Pentax Thread Size

[multiweb]

Anyone would know what the thread size is in the front cell of the lens? I'm trying to get a compression ring from whatever this thread size is to M48 so I can screw in a Baader filter. The ID is approx 51.20mm.

The lens is a SMC Pentax - M 200mm F1:4. I've posted on the Pentax forums but I thought I'd try my luck here too. Thanks for any pointers.

[Dennis]

Hi, Marc

If you mean SMC Pentax-M 200mm F4, it looks like 52mm according to this website:

http://www.pentaxforums.com/lensreviews/showproduct.php?product=75&cat=27

Cheers

Dennis

[multiweb]

Thanks Dennis. Yeah I suspect I need a 52mm to 48mm compression ring. I've found one on eBay and sent a question to the seller just to make sure it fits the lens.

[multiweb]

Well it is 52mm indeed so I got a step down ring 52mm to 48mm from eBay. I received my 100mm lens today and checked the front thread straight away. It's 49mm on that one. :lol: Can't win. By the time I'm done I should have all the compression rings between 52mm and 42mm. :P

[gbeal]

Sounds a bit butch perhaps, but just tape it on, and don't point it down, LOL. I have done this a few times, and also "blutac", worked well.
Gary

[multiweb]

I taped my NB filters inside the adaptor at the back and it worked well but the filter on this new lens needs to be at the front before all the glass and there is also a 49mm screw-on dew shield so blutac won't be an option on this one :)