M42 and T2 lens mount.

[virgo]

Hi,
I recently bought a second hand 135mm F2.8 lens on ebay with the intention of using it with my Nikon D60 camera using an adapter.
The lens was advertised as "M42 screw" and the reason I bought this lens was that it was quite cheap and it is possible to obtain a good lens for not a lot of money. I also have a camera which uses this type of lens.
Two problems soon surfaced: the lens was not a M42 screw, but a T2 mount which looks very similar. The difference is that the M42 has threads at 1.0 mm pitch, while the T2 has threads at 0.75mm pitch, naturally they are not interchangeable.
Adapters are available which will allow the lens to be attached to most cameras.
The second problem is that such a lens thus connected will, in all probability not focus to infinity, not much a problem with everyday photography, but very important to astro photographers. Again, there is a sloution at a price. An adapter with a internal lens will allow focussing to infinity.
So if you are buying M42 screw or T2 lenses with the intention of using them on your modern DSLR make sure that you get the correct adapter for your camera/lens setup.

[Paul Evans]

Hi Virgo,

I'm a big fan of M42 and T2 lenses - they provide a cheap and easy way into long focal length photography, if you're happy doing your own focussing and setting your own aperture. The optical quality of such lenses is usually pretty good and will often beat a modern zoom. Modern coatings are better, but the advantage of a prime lens is that it will have fewer glass surfaces for light to reflect from.

For astrophotography infinity focus is the only focus you need, but Virgo is right - sometimes M42 or T2 mounted lenses won't quite get there. However it is possible to adjust most lenses by loosening screws on the focussing barrel and holding the lens firmly whilst moving the barrel then retightening. A tricky procedure, but I've done it with 300mm and 350mm Soligors.

Paul.