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papamidnight

Solar detail frustration

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Is it possible to get surface detail of the sun using a standard OTA with front solar filter and eyepiece filters such as h-alpha, continuum etc?

I am not having any success and have tried both the above. OTA is 6" and I am using a Sony Nex 5 camera. There seems to be enough light to image except when stacking these filters, but even when used alone the image is just all red or all green with zero surface detail or prominences etc.

Please see brief video here:

It looks the same under higher power as well-just a solid uniform green or red.

Thank you for any thoughts!

Best,

~S

Edited by papamidnight

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Hi, when you say "front solar filter" what type of filter is this?

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You will get black sports with a white light filter. It is possible to see surface granulation, but it's not easy and it depends on the observing condition and your equipment.

Baader Continuum and night time Ha filter can improve contrast if you use an achromat, because these narrow band filters can get rid of CA. However, you need a specialist solar Ha filter to isolate prominences, filament and other Ha feature. The band pass of night time narrow band Ha are far too wide (7nm), compare to solar Ha etalon filter (<0.1nm).

If you want to see the sun in Ha, the cheapest solution is a PST (around £500). Standalone solar etalon generally cost in excess of £1K

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Hi Freddie and Keith. Sounds like these filters just won't help with detail on an SCT. The front filter is a Baader 5ml density -I am waiting on a kendrick photographic film version. I don't think the issue is the front filter since there is enough light and the edge is sharp. Looks like a PST might be in my future. Thanks!

Edited by papamidnight

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Get hold of a cheap 70 or 80mm scope as aperture isn't important with solar. Gar a white light solar filter for the front, you'll visually see sunspots with this set up..

Use you camera and take some avi's download registax (free) and load your avi into that.. Search the forum for stacking with registax and you'll find loads of info...

Taking a single avi and trying to see detail is virtually impossible....

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To be honest, I doubt you will get much better white light image than Baader film. The contrast on surface granulation is really weak and really hard to see in the best condition.

It will take some advanced processing to bring them out in an image and it's beyond my ability. Usually the best granulation images tends to be taken with solar wedges and apo, but solar wedges are incompatible with SCT or anything else other than refractor.

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Looks pretty burnt out to me , drop the Gain and Brightness settings , and Gamma right down.

Better an under-exposed sequence as you can drag detail out , but if over-exposed you cannot retrieve it.

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Most often any lack of surface detail is due to over-exposure of the image. It is surprising just how short an exposure time you need, even with a full "solar film" type filter. You will not see prominances or anything other than surface granulation and sunspots with a white light scope and filter. A "H-alpha" filter is NOT the same thing as a dedicated H-alpha solar scope! If you want to see filaments and prominances then you will have to go the dedicated H-alpha scope route. Companies like Coronado and Lunt supply these commercially but they are not cheap.

Below is a "white light" solar image taken with a 120mm refractor and Baader solar film, no other filters. The colour is false and was applied in Photoshop. This should give you an idea of what is possible with an "ordinary" scope. For H-alpha images you will have to look in the solar imaging section.

12July2012Annotated.jpg

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Steve hit the nail on the head, it's always better to under expose than over expose. Capture in mono if you can - and, if you haven't seen it, have a read of Bizibilder's guide.

Love the name Papa MIdnight by the way.

Edited by JamieW
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If you mean the surface detail as is produced with a PST then the answer is no.

They use narrow band Ha and Ca filters.

The ones that go on the front are generally termed White but often the green component gets through most and the solar surface has a green hue.

Unless you get something like a PST or Lunt then you get the "white" image that is OK for sunspots but that is it.

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Thanks for the replies.

I was able to get sunspots yesterday (and a nice tan) with just the front ND style film filter. The sun showed no spots today for me to compare. I did reduce the exposure time a lot..to the point I couldn't see the footage as it was recording. The clip above was middle of the exposure range. The continuum filter and the h-alpha just don't add detail from what I can tell, they seem to saturate the image into a blob of coherent color. I'll read the mentioned blog tonight and further talk myself into buying a solar scope. Appreciate it!

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The contrast on surface granulation is really weak and really hard to see in the best condition.

I guess it all depends - from where I observe (highlands, ca. 2000 ft elevation) I can see the granulation most of the time in my 4-inch achromat starting at 40x (using just the Baader ND5). It's subtle, but it's there.

Looks pretty burnt out to me

That's right. And if you have the exposure & gain correct for the sunspots, usually you will see slight limb darkening at the same time.

I did reduce the exposure time a lot..to the point I couldn't see the footage as it was recording.

Put a piece of dark fabric over your head and the screen while focusing & setting up - it made a day-night difference for me.

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Get hold of a cheap 70 or 80mm scope as aperture isn't important with solar.

That's not true. Look at Montana's fine pics with a 140mm scope - I've never seen anything approaching them with an 80mm.

What is true of solar is that seeing is really the king. If the atmosphere is swimming, as it often is on sunny days in the UK, then the advantage of a larger scope (in terms of resolution) is lost, however with the right seeing conditions, which may occur rarely, aperture will still win out.

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As Capricorn (and possibly others) have mentioned, in order to see much detail beyond sunspots you need the specialist internal filters that are only found in dedicated solar scopes, there are no alternatives as far as I'm aware.

These filters allow only a very narrow band of particles through, the ones that allow us to see the interesting part of the sun (where the prominences and surface granulation is). Without these dedicated filters you will get a lot of other particles passing through which will effectively blind you to the fine details. It is akin to observing the corona during a solar eclipse, the corona can't be seen most of the time due to the vast amount of light which blinds us to it; a solar scope blocks out this blinding light using specialized and highly precise components that are not found in a normal telescope.

I hope I got all of that correct, it was from memory from the manual and research I did before purchasing my Lunt. :D

Edited by jonathan
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Actually you can retro fit a normal scope with sub angstorm narrow band filters. Daystar, baader and a few other companies make them in addition to Coronado and lunt.

You can get calcium h, sodium d, helium d3, and hydrogen beta filters in addition to the usual Ha and Cak. The drawback is these external filters are much more expensive than dedicated ha scope.

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Actually you can retro fit a normal scope with sub angstorm narrow band filters. Daystar, baader and a few other companies make them in addition to Coronado and lunt.

You can get calcium h, sodium d, helium d3, and hydrogen beta filters in addition to the usual Ha and Cak. The drawback is these external filters are much more expensive than dedicated ha scope.

I stand corrected. Do these add-ons include tuning systems? That is what makes the solar scope work as far as I'm aware, besides the static filters.

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I stand corrected. Do these add-ons include tuning systems? That is what makes the solar scope work as far as I'm aware, besides the static filters.

I believe they use temperature controlled oven for tuning, which is suppose to eliminate the sweet spot you get in tilt and pressure tuned system. However, I've never seen one in person, so I am just saying what I hear and I don't expect I will see one ever. For a start these filters are horrendously expensive, a 0.7 angstorm Daystar Quantum cost £2.6k, compare to £1.25k for a 0.7A Coronado Solarmax 60.

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Great Discussion-learning a lot!

I will post a video of everything (minus a dedicated solar scope) I have tried to show the different approaches in a few weeks.

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Thanks for the help guys. The image quality is much better with only the white light fliter. The h-alpha and continuum 1.25 doesn't add anything to the detail from what I can tell. The h-alpha I was using is 7nm.

I did stop the image down 1.5 from what looked right on the LCD whie recording which seems to have helped too.

This is just a front ND filter:

How do I get ride of those eyepiece flare like circles? This was an orion 9mm plossul.

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