Epson R-D1: Crop Factor, NPF Rule & Hyperfocal Chart

Name: Epson R-D1
Brand: Epson

The Epson R-D1 uses the Leica M mount with a 1.52× crop factor (about 23.6 × 15.7 mm sensor). Below: equivalent focal lengths, maximum shutter speeds for sharp stars, a hyperfocal distance chart, compatible lenses and how to check the shutter count.

Mount

Leica M

Crop factor

1.52×

Sensor (approx.)

23.6 × 15.7 mm

Circle of confusion

0.0197 mm

Equivalent focal length & field of view

Lens focal length	Full-frame equivalent	Diagonal FOV	Horizontal FOV
8 mm	12 mm	121.1°	111.7°
10 mm	15 mm	109.6°	99.4°
12 mm	18 mm	99.5°	89.0°
14 mm	21 mm	90.7°	80.3°
16 mm	24 mm	83.1°	72.8°
18 mm	27 mm	76.4°	66.5°
20 mm	30 mm	70.6°	61.1°
24 mm	37 mm	61.1°	52.4°
28 mm	43 mm	53.7°	45.7°
35 mm	53 mm	44.1°	37.3°
50 mm	76 mm	31.7°	26.6°
85 mm	130 mm	18.9°	15.8°
135 mm	206 mm	12.0°	10.0°
200 mm	305 mm	8.1°	6.8°
300 mm	458 mm	5.4°	4.5°
400 mm	610 mm	4.1°	3.4°

Multiply by the 1.52× 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	22.5 s	26.9 s	14.5 s	41.0 s
10 mm	18.0 s	21.5 s	11.6 s	32.8 s
12 mm	15.0 s	17.9 s	9.7 s	27.3 s
14 mm	12.9 s	15.4 s	8.3 s	23.4 s
16 mm	11.2 s	13.4 s	7.3 s	20.5 s
18 mm	10.0 s	11.9 s	6.5 s	18.2 s
20 mm	9.0 s	10.8 s	5.9 s	16.4 s
24 mm	7.5 s	9.0 s	4.9 s	13.7 s
28 mm	6.4 s	7.7 s	4.2 s	11.7 s
35 mm	5.1 s	6.1 s	3.4 s	9.4 s

NPF = (35 × f-number + 30 × pixel pitch) ÷ focal length, with a pixel pitch of 3.9 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	1.8 m	0.9 m	0.6 m	0.5 m	0.3 m
14 mm	3.6 m	1.8 m	1.3 m	0.9 m	0.6 m
16 mm	4.7 m	2.3 m	1.6 m	1.2 m	0.8 m
18 mm	5.9 m	3.0 m	2.1 m	1.5 m	1.0 m
20 mm	7.3 m	3.6 m	2.6 m	1.9 m	1.3 m
24 mm	10 m	5.2 m	3.7 m	2.7 m	1.9 m
28 mm	14 m	7.1 m	5.0 m	3.6 m	2.5 m
35 mm	22 m	11 m	7.8 m	5.7 m	3.9 m
50 mm	45 m	23 m	16 m	12 m	8.0 m

Focus at the hyperfocal distance and everything from half that distance to infinity is acceptably sharp (circle of confusion 0.0197 mm). Use the hyperfocal calculator for other settings.

Compatible lenses (2 in our database)

Lens	Focal length	Max aperture	Mount
Voigtländer Nokton 28mm F1.5 Aspherical	28 mm	f/1.5	Sony E, Nikon Z
Venus Laowa 85mm f/5.6 2X Ultra Macro APO	85 mm	f/5.6	Sony E, Canon RF

Native and adapter-free compatible lenses from the Lensfun database. Third-party and adapted lenses may also work.

How to check the Epson R-D1 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)

Other Leica M cameras

FAQ

What is the crop factor of the Epson R-D1?

1.52×. A 24 mm lens frames like a 37 mm lens on full frame.

What shutter speed should I use for the Milky Way with the Epson R-D1?

With a 8 mm lens at f/2.8, about 27 seconds keeps stars sharp (NPF rule).

How do I check the shutter count on the Epson R-D1?

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".

Which lenses fit the Epson R-D1?

Lenses for the Leica M mount — 2 are listed above.