1? Brown Street 
Providence, R.I. 
March 24, 1934 
hear iernald: 
When 1 wrote you on the 21st 1 came near writing you concerning 
one great drawback to enlarging from a print, but decided finally to send the 
xlO and x50 prints without comment and await your reaction, so long as you 
said there was no special hurry. 
A photographic negative depends for its contrasts upon whether or not the 
silver granules in the emulsion (sensitized) have oeen exposed to the influence 
of light. These granules are too small to be seen with the naked eye, but 
under a strong hand lens or binocular they can be seen as a very minute 
'•grain'* or stipple-like effect. This ’’grain'* also is seen in glossy prints 
made from a negative that is very sharp. If you will look at the xlO*print 
that 1 sent you, using a strong lens, or, better, a binocular microscope, 
you will readily see just what 1 mean. This grain will be seenubest in parts 
of the print that are neither white nor black, though it can often bed seen 
in both black and nearly white parts. As this grain is in the emulsion it 
makes no difference whether the object being photographed is reduced, natural 
size, or enlarged to xlO, x50, or xlOOO, the grain will be the same-invisible 
to the unaided eye. BUT, just as soon as you make a negative enlarged from 
another negative, or a glossy print made from it, you are enlarging not only 
the object photographed (in this case the seed) but also the grain. The seed 
and the grain have both been enlarged 5 times in the x50 print, and the grain 
can^ easily be seen with an ordinary hand-lens, or even without a lens if one 
has a sharp eyesight. It is this magnified grain that is mainly responsible 
for the lack of sharpness in the x50 print and not lack of focus. In fact 
this magnified grain shewing so sharply in the x50 print is an indication that 
the focus was really sharp rather than otherwise. 
What 1 have said in the last paragraph may be nothing new to you but it 
leads up to what follows. The smallest stop in your Hicro-Tessar lens is 
only about half the diameter of the smallest stop in our Hicro-Summar lens 
here, otherwise the two lenses are essentially identical except that yours 
will give less blurring of outline that is slightly out of focus than will 
ours; in other words yours will give a deeper field with less out-of-focus 
blurring than will ours. So far as the "grain* is concerned 1 imagine there 
will be little or no difference between the two lenses, as both are made by 
expert lens makers. An enlargement from a negative (or print) made with either 
wouhd would show the enlarged "grain" identically the same, assuming that the 
focussing has been the same in both cases. 
The only way, so far as 1 know, of getting rid of this magnified "grain"’ 
is to enlarge directly from the seed to the size negative you want (i.e., x50). 
This can be dene with a very long bellows (6 to 7 feet) on a camera along the 
lines mentioned in the second paragraph of my letter of the 21st. It can 
also be done with a stronger lens and shorter bellows but with some loss of 
depth of focal plane. If -1 can think up some method of focussing the large 
studio camera, and perhaps 1 can, 1 think the principal snag will have been 
surmounted. If 1 should recommend making some alterations along the^ lines 
suggested 1 think the Department here at Brown would be willing to bear the 
expense, for it would make their camera more useful to them. More later. 
1 will mail you the Lraua and mdwigia prints early next week as 1 am 
uncertain about getting up to Cambridge before April 6. 
Sincerely, 
ft 
