Your astrophotography copilot
Detail check
Will your camera and telescope put enough pixels on the target you want? Pick a setup and a target, and see how big it comes out, how much of the frame it fills and how much detail to expect. Add a second setup to compare them.
Lots of pixels. Fine detail will be limited by your sky and focus, not the camera.
- M42 across
- 2,367 px
- Pixel scale
- 2.15″ per pixel
- Frame
- 1.80° × 1.80°
- Sensor
- 3,008 × 3,008 px
- Finest real detail
- about 4.3″
- Details across the target
- about 1,184
About 1 to 1.5 pixels across a star: a little coarse, which is common for wide-field rigs. Stars stay fine at normal viewing sizes, and drizzle integration can win some detail back.
Zenithstar 61 II + SV605MC / SV605CC and Seestar S50
Each target below fits one frame on both setups, so this is about the pixels, not the framing. The score is how many real details land across the target at your seeing (0 to 100), and the list is ordered by the weaker setup, so every target here is decent on both. Tap one to check it above. Use Compare with another setup to change the second one.
This is a guide, not a measurement. It uses the target’s longest dimension from the catalog and counts the finest detail as the largest of your star size, twice your pixel size and your telescope’s own sharpness limit. Many bright targets are bigger or fainter than their catalog size suggests, and the thresholds are rules of thumb.
- How is this different from the field of view calculator?
- The field of view calculator tells you how much sky your setup covers. This tool adds a target and your pixel size, and answers a different question: once the target is in the frame, are there enough pixels on it to show detail?
- What does "finest real detail" mean?
- A picture can only show detail as fine as its blurriest limit. The tool takes the largest of three numbers: the width of a star in your sky (set by seeing and tracking), twice your pixel size, and your telescope's own sharpness limit. Dividing the target's size by that number gives the count of separate details that fit across it.
- Why does the verdict say a target is too small when it is in the frame?
- Because fitting in the frame and showing detail are different things. A small planetary nebula can sit neatly in the middle of the frame and still be only a few dozen pixels across. It will look like a small disc, not a structure. A longer focal length or a camera with smaller pixels spreads it over more pixels, though only up to what your sky allows.
- Would a camera with more megapixels fix it?
- Only up to a point. Once a star spans more than about three pixels, extra pixels stop adding detail and only make each pixel noisier. The sampling line under each result tells you where you are. See the megapixels guide for the full story.
- How reliable are the thresholds?
- They are rules of thumb. Under about 25 separate details across the target reads as too small to show structure, 25 to 80 as modest, 80 to 250 as good and over 250 as rich. Target sizes come from the catalog's longest dimension, which for faint nebulae is often smaller than what long exposures reveal.
More on pixel size in Megapixels, pixels & noise, and your frame size in the field of view calculator.