Results with large aperture ERF

this is the main message area for anything solar :)
Post Reply
User avatar
Carbon60
Way More Fun to Share It!!
Way More Fun to Share It!!
Posts: 14204
Joined: Wed Mar 07, 2012 12:33 pm
Location: Lancashire, UK
Has thanked: 8415 times
Been thanked: 8161 times

Results with large aperture ERF

Post by Carbon60 »

We had a brilliant blue sky day here today and I was lucky enough to get some time on my scope before the working day began. This was the first proper use of my 250 mm RCT truss tube reflector on the Sun after waiting patiently for months for good weather, the right season and after learning how to collimate it properly.

Fitted with a large aperture 3-band ERF (from Valery) I set up with a red filter (Ha 7nm FWHM) with the aim of capturing solar granulation. Initially the image was very bright and I was unable to reduce the exposure time sufficiently to prevent over exposure, even with a 2.5x Powermate fitted. The only way to reduce the brightness (for me) was to fit a double polarising filter and cross them to almost black.

Anyhow, here is the resulting image. A first for me :) No way perfect, but I'm quite pleased for the first attempt.

Image20180_Red filter_Polariser_Barlow by Stuart Green, on Flickr

I then switched to 'G-band' and did pretty much the same, except that I didn't require the polarising filters. Again a first and again not perfect with some parts out of focus. The seeing was pretty darn good, so I can't blame that.

Image201804_G-Band_Powermate by Stuart Green, on Flickr

I decided to remove the Powermate and collect images to make a FD mosaic.

Image201804_G-Band_FD_Colour by Stuart Green, on Flickr

Looks like something's peeping into view on the eastern limb :)

I then switched over to CaK using my B600 module as the prime filter and the 2.5x Powermate to get a closer view. At that point I saw horrible bright reflections which I could only deal with by moving the scope around the disk to a place where they were minimised. Flat fielding sorted the problem but there is something fundamental that needs attention in this arrangement.

Anyhow, here is the resulting image. Again, not perfect (I couldn't get it to sharpen beyond this point without it looking worse), but I'm astonished with the apparent texture in this image. I presume this is real and not a processing artefact.

Image201804_CaK_Colour by Stuart Green, on Flickr

Overall I'm quite pleased with the results and with a bit more practice and refinement, tweaking and good luck I'll get there. The only problem is that mornings like the one we had this morning are all too few and far between.

Thanks for looking.

Stu.


H-alpha, WL and Ca II K imaging kit for various image scales.
Fluxgate Magnetometers (1s and 150s Cadence).
Radio meteor detector.
More images at http://www.flickr.com/photos/solarcarbon60/
User avatar
MalVeauX
Way More Fun to Share It!!
Way More Fun to Share It!!
Posts: 1858
Joined: Tue May 09, 2017 7:58 pm
Location: Florida
Has thanked: 1171 times
Been thanked: 1360 times

Re: Results with large aperture ERF

Post by MalVeauX »

Nice convection cells!

Very best,


User avatar
ffellah
Way More Fun to Share It!!
Way More Fun to Share It!!
Posts: 11168
Joined: Mon Oct 27, 2014 6:46 pm
Location: Westport, CT USA
Has thanked: 9143 times
Been thanked: 6024 times

Re: Results with large aperture ERF

Post by ffellah »

Great first results Stu ! I am looking forward to seeing your next set. The granulation is lovely.

Franco :band


User avatar
Valery
Way More Fun to Share It!!
Way More Fun to Share It!!
Posts: 4059
Joined: Sun Nov 18, 2012 3:13 pm
Has thanked: 156 times
Been thanked: 893 times

Re: Results with large aperture ERF

Post by Valery »

Hi Stu,

Congratulations with the first light. Your first results are significantly better than were my first light results using largr aperture scope.

Some suggestions if I may.

1. If the camera frame size is a limiting factor for the recording speed, use smaller ROI without any hasitation. I usually framing the FOV with 50-60% of the camera full frame height. The smaller the height, the higher the fps (if not limited by the exposure time).
I can then create a mosaic from two narrower frames.

2. For granulation you can easily use larger scale. This will allow to extract small details easier. See the crop from your first image where I makes it larger - 130% and increased contrast.

