K10D - Diopter Correction Lens Adapter M

Does anyone know where I can buy a viewfinder Diopter Correction Lens Adapter M for a Pentax K10D, please. I need the strongest one available ie the -5.0 > -1.0 version.
Alternatively, can anyone categorically confirm whether any viewfinder correction lens adapters for later Pentax DSLRs will fit the K10D, and if so, which? With thanks.

Correction lenses M were available in a range fro, -5 to +3, but the need for these has no doubt reduced drastically as dioptre correction is now built into cameras.

I wear glasses and the dioptre correction range is fine with those. If you need to adjust it further then perhaps an optician could make something suitable.

As far as I know the current fitting is M series size, so you might be lucky and find something second hand. The original correction lenses are quite rare, but maybe a phone around dealers and a visit to a camera fair could be the answer.

Other thing to watch out for is astigmatism which "twists" the light beam as it enters the eye.

I have always had strong astigmatism and, for example, when using a camera or binoculars with dioptre adjustment, never found a comfortable solution without keeping my specs on my nose and using the correction at 0D!

However, I am sure that if I were to pay "someone" "enough" to create custom viewfinder adaptors with both D AND astigmatism corrections then I could use that approach. Problem would then be "where the hell did I put my specs?" after I took them off so that I could look through the corrected viewfinder!
(I lose them enough without that problem on top)

John

Thanks for your comments, folks.
I should perhaps clarify my original post; the in-built diopter correction on the K10D ranges from -2.5 > +1.5, so what I need is an 'M' adapter of strength -2.5 (to create a -5.0 > -1.0 range).
I have always found wearing spectacles while using a viewfinder problematic; glasses tend to mist up on the inside as they get pushed closer to my face, whereas I rarely have problems with the viewfinder misting up when it is close to my eye.
This need for additional correction is just an age thing; interestingly, I also have a Ricoh GX200 with the VF-1 LCD viewfinder; this has enough diopter correction to still accommodate me!

I have been meaning to ask this for a long time so I just messages cilliaryblue and asked if they could put a prescription lens into my o-me53 magnifier, here is the reply.

Hi Gary
We have done them before but not that one specifically. We should be able to do it, the cost would be £15-20, they come fully coated.
Regards
Chris

So I will be sending mine off once I get my eyes retested....

I'd be interested to know how you get on. When I tried round my local opticians they could not do it because the machines they used did not go small enough for the size of the O-ME53 lens

Can't you just cut down an old lens? I thought they
were just plastic?

For anybody looking for reading glasses (+2 etc. ) you
can buy tiny credit card size specs that fit in your
wallet. They should cut down easily.

Don't forget that all viewfinders have something like
-1 diopter already built in..... something to do with
the apparent viewing distance of the image.

I think the problem with spectacle glasses is that they are curbed to fit the frame when fitted. I could be wrong though...