November 16, 1990
Matthew S. Holt
System Description:
The equipment consists of a camera and adjustable stand, an ultra-violet light source, and a housing unit to provide a "mini-darkroom" for UV light photography. All equipment was purchased from Fotodyne, Inc.
1. Foto Camera #3-3500 - consists of an object viewer and film cassette holder mounted on a sliding platform above a Polaroid MP-4 Land Camera, all attached to an adjustable shaft.
2. Foto UV300 #3-3000 - consists of a platform with a UV light source mounted under a water-proof glass shield.
3. Foto Cover #3-4494 - consists of a housing unit to which the camera attaches at the top and covers the Foto UV300 transilluminator (onto which the object to be photographed is placed). The housing has a built in visible light, with its switch in back at the right hand side of the cover.
Safety Precautions:
Any exposure of skin or eyes to shortwave and midrange UV light can be harmful. View object under UV radiation through the object viewing port only. If the doors are open when the UV source is on, protect eyes and skin with UV blocking eyeglasses and/or a faceshield.
To photograph a gel:
1. Place the gel on the UV transilluminator. Close the doors and the viewing port.
2. Turn on the visible light source on by flipping the toggle switch located on the top of the cover in back.
3. Slide the view finder over the camera lens by pressing the gray tabs on either side of the sliding platform. Never force any moving parts. Get assistance if any mechanism jams.
4. Remove the orange UV filter assembly by pulling out the black knob on the right immediately below the camera lens. Note: the UV filter can be damaged if it gets wet.
5. Adjust the photo field size: Loosen the screw handle (on front of camera stand shaft) while holding the crank handle on the right of camera stand shaft. Make sure the screw handle is not scraping against the shaft while moving the camera. While viewing the gel through the view finder, reduce or enlarge the field by turning the crank clockwise or counter-clockwise (raises and lowers the camera). Lock the camera in position by re-tightening the screw handle. Note: Drastically changing the focus will also change the field size. It is advisable to roughly adjust the focus (located at left of camera) simultaneously with adjusting the field size.
6. Fine-tune the focus by placing a white film tab (or any paper with fine print) on the gel surface and adjusting the focus until the tab's lettering is clear. The gel should be centered in the brackets visible through the camera view finder.
7. Slide the film cassette over the camera lens by pushing the gray tabs, re-insert the orange UV filter, and turn off the visible light.
8. Set the shutter speed on the camera by turning the silver dial located immediately below camera lens to any one of the pre-set shutter speeds. The numbers represent the inverse of the speed in seconds: 1 = 1 second, 125 = 1/125 second, 16 = 1/16 second, etc. The "B" setting is for manual control of the shutter; as long as the shutter release is pressed, the shutter will remain open. Generally, a 1 second exposure will give adequate photos. For brighter objects (e.g., high ethidium bromide staining) try a faster exposure setting. Faint objects may need a long exposure, accomplished by selecting "B" and holding the shutter open for 15 seconds to one minute.
9. Setting the aperture (the shutter diaphram) requires adjusting two separate controls (the f-stop); a black dial immediately below the silver shutter speed setting and a silver lever on a horizontal plane immediately above the shutter speed setting. Both these controls should be set identically. The aperture controls the amount of light entering the lens; its setting affects the photograph's contrast. Generally, an aperture setting of f 5.6 gives satisfactory contrast. Opening the aperture one stop doubles the amount of transmitted light.
10. Turn the UV source on by flipping the toggle switch located at the left of the Foto UV300. Check that the doors and the view window are closed, and that the visible light is turned off.
11. Take a picture by pressing in the cable release plunger. If the cable is not used, find the silver shutter release knob located on left of the dial and push back.
12. Pull film from cassette by first pulling out white film tab on right of cassette and then pulling the actual film tab. Always pull tabs level and square to the cassette with swift and continuous motion, because pulling the tab at an angle will cause it to rip or the film to jam. After 30 seconds developing time, peel the photograph from its backing. Record in your lab notebook the date and type of exposure used (speed and f-stop) for each photograph.
13. When finished, clean the UV box surface and turn off the UV transilluminator.
Note: Visible light photographs can be taken with visible light souce on and the doors housing doors open: remove the UV filter, set the f-stop to 16, and use a shutter speed of 1/125 or 1/60 second.
To change film packs:
Film packets (Polaroid #667 Instant Pac) contain eight sheets of film. To replace empty packet remove the cassette holder by lifting the right end of the spring-held bracket on the sliding platform and pull the holder out to the right. Release the black clamp on right of holder and remove the empty film pack. Place a new pack with open side down and black shield tab sticking out of the right end of the holder and replace holder clamp. Return cassette to the sliding platform by lifting the right end of spring-held bracket and gently pushing the cassette to the left. Remove black film shield by pulling out to the right.
Each time a new film pack is installed, check the condition of the rollers and clean any buildup to avoid film jams. The silver roller assembly snaps out of the film holder for cleaning.
