56 
HINTS TO TRAVELLERS. 
Lenses —There are many lenses in the market, and as it is impossible 
to do good work with an inferior lens, it is necessary to exercise great 
care in selecting this part of a photographic outfit. Lenses known as 
rectilinear or symmetrical are the most useful to a scientific explorer, and 
are equally well fitted for producing pictorial effect in his work. 
Ordinary portrait lenses are designed specially for rapid work, and this 
is attained at the cost of qualities in a lens most useful to an explorer. 
The so-called portrait combination should therefore be avoided, and there 
is all the more reason for this as rapid rectilinear and symmetrical lenses 
are well adapted for out-door portraiture. 
Rectilinear and symmetrical lenses give true images of objects to be 
photographed free from distortion, so that straight lines are reproduced 
as straight lines. In this way they are invaluable where accurate measure¬ 
ments have to be taken from photographs produced by them. 
Ross and Dallmeyer’s ordinary symmetrical and rectilinear lenses are 
excellent for all sorts of landscape work and for photographing buildings, 
exterior and interior. In using a camera 7i in. x 5 in. the following 
lenses are recommended:— 
a. Ross’s Symmetric Anastigmafc, 9 in. focus. (This embraces an angle 
of about 45° on the long diameter of the plate, and is useful for an open land- 
Ross Rapid Symmetrical. 
Zeiss Lens. 
scape or for groups.) b. Dallmeyer’s single meniscus lens, 7 in. focus. (This* 
includes an augle of about 45° on the 7£ in. plate, and will be found the 
most universally useful lens for ordinary landscapes, giving a brilliant 
