ISS with 80mm refractor.

[asimov]

Move this if it's not in the right place mods.:shrug:

A guy I just met on the internet sent me this just now.

Boy I'm impressed!! Taken with an 80mm F11 achro refractor @ F16 & nikon DSLR :thumbsup:

Good on ya Robert!

[[1ponders]]

Oh wow! Now that is a cool shot.

Though I must admit I'm a little suspect of his claims. A nikon DSLR attached to that scope would only give a magnification of around 40X. I'd like to see the original image uncropped to judge the field of view.

According to my calculations (assuming the nikon has a similar chip size to the canon) the field of view should be 38.5 X 58.5 arc min with a resolution of 1.14 arcsec/pixel. If the IIS is 80 m long and orbits at an average of 350 Km then its angular size in arcsecs as viewed from earth is only 47 arcsec. This means in his original image the ISS would have only been 41 pixels long. A standard high res Canon image is 3072 X 2048 pixels. With an uncropped image and the knowing the objects size and distance from us then the imaged resolution can be worked out and finally the telescope f/ratio and focal length.

If you can get the full imaging details I'd love to know how he did it.

[acropolite]

I seem to remember getting the ISS in binos one night and being able to make out some shape at 8x so at 40x it may be possible to capture the detail shown.

[janoskiss]

Paul, the image does look like an enlargement (digital zoom, if you like) from a tiny one, few dozen pixels across.

[Starcrazzy]

WoW. .I don't know whats more i mpressive,,, the shot or ponders Maths...;)

[acropolite]

It should be possible to capture with ToUcam/LPI, it would be interesting to see some stacked frames from that.. :confuse3:

[[1ponders]]

It has been done with a ToUcam many times. If someone doesn't find it before me I'll track the info down tonight.

[[1ponders]]

Ok here are a couple of images taken with longer FL instruments with much higher magnification, greater aperture to provide better resolution and multiple image stacking to improve signal to noise.

The first (http://www.vt-2004.org/photos/images/vt-photo-01-toma.jpg) is an image from here (http://www.vt-2004.org/photos/vt-photos-top01.html)

Another using a Celestron 9.25 (http://www.djcash.demon.co.uk/astro/webcam/spacecraft.htm) and ToUcam

Another interesting one (http://www.eastsideastro.org/observatory/spacecraft/ISS_oct13.jpg) from here (http://www.eastsideastro.org/observatory/spacecraft.html)

To get his shot with a single image with a DSLR through a 80mm scope operating at f/16 (wonder how he did that and still work at prime focus, negative projection using a barlow or teleconverter I guess, or positive eyepiece projection) Everything must have come off just perfect at that moment.

Don't get me wrong. I'm not saying that the image isn't as Asi says it is, but I am a tad scepticle, principally due to the resolution he has achieved with the given aperture of the scope and would really like to know how it was done.

[asimov]

I'm only quoting what the guy told me, but I left out where he used a 1.4X 'converter' ?? to get his F16 & 1/25th exposures....about a dozen stacked in registax...& now you know just as much as I do lol.

I'll be asking some more questions I think...:)

[[1ponders]]

I've just been doing a bit more digging for comparison images and resolution obtainable with an 80mm scope and came across a few Peter K has on his K3CCDTools website of sunspots taken with an 80mm refractor at various focal lengths. A couple of the closeup ones are taken at f/14+ so it is possible to compare them with this one (http://www.vt-2004.org/photos/images/vt-photo-01-toma.jpg) which covers a similar field of view and includes the IIS

The K3 details are here (http://www.pk3.org/Astro/index.htm?sun.htm). Nice shots too.

[ving]

real or not, its a good shot :)

[[1ponders]]

There is no denying that ving. It has great depth contrast that makes it look 3D to me.

[MiG]

"This means in his original image the ISS would have only been 41 pixels long"

That image does look like it's magnified a lot so I think your calculations justify its authenticity.

[asimov]

Heres the original uncropped image. Nearly half a meg so I had to do a bit of compression to get it on here, otherwise untouched.

[[1ponders]]

Man what a difference good seeing makes. That is fantastic focusing as well. I'm willing to heat humble pie :bowdown: That ISS image is only half what I calculated at about 25 pixels in this compressed image. Fantastic processing in the enlargement.

[h0ughy]

All hail ASI's ISS imager. and as for the Ponders school of astrophysics, are you really a mad scientist that teaches horticultural stuff to cover your real identity!

[[1ponders]]

Just a sic puppy h0ughy :D And yes I do teach hort stuff. Gotta pay for this hobby somehow.