3. In CaK and especially in G and H-a (continuum) you can use longer recodring cadence in the goal to record more good frames.

The CaK image looks a bit off-band. May be due to tilt of the CaK filter, may be due to low temperature of the filter. Sometime I have a very similar CaK pictures - off band. I do use PST CaK filter. Such specially made filters like Christian Viladrich does use keep their CWL very firmly at the center of the CaK line. Quark Ca H also better keep it's CWL exactly at the center of the Ca H absorbtion line and allows also some tweaking of the CWL.

BTW. I have the same bright reflections when use some TV barlows. Didn't recognise the root reason of this.


BTW2. Which narrow band H-a do you plan to use?


Valery
Attachments
RC250-H-a-continuum-crop.jpg
RC250-H-a-continuum-crop.jpg (285.8 KiB) Viewed 1465 times


"Solar H alpha activity is the most dynamic and compelling thing you can see in a telescope, so spend accordingly." (c) Bob Yoesle.

Largest full size 185 - 356mm Dielectric Energy Rejection Filters (D-ERF) by ARIES Instruments.
User avatar
Carbon60
Way More Fun to Share It!!
Way More Fun to Share It!!
Posts: 14204
Joined: Wed Mar 07, 2012 12:33 pm
Location: Lancashire, UK
Has thanked: 8415 times
Been thanked: 8161 times

Re: Results with large aperture ERF

Post by Carbon60 »

Many thanks for your comments, Marty, Franco.

Valery, I always appreciate the time you take to explain things in detail, thank you. Good tips and advice.

Stu.


H-alpha, WL and Ca II K imaging kit for various image scales.
Fluxgate Magnetometers (1s and 150s Cadence).
Radio meteor detector.
More images at http://www.flickr.com/photos/solarcarbon60/
Derek Klepp
Way More Fun to Share It!!
Way More Fun to Share It!!
Posts: 12900
Joined: Wed Oct 19, 2011 10:02 am
Been thanked: 171 times

Re: Results with large aperture ERF

Post by Derek Klepp »

Looking good Stu.


User avatar
Valery
Way More Fun to Share It!!
Way More Fun to Share It!!
Posts: 4059
Joined: Sun Nov 18, 2012 3:13 pm
Has thanked: 156 times
Been thanked: 893 times

Re: Results with large aperture ERF

Post by Valery »

Stu, what the H-a main filter do you plan to use with the 250mm RC?


Valery


"Solar H alpha activity is the most dynamic and compelling thing you can see in a telescope, so spend accordingly." (c) Bob Yoesle.

Largest full size 185 - 356mm Dielectric Energy Rejection Filters (D-ERF) by ARIES Instruments.
User avatar
Carbon60
Way More Fun to Share It!!
Way More Fun to Share It!!
Posts: 14204
Joined: Wed Mar 07, 2012 12:33 pm
Location: Lancashire, UK
Has thanked: 8415 times
Been thanked: 8161 times

Re: Results with large aperture ERF

Post by Carbon60 »

Hi Valery,

I'm unsure, yet. The original plan was to swap out the guts of the 150 mm/DS Lunt 35 mod, but I'm loathed to keep swapping back and forth once set up and 'optimised'. It's all working pretty well on the 150 at the moment. I'm bouncing between a good PST, or something more substantive like a Quantum or Spectrum, but they're a bit expensive for a scope that will likely be used infrequently because of 'seeing' limitations.

Thoughts?

Stu.


H-alpha, WL and Ca II K imaging kit for various image scales.
Fluxgate Magnetometers (1s and 150s Cadence).
Radio meteor detector.
More images at http://www.flickr.com/photos/solarcarbon60/
User avatar
mattwastell
Way More Fun to Share It!!
Way More Fun to Share It!!
Posts: 5005
Joined: Tue Feb 14, 2012 9:35 am
Has thanked: 2 times
Been thanked: 72 times
Contact:

Re: Results with large aperture ERF

Post by mattwastell »

These are fantastic Stu - heaps of potential for sure - congratulations on the first lights!


Matt Wastell



Look up, look good!



http://www.pbase.com/mattwastell
Post Reply