Proms - Saturday 22nd May 2010

[astroshot]

Some great proms on the Sun this morning.

Images taken with TEC140, Baader 135mm D-ERF, Daystar 0.6A T-Scanner, Celestron f/6.3 focal reducer + DMK21 camera

Let's keep our fingers crossed for a great summer!

Regards,

Michael.

[brianb]

Very nice indeed .... but I'm confused, what's the focal reducer for?

[astroshot]

Gives a wider FOV.

I can change the FOV by varying the distance between camera and FR.

[Beyond_Vision]

Nicely done, some very good detail being picked up

Regards

Kevin

[NickH]

Great setup and beautiful shots

[AztecastroMcJ]

great images

[ASIGN_Baz]

Absolutely wonderful images Michael and a worthy POW.

I was wondering, can you please tell me how you verify/quantify the scale of the planet earth against the sun? I would like to quantify it for some of my shots around the sky. A scale in the image might be interesting too.

Baz.

[brianb]

can you please tell me how you verify/quantify the scale of the planet earth against the sun?

The Sun is 108 Earth diameters ....

[ASIGN_Baz]

The Sun is 108 Earth diameters ....

So you just measure the diameter of your solar photo and divide by 108 to come up with the right size picture of the earth for correct scale?

[womblemaster]

Whats the name of you spaceship, is it parked under the swimming pool?

[stefski]

Spectacular!

[brianb]

So you just measure the diameter of your solar photo and divide by 108 to come up with the right size picture of the earth for correct scale?

Yeah ... actually measuring the diameter isn't easy because you only have a small section of limb but you can measure the distance in pixels between two features, scale that using a measure from a smaller scale image & work bak until the "two features" are opposite points on the limb, which gives you the diameter.

What you can't (or shouldn't) do is assume that stated focal lengths, barlow lens magnifications etc. are accurate, they usually aren't!

[russ]

wow superb set of images. Amazing setup too.

[MrJulius]

Michael superb images, you also have som great B/W deep sky images on your website too

[Yoddha]

Amazing images! Congratulations for wining POW!

[astroshot]

Thanks for the kind words folks. Much appreciated.

Baz,

Good question re scale.

The difficulty in estimating the scale on these images accuratley is due the small amount of the Solar disc edge in the image. I'm a civil engineer and so use AutoCAD every day at work. I simply import a copy of the image into AutoCAD, draw an arc at the edge of the Sun and measure the diameter of the arc.

Sun diameter = 1,400,000 km

Earth diameter = 12,756 km

So, I then draw a circle in AutoCAD on top the image to the appropriate scale to represent Earth, re-save the image, import it back into PS and then accurately apply the Earth as a separate layer to the precise scale.

Sounds much more complicated than it actually is - only takes a minute or two in reality and I save the reference image for future use at the same focal length.

If you want me to do this for a couple of your images so you can set your scale accurately, let me know - no problem.

Regards & Thanks,

Michael.

[Gill Rockwell]

here's how it works .) Radius of an Arc or Segment- Math Open Reference

through a given 3 points you can only draw 1 circle...

looking at the section in your frame i'd say you might be in for quite a margin there .)