### D40 : Kit lens (18-55mm Nikkor Af-S G)

You need to watchout for depth of field at 55mm. I have to reprogram myself after 4 years of using a compact. I keep thinking f5.6 is 'Ok for things at inifinity, like that building over there'

But it ain't. You have to do tricks like 'hyper focus', i.e. focus at infinity (like a building behind this one) and then recompose, or stop down the lens more.

Lets actually work this out:
Circle of confusion (Zeiss formula)
c = d/1730
where d = sqrt(23.7^2 + 15.6^2) = 28.37mm
c = 0.0164mm

Hyper focal distance (Wikipedia)
H = f^2/Nc
f = 55mm
N = 5.6

H = 32937.71 mm = 32 m

The building was probably 10-15m away, and I focused on that, reducing my DOF. I should have kept my aperture at around

N = f^2/Hc = 55^2/(15000*.0164) = f12 for a good shot.

Alternatively, I should have focused on the farthest part of the building, locked focus and recomposed.

Stop down the lens Kaushik, stop it down. This 'ere's a REAL camera :)

### Python: Multiprocessing: passing multiple arguments to a function

Write a wrapper function to unpack the arguments before calling the real function. Lambda won't work, for some strange un-Pythonic reason.

import multiprocessing as mp def myfun(a,b): print a + b def mf_wrap(args): return myfun(*args) p = mp.Pool(4) fl = [(a,b) for a in range(3) for b in range(2)] #mf_wrap = lambda args: myfun(*args) -> this sucker, though more pythonic and compact, won't work p.map(mf_wrap, fl)

### Flowing text in inkscape (Poster making)

You can flow text into arbitrary shapes in inkscape. (From a hint here).

You simply create a text box, type your text into it, create a frame with some drawing tool, select both the text box and the frame (click and shift) and then go to text->flow into frame.

UPDATE: