How to read A/B codes
Quick start (3 steps)
- Pick scope/camera presets or enter custom values.
- Choose input mode (sensor or pixel).
- Compute to get Field of View (FOV), arcsec/px, diffraction limits, and sampling guidance.
Inputs
Summary
FOV preview
Details
Definitions & notes
- Effective focal length is focal_length × reducer × barlow.
- FOV uses geometric sensor projection: 2 * atan(sensor / (2 * focal)).
- Pixel scale uses 206.265 * pixel_size(um) * bin_x / focal(mm).
- Sampling label is seeing-based guidance, not an absolute quality verdict.
- CSV column order is fixed for workflow compatibility.
How to use this calculator effectively
This guide helps you use Imaging Planner (FOV, Pixel Scale, Resolution) in a repeatable way: define a baseline, change one variable at a time, and interpret outputs with explicit assumptions before you share or act on results.
How it works
The page applies deterministic logic to your inputs and shows rounded output for readability. Treat it as a comparison workflow: run one baseline case, adjust a single parameter, and measure both absolute and percentage deltas. If a result seems off, verify units, time basis, and sign conventions before drawing conclusions. This approach keeps your analysis reproducible across teammates and sessions.
When to use
Use this page when you need a fast estimate, a classroom check, or a practical what-if comparison. It works best for planning and prioritization steps where you need direction and magnitude quickly before investing in deeper modeling, manual spreadsheets, or formal external review.
Common mistakes to avoid
- Changing multiple parameters at once, which hides the true cause of output movement.
- Mixing units (percent vs decimal, monthly vs yearly, gross vs net) across scenarios.
- Comparing with another tool without aligning defaults, constants, and rounding rules.
- Using rounded display values as exact downstream inputs without re-checking precision.
Interpretation and worked example
Run a baseline scenario and keep that result visible. Next, modify one assumption to reflect your realistic alternative and compare direction plus size of change. If the direction matches your domain expectation and the size is plausible, your setup is usually coherent. If not, check hidden defaults, boundary conditions, and interpretation notes before deciding which scenario to adopt.
See also
FAQ
What does 206.265 represent?
It is the conversion constant used to map focal-plane size to angular size in arcseconds when using millimeters and micrometers.
How should I read undersampled / oversampled?
Those labels compare your arcsec/px to a seeing-based range (seeing/3 to seeing/2). They are planning hints and should be balanced with target size and processing goals.
Can reducer and barlow be set together?
Yes. This planner multiplies both factors and recomputes every derived value from the resulting effective focal length.
What should I do first on this page?
Start with the minimum required inputs or the first action shown near the primary button. Keep optional settings at defaults for a baseline run, then change one setting at a time so you can explain what caused each output change.
Why does this page differ from another tool?
Different pages often use different defaults, units, rounding rules, or assumptions. Align those settings before comparing outputs. If differences remain, compare each intermediate step rather than only the final number.