I own a photography studio and need to buy bayonet mount rings for all my students' cameras. Where can I buy them in bulk?

You can hire Studio Pep Photography. They are available at affordable prices. You can see their album at their website. Visit: http://www.studiopepphotography.com/about.html

The praktica BC1 camera uses a bayonet mount described as PK. You need to search on ebay for "PK to EF adaptor". You will get plenty of results. Make your choice depending on whether you want focus confirm or not.

Vivitar makes lenses with a variety of camera mounts, most of which are bayonet style. What modern cameras they may work with depends on the lens mount. If the lenses have a Nikon mount, for example, they'll work with any Nikon DSLR. If they have a Minolta mount, they'll probably work with any Sony DSLR (Sony bought the photography business when Minolta went bankrupt). If the lenses have some other mount then they'll probably work with cameras using the same mount.

A bayonet mount allows lenses to be changed quickly and ensures they are locked into place

I did some searching for you and the average price of a bayonet mount ring is $7. Here are some websites where you can purchase what you need.

http://www.amazon.com/NEEWER%C2%AE-Bayonet-Mount-18-105-55-200mm/dp/B005HTP7MK

http://www.amazon.com/Neewer-Bayonet-Mount-18-105-55-200mm/dp/B005JQEFEM

http://www.dealextreme.com/p/designer-s-nokia-18-55mm-18-105mm-55-200mm-lens-button-cover-130802

http://www.aliexpress.com/store/product/Freeshipping-BAYONET-MOUNT-RING-FOR-NIKON-18-105-55-200-MM-LENS-retail-wholesale/207456_477457118.html

There is a great video on YouTube that will provide you with a thorough tutorial that will guide you through replacing your bayonet. I will post the link for you here.

http://www.youtube.com/watch?v=Pd6pvvQ1_So

You don't need an adapter ring, you simply need the correct lens. Like many aftermarket lenses, the Hanimex was made in a number of different versions to fit many different camera mounting systems.

Your camera accepts lenses with a Pentax K bayonet mounting, so the fix is to sell your lens (it's not worth very much though) and buy another which also shouldn't cost very much. You can even get them for free simply by asking on FreeCycle, it's where virtually all of my film camera equipment has come from.

It *might* be possible to get an adapter, but it depends entirely upon which mount the Hanimex currently has (you didn't say, and it's not always obvious just by looking at the lens), and very few can be adapted to a K mount. Those that do will lose automatic aperture coupling, making the lens and camera rather awkward to use, and the coupling will likely cost more than another similar lens in the same zoom range.

If it's the VR lens:
http://uscamera.com/jaa79851-b37.htm

If it's not the VR lens:
http://uscamera.com/jaa79351-f.htm

As to whether you can replace it yourself, can you use a screwdriver and a soldering iron?

Probably screws that are on the part of the lens mount that touches the camera bayonet