A wonderfully detailed image of AR 1476 (Brisbane 10th May 2012)

[Dennis]

I was delighted to obtain a wonderfully detailed image of AR 1476 from our back garden in Brisbane, recorded on 10th May 2012 at 10:56am AEST (GMT+10). I used a Takahashi Mewlon 180 F12 ‘scope with a Tak x1.6 Extender and the camera used was an Imaging Source DMK31AF04.AS industrial webcam.

To obtain this breathtaking detail, I recorded an AVI of 2500 frames and then let AVIStack select the best 154 frames whilst I had a cup of tea.:)

The skies were sparkling and although I was just inside the edge of a turbulent jet stream pattern, there were sufficient moments of excellent seeing for the details to pop through. :)

Cheers

Dennis

[jjjnettie]

sigh.....that's sublime Dennis. :)
Thank you for the view.

[iceman]

Wow, stunning!

[[1ponders]]

Beautiful Dennis.

[Paul Haese]

Lovely Dennis. I did not have that nice a morning of seeing. The detail is great and lovely processing.

[Shiraz]

that is a cracker of an image Dennis. Regards Ray

[h0ughy]

:thumbsup: wow

[Dennis]

Thanks for all the nice comments everyone, I’ll pass them on to the “gods of seeing”...:lol:

I was using a full aperture solar filter made from Baader astro solar film, the photographic density type. In addition, for the 1st time, I also used a 1 ¼” Baader Solar Continuum Filter (BSCF) fitted to the DMK31, ahead of the standard IR block filter.

With just the IR cut filter, the DMK31 settings were 1/2000 sec with a Gain of around 295. With the addition of the BSCF, these changed to around 1/120 sec with a gain of around 450, quite a significant loss of light.

As the seeing was quite variable, I was pausing/re-starting the 2500 frame avi’s whilst eyeballing the screen and I think that the BSCF definitely revealed finer detail and seemed to cut through the seeing, although this effect was quite subtle – you still very good seeing to harvest this level of detail.:D

Cheers

Dennis

[sheeny]

I second that.

Al.

[strongmanmike]

Awesome Dennis

MIke

[Quark]

Outstanding work Dennis, such amazing structure and wonderful depth of detail. You certainly have quite diverse interests, regarding the objects that you image but regardless of what you post it is always of the highest quality.

Regards
Trevor

[Dennis]

Thank you Al, Michael & Trevor, I appreciate your comments.

Cheers

Dennis

[Dennis]

A few people have asked me about the solar filter used on my Mewlon 180 F12 ‘scope, so here are some details.

The full aperture solar filter that I use on my telescope for high magnification astrophotography is made from Baader AstroSolar ™ (http://www.baader-planetarium.com/sofifolie/details_e.htm) Photo Film which has an Optical Density of OD = 3.8. The Baader website writes that:

“AstroSolar™ PhotoFilm is not intended for visual observation. PhotoFilm is only for use with telescopes for high magnification photographic work. Do not use it for producing solar eclipse viewers, do not mount it onto DSLR camera lenses.”

For visual use, Baader also produce AstroSolar ™ Safety Film which has an Optical Density of OD = 5.

WARNING: Never look at the Sun through an optical instrument without a specialised, full aperture, astronomy filter – otherwise you will destroy your eyes.

To make my filter cell, I used high density, closed cell foam. This is the tough stuff that is hard to compress, not the soft, floppy stuff which offers little support.

The following photos provide some details on how I made the filter and importantly, how I secure it to the front end of the telescope so that a gust of wind will not blow it off.

After cutting the correct length of foam strip, I joined the ends of the strip to form the cell body, using contact adhesive, staples and gaffer tape. I used contact adhesive to glue the solar film onto the cell body and contact adhesive for gluing the foam ring to the solar film at the top of the cell.
I drilled 1/8 inch pilot holes spaced at 120 degree intervals around the circumference of the cell body and fitted x3 off ¼-20” nylon bolts (trimmed to length) to act as retaining lugs for a rubber retaining band.
The large rubber retaining band was purchased from Bunning’s in their electrical cable section – I removed a plastic slider so the band fits nicely around my OTA.

The Finderscope filter was made using the visual use Baader AstroSolar ™ Safety Film which has an Optical Density of OD = 5.

I used 1 inch thick closed cell foam and glued the Safety Film to the foam using contact adhesive.
My finder is close to the OTA so I had to cut a flat side on the finder scope filter cell, to fit it to the finder scope – it is a tight fit and will not blow off.

If you do not know what you are doing, do not risk your precious sight – purchase an approved, ready made filter suitable for your particular ‘scope.

Cheers

Dennis

[Derek Klepp]

Great pic Dennis and thanks for the Filter Build info. I used cardboard but found it only good for up to 5" aperture.

[SkyViking]

That's an incredible image Dennis, now you're ready for the Venus transit!

[Dennis]

Thanks Derek & Rolf, I appreciate your comments, although I’m mulling whether or not just to kick back and enjoy the whole spectacle at a more leisurely pace, as a visual experience only.:shrug:

No doubt there will be a plethora of wonderful images and animations soon available, globally; it hardly seems worth the effort in adding my 2c worth.

