(12C) Hyperfocal Distance

[Dieter]

(04-30-2018 09:22 AM)Gamo Wrote:  Hyperfocal Distance is the closest distance at which a lens can be focused while keeping objects at infinity acceptably sharp.

Ah, great – finally something photography related. ;-)

(04-30-2018 09:22 AM)Gamo Wrote:  Formula: H = (f^2 / Ac) + f

A simple formula – no need to waste three registers for this.
Hey, it's RPN – you can do such things directly on the stack:

Code:

01  RCL 0
02  0
03  +
04  x
05  X<>Y
06  ENTER
07  x
08  X<>Y
09  /
10  +
11  EEX
12  3
13  /
14  GTO 00

Note: the CoC is assumed to be stored in R0 here.

The trick here is the "0 +" which pushes the focal length to T and pops it back to Z. This way it fills the higher stack registers and can be conveniently added in step 10.

But it's still 14 steps. So here is the definite nerd version:

Code:

01  RCL 0
02  0
03  +
04  x
05  /
06  x
07  +
08  EEX
09  3
10  /
11  GTO 00

That's better. ;-)

Hint: After step 04 has been executed A·c is in X and the rest of the stack is filled with f. So the next steps calculate f/Ac, then f·f/Ac, and finally f·f/Ac + f.

You don't even have to prestore the CoC in R0 (or R2). If you want to, you can also pass it on the stack: Simply replace the initial "RCL 0" with an ENTER (just to be sure to terminate number entry, you can also simply remove the first line).

This way you can type  f [ENTER] A [ENTER] c [R/S]

35 [ENTER] 11 [ENTER] 0,03 [R/S] => 3,75

Dieter