Homebrew Gel Documentation System - Burnout of Digital Camera? - (May/14/2008 )
I threw together a 'gel documentation system' using an old difital camera (I was sick of the stinky polaroid). I made an adapter out of card board so I could place the digital camera where the old polaroid sat. Works pretty good, gives a fire color through the yellow filter!
Anyway, it seems to be fading?
It fades markedly while taking pictures in one sitting. Below is a picture (15second shutter) that took immediately, then the other picture is one I took with the same settings after taking a few with different shutter times.
Does anyone know anything about digital cameras, UV, ...? What's going on here? 
UVwill affect the sensor - you need to have a filter in place to prevent damage to the camera
I have the yellow filter from the polaroid setup (Tiffen yellow 15 I think).
you may also want to put a uv filter in front of the lense (you don't need to let the uv through, only the visible fluorescence).
does the camera recover over time or is the damage permanent?
you may also want to put a uv filter in front of the lense (you don't need to let the uv through, only the visible fluorescence).
does the camera recover over time or is the damage permanent?
It recovers over time, but seems to be slowly getting worse?
check to make sure that your lens is not fogging. it may have a uv sensitive coating or it may be a plastic lens.
Ok, so perhaps this obvious, anyways. Overtime, DNA gets nicked when exposed to UV light. I have found that (by taking a video through the digital camera and then playing it at 4X speed) you can actually see DNA being photo-bleached by UV over a 5 minute period. Could this be it? I too am using a DIY geldoc, using a 8MP cannon camera (overkill, I know) using the shortest f-stop available (2) and an exposure of only 1.5 seconds...I too use a Wratten filter (orange one that gives the same orange hue as yours) and do not use any sort of UV filter...But my transiluminator is a crap one and only gets out around 8 watts of 312 nm UV light...Hope this helps in anyway...
312nm is relatively long wave uv and won't cause the damage that shorter wavelength uv will (not as quickly, at least).
Well, I don't think it's the photobleaching of the DNA by UV. Because with my eyes I don't see much difference, but if you look at the two pictures above there is a marked change.
I use a Tiffen, not wratten, but I don't see any fogging of the lense.
Very curious, I do use a higher f-stop and longer exposure, I think I read higher f stop gives a larger range of focus, I guess I could switch that up if I have too in the future (when it fades more). Perhaps such long exposures do damage the camera.