' body tho…..
You're welcome... Search around these forums, you might find more information. Also, MFLenses Forums is a good source for these and all manual lenses.
05-11-2019, 12:18 AM   #7
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QuoteOriginally posted by Aaron28 Quote
thank you edom! you have been very helpful with this and other film camera questions I have had recently
much appreciated!

that es thread does not really address any dangers of being mounted on a 'K' body tho…..


I have a Sigma 21-35mm in M42, the early version with the built-in lens hood, that has these "lumps and bumps" on the mount, I often wondered what they were there for


I've used this lens on a wide range of cameras since the '70's, both screw-mount and bayonet mount Fujica film cameras and more recently Pentax film and digital cameras, with a Pentax M42-PK adaptor. Never had a problem with any of them, though the auto-aperture pin has needed to be "restrained" for use on the Pentaxes as there's no A/M switch.


Good luck!
05-11-2019, 12:43 AM - 2 Likes   #8
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Using the lens in the ebay listing that you linked to as an example, here's what the components on the mount are:

The pin at the 12 o'clock position (in the ebay photo) is the stop-down pin that opens the aperture for focusing then stops the lens down to the taking aperture when you press the shutter.

The rectangular piece at about 6 o'clock is the aperture follower. This moves a variable resistor inside the camera body that allows it to meter with the lens wide open.

The square piece at about 9 o'clock is to make sure that the lens stops screwing into the camera mount at the right position for the aperture follower to work.

There might also be another small interlock pin, although I can't see one in the ebay photo. None of these components acts as a bayonet that locks the lens to the camera, and they shouldn't cause any problems on a K mount adapter.

05-11-2019, 02:47 AM   #9
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First, not seeing bayonet anywhere in those pictures.

Second, I do see an aperture linkage arm, and I think I understand your concern. If you mount this lens to an adapter, you're wondering if it would line up correctly or interfere... right?
05-11-2019, 05:56 AM   #10
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QuoteOriginally posted by Dartmoor Dave Quote
None of these components acts as a bayonet that locks the lens to the camera, and they shouldn't cause any problems on a K mount adapter.

great that's what I was wondering since it does move. thanks!!!!!..bayonet was a way to describe with my limited vocabulary

QuoteOriginally posted by UncleVanya Quote
If you mount this lens to an adapter, you're wondering if it would line up correctly or interfere... right?
yes.......pretty sure I read on one of these (have no idea which one) that stevebrot encountered problems with a faulty bayonet that hurt a body from use but could not remember details

---------- Post added 05-11-19 at 07:58 AM ----------

QuoteOriginally posted by kypfer Quote
I've used this lens on a wide range of cameras since the '70's, both screw-mount and bayonet mount Fujica film cameras and more recently Pentax film and digital cameras, with a Pentax M42-PK adaptor. Never had a problem with any of them, though the auto-aperture pin has needed to be "restrained" for use on the Pentaxes as there's no A/M switch.
great info thanks! figured that pin would hafta be held down on a body that does not have that automation without a switch.....lens in question and a 50/f1.7 do not have the 'a'/'m' switch
05-11-2019, 12:28 PM   #11
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Bayonet is a military term for a knife, sword or spike attached to barrel of a rifle or musket. The rifle or musket can then by used as a stabbing weapon such as a spear. Bayonets are typically attached to the long gun (rifle or musket) with either a rail or pin and slot device. The latter method of attachment is used for light bulbs, electrical connectors and interchangeable lens. These connectors are known as bayonet sockets, connectors or mounts. For greater security and stability lens mounts will use tabs rather than pins. In sloppy, lazy, colloquial use most people simply say "bayonet" rather than "bayonet mount" even though the lens itself would actually be analogous to the knife, sword or spike attached to the long gun (camera body).

I can see "fixed bayonet" as being appropriate as the pin is somewhat reminiscent of a spike bayonet "fixed" at the end of a long gun barrel.
05-11-2019, 01:15 PM   #12
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QuoteOriginally posted by Not a Number Quote
In sloppy, lazy, colloquial use most people simply say "bayonet" rather than "bayonet mount" even though the lens itself would actually be analogous to the knife, sword or spike attached to the long gun (camera body).
hahaha! yes lack of vocabulary or a better set of words reckon I will keep it in my bag to defend myself if confronted by a would be 'robber'
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