Any photographer worth his salt will have basic lens care products in his bag. Today's 35mm and digital SLR camera lenses have a protective coating on them but cleaning the lens and shutter mirror is still occasionally required. A soft bristled lens air brush, lens cloth and liquid lens cleaner solution is a must in any photographer's toolkit. A lens maintenance kit can be purchased at camera shops and department stores for just a few dollars. Replacement tissues are available at just about any optical or drug store. Some photographers use small personal packs of facial tissues but I have found these leave small tissue fibers on the lens that are next to impossible to remove. Replacement lens cleaning fluid is also available anywhere eyeglasses are sold.
Regarding lens cleaning, one drop of lens cleaner will suffice. Forego cotton swabs, as they will scratch the lens' protective coating. For all lenses, I recommend the use of a ultra-violet (UV) polarized or anti-haze filter. These filters protect the lens, are easily replaceable if scratched, and eliminate pesky glare and sun spots.
If using a fixed focal length lens, then a set of magnifications rings are must. Magnification rings screw onto the end of the lens and can be used with existing filters. When using a filter make sure the magnification rings are sized for the filter as opposed to the lens. These rings are used for close-up or macro photography and can be combined for various magnifications.Flash and lighting tools
Every photographer's toolkit should include several flash and lighting tools. The first device, considered an absolute must, is an off-camera cord that mounts to the camera's hot shoe at one end and the flash shoe at the other. An off-camera cord allows the photographer to direct the flash where needed when using oblique or fill flash techniques and is required when photographing shoe and tire impressions.
The next item to include is a flash diffuser, which is used to reduce flash output when photographing highly reflective items such as jewelry. All camera shops sell clip-on flash diffusers. These devices are usually flash-model specific and have a fixed opacity that may not provide adequate flash diffusion. One solution for flash diffusion is a 12-inch by 12-inch piece of white cotton cloth and a rubber band. The photographer controls the amount of flash diffusion by folding the cloth over on itself, multiple times if needed, and securing it to the flash head with a rubber band. I cut my cloth from the back of worn out white T-shirts. Another source of white cotton cloths, usually under $10 for six or so would be white cotton polishing cloths available where automotive care products are sold.
Another handy item is non-reflective backing to place items for close-up photos. My preferred backings are blue surgical towels. Multiple blue surgical towels come in a single package. Once the package is opened, the unused towels are no longer sterile and are disposed of. Befriending a surgeon or surgical assistant can unearth an endless supply of these nifty little items. Blue shop towels, available from auto parts stores, also work. Make sure these towels are new and unused, not gently used and cleaned cloths, which may have oils or solvents embedded in the fibers.
A diffusion dome comes in handy when photographing reflective evidence. These pricey little items are found in the photography section of most crime scene product catalogues. Diffusion domes allow the photographer to place the camera lens in an opening at the top of the dome and put the flash against the side to diffuse and bounce the flash when the photo is taken. The MacGuyver solution to the expensive dome is at hand, using a discarded plastic milk or orange juice jug. Simply cut the bottom off the jug and cut a hole in the top large enough for the lens to pass through to create a low-cost diffusion dome. Any type of white or frosted plastic container will work, but be sure to test the opacity to make sure light will pass through it. This can be done by placing a small flashlight against the side and seeing how much light shines through.
Perhaps the most important item to include is two to three extra boxes of flash batteries. Not only will it save time but regularly replacing flash batteries keeps the flash unit operating at optimal efficiency. Keep in mind, alkaline batteries deteriorate during extreme changes in temperature, so rotate these batteries frequently if the kit is stored in the squad car trunk.Little things to complete the kit
It's often said little things mean a lot. This is true of the items that complete the basic crime scene photographer's toolkit.