Question: Zenit M39 SLR J9 to Pentax M42

[Hibbs]

Years ago I bought a chrome Jupiter 9 in thread mount.

Lens looks like this:

I think it is a Zenit M39 SLR mount and NOT a preset.

I'd like to use it on my Pentax S3 M42 thread mount.

My question is which adapter do I need and will I lose focus at infinity?

Also...can someone suggest a quality adapter? There seems to be so many cheap ones online.

Thanks kindly.

 

[johnf04]

You won't lose infinity focus - Zenit E cameras were produced in M39, then changed to M42, with only the lens mount changing. Since there is no automation involved with the mount, the only requirement would be to fit both threads. I had an M42 Helios lens machined to fit M39, to use on my Zenit 3m.

 

[johnf04]

I should add - your lens looks like a preset - the multiple rings on the front suggest this.

 

[xayraa33]

Those online cheap adapters work just fine if you buy the metal ones.

It is a simple and thin adapter no matter who makes it.

I got a fine m39 mount Jupiter 11 lens from the same era as your J-9 lens and the adapter just stays mounted on the lens and has never given me problems mounting it on a L series Praktica or a Chinon M42 SLR.

 

[newst]

The Zenit SLR has a flange distance of 45.2mm while an M42 camera has a flange distance of 46.5mm. Very close but not identical.

You will need a simple adapter ring, M39 internal, M42 external. Available on Ebay for about $1.50 US.

In 98% of the usage envelop it will work just fine. However, the difference in flange distances will prevent you from achieving infinity wide open, while if you stop down enough the depth of field can cover the difference.

 

[Hibbs]

Thanks for the input. I got the Asahi Pentax S3 + Tak 58 and 135 for $10CDN.
Today I bought a 28mm 3.5 in great shape.

Just wanted to use the 85 as it is between the 58 and 135.

 

[xayraa33]

Thanks for the input. I got the Asahi Pentax S3 + Tak 58 and 135 for $10CDN.
Today I bought a 28mm 3.5 in great shape.

Just wanted to use the 85 as it is between the 58 and 135.

The J-9 lens is an excellent lens...a fine portrait lens that is comparable to the (also Sonnar derived) Nikkor 85mm f2 lens for RF cameras in my humble opinion.

I have the J-9 lens in M42 mount and in Kiev/Contax RF mount and in LTM, so as you can imagine, I think very highly of it.

 

[johnf04]

The Zenit SLR has a flange distance of 45.2mm while an M42 camera has a flange distance of 46.5mm. Very close but not identical.

You will need a simple adapter ring, M39 internal, M42 external. Available on Ebay for about $1.50 US.

In 98% of the usage envelop it will work just fine. However, the difference in flange distances will prevent you from achieving infinity wide open, while if you stop down enough the depth of field can cover the difference.

The M42 flange distance is 45.46mm. I measured the difference in depth between a Zenit M39, and a Zenit M42 mount, and it is about .2mm.

 

[newst]

The M42 flange distance is 45.46mm. I measured the difference in depth between a Zenit M39, and a Zenit M42 mount, and it is about .2mm.

Yes, I mistyped. Still, the difference can be felt at the extremes of focus, like at infinity with an extremely narrow depth of field.

 

[David Hughes]

Yes, I mistyped. Still, the difference can be felt at the extremes of focus, like at infinity with an extremely narrow depth of field.

I never worry about infinity as the distance to the horizon on this planet Earth is minute compared to infinity. Same goes for the distance to the moon, etc...


Regards, David

 

[Hibbs]

Took a closer look and there are not two rings at aperture so I don't think it is a preset.

Weird thing...when I close down to f16, the aperture opens right up. If I rotate to f2, it closes down to f16. I think this lens has been messed with.

As I will be using with the Pentax, I'll just use it open or 1-2 stops closed and meter based on that.

Hibbs

 

[newst]

I never worry about infinity as the distance to the horizon on this planet Earth is minute compared to infinity. Same goes for the distance to the moon, etc...


Regards, David

Sounds like a mystical eastern approach to photography, or philosophy, or something. 🙂

 

[xayraa33]

Took a closer look and there are not two rings at aperture so I don't think it is a preset.

Weird thing...when I close down to f16, the aperture opens right up. If I rotate to f2, it closes down to f16. I think this lens has been messed with.

As I will be using with the Pentax, I'll just use it open or 1-2 stops closed and meter based on that.

Hibbs

These non auto lenses made for SLRs have one ring to manually fully open the aperture after you set it on the other ring.. to give you a bright view on the SLR viewfinder to help you focus.

So you set the desired f stop then use the other ring to open the aperture then you focus and then you stop down to your chosen aperture with that same ring you opened the aperture with before you press the shutter release on the camera.

Some manual stop-down lenses like the Hugo Meyer Lydith 30mm f3.5 lens had a combined aperture ring that you pulled out and pushed in to do both jobs.

 

[Sarcophilus Harrisii]

If the adapter ring doesn't come with spanner notches I'd suggest adding some on each side, will be glad they're there if the adapter gets stuck on either camera body or lens. Otherwise a small rubber sheet might aid removal. Or it might not...

 

[David Hughes]

If the adapter ring doesn't come with spanner notches I'd suggest adding some on each side, will be glad they're there if the adapter gets stuck on either camera body or lens. Otherwise a small rubber sheet might aid removal. Or it might not...

Tightening a minute fraction and then trying to unscrew often works.

Check it's not a left hand thread is also a good general rule. They like to put one somewhere to catch you out...

Regards, David

 

[David Hughes]

Sounds like a mystical eastern approach to photography, or philosophy, or something. 🙂

Mystical? No, mathematical.

Think of zone focusing; I use the ∞ mark against the DoF scale and it works. Better still, use it against the next widest aperture...

Regards, David


PS If it worries you, try being philosophical and not think about it!

 

[Sarcophilus Harrisii]

Tightening a minute fraction and then trying to unscrew often works.

Check it's not a left hand thread is also a good general rule. They like to put one somewhere to catch you out...

Regards, David

Generally, that's a good idea. But as both the M39 and M42 SLR mounts used conventional right hand threads, a left hand threaded adaptor would be about as much use as a jackhammer in a lifeboat.

 

[Perry_B]

Took a closer look and there are not two rings at aperture so I don't think it is a preset.

Weird thing...when I close down to f16, the aperture opens right up. If I rotate to f2, it closes down to f16. I think this lens has been messed with.

As I will be using with the Pentax, I'll just use it open or 1-2 stops closed and meter based on that.

Hibbs

What you are describing is the normal way these lenses operate. The aperture is set by turning the front ring (the one with the aperture values engraved on it). These can be a bit stiff. The second ring from the front (with the red index dot on it) opens and closes the diaphragm to the preset value. It is turned anticlockwise (to the f/2 value) to close the diaphragm, and clockwise to open it (or to set f stop values).