Wild / Leica M420

[Pete Askew]

I have been looking for a Wild / Leica M420 for quite some time and managed to get one on eBay here in Germany a few weeks back. Unfortunately the trader selling it had an accident before he could send it and so all went quiet. He then made contact, apologised and said it was being dispatched. Nothing turned up and all communication stopped and I was forced to initiate a complaint through eBay. Then, out of the blue, it appeared by DHL today!

As with the Zeiss Tessovar (http://www.realphotographersforum.com/forum/threads/technical-imaging-zeiss-tessovar.4309/), it may look like a microscope, but it is in fact also a macro lens on a stand with eye-pieces. A camera / photo-device (I'll be using a 20 MP CCD-based microscopical sensor when the adapter arrives) fits to the vertical housing and the eyepieces are for composing etc. It has a variable aperture and this example is fitted with the 5 : 1 achromatic zoom (there is also a 6 : 1 apochromat, but they are extremely rare and very, very expensive) and it has a transmitted lighting base. Here the specimen (a large tropical seedpod) is illuminated by two 4K Relio macro-lights (turned down to their minimum setting for the purposes of the picture). There is a dealer here who has a coaxial lighting unit for one of these and, now that the M420 has arrived, I'll probably order that even though I will normally use angular lighting most of the time to improve contrast.

As soon as the CCD adapter arrives I'll take some shots through it.

 

[Brian Moore]

What does it do that your existing gear doesn't, Pete?

 

[Pete Askew]

Surely that is obvious, Brian. Absolutely nothing!

Actually, what it does do is be in the same country as me! The Tessovar is in the UK.

 

[Brian Moore]

Surely that is obvious, Brian. Absolutely nothing!

Actually, what it does do is be in the same country as me! The Tessovar is in the UK.

I understand the compulsion totally!

 

[Rob MacKillop]

I'm not surprised you had trouble with the seller, as anyone who owns one of them must be completely mad

Well, I for one am excited about what you will do with it.

 

[Brian Moore]

I'm not surprised you had trouble with the seller, as anyone who owns one of them must be completely mad

Well, I for one am excited about what you will do with it.

 

[Rob MacKillop]

BTW, nice picture on the wall. One of yours, Pete?

 

[Brian Moore]

BTW, nice picture on the wall. One of yours, Pete?

I was wondering the same thing.

 

[Pete Askew]

A new addition. Although the Relio units work very well with the M420, in the UK I usually use fibre-optic lamps with the Tessovar to minimise heat input. While looking for a set of large polarisers I stumbled upon a fibre-optic ring light with 2 polarisers that was perfect for the job (they should arrive on Monday): the ring-light will fit the M420 also. And so of course I needed to buy a fibre-optic generator to go with it!

Anyway, here is the M420 setup plus a fibre-optic illuminator (normally I would place it to the rear and position one head to each side, but this suited what I was looking at and saved me having to move the microscope / printer (the M420 still hasn't found a proper home). As you can see, the unit is a Leica ML2500 LCD and has a 'calibrated' colour temperature output selected by the click-stops on the intensity control (left hand knob): I have not yet checked it with a meter, but it seems about right. The right hand knob also controls light output, but using aperture plates and so does not shift the colour temperature. There is also a filter wheel recessed into the right hand side of the casing that can be populated with coloured filters (there are none in it) for special effects, fluorescence excitation etc (maybe IR too, I'll have to have a look). It uses a 24V 250W halogen lamp and so has a cooling fan in it so it is not silent, but not especially noisy either.

Although badged as a Leica unit (and no doubt specified by them too), it is made by Schott and the fibre optic heads are interchangeable using a standard bayonet with other Schott units and come as single and multiple swan necks (as here) which can be fitted with focusing heads etc, fully flexible heads, ring lights, dark-field illuminators etc.

 

[Brian Moore]

I just bought one of Hamish's Pixl-Latrs and I could use that copy stand Pete.

 

[Pete Askew]

Probably more use for checking for dust on the films (I know what a stickler you are for that!) than as a light source for the Pixl-ltr, Brian.

https://www.pixl-latr.com

 

[Pete Askew]

The ring-light / polariser turned up yesterday and, after making a reducing ring for it, I fitted it to the M420. It works well.

There is a ring of polarising film fitted to a rotating collar that sits in front of the light slit that is fed by the fibre-optic connector and a second filter across the lumen of the ring-light, above the slit. In this way, the light emerging from the ring-light is polarised and any light reflected back from the specimen can subjected to cross / partial / no polarisation also. This allows one to both look at the effect of polarisation on the specimen and to cut out reflections and specular highlights.

These two image show the microscope equipped with the ring-light and show how it is attached to the light generator (in place of the swan necks). The close-up shows the unit in more detail.

This sequence shows the effect of cross polarisation on image contrast, reflections and certain surface defects in a mineral specimen (a type of quartz).

Cross-Polarisation (90º)

Partial-Polarisation (45º)

Aligned-Polarisation (0º)

 

[Brian Moore]

Probably more use for checking for dust on the films (I know what a stickler you are for that!) than as a light source for the Pixl-ltr, Brian.

https://www.pixl-latr.com

Cheeky bugger! (They're stars!)