T2 \ M42 \ M48 etc

[AlistairW]

Hello,

Please can someone explain what is meant by T2 and M42 when talking about adaptors . And what is the best way to work out what size connections my equipment has (I do have callipers) .

Thanks

Alistair

[Davey-T]

T2 is similar to M42 so the only one you can confuse, M42 is the old thread used on screw thread camera lenses slightly different pitch.

M48 is a common astro thread used on 2" filters but as you say you can measure with calipers.

Dave

[newbie alert]

I'm sure the m stands for metric..so m42 is 42mm and m48 is 48mm.

[Louis D]

T2 is 42mm diameter, 0.75mm thread pitch.  It was created by Tamron years ago as a universal camera lens adapter size.  Others adopted it as a standard for attaching cameras to various optical equipment such as telescopes and microscopes.

M42 is 42mm diameter, 1mm thread pitch.  It was created by Praktica years ago as it's camera lens mount.  Many other makers including Pentax adopted it, earning it the moniker Universal thread or screw mount.