Photographing Gels with the Polaroid Camera
Photograph the gel following instructions below. Discuss interpretation of the gel with your instructor. Identify RNA and DNA. Keep the photograph in your data book.
Caution: You will be using a transilluminator. Transilluminators emit ultraviolet light in the 250 nm range. This range of light is mutagenic. Eyes are sensitive to UV light. Short term exposure will lead to sunburn. Long term exposure can cause cataracts. UV light can also cause skin cancers. Protect your eyes and skin from UV exposure
Place gel on transilluminator
Place small piece of news print on top of gel at the edge to aid focusing
Slide the viewing screen to the right. Open the diaphragm by pushing the lever on the right of the lens away from you (don’t push hard, you will push the lens out of the camera)
Carefully push the orange cellulose filter away from the lens to increase your ability to see through the lens. Do not handle this filter. It is easily damaged.
With Polaroid viewing screen to the right, enlarge (or reduce the gel) by moving the bellows up and down. When the gel is the right size, focus by moving the entire camera up and down. You will need extra light on the gel to be able to see the gel clearly.
Close the diaphragm by pulling the lever on the right of the lens towards you. Check that the diaphragm is closed by looking through the viewing screen (pull gently).
Return the orange cellulose filter to it’s place in front of the lens
Slide viewing screen to the left.
Turn lever on camera to L (or away from you, L = load)
Push in Type 57 film, metal end first. When film engages, pull cover out gently (don't pull everything out of the camera). Make certain the correct side of the film is facing down (The film cover indicates which side is towards the lens or down.)
Turn on lamp and turn off overhead lights.
Cover face with face shield, shield the gel with the plastic cover and turn on transilluminator. Turn off the lamp.
Photograph at t = 1/4 sec (4 on dial)and F between 4.5 and 5.6 by pushing back lever on the left (gently). You will hear the diaphragm open and close. [Exposure time may vary depending upon the intensity of fluorescence staining of DNA or RNA on the gel and you may have to adjust timing.]
Turn off the transilluminator. Turn on a light
Push film cover back in.
Turn lever to P (P= process or towards you)
Pull entire film cartridge out. Wait 20 secs and open.
Coat and label film.
TYPE 55 FILM (Positive and negative film): The exposure time for type 55 film is different. Use a 30 second exposure at an opening of 4.5. You will have to hold the lens open by hand and use a timer to get the 30 seconds. Before using type 55 film, you will need to make a sodium sulfite solution and some photoflow solution. 18% sodium sulfite = 32g sodium sulfite in 200 mls luke warm water. Place in small square dish large enough to hold the negative.