Casio EX-FH20: Crop Factor, NPF Rule & Hyperfocal Chart

Name: Casio EX-FH20
Brand: Casio

The Casio EX-FH20 uses the built-in lens (fixed-lens camera) with a 5.68× crop factor (about 6.3 × 4.2 mm sensor). Below: equivalent focal lengths, maximum shutter speeds for sharp stars, a hyperfocal distance chart and how to check the shutter count.

Mount

Fixed lens

Crop factor

5.68×

Sensor (approx.)

6.3 × 4.2 mm

Circle of confusion

0.0053 mm

Equivalent focal length & field of view

Lens focal length	Full-frame equivalent	Diagonal FOV	Horizontal FOV
8 mm	45 mm	50.6°	43.0°
10 mm	57 mm	41.5°	35.0°
12 mm	68 mm	35.0°	29.4°
14 mm	80 mm	30.3°	25.4°
16 mm	91 mm	26.6°	22.3°
18 mm	102 mm	23.8°	19.9°
20 mm	114 mm	21.4°	17.9°
24 mm	136 mm	17.9°	15.0°
28 mm	159 mm	15.4°	12.8°
35 mm	199 mm	12.3°	10.3°
50 mm	284 mm	8.7°	7.2°
85 mm	483 mm	5.1°	4.2°
135 mm	767 mm	3.2°	2.7°

Multiply by the 5.68× crop factor for the full-frame equivalent field of view.

Milky Way exposure: NPF and 500 rule

Focal length	NPF @ f/1.8	NPF @ f/2.8	Strict NPF @ f/2.8	500 rule
8 mm	16.9 s	21.2 s	11.6 s	11.0 s
10 mm	13.5 s	17.0 s	9.3 s	8.8 s
12 mm	11.2 s	14.2 s	7.7 s	7.3 s

NPF = (35 × f-number + 30 × pixel pitch) ÷ focal length, with a pixel pitch of 2.4 µm (typical for this format — exact resolution not in our database). The strict version (Michaud's detailed NPF for the galactic core) gives pin-point stars at 100% view; the 500 rule is a loose rule of thumb that shows trailing on modern sensors.

Hyperfocal distance chart

Focal length	f/2.8	f/5.6	f/8	f/11	f/16
10 mm	6.7 m	3.4 m	2.4 m	1.7 m	1.2 m
14 mm	13 m	6.6 m	4.6 m	3.4 m	2.3 m

Focus at the hyperfocal distance and everything from half that distance to infinity is acceptably sharp (circle of confusion 0.0053 mm). Use the hyperfocal calculator for other settings.

How to check the Casio EX-FH20 shutter count

Not every maker writes a shutter count into image files. Try `exiftool -a -G1 -s image` on an unedited original and look for a tag containing "Shutter" or "Count".

ExifTool tag: (varies). Always test an original, unedited file straight from the card.

Where to buy

Compare new and used prices at these retailers:

B&H Photo Amazon KEH (used)MPB (used)

FAQ

What is the crop factor of the Casio EX-FH20?

5.68×. A 24 mm lens frames like a 136 mm lens on full frame.

What shutter speed should I use for the Milky Way with the Casio EX-FH20?

With a 8 mm lens at f/2.8, about 21 seconds keeps stars sharp (NPF rule).

How do I check the shutter count on the Casio EX-FH20?

Not every maker writes a shutter count into image files. Try `exiftool -a -G1 -s image` on an unedited original and look for a tag containing "Shutter" or "Count".