Sunspots this morning

[geppetto]

Took a few AVI's of the sunspots this morning.

Bloomin hot out there :sunny:

When I've cooled down a bit, I might try getting an afocal shot

with my Nikon 5400.

[Grant]

Great image geppetto, I really do love seeing solar images!

Looking forward to your afocal shots if you get some

[geppetto]

This one using the Nikon 5400 afocal to get a full disc image.

[daz]

Great shots Phil!!!

I have been playing with my new 350D and the PST, and have a couple of shots I'll post up later.

[mark_smith]

Great Picture just getting into solar observations myself keep up the good work.

mark_smith

[Astroman]

What filter are you using, Phil? May I use one of these in a talk I'm giving in July?

[geppetto]

What filter are you using

Its a piece of Baader Planetarium Astro Solar Filter Safety Film

fitted into an end cap which covers the front end of the scope.

Fairly cheap and cheerful but works very well

<......May I use one of these in a talk I'm giving in July.....> by all means

[Astroman]

Thanks. I asked because the color looks like an Orion glass solar filter. Is this the color it looks normally? Baader film usually appears bluish white to my eyes unless an eyepiece filter is inserted.

[FLO]

Why is the outer edge darker than the center?

[Astroman]

Limb Darkening. Since the Sun is a ball of plasma, (gas), when we view it straight on in the middle, we look straight through the gas. When seen along the edge, we're looking through a lot more gas, so it appears darker.

[geppetto]

Re the colour, both the Toucam and the Nikon tend to colour the sun shots

when they are set to auto white balance.

I sort of like the tint and tend to leave it but I suppose its not

technically correct.

Some of the darkening around the rim might be down to the camera setup.

I have to crank everything back to fit a full disc into the Nikon's field of view

and its just on the edge of vignetting with the 1.25" afocal adaptor.

Again it sort of looks nice, I think it makes the sun more of a 3D globe than

a flat disc.

Interesting info about Limb Darkening, something else new that I've learned today 8)

[Astroman]

The darkening at the top of the second photo is due to vignetting. At the bottom, it's limb darkening.

[FLO]

Limb Darkening. Since the Sun is a ball of plasma, (gas), when we view it straight on in the middle, we look straight through the gas. When seen along the edge, we're looking through a lot more gas, so it appears darker.

I follow your explanation but surely its the other way around. We look thru more at the center and less at the edge?

[Astroman]

Nope. Think of the atmosphere here on Earth. Looking straight up, you look through what, 6 miles of atmosphere? Watching the Sun set you look through maybe 60 miles. Same on the Sun, only orders of magnitude higher.

[FLO]

I am sure you are right but, the atmosphere on earth isn't glowing. If we look into the center of a fire it is hotter/brighter than at the edge.

Just trying to understand

[Astroman]

Plasma doesn't behave as a chemical fire does. It's more uniform across the Sun because the Sun is almost a million miles across. When we look straight into it, it's more or less transparent for about 5,000 miles. Along the edge, it's more on the order of 70 or 80,000 miles. That's a lot of gas. You can check this out in Jay Pasachoff's fine book, "Nearest Star". I highly recommend it.

[FLO]

I understand - thanks AM

[geppetto]

Yes, thanks AM, very interesting 8)

[Greg]

Excellent photo's Phill...

Thanks for the solar lesson AM..Very good read.

I'm just starting on this branch of astro..When I started this hobby I was reluctant to look at the sun because of safety reasons and I didn't think much happened to it!

How things have changed over the last 2 years!!!

Greg (Solar apprentice!!)

[Jamie]

How things have changed over the last 2 years!!!

Greg (Solar apprentice!!)

Yep you have come a long way mate.

Jamie (life apprentice)