This section is from the book "Complete Self-Instructing Library Of Practical Photography", by J. B. Schriever. Also available from Amazon: Complete Self-Instructing Library Of Practical Photography.
Flat Cloud Effects. Flat cloud effects are invariably due to over-exposure. When it is desired to secure the landscape on the same negative with the sky, the light from the clouds, which strikes the sensitive plate, must be retarded sufficiently to allow enough exposure to bring detail out of the landscape. To produce strong cloud effects, with depth and roundness, employ color corrected materials, as directed in Chapter XIII (Photographic Printing). A careful study of this chapter will enable you to secure the very best results possible to obtain.
Difficulty In Photographing Clouds. The greatest difficulty in securing the right kind of cloud negatives will be your inability to obtain the proper subjects at the right time. Therefore, you should always be on the lookout for various cloud effects, and even if you have no particular use for the cloud at the time, you should make one or more negatives of it, so that you may have it on hand to use whenever you desire it.
446. In making regular cloud negatives select a place where you can secure a clear view of the horizon, unobstructed by telephone poles, trees, houses, etc. The seashore is the best place for photographing clouds; but from house-tops, or even from open fields in the country, you can secure the proper results. We would again urge the importance of giving short exposure. Over-exposure always flattens the effect, and in cloud photography, especially, there is great danger of ruining an otherwise pleasing cloud effect.
Moisture Gathering On Lens. If the lens is taken from a warm room into the cold air, moisture will form on its surface. In this condition no exposure should be made, as the resulting negative will be under-exposed and appear very foggy. It may be necessary to wipe this moisture off perhaps two or three times, or until the temperature of the lens becomes the same as the atmosphere. In a short time, the moisture will not gather and you may then proceed to make the exposure. In wiping the lens always use a soft cloth - one which will not scratch the surface of the lens.
448. Focusing Snow Scenes - (a) If difficulty is experienced in focusing and securing sharp image on the ground-glass, the trouble will invariably be due to a strong reflected light which strikes the lens and gives a hazy, foggy image on the ground-glass. The lens must be shielded in some way. Usually, holding the slide of the plate holder or any other dark object of a similar nature under the lens, will cut off the reflected light from the snow and allow of a sharp image being formed on the ground-glass. A conical-shaped hood may be placed over the lens as described in Paragraph 431. In fact when making snow scenes, it would be advisable to always employ a hood of this kind, as you will almost invariably experience difficulty from cross reflections and reflected light from the sun. (b) If the lens is pointed directly towards the sun, it will be impossible to secure a sharp image on the ground-glass. Especially when making snow scenes you should aim to have the sunlight fall from the side but not towards the lens. Light coming from the side will invariably do away with any serious amount of reflected light and you will be able to focus without any trouble whatsoever.
4-19. Flat Snow Negatives. - Flat snow negatives will invariably be due to over-exposure. A minimum amount of exposure should be given as this is one instance where you should err on the side of under, rather than over-exposure, for it is not at all difficult to secure detail even in the deepest shadows when photographing snow scenes. Less than half the exposure is necessary to secure a snow negative full of detail than is required for producing the same amount of detail when there is no snow on the ground. Care must be also exercised when developing snow negatives that the developer is not too weak, for in this condition it would bring out detail rather than produce density and in order that a correct rendering of the snow scene be secured, it is absolutely necessary that the highlights be strong, yet full of detail. A normal developer is usually the best to employ.