Response to development times:condenser vs. diffusion

Hi Jim,

question 1: The light from a diffuser enlarger passes the negative diffused (that's obvious). In a nutshell you can compare it with the sunlight on a clear and a overcast day. On a clear day the shadows will be hard and defined as the light comes from one defined lightsource. On a overcast day the shadow, if any, will be soft because the light is spread around the object because of the clouds. In a condenser enlarger the light from the lamp passes through a clear piece of glass and then through the negative, the lens and on the paper. Simply said the lens sees the image as if illuminated from behind by a spotlight and projects the image more bright and contrasty on the paper. This is called the Callier-effect. In simpler terms the light hits the edges of the black exposed area with very little lightbeams being sent in a different direction but down, and thus isn't bothered with a softer negative. The grain of the emulsion, as well as dust and scratches will be clearly visible. A stronger negative will create a harder ( often too hard) image. A diffuser enlarger spreads the light inside the enlarger around, and the part of the light that goes in the direction of the negative around the image on the negative, thus messing up any hard edge, let alone what will happen when the negative is soft. Longer developing will increase a higher contrast in the negative ( the 'gamma' curve, soft neg is low gamma, hard neg is high gamma) thus partially countering the effect of the diffused light. For condensor a enlarger a gamma is recommended of Beta 0,55, for diffuser enlargers a beta 0f 0,70 question 2 Yes it matters, it will save a lot of time and manipulating in the darkroom. Although Multigrade has made the job a lot easier, you will still need to find out the right gradation, and find it demands 'extra soft' or 'extra hard' to begin with and then still having to burn or hold back certain area's, quite a lot of work and time, and maybe not get optimal black or white. question3 How do you mean what gives? If you mean if it is important, see the above. If you mean can it be done, of course. If you want timetables for different types of films, sorry can't be done, as much depends on temperature and agitation while developing, in essence personal developing style. An aspect often overlooked nowadays is that under- and over development can be used in combination with under- and overexposure to create a printable negative of constant quality using basically always the same grade of printing paper with different subjects under strongly varying light condition. The socalled 'zone-system' of Ansel Adams still is basis of a school of photography, of which this is the very foundation. Hope this answers your question, Paul

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