RECORDING INVISIBLE IMAGES

By Terry Hardy (Area 22)

With reference to a piece in the Area 22 Newsletter on Night Photography I too have witnessed the phenomenon of recording images not normally visible to the naked eye. In my case it results from having an interest in astro-photography. What I find interesting is the amount of detail which can be resolved when using camera lenses of standard focal lengths or those used in normal everyday photographic assignments. You see, I don`t possess an astronomical telescope and the highest magnification I can achieve is with a 300ml lens. Of course the exposures that I make are quite lengthy and the camera/lens set up has to be on a driven mount to counteract the earthæs rotation. The other interesting fact is the way in which the colours of stars are depicted when using colour transparency film; I use Konicachrome exclusively. 

When stars are viewed by the naked eye or by binoculars they usually appear white; there are of course one or two well known exceptions, such as Betelgeuse in Orion, which should appear reddish; but when viewing a projected slide the colours really come to life. What I find is even more dramatic is to use a fine grained B&W film, and to view the negatives as projected slides, the heavenly bodies appearing as black `dots`; the amount of detail that can be resolved here is amazing. However, this is nothing new, since professional astronomers use this procedure; they don`t spend all night squinting through a telescope, they just stick a camera on the end and study the developed negative at their leisure, or so I`m made to believe! 

ENLARGING EXPOSURE METER

By Dennis O'Connor (Area 20)

Here is a means of constructing a device, which will allow a standard light meter to be used as an enlarging exposure meter. As the accompanying sheet explains, it consists of a prism from an old SLR camera, mounted so as to re-direct the enlarger light at right angles into the exposure meter. The method of operation is simple.  Make an acceptable print. Without altering anything, place the prism/meter under the enlarger and take a reading. The negative or height or both can now be changed. Focus the image on the baseboard. Re-position the prism/meter in the print area. Adjust the enlarger lens aperture to give the same reading value as previously.

I have used this device with and without a diffuser over the lens (depending on what you want to achieve). The area of selection can be reduced if you wish by reducing the `clear` area on the TOP prism face with some matt black paint (a `painted` ring binder re-enforcing ring makes a good option).

The sketch shows how an exposure meter can be used as an enlarger meter. It consists of a prism from a scrap SLR camera which is used to direct the light from the enlarger head to the light meter. The prism is held in place with `Plastic Padding`. The height of the light meter can be adjusted by means of flat sheets, and held in place using elastic bands. The basic idea can be altered to account for different types of meter design.

I enclose a sketch of the device I made. It allows an exposure meter to be used as an enlarger meter. It consists of a prism from a scrap SLR camera which is used to re-direct the light from the enlarger head to the light meter. The prism is held in place using elastic bands. The basic idea can be altered to account for different types of meter design.

Slide Copying on a shoestring

Editorial

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