I have compared the telephoto optics and sensors of each smart scope, and THINK I’ve done a reasonable analysis. However, I am unable to see a clear “winner.”
Telephoto Optics
Dwarf 3: 150mm fl, 35mm aperture, f3.85, 4 or 5-element APO
S30 Pro: 150mm fl, 30mm aperture, f/5, 4-element APO
Slight nod to the Dwarf on aperture, but lens sharpness and correction is not accounted for
Sensors
Dwarf 3
Sensor: IMX678 Starvis 2
Frame size: 1/1.8” (8.86mm diag.)
Pixel Pitch: 2.0um
Resolution: 3840x2140, 8.3 Mpx
Well depth: 11.6 ke
Read noise: 2.43 - 0.42e
QE: 83%
ADC: 12-bit
SNR: 42dB
FOV: 2.93 x 1.65 deg or
2.75 arc-sec/px
Seestar S30 Pro
Sensor: IMX585 Starvis 2
Frame size: (12.85mm diag) 11.2x6.3 mm
Pixel pitch: 2.9um
Resolution: 3840x2140, 8.3 Mpx
Well depth: 47ke
Read noise: 0.8 e
QE: 91%
ADC: 12-bit
SNR: 88dB
FOV: 4.3 x 2.4 deg
3.99 arcsec/px
Sensor-wise, the advertised S30 Pro seems to have the upper hand: its IMX585C is a 50% larger sensor than the Dwarfs IMX678. The 585 sensor also has about 4x more full well capacity, and an additional 46db of SNR (88dB vs 42dB). Read noise, from what I could find, is about the same. The Dwarf 3’s sensor pixels are about 1/3 smaller, which (per Astronomy Tools) allears to be a better match for the focal length. The FOV of the Dwarf 3 is about 2.75 arc-sec/pixel, whilst that of the S30 Pro is 3.99 arc-sec/pixel.
In comparison, my Ha-modified T3i with my 150mm f/4 Sonnar lens has an FOV of 5.9 arc-sec/pixel. My ASI294MC, coupled with my AT70ED scope and 0.8x flattener/reducer, has an FOV of 2.78 arc-sec/pixel - an even match with the Dwarf 3.
I am attracted to the sensor capabilities of the IMX585, but am a bit concerned about the FOV per pixel. Would I come to regret that in the long term, or would I be better off with the better well depth of the 585 chip? I’d appreciate your thoughts.
Clear Skies to All!
Edited by martinontheroad, 11 June 2025 - 10:24 AM.