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Rusted

Wot no granulation?

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Hi,

Yet another clear, sunny morning but I still can't see any granulation at any power up to 450x in the 7".
Pop the Neximage5 into the Lacerta prism and I see instant and continuous granulation regardless of any supposed "seeing conditions." 

I even dug out my old Baader solar foil, full aperture filter to double check it wasn't the prism.
More false colour on a slightly softer limb [with the foil] filter] but still no granulation.

I did some homework and the chap on S&T says he can see granulation even at 28x in quite a modest refractor.
I've tried countless times to adjust the focus in and out and played with magnification from the ridiculous to the sublime.
Nothing has provided me with my missing surface texture.

And yes, I do have a polarizing filter and a green Baader Solar Continuum and no they don't help. :blush:

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No idea why mate, it's many years since I did any white light observing / imaging, tend to do all HA now.

At least you've got Sun even if there's nothing to see you can top up your tan, cloud here.

Dave :clouds1:

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To put this in context I will quote from Jamey L. Jenkins excellent book Observing the Sun, a pocket Field Guide. “Granulation is difficult at best to observe. The short life span combined with the necessity of excellent seeing conditions makes studies for the typical solar observer a challenge. “

I have been able to see them under very steady skies and at magnifications of around 100 x, always using a solar continuum filter. However when seeing is only average they can not be detected. I use a Lunt Herschel wedge, but I don’t think the Lacerta one will be any different. Focusing is difficult, especially when there are no other surface features to help. They also often pop in and out of view as the seeing changes. I my humble opinion there is no way you can see them at 28x. They are only slightly bigger than 1arc second in size. The observer was almost certainly seeing supergranulation. Imaging is the recommended way to study granules, as you have found using your camera.

Hope this helps,

John.

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Thank you John. An excellent summation.  Baxter agrees with you.
Where I beg to argue is that it so easily and repeatedly seen with a camera.
What unique advantage does a camera have over the Mk1 human eye?
"Seeing conditions" and "optical quality" must surely apply equally to both the eye and the camera.
Do they not?  :icon_biggrin:
 

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I would agree with almost all of what John has said. It is very dependent on seeing, and any low power viewings are purely seeing the changes in density of the cells over the solar disk, not the cells themselves. The only difference is I would say it is rare to find times when it can't be glimpsed at all, even if a little patience is required.

I find thr cells easiest in the centre of the disk, I've always assumed because you are then viewing them head on for best contrast, and at powers of x200 in excellent seeing the views can be mesmerising. My first time actually seeing the tiny cells was a revelation after fooling myself for years that I was seeing them at lower powers.

As for the difference between visual and camera I'm not sure. Would a reasonable frame rate video camera perhaps 'freeze' the seeing better than the brain does? Guessing here!

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Thank you, Stu.

I understand the conventional wisdom that good seeing is everything in seeing granulation.
Which means I should be out there as soon as the sun rises to catch the steadier air.
I have the disadvantage of low altitude [60m] but do enjoy a rural setting surrounded by fields.
My raised observatory should be well above thermal ground currents.

I'm still lost on why the humble Neximage5 shows surface texture during the live, on screen view in the capture software?
[Re]searching online around the subject still hasn't found the answer to the camera's obvious superiority.
Capturing the detail and using stacking software to improve the final image is another thing altogether.
 

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I think the surface detail captured by your camera is probably supergranulation, but why you can not see it visually stumps me. I see it at my usual working magnification of 50 to 60x even in average seeing conditions. Like Stu I thought this was granulation, but once you see the real thing the differences are obvious. I probably see it less frequently than Stu for 2 reasons. He is a much better observer than me and to be honest I do not look for it that often, only when the seeing is very good.

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3 minutes ago, laudropb said:

He is a much better observer than me and to be honest I do not look for it that often, only when the seeing is very good.

I would certainly contest your first point John, but on the second one perhaps I do have a stubborn determination to see these things, I'll even stare at a blank disk until I see something!! 🤣🤣

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I've been doing white light solar for a few years and I've only seen granulation a couple of times if my memory serves me right. Both times I was observing across fields or open space rather than over houses that cause small but enough heat turbulence to kill seeing granules for me.

I go out for a bit of white light observing regardless of if there are sunspots on show. There's still faculae, limb darkening, and granules to have a go at and I will go out without checking if there are spots on show as it adds to the excitement if there is one.

I think anyone masochistic enough (e.g. me) to enjoy picking out faint fuzzies in the cold and dark at the limit of even being detectable is not going to be out off by a lack of sunspots!

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10 hours ago, laudropb said:

I think the surface detail captured by your camera is probably supergranulation, but why you can not see it visually stumps me. I see it at my usual working magnification of 50 to 60x even in average seeing conditions. Like Stu I thought this was granulation, but once you see the real thing the differences are obvious. I probably see it less frequently than Stu for 2 reasons. He is a much better observer than me and to be honest I do not look for it that often, only when the seeing is very good.

I think you are exactly right. I have been seeing what I call "frog spawn" on the laptop screen.

A bit more online homework confirms this. The real granulation cells are far more distinctive, dark edged and probably much smaller in scale.

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9 hours ago, Stu said:

I would certainly contest your first point John, but on the second one perhaps I do have a stubborn determination to see these things, I'll even stare at a blank disk until I see something!! 🤣🤣

It is true that practice often helps to bring out the subtle. 

As a recent convert to the Light Side I am still finding my way around.

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9 hours ago, Paz said:

I've been doing white light solar for a few years and I've only seen granulation a couple of times if my memory serves me right. Both times I was observing across fields or open space rather than over houses that cause small but enough heat turbulence to kill seeing granules for me.

I go out for a bit of white light observing regardless of if there are sunspots on show. There's still faculae, limb darkening, and granules to have a go at and I will go out without checking if there are spots on show as it adds to the excitement if there is one.

I think anyone masochistic enough (e.g. me) to enjoy picking out faint fuzzies in the cold and dark at the limit of even being detectable is not going to be out off by a lack of sunspots!

I have wasted years avoiding looking at the sun except during transits and eclipses.

Masochism is not quite the term I'd use.  Obsessive-compulsive behaviour is nearer the mark for the infinite patience which many amateur astronomers share.

I like to understand the reasons for things. So that I can maximise my success rate and thereby increase its enjoyment more often.

The sun is already on the dome so I'd better get out there. I've already wasted an hour of Summer Time! :wink2:

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Early morning viewing produced nothing in WL. :crybaby2:

Nice clear view in H-a. :biggrin:

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