Recently I bought the smallest digital Interchangeable Camera System from Craigslist. It´s called Q and it is made by Pentax (now Ricoh). The Pentax Q System consists of several Interchangeable Lenses and one of them is particularity interesting because it is very very slim, just 6.9 mm. It is the Pentax Q 07 Body Cap Lens aka the “Mount Shield Lens”. Body Cap Lenses have no focus mechanism and typically no aperture to choose from. What you gain from this minimalistic Zen-Design is the opportunity for real Snapshot Photography! This lens is by far not the only model around. Read on and compare available Body Cap Lenses and Pinhole Lens Caps for interchangeable Camera mounts…

There are two different types of fixed distance (lens) designs:

• Body Cap Lens has usually a plastic lens element integrated.
  • Advantages
    • Light and durable
    • Cheap
    • Fixed Focus
    • Quick and fun to use
  • Drawbacks
    • Less sharp compared to glass lenses
    • No aperture control (with exceptions)
    • Resulting images look often soft in the corners
• Pinhole Lens Cap has no lens element at all, there is only a tiny hole in a cap.
  • Advantages
    • The lightest possible (lens)
    • Cheaper
    • Fixed Focus
    • Huge Depth of Field
  • Drawbacks
    • Very long exposure times! (Hand held shooting not recommended)
    • Almost no preview (live-view) possible because it´s too dark
    • Resulting images look overall soft, very soft!

Lens or Pinhole?	Manufacturer	Model Name	Field of View (Full Frame equiv.)	Aperture f/stop	Picture	Infos and Reviews	Available mounts
Pinhole	You	You name it	01mm	f/0	Make Your Own	Do It Yourself Tutorial on WikiHow	All
Pinhole	Skink Pinhole	Pancake Pro and Classic	45mm	f/150	Shop		Canon Fourthirds Fujifilm Hasselblad Leica mFT (m4/3) M42 (screw mount) Nikon Olympus Panasonic Pentax Sigma Sony
Pinhole	Holga	HPL 299120 Pinhole Lens	38mm	f/125		Hands on Video Review	Canon mFT (m4/3) Nikon
Pinhole	Pinholeressource	Digital Pinhole No Dust Cap	48mm	f/166	Shop		Canon Nikon
Pinhole	Daystar Laser Inc.	Pinhole Cap	43mm	f/180	Shop		Canon EF / FD Leica M / R mFT (m4/3) Minolta SR/MD Nikon F Olympus OM Pentax K Sony/Minolta A
Lens	Loreo	Lens in a CAP 9002MD	35mm	f/5.6-64	Shop	Hands on Video Review	Canon EOS / FD Minolta MD M42 (screw mount) Nikon N (F) Olympus OM Pentax K Sony/Minolta AF
Pinhole	Wanderlust Cameras	Pinwide Digital Pinhole Cap	22mm	f/96			m4/3
Lens	Olympus	Fisheye Body Cap Lens	18mm (Fisheye)	f/8	Shop	Hands on Review	mFT (m4/3)
Pinhole	SLR Magic	Pin Hole Lens	24mm	f/128	Shop	Hands on Review	mFT (m4/3)
Lens	Olympus	Body Cap Lens	30mm	f/8	Shop	Hands on Video Review	mFT (m4/3)
Lens	Pentax	Q 07 Mount Shield Lens	53mm	f/9	Shop		Pentax K

If you notice that a information about a lens is missing, please let me know in a comment below!