2012 Jan 09 Sun - part 2 Solar Surface

[PTS]

Hi,
This part are images of the solar surface.

Telescope: AP Starfire EDT 155 mm f/9.
stopped to 50 mm for disc images, with 4X telecentric lens (f/36) for closeups
filter: Solar Spectrum SO1.5/0.3A with CERF prefilter
Camera: Imperx 4M15

PTS

[PTS]

more images

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more images

[Wah!!]

Very high res~!

[universe24]

I am wondering why there is uneven illumination on those close-up high res images...???
What is the filter size of the solar spectrum?

[PTS]

I am wondering why there is uneven illumination on those close-up high res images...???
What is the filter size of the solar spectrum?

The So1.5 is 25mm in diameter. But the problem should not be from the filter, otherwise the uneveness should follow when I rotate the filter.

I am working on this problem. Most likely it is the extension tube which I machined to comply with the 220 mm back focus of the telecentric lens. This tube is not blackened inside. I am making a new adaptor tube for this.

pts

[universe24]

Hope the problem will solve afterward....good luck!
You got nice equipment for the Sun...
Have you ever think to make full disk surface detail image? (not mosaic)

[PTS]

Hope the problem will solve afterward....good luck!
You got nice equipment for the Sun...
Have you ever think to make full disk surface detail image? (not mosaic)

It is simply not possible with my setup.
The AP 155mm f/9 has a focal length of 1395 mm, just good for the Imperx camera (15 x 15 mm sensor). When I use prime focus for whole disc image, I have to stop it down to 50mm to comply with the minimum f/28 (actually my setup is just f/27.9) requirement for using the Solar Spectrum filter. Thus all my full disc images are of limited resolution. These are for reference of the many active regions only.

When I image at full aperture to get the high resolution power, I have to add a 4X telecentric lens. The setup becomes f/36 which is very ideal for high resolution work. At this focal length (5580 mm) the disc is simply too large for my camera.

Another point: even if large format ccd is "available" (surely not affordable for me), the frame rate will not be what I like to have (I am imaging at 15 fps all the time). This is the way to "catch" the quiet moments of the atmosphere.


pts

[daniel cck]

good job!

[universe24]

Hope the problem will solve afterward....good luck!
You got nice equipment for the Sun...
Have you ever think to make full disk surface detail image? (not mosaic)

It is simply not possible with my setup.
The AP 155mm f/9 has a focal length of 1395 mm, just good for the Imperx camera (15 x 15 mm sensor). When I use prime focus for whole disc image, I have to stop it down to 50mm to comply with the minimum f/28 (actually my setup is just f/27.9) requirement for using the Solar Spectrum filter. Thus all my full disc images are of limited resolution. These are for reference of the many active regions only.

When I image at full aperture to get the high resolution power, I have to add a 4X telecentric lens. The setup becomes f/36 which is very ideal for high resolution work. At this focal length (5580 mm) the disc is simply too large for my camera.

Another point: even if large format ccd is "available" (surely not affordable for me), the frame rate will not be what I like to have (I am imaging at 15 fps all the time). This is the way to "catch" the quiet moments of the atmosphere.


pts

Yes, I understand that. Just wondering how is the illumination on full disk.
Do you ever think of using optic relay system to make the light pass through the filter parallel and then refocus on CCD? That would give you full disk at full aperture.
The 4MP chip can go 15fps is already amazing for me...how I hope I also can own one...

[PTS]

Yes, I understand that. Just wondering how is the illumination on full disk.
Do you ever think of using optic relay system to make the light pass through the filter parallel and then refocus on CCD? That would give you full disk at full aperture.

The 4MP chip can go 15fps is already amazing for me...how I hope I also can own one...[/quote]

I have considered this arrangement. However, the setup will be very cumbersome.
Firstly I need a collimating lens before the filter. This will add fl of the collimator. Then, after passing through the filter, I need an imaging lens of some 1400 mm fl to fully utilize the 4M15 ccd. Most important of all, the optical chain must be of comparable quality to the original setup.
I suppose these will not be affordable, both in terms of money and hardware-setup. I have to take my 20-kg AP refractor to the roof each time I observe, together with another 15-kg of accessories. The German mount, while "transportable" (20-kg for the equatorial head, another 20-kg for the pier), is semi-permanently setup on the roof.

Thus, there is no intention of making full-disc imaging at high resolution. This task should be left to Wah or David who have demonstrated with their excellent images..
My aim is to make time-series observation of active regions when I have solved all the problems of the 2-D images (un-even brightness, fringes and dust problems, etc).

My other project will be to measure magnetic fields of these active regions, using the Zeeman effect. Another 150-mm f/10 refractor is being constructed for this purpose. This will be a folded refractor to avoid the long OTA, with a LHires III spectrograph.

Ultimately I'll make a strong equatorial mount to support these 2 refractors so that I can make simultaneous observations of H-alpha imaging and spectroscopy. The polar axis part is nearly complete, and design for the declination axis is on the way.

pts