The Holga is a medium format camera that recently became ultra-popular, partly as a response to the digital consensus with modern photography, and in part as a low-cost, unpredictable means of using film. The Holga is quite cheaply made and consequently is relatively low in cost, making it also a more interesting entry-level type of camera. Everything in the camera is plastic, including the lens, and this leads to blown-out, wild-looking photos with plenty of light leaks.
You can get Holgas modified to do different things and with different features. For instance, some "modded" Holgas can shoot 6x6cm frames, others only 6x4.5, while others have been modified to include cable releases, tripod mounts (on the original 120S), and even to shoot 35mm film. Holgamods.com explains the common modifications and what they do. Holgamods.com is currently working on a 35mm Holga modification that adds a rewinding knob to the bottom of the camera so that a dark room is not needed for winding the film.
Holga 120 N
Accessories exist that will do the same thing as a modified Holga without the need for physical modifications as well as accessories for special effects. Such accessories include:
Cable release, which which slips onto the lens so that a cable release can depress the shutter. Also includes tripod mount since the Holga 120N's mount is covered by the accessory.
35mm Film Adapter, available in two models: full negative and "panoramic." Both adapters come with a light-proof back and a mask made to hold the 135 cannister in place. The only difference between the two models is the size of the mask. The "panoramic" adapter will mask out the sprocket holes. A rarer model available in Japan is an all-in-one back and cartridge unit.
Filter holder and filters. Filter holders can hold one or two filters, depending on the model of the holder. Filters come in special effect filters, color filters, and center spot filters (which leaves a normal center, but a coloured surrounding).
Holgon Flash, a small normal flash for Holgas with a hot shoe.
Holgon Strobe Flash, a bulky flash which features multi flash strobe (which keeps flashing as long as the shutter stays open in bulb mode) or single flash (a more powerful flash, which will flash once on pressing the shutter and a second time on release). Features vertical adjustable angles.
Holgon Slave Flash, a small, round slave flash meant for placing on a surface or handheld. Good for any kind of secondary light. Some units will come with multi coloured filters to place over the flash.
Camera bags, available in a small and a large size. Will fit the Holga, a Polaroid back, and some accessories.
Holga Enlargers, an inexpensive darkroom enlarger with two available lenses and several masks/negative carriers for both 120 and 35mm formats.
Velcro used to secure back
Loading film into the camera is notoriously difficult and it is often hard to tell whether it's loaded correctly until the whole roll has been shot and developed. The back is also prone to falling off halfway through a roll, ruining the film, so its a good idea to tie the back on using velcro or elastic bands (this problem can be eliminated by bending the metal clips that hold the back on to be tighter with a pair of needle-nosed pliers). The shutter release is placed beside the lens as opposed to the standard place on top, which can be confusing for first-time users.
Holga 120 FN
Recently, Holgas have become available in a kit form which acknowledges and even celebrates their low-tech nature. The kit includes a manual that details the camera's idiosyncrasies, as well as a roll of black tape for taping up light leaks, though the manual notes that many Holga devotees regard light leaks as part of the camera's signature style. Holgas are also now available in special edition colours for some models, including White, Silver (which adds silver accents to some areas of the Holga), and Gold. These special edition colours normally sell for $40-$50.