Cosina used to make all kinds of PK lenses and then place different names onto them. Back in the 80's Cosina sold more PK lenses than even Pentax. One of their larger names that was added to the front lens barrels was the North american name (borrowed from/added in?) from Ritz Camera - the Quantaray name.

Optically the Cosina is an above average lens; even full frame capable (on former film or in future Pentax digital). Since it's a prime it's naturally optically better than any zoom lens. Not quite as good optically as the 28mm.

An incredibly durable lens that will do nothing but last. The manual focus brings back the good ole days.

Depending upon model; (some come with this others variations do not) the Cosina 24mm may have automatic aperture lock and/or also very well defined aperture guides for marking depth of field and all.

I used to own one of these back in the day, and use it on film camera bodies such as the Pentax LX and even the (ultra rare) Ricoh XR-S

Actually based on the known location of the stars and all... It's a low Earth orbit satellite, "flying" in at about 180km orbit

Wait a few more days for the 83x optical (not a typo - eighty three power) Nikon COOLPIX P900 Digital Camera.

Or wait a few more weeks for two different models with 100x optical

Then there's the unfortunate film issue when traveling to places such as america.

Using most any type of mailing service almost guarantees that the film will be fogged by extensive xray devices. Between american TSA and other border protection agencies; one is also not guaranteed visual inspection of film

First please consider this one...

For most Pentax camera bodies... While doing certain types of physical activities and carrying a camera (in most any type of rucksack/gadget bag) turn OFF the Pentax in camera SR. I've seen many cameras accidently either left on, or bumped into the on position. In which case, it is eventually possible to have issues with the SR and some Pentax camera bodies.

If it is not off to service just yet...

Has the lens been tried out on a second camera body yet? That even if one doesn't own a second body then perhaps one could find another Pentax body from a friend or retail store

Sure there are almost fifty full-frame PK lenses on the market, but... With items such as the Pentax FA50 (emphasis on!!) macro... Great lens optically, yet...

The Pentax 50 macro (given it's mechanical linkage focusing) is also the second slowest auto focus lens on the market I've ever used. It's almost faster to go full manual focusing and/or to use the depth of field and then lock in the focusing. Please tell me this lens will NEVER be marketed with any full frame camera; imagine the reviews

But...

For some people out there who aren't really into items like: photography (in depth, the ones who leave their cameras on the fully automated settings), computers in general, or the internet... A fair number of people have been online stalked (and worse) by posting their photographs online and then leaving the gps coordinated "attached" to the photographs.

It also depends upon additional factors...

The Pentax K3 offers some of the best WR on the market. Add quite the variety of lenses that have the WR attached to them; something that even Nikon does not offer (Nikon only offers WR on their camera bodies, not their lenses).

Better yet, wait until full-frame arrives in (most likely) November for Pentax. So far the Pentax company is claiming that they will stick with PK; which includes almost fifty existing full-frame lenses. Or if one has the need to go outside of full-frame and may want the cropped sensor to switch over; one can simply use non full-frame glass.

This might just be the largest game changer ever for Pentax - if it's done right

About filters on the Sigma 24-70...

Basically only one filter will work on the end of the lens; especially if it is a filter such as a rotating polarizer. In most cases if two 82mm filters are used, it manages to get into the image edges