Well to answer all queries and thoughts....... I`ve learn`t a great deal with this lens. Green button is being well used now! I like how I actually `use` the camera more now than with a auto lens.
I now officially have LBA haha.... I`m looking for more M lenses to buy. I just recently purchased a SMC Pentax 50mm F1.7 and I`ve never come across a lens that is so easy to use! Beautiful colours and contrast.
I have a sort of long story abour the M 300mm f4 so I`ll cut it down to size a bit.
Aperture not working....take the rear of the lens apart and repair the slide lever.
Find a filter to fit the front and in taking off the filter found the front of the lens was loose so I cleaned the front element and `seated` the glass properly where I now experience very little CA!
Most pics are nice and sharp now
Cheers for all the advice guys.
Chris