First Foray into "Hi-Res" Solar.

[p_zetner]

Hello Everyone.

First light of Celestron C8 equipped for solar viewing.

Here are two preliminary shots (20 frames out of 2500) to test. A little soft and noisy but much more data to process and, hopefully, yield improved image quality.

083526_00_pp_ARL7x7-25_proc0_crop_shrp2_lbls.png (416.25 KiB) Viewed 3830 times

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The rig:

IMG_0744.png (673.61 KiB) Viewed 3830 times

Aries ERF,
Celestron NexStar C8,
Motorized Baader focuser,
Edmund Optics 0.3x telecentric (in reverse),
Daystar QPE 0.6A,
PGR Grasshopper 6Mpx.

Operation at f/33 (~6700 mmf).

Cheers.
Peter.

[eroel]

Peter:
Very good solar image with a 8" scope.
Best wishes,
Eric.

[mattwastell]

Hi Peter - that is an excellent beginning - looking forward to your future HR work!

[Derek Klepp]

Very promising Peter and thanks for the setup pic.

[oreoluna]

Hi Peter.
I do not want to be negative, but I would be horrified with the results .... You have perfect equipment but the images at 8 " must be better by length also with the first light

Try this: 2x binning 1500 frames and 8-10% stack. That works with my 7 "very well.

Jozef

[Valery]

Hi Peter,

Congrats with the first light.

Not sure I understand why your telecentric must be in a reverse orientation. Can you, please, explain this?

I always wonder why peoples use all these loooong telecentrics. I have used TeleVue Powermate barlows (telecentric designs) and they work. No need to have such a long tail on a short telescope!

I have used 2x, 2.5x and 4x TV PM models and they all work great for me when I use them with de-barlowed Quark Chromosphere.

Valery

[p_zetner]

Thanks for your comments everyone.

Valery: The Edmund Optics telecentric is designed (for machine vision) to give 0.3x magnification of some object of interest, at a working distance of 13cm, with telecentricity in the object space of the lens. In reverse, the image field is telecentric with magnification of 1/0.3=3.3x. In future, I will use a shorter optics train in back of the telescope. I have an existing telecentric which I need to modify slightly to achieve f/30 or greater with the C8. Just had an opportunity to test the system today, so used the Edmund lens at hand.

Here are the final processed images of today's session (about 100 frames stacked out of 10000 for each image). On-camera 2x2 binning was used. It seems a faster frame rate (currently 42 fps) might be beneficial. Finding focus was also quite difficult as seeing conditions deteriorated quickly during the session.

Cheers.
Peter.

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[yltansg]

Hi Peter,

That is a great start. Will be looking out for more from you.

Alfred

[marktownley]

Great setup and great opener into the world of hi-res. You will find at these apertures the seeing is the main factor affecting image quality.

[Valery]

Great setup and great opener into the world of hi-res. You will find at these apertures the seeing is the main factor affecting image quality.

For a CaK I found that a spherical aberration is also a main destroying factor.

[marktownley]

Great setup and great opener into the world of hi-res. You will find at these apertures the seeing is the main factor affecting image quality.

For a CaK I found that a spherical aberration is also a main destroying factor.

Totally agree Valery

[p_zetner]

Hi Mark and Valery.

Mark: Can you tell me what frame rate you use with your HaT? I seem to remember something over 100fps. How do you achieve it? I'm currently using the PGR Flycapture software which, I assume is pretty limiting. I was using an exposure of about 4ms for the disk which would allow me 250fps, if I could get there!

Valery: Is uv spherical aberration significant for a Schmidt Cassegrain?

Cheers.
Peter.

[marktownley]

Hi Peter. I'm getting between 110-120fps with my PGR CH3 with 2x2 binning. The breakthrough was when I went from firecapture 2.3 where I was getting 55fps to updating to firecapture 2.4. I don't use the PGR flycapture it is horrible - try firecapture instead

[p_zetner]

Thanks, Mark!

[Ewan]

Very nice 'start' you have achieved there.
Have you not tried Genika Astro yet ? I thought it came with the camera ?
Flycap is horrid & Genika 'focus aid' does seem to work.
I set my exp to 12ms, Gamma 0.8 gain to fill about 70% of histogram then use the preview Black & White point sliders to get a very contrasty preview image, it makes it so much easier to achieve focus.
20 frames doesn't seem a lot for a stacked image so I would expect it to be noisey.
Atb

[DJD]

Not that I am expert at all, but I echo Ewan's comments. I use Genika Astro and find it more than adequate for my needs
and very easy to use. I don't use the focus aid, but find the 2x enlargement( function buttons) together with ROI makes live focusing
quite easy.
Best wishes,
David

[Valery]

Valery: Is uv spherical aberration significant for a Schmidt Cassegrain?

Cheers.
Peter.

Yes, SA at 393nm is VERY significant. You can still image here too, but at smaller scale with some resolution loss.
For better results one need a special corrective optics. See my test here: viewtopic.php?f=4&t=22884


Valery

[p_zetner]

Thanks for your advice, Ewan and David.
I've been eyeing Genika for camera control and you've convinced me to adopt it. I especially like the option of triggering acquisition with the SSM .... very useful under my poor seeing conditions.

Valery, it looks like I'll stick to my triplet apo for uv. It seems to be well corrected at 400 mm.

Cheers.
Peter.

[marktownley]

it looks like I'll stick to my triplet apo for uv. It seems to be well corrected at 400 mm.

What scope is it Peter?

[robert]

Hi Peter. I'm getting between 110-120fps with my PGR CH3 with 2x2 binning. The breakthrough was when I went from firecapture 2.3 where I was getting 55fps to updating to firecapture 2.4. I don't use the PGR flycapture it is horrible - try firecapture instead

Mark. Can you adjust gamma on pgr ch3 in firecapture 2.4? I found it was only possible in 2.3 on my setup. Win 7 etc. So I still use that but extra frame rate would be nice.
Robert

[p_zetner]

Hi Mark.

I've been using my Stellarvue 115mm f7 for CaK imaging.
Here's a link to a pic: http://www.pbase.com/p_zetner/image/161131111/original

Cheers.
Peter.

[marktownley]

Hi Mark.

I've been using my Stellarvue 115mm f7 for CaK imaging.
Here's a link to a pic: http://www.pbase.com/p_zetner/image/161131111/original

Cheers.
Peter.

Looks like a winner!

[marktownley]

Hi Peter. I'm getting between 110-120fps with my PGR CH3 with 2x2 binning. The breakthrough was when I went from firecapture 2.3 where I was getting 55fps to updating to firecapture 2.4. I don't use the PGR flycapture it is horrible - try firecapture instead

Mark. Can you adjust gamma on pgr ch3 in firecapture 2.4? I found it was only possible in 2.3 on my setup. Win 7 etc. So I still use that but extra frame rate would be nice.
Robert

Hi Robert,

Yes, there's an active gamma slider on there.

Mark