Is 9 MP zwo output enough for prints

[Sreesha]

I intend to print 18 x 24 inches.  Is ZWO astro camera with 9 MP enough reso for this?

[pete_l]

The "industry standard" for glossy magazines is 300dpi (pixels per inch). Your camera will be about 3300 x 2500. So in theory, if you were publishing for Vogue or somesuch, then no. However in practice it will be fine.

The reason is that the larger a print (or screen), the further away people view it from. So the 300dpi rule isn't really anything more than a historical fiction for people who revel in searching out imperfections, rather than enjoying the big picture (literally 🙂 ). For example, a 27 inch (diagonal) monitor is a little less than 600mm wide. A 1920x1080 image viewed at a normal distance is perfectly acceptable. Even though it is only 3.2 pixels per millimetre or 80 DPI.

[Sreesha]

Okay thanks.  So then if I print at 18 x 24 and see if from a close distance say 1 feet, it will look fine?

[ollypenrice]

How do you define what's acceptable? Simply turning camera pixel count into print DPI ignores the resolution in arcseconds per pixel at which the image was captured. Ultimately the quality of the image depends on its resolution in arcseconds per pixel, its eventual signal to noise ratio and the skill of the processor in terms of noise reduction, sharpening and many other things. I don't think you can just say, 'This chip can be printed out at that resolution.' This may or may not be possible with daytime images (I don't know, I don't take them other than casually) but astrophotos are different. They have been highly stretched and heavily processed and they are often seeing-limited in resolution. 

Olly

[wimvb]

You can always resample the image to get any nr of pixels you like, but it won't get you any more detail. 

The only resampling that can get you slightly more detail is drizzle integration. You'll need a fairly large number of subs that are (somewhat) undersampled. It comes at a cost of reduced signal to noise ratio. (There ain't no such thing as a free lunch. Certainly not in astrophotography.)