[ravimuvvala]

Guys i'm here to learn more about Pentax M42 's; help me out

[usn ret]

Here is a place to start, then ask questions. Folks here will be more than happy to answer any question you might have. Your homework assignment link to Pentax M42

Welcome aboard. Do yo have gear yet? If so what do you have?
link http://en.wikipedia.org/wiki/M42_lens_mount

[ravimuvvala]

I hav a nikon slr, with two 50mm / 28mm M42 's.....

[ravimuvvala]

pentacon 135mm f/2.8 or Pentax Telephoto 135mm f/3.5 which one is better?

[ravimuvvala]

pls suggest primes to buy in M42 for my SLR in zoom lens.......

[usn ret]

You need a SLR that will accept the M42 lens

Click on the link in my original post.............. M42 lens mount-Wikipedia, the free encyclopedia

This references M42 lens applications. Nikon does not have an M42 lens mount....Cliff

[RioRico]

The only way to use M42 lenses on any Nikon SLR is for closeups. Nikons can only use Nikon-mount lenses, or lenses with interchangeable mounts like T2 or Adaptall. M42 lenses can be used on Pentax, Canon, Sony, and m4/3 cameras, but not on Nikon.

Both of the 135mm lenses you asked about are good, but not for you. Your choices: 1) Look for Nikon-mount lenses, or 2) look for another camera. Good luck!

[Douglas_of_Sweden]

The only way to use M42 lenses on any Nikon SLR is for closeups. Nikons can only use Nikon-mount lenses, or lenses with interchangeable mounts like T2 or Adaptall. M42 lenses can be used on Pentax, Canon, Sony, and m4/3 cameras, but not on Nikon.

Both of the 135mm lenses you asked about are good, but not for you. Your choices: 1) Look for Nikon-mount lenses, or 2) look for another camera. Good luck!

Well, there is an adapter m42 to Nikon F that includes optics and allow infinity focus, but it works like a bad converter and really degrade the image quality. Then there are those adapters without optics, but they don't allow infinity focus. The difference in registration distance works like a small extension tube. m42 macro lenses may still be of interest, but that is all. So I'd suggest you go for RioRico's 2nd option if you want to use m42 lenses.

[RioRico]

Well, there is an adapter m42 to Nikon F that includes optics and allow infinity focus, but it works like a bad converter and really degrade the image quality.

I didn't mention that option because I consider it abuse, not use.

But really, Nikon SLRs are in a peculiar niche, or their own corner of hell, or whatever.

It's all about register, the distance from the lens mount to the frame (film or digital). Nikon register is longer than Pentax, which is longer than Sony Alpha, which is longer than Canon, which is longer than m4/3, which is longer than Sony NEX. Longer-register lenses can be fitted to shorter-register cameras, and will focus to infinity. But shorter-register lenses on longer-register cameras can only reach infinity with optical adapters that hurt the image. Nikon-mount lenses can be fitted to all those other cameras, but Nikon cameras can't use lenses from any other 35mm or APS-C or smaller system.

CORRECTION: Nikon cameras can't use lenses from shorter-register systems EXCEPT WITH OPTICAL ADAPTERS that hurt image quality.

So if you want to use M42 lenses, you need a Pentax or Sony or Canon or m4/3 camera, and that is the grim truth. Good luck!

[Douglas_of_Sweden]

Well I mentioned it since the OP might encounter it and think we just talked bullshit, so it was better to warn him.

[RioRico]

Well I mentioned it since the OP might encounter it and think we just talked bullshit, so it was better to warn him.

Good idea, and I just corrected my last piece about using other lenses on Nikon cameras.