diegop

Wow! Thanks a lot vlaiv, i am left speechless. I will try to understand everything and i'll write you back with doubts

Best regards

58 minutes ago, vlaiv said:

Yes of course it is - provided that you have enough precision.

You need to know plate scale / your sampling rate - it can also be measured or calculated.

For calculation you need to know focal length of your lens and your camera pixel size, and this will give you arc seconds per pixel. Alternatively - take one image of the known part of the sky - identify two stars. Measure distance in pixels between two stars (in imageJ - line selection tool will give you distances. Measure distance between two stars in Stellarium using angle measure tool.

Divide two values to get arc seconds / pixels measure.

Another alternative is to upload image to astrometry.net and have it plate solved - this will give you pixel scale as well.

Now that you have pixel scale - open both images in ImageJ and create small stack out of them (stack in imagej is just sequence of images). Z-project them using max - this will give you image where you'll have stars from both images visible. Identify same star that is duplicated and measure distance in pixels it moved.

Take pixel scale and multiply with distance in pixels - this will give you arc seconds that image moved between shots.

Alternative - upload both images to Astrometry.net, have them both plate solved - it will give you centers in RA/Dec coordinates - and just calculate distance in arc seconds between those two points in RA/DEC.

By the way - welcome to SGL

Hello vlaiv,

what an awesome answer. Many thanks, really appresiated. I am a completly beginner in AP and i think that starting learning the basis should be the best.

I am just starting with what i have at home. 

Hello vlaiv, many thanks

what an awesome answer. Much appreciated. I am a completly beginner in AP and i think that starting learning the basis should be the best. I have never use ImageJ and i have try to calculate such thing as this, but i want to learn

I am just starting with what i have at home. Sorry but i am not already familiar with this concepts:

• plate scale
• sampling rate

Telescope

Refractor Skywatcher 102/1000 (i know is too slow for AP, i am using it to just start learning)

Mount

EQ3-2 helios skycan 2001

Camera

Old compact camera Nikon coolpix l15

https://www.digicamdb.com/specs/nikon_coolpix-l15/

Focal length (35mm equiv.):    35 - 105 mm

So the data i first need to know is:

pixel scale (is it the same that plate scale?) 

Seems the Astrometry.net alternative should be more easy, i'll try first the astrometry.net method and then with ImageJ because i really would like to learn measure it with the imageJ.

let's do it!

Best

Hello All

i wonder if is it possible to measure the deviation between two images in degrees. What i am trying to do is measuring the backslash of a telescope equatorial mount. I attach a digital camera and i take two pictures,i would like if i can measure the deviation between both images using imaging software (like imajeJ or another one). 

The camera is attached this way

Best