Frankenscope Images and Images from Eclipse 9 Mar 16

[yltansg]

It has been a while since I last posted in this forum.

After months of work, I finally got this frankenscope working.



Imaged on Good Friday (25 Mar 16) morning



Solar Eclipse Images will be up later....

[Airconvent]

Thanks for sharing!
First time I come across "frankenscope". Read up on it and technically, that it what it is...imagine that.

[kochu]

Great Image Alfred
Kochu

[yltansg]

Thanks Kochu and Airconvent.

I need to do more work to fine-tune the setup for maximum performance.

Will try double-stacked version soon

[yltansg]

As promised, here are some images from the recent eclipse:

Six images showing the key stages of the 9 Mar Eclipse. The gain of the 3rd image was raised to see the proms.


4 images showing the last 3 minutes:


I seldom take images of the Sun with a colour camera. Made an exception because there were many requests to see the actual colour of H-Alpha emission by hydrogen atoms.

Enjoy and give me your feedback.

Alfred

[Dark Neptune]

How heavy is the whole setup? Lol.

[yltansg]

Hi Dark Neptune - It is manageable - 94cm long and weighs 10 kg (with PG Grasshopper 3 camera).

My setup consists of a Celestron 150mm F/5 Omni XLT telescope fitted with ASK3 kit, a Lunt LS50TH telescope and Point Gray Research (PGR) Grasshopper 3 (Sony ICX674 chip). It can be transformed to a double-stacked imaging configuration by adding a second H-Alpha etalon in front of the Lunt LS50THA telescope.

The ASK3, with a designed Strehl ratio of higher than 0.97 across entire 1 degree field (in H-Alpha wavelength), consists of two parts:

a. A 60mm cemented triplet collimator lens which transforms the F/5 cone beam from the 150mm refractor into a parallel collimated beam of about 50mm diameter. The collimator lens also provides correction for spherical abberation (at H-Alpha wavelength), coma and astigmatism. This collimated 50mm diameter beam will enable the Lunt LS50THA to operate at its best efficiency.

b. A 60mm doublet objective lens which refocuses the parallel beam and passed it to the etalon(s). The objective lens, acting with the triplet collimator produces a flat unabberated image of 1 degree diameter.

Focussing is done using the helical focuser on the LS50THA which can be a challenge. I believe the greatest challenge is to tinker the double-stacked etalons to achieve the orientation of the etalons and blocking filter for best image. So there is lots of work required to squeeze the most out of it for best performance

[superiorstream]

Hi Alfred
Great work! A 150 f/5 wt 7 kg--so 3 extra kg of Ha equipment.
One big question---always useful or scope useful only when atmosphere is super steady?My experience with the sun at
540nm with this scope is nasty......picking up lots of atmospheric
turbulence. What's yours? Thanks.

[yltansg]

Hi Mr Chia,

Thank you for your kind comments.

Quote
[[One big question---always useful or scope useful only when atmosphere is super steady? My experience with the sun at
540nm with this scope is nasty......picking up lots of atmospheric turbulence. What's yours? Thanks.]]

Imaging the Sun in 540nm? - that is the wavelength that I seldom image in. If I do, I would usually use a Baader Herschel wedge. I have obtained mixed results.
You are right that atmospheric conditions affect result. Here are 2 samples in 540nm





For the frankenscope, I image in 656.25nm. Without this scope, I was only able to get good hi-resolution images on extremely good conditions.
Here are 2 examples:





With the frankenscope, I am hoping to get more high resolution images, even in so-so condition. That first image that
I shared was taken in almost boiling condition with lots of turbulence.

[superiorstream]

Hi Alfred
Thanks for the reply.
As for me I discovered that the optimal aperture is between
90mm to 100mm.Have you try stepping down the aperture
to say 100mm during turbulent atmospheric conditions? I did that and it works.....at 540nm......wonder if it works at Ha.Of course there is some sacrifice in theoretical resolution. Thanks.