Mounting a Tokyo Kogaku RE auto-Topcor lens

[mark harverson]

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I have found a 35mm f2.8 version of this lens. Will it adapt to my M8?

not a range of lenses I’m familiar with

[horosu]

If it's LTM, then, yes

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[chris_livsey]

Although bayonet fitting these were Exacta SLR mount ISTR, the flange distance being 44.7 mm. Canon SLR Nikon SLR etc adapters are order of the day.

The clue is also the "auto", only SLRs require, or it is desirable to have, an auto diaphragm, rangefinders have no need for such mechanical wizardry.

Edited May 15, 2023 by chris_livsey

[mark harverson]

Hi

does this mean I can’t successfully adapt and use this lens on my M8?

[chris_livsey]

11 hours ago, mark harverson said:

Hi

does this mean I can’t successfully adapt and use this lens on my M8?

Regrettably that is correct.

The very short flange distance, that is the distance from the lens mount to the film/sensor, of the M series being 27.8mm means the native lenses focus at that point. The Topcon focuses at 44.7mm so the focus point is well behind the M mount sensor and there is no way to obtain focus even if it could be mounted plus the extra distance added by an adapter.

To mount a none native lens and for it to focus it must have room for the adapter distance and still be short of the receiving body focus point, the adapter is then made to match the distance required. Rangefinders not having a mirror box do not need to have that longer distance and if they did would be unnecessarily bulky. No SLR lens is going to mount on a rangefinder. The reverse is true so rangefinder lenses will mount on an SLR, but rarely done as the lack of an auto diaphragm is very cumbersome, less so with mirrorless where the viewing through the lens stopped down is workable.

Sorry to break bad news, perhaps you have return rights on the purchase?

 

[mark harverson]

Many thanks

i bought the lens for my SL which works well.

I shall move on

[chris_livsey]

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4 hours ago, mark harverson said:

Many thanks

i bought the lens for my SL which works well.

I shall move on

That's good then, look out for LTM (Leica Thread Mount) lenses they are abundant and some are inexpensive if you avoid the usual collectors suspects, the adapters are small and can stay on the lens so they become bayonet mount always ready and have always been made by Leica and many others most recently by Cosina/Voigtlander avoid the "cheap" ones they are there for the unwary. They come in different configurations to set the correct framelines for the lens they are attached to but will fit any LTM lens and M series body.

[farnz]

One important requirement in lenses you'd like to adapt to the M8 is that they are rangefinder coupled.  This means that as the lens's focussing ring is turned it meshes with the M8's focus-follower tab and adjusts the EVF's focus at the same time to indicate what the plane of focus is falling on.  If your lens doesn't have this facility, regardless of whether it can physically be adapted to fit to the M8, then you won't be able to tell what the lens is focussed on other than by the vague distance measurements on the lens barrel, which is only really workable at small apertures where 'depth of focus' will be large.

Since the M8 is a CCD camera and doesn't have LiveView you can't use the LCD to focus visually unfortunately.

Pete.

[chris_livsey]

It is however possible to "zone focus"  by utilising depth of field without coupling as I do with my Rollei 35, shooting at f1.8 though is NOT recommended 😂

[tommonego@gmail.com]

Am 17.5.2023 um 09:31 schrieb chris_livsey:

It is however possible to "zone focus"  by utilising depth of field without coupling as I do with my Rollei 35, shooting at f1.8 though is NOT recommended 😂

I feel that any lens above 28mm becomes zone unfocused unless you have a starting point via the rangefinder. Never liked the Rollei 35 I had, could have been the Triotar lens or the zone focus, was never sure. I did use a 20mm Nikkor on my M8 zone focusing, worked reasonably well in the f4 - f8 range, I ended up replacing it with an 18mm f4 Zeiss rangefinder coupled.