How much magnification can lucky imaging help with ?

[powerlord]

Last time I shot the moon I think I used my 9.25 with 6.3 reducer and just my asi1600, since I was also shooting DSO stuff that night. So not very good fps, but good FOV. And the shot was good enough that it's now an 80cmx80cm canvas print on my wall 🙂

Obviously I could shoot without it.. but I assume also I could use my 2x barlow ? that's take me to 4700mm. and then use my ASI224 ?

I'll just capture a tiny wee bit, but at very high FPS. I'm interested in just what the limit is I can get from lucky imaging ? I know I'm hardly the first, and probably I'm wasting my time, but just feels like a cool experiment. Probably the moon guru, @neiil phillips will be able to tell me ?

anyhoo, that's the plan for wed night - shoot apollo 15 or 17 landing site. I am expecting to see the lander and flag flying 🤪

stu

[vlaiv]

13 minutes ago, powerlord said:

but I assume also I could use my 2x barlow ? that's take me to 4700mm. and then use my ASI224 ?

Actually no

Optimum F/ratio depends on pixel size, and there is simple formula to calculate it:

F/ratio  = pixel_size * 2 / wavelength

(pixel_size and wavelength are in same units - say µm or mm. Wavelength is best used 500nm for color images or exact wavelength for narrowband - say 656 for Ha if you shoot the moon with Ha filter or 850nm if you use IR pass filter).

F/ratio = 3.75µm * 2 / 0.5µm = 15

F/15 for ASI224

You actually need x1.5 barlow for C9.25 as it is F/10 scope.

 

 

[powerlord]

Ok thanks Vlaiv, but I don't have a 1.5x barlow. Just have to make do with what I've got. With IR pass that comes out to 8.8.. so not so bad ?

[Nik271]

If you can adjust the distance of the barlow lense to the sensor you could convert it to 1.5x barlow, the closer it is to the sensor the less magnification factor.  

[vlaiv]

21 minutes ago, powerlord said:

Ok thanks Vlaiv, but I don't have a 1.5x barlow. Just have to make do with what I've got. With IR pass that comes out to 8.8.. so not so bad ?

Like Nik said - actual magnification of barlow lens depends on sensor distance.

You can measure it during the day - just insert camera with / without barlow and record some distant feature that you can use to measure pixel scale with - say building or tall pole or whatever. Just measure length of it in pixels in regular and barlowed image and ratio of the two will give you magnification.

If you have barlow element that can be screwed off the body - then you can use different extensions to dial in magnification.

[powerlord]

ah, ok. will try that. thanks.

 

stu