Linked astronomy tools
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
Use Imaging Planner to balance focal length, sensor size, and seeing before you commit to a capture setup. Start with one telescope and one camera, then compare reducer, barlow, or binning changes one at a time.
How it works
The page computes effective focal length, field of view, pixel scale, diffraction limit, and seeing-based sampling guidance from the setup you enter. Treat the output as a planning pass for framing and sampling, then verify the exact target timing or charting in the next astronomy tool only after the imaging setup is coherent.
When to use
Use this page when you want to decide whether a scope and camera combination fits the target and whether the sampling is reasonable for your local seeing. It is most useful before a session, when comparing optical accessories, or when preparing a shareable setup note.
Common mistakes to avoid
- Changing focal length, reducer, and binning all at once, which makes it hard to see which choice fixed or broke the setup.
- Comparing two rigs without checking that sensor dimensions and pixel size were entered in the same mode.
- Treating undersampled or oversampled labels as absolute pass/fail rules instead of seeing-based guidance.
- Skipping the next-step astronomy tool after the setup looks correct and before the actual target framing is checked.
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 enter first for an imaging plan?
Set sensor, lens or focal length, target size, and working distance first. Then compare field of view, pixel scale, or framing changes one parameter at a time.
Why can an imaging plan results differ from nearby tools?
Differences usually come from sensor size, focal length, distance, target size, and pixel scale assumptions. Match those assumptions before comparing this result with another CalcBE page, spreadsheet, or external tool.