Just think, no PC’s , no cameras, no processing, etc., just a leisurely peek into the (full aperture solar filtered) eyepiece in between refreshing cups of tea, with lashings of hot buttered toast, Danish pastries or toasted English muffins!:)

I sometimes wonder if the majesty of these events can become a little marred by the dominance of the technical side of our minds rather than appreciating the more aesthetic value with the artistic side?:shrug:

Cheers

Dennis

[multiweb]

Awesome shot as usual and thanks for posting all the bits and pieces. Going to get some foam this week-end. :thumbsup:

[Matt Wastell]

10/10 Dennis!

[StephenM]

Very impressive Dennis.

Cheers,
Stephen

[originaltrilogy]

So is the 3.8 Astrosolar designed for *film* cameras and not CCDs?

[Dennis]

I am not a Baader representative nor do I have any technical background with these films, so I cannot offer any advice re their design for film and/or CCD’s.

I have used the Baader AstroSolar™ PhotoFilm, as recommended on the Baader data sheet, with a telescope for high magnification photographic work in conjunction with a Baader Solar Continuum filter and did not encounter any issues.

As per the Baader data sheet, I would not use the Baader AstroSolar™ PhotoFilm for any SLR or DSLR using typical lenses, or any such normal terrestrial camera or optic – at best you are likely to fry the instrument, at worst you may cause yourself some serious damage.

Cheers

Dennis

[andyc]

wow! :eyepop: That's an incredibly detailed image. Very impressive.

[Octane]

That is so good, Dennis. Astounding, really.

I'd imagine a print of that would be a fantastic talking point in your living room.

Where did you get your film from? It says not to use DSLR lenses, but, I'm wondering if that also means that it cannot be used on DSLRs, period... ?

H

[Dennis]

Thanks H. I think that I purchased my Baader Astro Solar Film (ND5 and ND3.8) from the now defunct York Optical; they used to stock a range of Baader stuff when they were in business in Brisbane.:(

In terms of safety, with the Mewlon 180 F12 operating at an effective focal ratio of F19.2 (using the Tak x1.6 extender) I am shooting at 1/2000 sec with my DMK31 at a Gain of around 300 (range=180 to 1024). For comparison, when I then insert a Baader Solar Continuum filter (in front of the IR cut filter), I’m shooting at around 1/120 sec with a gain of around 400 with the DMK.

I have used the Canon 7D and 40D DSLR at the F12 prime focus of the Mewlon 180 shooting at ISO 100 and 1/3200. I also experimented with 1/2000 sec but the histogram (blue end) was uncomfortably close to the right hand edge. I’ve also used the 40D with my Vixen 102mm F9 refractor with Canon EF 1.4 Extender (efr F12.6) shooting 1/8000 sec at ISO 100 with the 3.8 although I do not recommend this for beginners.

I’m always very cautious when writing about optics and the sun. Not for the 9999 out of 10,000 amateur astronomers who know their stuff, but for the 1 in 10,000 newbie who knows little about astro photography and the enormously destructive energy of optically focused sunlight, be it visible, IR or UV.:scared2:

I’m not sure if kids these days still burn holes in paper with a magnifying glass like we used to, garnering a healthy respect for old Sol!;)

I recently ordered some astro stuff from My Astro shop (http://www.myastroshop.com.au/products/baader-filters.asp)and noticed that their website did list Baader film, although I don’t think it indicates stock levels? They usually answer e-mail queries within 24 hours so maybe give them a go?

Cheers

Dennis

[Octane]

Thanks, Dennis!

I would be operating at 800mm focal length and f/8 (FSQ with Extender-Q 1.6) using the 5D Mark III.

I hadn't thought of popping the 1.4 extender into the mix. Although, I doubt I'd be able to reach focus with both teleconverters stacked together.

Cheers for the heads up!

H

[Dennis]

Don’t forget to tape the back pins of the Extender so that the camera body thinks that it’s just a lump of unintelligent metal. If you don’t, you will likely get an “Err” code as the camera will not be able to recognise the ‘scope that the body/extender is connected to.

Cheers

Dennis

[Octane]

Good tip. I would have had to have learn that the hard way. :)

I think I'll just stick to the Takahashi Extender-Q for the time being. For future though, it will be an option.

Cheers!

H

[Martin Pugh]

Brilliant.

well done
Martin

[Dennis]

Hello,

First of all, apologies for resurrecting this older post, but I thought it appropriate to post this newly processed full solar disc in the same post for comparison, as it was also taken on the same day as the DMK image, but using my Vixen 4” ED102S F9 refractor.

I used the Canon x1.4 Extender II on the 40D with the pins at the rear of the Extender taped up, so they could not make an electrical connection with the 40D and return an “Err” message.:)

This set up gave me an effective focal length of 1285mm at F12.6 and the solar disc nicely filled the field of view.

A full aperture Baader solar filter (OD=3.8) was used.

Cheers

Dennis

[h0ughy]

that film makes the poor old thousand oaks filter seem like a 10 oaks ;)