109 
Synopsis of Magnifiers. 
No. 
Type 
Magni- 
fication 
i \J\j<X)L 
distance 
mm 
field 
mm 
Price 
Mks 
6 
34 
18 
12 — 
78 
Steinheil 
12 
20 
20 
10 
9 
3.5 
12.— 
12.- 
aplanatic lenses 
< 
7Q 
to 
Improved 
aplanatic lenses 
i 
\ ' 
32 
12 
30 
15 
15.— 
15 — 
a) 
17 
13 
4 
6.— 
80 
Doublet < 
.) 
33 
5 
2 
6.— 
Ic) 
70 
2.5 
1.2 
9.— 
81 
and 
82 
Magnifier 
10 
13 
14 
4. and 6.-r- 
83| 
Brucke 
5 
70 
20 
11 — 
841 
dissecting" lenses 
5—10 
70—60 
13—7 
30 — 
Remarks. The magnification is calculated for a normal image distance 
of 250 mm (10"). 
The focal distance is the distance between the object and the lower 
surface of the lens, as adjusted by a normal-sighted observer. 
The distance given above is rather smaller with short - sighted and greater 
with long-sighted persons. 
The same applies to the given linear diameter of the field. 
These values are , therefore , only approximated and intended to give a 
rough idea. 
