Jump to content

NLCbanner2024.jpg.2478be509670e60c2d6efd04834b8b47.jpg

Slow cook Jupiter, Sept 1st

Starman

By Starman
in Imaging - Planetary

Recommended Posts

skybadger

skybadger

Posted
Posted

Hi Pete

You can't get away with posting that wonder without posting the details of how it was collected, what scope, the seeing and post processing. Especially since I'm trying hard to improve mine and need all the advice I can get.

Other than that, entirely passable. :>

regards

Mike

Link to comment
Share on other sites
Starman

Starman

Posted
  • Author
Posted

I can Mike and I did :o

The full details will be on the final result, this was just a heads up while the other channels are processing (and they look quite nice!). The scope was a C-14 and I was using a 2x Barlow (f/35) + Astronomik RGB filters, or rather, just the R in this case. The camera was a Lumenera SkyNyx 2-0M.

Link to comment
Share on other sites
barkis

barkis

Posted
Posted

That taster looks fantastic Pete. That C14 must be some instrument, though I know it takes a lot more to create something this good.

I'm a lIttle perplexed over the F35 from the x2 Barlow, unless it was extended in some way, or your C14 is F17.5 :o.

Ron.:)

Link to comment
Share on other sites
Starman

Starman

Posted
  • Author
Posted

The f/35 is estimated Ron - I still need to measure it properly to get the final value, but I believe it's about right.

Between the Barlow and the scope there's a filter wheel which effectively extends the Barlow and increases it's power to about 3.2x.

Link to comment
Share on other sites
Starman

Starman

Posted
  • Author
Posted

That's quite straightforward. Simply measure the equatorial diameter of the planet (rotate it first so it's equator is horizontal) in pixels. Then use a program such as WinJupos (Google it and download for free) which will give you the apparent diameter of the planet at the time of the observation. Divide this figure (arcseconds) by the measured number of pixels in the diameter to give you your image scale in arcseconds/pixel - call this value A.

To calculate the effective focal length, use the formula

F = 206 * Dp / A, where Dp = the size of your camera's pixels in microns.

As an example, for me last night, my Jupiter images measure 360 pixels wide. The diameter of Jupiter was 49.1" so this gives me an image scale (A) of 0.136"/pixel.

The size of my camera's pixels is 7.4 microns. So the calculation is...

F = 206 * 7.4 / 0.136

F = 11209mm

My scope has a diameter of 350mm so this gives me an effective f/ratio of f/32, slightly less than f/35 that I'd estimated. Excellent, room to push a bit further then :o

I have used extensions between the filter wheel and Barlow before, yes. I'm not using this technique at the moment though.

Link to comment
Share on other sites
Starman

Starman

Posted
  • Author
Posted

It's not a dumb question at all. The quickest way to do it is to rotate the planet so that it's horizontally aligned on the image and then use a rectangular selection marquee to select a strip of the planet from one side to the other. Copy this selection and if your editor supports it, create a new image from it. The width of the new image will be the width of the planet.

Link to comment
Share on other sites
skybadger

skybadger

Posted
Posted

There is a stock formula to calculate the effective focal length usiing barlow projection, depends on the fpcal length of the barlow, the distance of the barlow inside focus and the distance between the barlow and the camera plane. Its in Covington somewhere (and others).

Mike

Link to comment
Share on other sites

Archived

This topic is now archived and is closed to further replies.

Go to topic listing

  • Recently Browsing   0 members

    • No registered users viewing this page.
×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue. By using this site, you agree to our Terms of Use.