Most people may think, “an overhead projector is an overhead projector is an overhead projector”, but you need to keep a few things in mind when purchasing them. Brightness, bulb availability, and features are important to consider when choosing an overhead projector, or OHP for short.

   Choosing an OHP for a completely dark room is much different than choosing one for a room that has several windows or lights on. I recommend a minimum of 4000 lumens output from an overhead projector, which usually translates into using 410w FXL halogen bulbs. The projector I use in my setup puts out 2700 lumens: it is a little dimmer than I would like but it works beautifully when my room is dark.

If the lumen rating of an overhead projector is not listed in the description (which it most likely won't be), once again it is a good idea to contact the manufacturer. I was unsure of the rating of my OHP (an Elmo HP-L355 Deluxe), so I emailed Elmo about it and within a day they responded with the rating.

Just like in grade school!

   So you found an OHP that puts out 7000 lumens. That's great, except that you'll be paying $100 or more every time that you need to replace a bulb. A balance must be kept between brightness and bulb cost. OHP bulbs have 3 letter codes for their ratings, such as ENX or FXL. ENX is rated at 82v/360w while FXL is rated at 82v/410w. Both of these bulbs have retail prices of around $15 which means you can find them even cheaper if you look online, such as places like eBay once again (get the drift?). Also find out the approximate life span of the bulbs you'll be using. ENX last about 75 hours and FXL last about 50 hours if my memory servers me correctly. This may not seem like a long time, but chances are you don't leave the projector on when you're not in the room. Having a spare bulb handy is always a good idea, and some of the features of the OHP might just make it easier to replace them.

   The feature I am talking about is having 2 slots for bulbs at one time. Most OHPs I have seen have this. It is a pain if you're in the middle of a movie or game if a bulb decides to die on you and you need to open up the projector to put a new one in. Look for an OHP that has a lever to switch between bulbs in the event that one dies. Being able to dim the light passing through the panel may be called for in completely dark rooms if you have a bright OHP. This will also lengthen the bulb life if it is not being stressed to its maximum at all times. Some OHPs are designed for transport and have folding arms. Some leak light more so than others (this is a problem I'm battling with mine now...), so be aware of any problems you may have with an OHP before you buy one.

   For a decent quality (such as dukane or 3m), 4000 lumen OHP expect to pay about $75 or more. A 2700 lumen OHP may be found for much less, maybe $25 and up. These prices depend on how well the unit is listed, what kind of condition they are in, and the warranty information from the seller. Keep this in mind while searching, because they could be found for much cheaper or much more expensive. Because OHPs are more common than projection panels, try searching yard sales or auctions for them. The quality may not be quite as good as you'd like, but in example my OHP was found for $1 at a yard sale and all it needed was a new bulb and a little dusting off.