Light Gathering Power vs Eye Calculator
Effective unobscured collecting area×independent throughput relative to eye pupil, not visual surface-brightness gain or photopic sensitivity. Model only, not an ephemeris, measured stellar identity or observational guarantee.
Description
Clear collecting area and optical throughput affect relative photon collection.
Clear collecting area and optical throughput affect relative photon collection.1
That area ratio is distinct from perceived visual brightness or usable resolution. Use Light Gathering Power vs Eye Calculator to evaluate the supplied inputs under the model explained below.
When to use Light Gathering Power vs Eye Calculator
Use Light Gathering Power vs Eye Calculator to evaluate the supplied inputs under the model explained below. Establish the units, measurement scope and model assumptions before entering values.
How to use Light Gathering Power vs Eye Calculator and understand its results
- Establish the units, measurement scope and model assumptions before entering values.
- Enter Aperture diameter mm, Central obstruction diameter mm, Eye pupil diameter mm, Caller optical throughput fraction using the field table and validation rules below, then run the tool.
- Read Conditional relative photon collection; interpret the units, signs, ordering and unknown-value placeholders described below.
- Correct reported input errors and rerun. Apply successful results according to their specific meanings and check the assumptions before using them in a decision.
| Input field | Meaning | Value type | Requirement |
|---|---|---|---|
| apertureDiameterMm | Aperture diameter mm | number | Required; constraints below |
| centralObstructionDiameterMm | Central obstruction diameter mm | number | Required; constraints below |
| eyePupilDiameterMm | Eye pupil diameter mm | number | Required; constraints below |
| callerOpticalThroughputFraction | Caller optical throughput fraction | number | Required; constraints below |
Enter positive aperture and eye-pupil diameters, nonnegative obstruction diameter smaller than aperture, all in mm, and optical throughput from 0 to 1. Return clear squared-diameter area divided by eye squared diameter, times throughput. Zero throughput returns zero; no visual-brightness or point-source detection model is supplied.
relativePhotonCollection=((aperture²−obstruction²)/eyePupil²)×throughput Use the field order, units and branch conditions described above.
| Output field | Meaning | Value type |
|---|---|---|
| conditionalRelativePhotonCollection | Conditional relative photon collection | number |
{
"input": {
"apertureDiameterMm": 100,
"centralObstructionDiameterMm": 20,
"eyePupilDiameterMm": 5,
"callerOpticalThroughputFraction": 0.8
},
"output": {
"conditionalRelativePhotonCollection": 307.20000000000005
}
}Limitations and assumptions
That area ratio is distinct from perceived visual brightness or usable resolution. Apply the exact scope and assumptions explained above.
All listed fields require explicit values. Unexpected fields, incorrect types, nonfinite numbers and sparse arrays fail validation. Domain-specific bounds, alignments and supported tokens are explained above; extremely large inputs or outputs can also be rejected. Input errors differ from successful false results, empty match lists and unknown-evidence placeholders.
Alternative or Complementary methods
Use Aperture Area cm² Optics Calculator for a related task: A central obstruction subtracts area from a telescope's circular collecting pupil.
Use F-Ratio Image Brightness Factor for a related task: Extended-source image irradiance scales with the inverse square of focal ratio under matched conditions.
References
-
Light Gathering Power vs Eye Calculator — tool.io
Similar or alternative tools
- Aperture Area cm² Optics Calculator
A central obstruction subtracts area from a telescope's circular collecting pupil.
- F-Ratio Image Brightness Factor
Extended-source image irradiance scales with the inverse square of focal ratio under matched conditions.