Search found 171 matches

by thesmiths
Mon Jul 03, 2017 6:37 pm
Forum: Great American Solar Eclipse August 21 2017
Topic: Telephoto lens or short refractor?
Replies: 4
Views: 838

Re: Telephoto lens or short refractor?

Mark, in another post you wrote: "I'm probably going to use a DSLR and a 70/420mm refractor for my travelling setup." Did you change your mind? I actually thought around 420mm on a crop DSLR camera was a perfect compromise. I think that's was Alexandra is planning on using. The Tecnosky 65Q 420mm qu...
by thesmiths
Sun Jul 02, 2017 1:37 am
Forum: Great American Solar Eclipse August 21 2017
Topic: Telephoto lens or short refractor?
Replies: 4
Views: 838

Telephoto lens or short refractor?

Now that it's getting close, I am considering my options. Flying from Europe suggests travelling light. I did a dry run today with a Canon EF 300mm F4 IS camera lens vs an APM 480mm F6 telescope. The camera was a Canon EOS 100D. In terms of solar image size, I can see that the wider field of view of...
by thesmiths
Sun Jul 02, 2017 12:37 am
Forum: Great American Solar Eclipse August 21 2017
Topic: Using eclipse images to capture gravitational lens effect?
Replies: 3
Views: 570

Re: Using eclipse images to capture gravitational lens effect?

In the famous observation of 1919, there were actually two expeditions: one to Sobral in nothern Brazil and a second to the island of Principe, about 120 miles from the African coast. In Sobral, the eclipse took place around noon UTC, so about 8am local time. This meant they only needed to wait a fe...
by thesmiths
Sat Jul 01, 2017 1:35 pm
Forum: Solar Radio, Magnetometry and Spectroscopy
Topic: Fulvio Mete - Zeeman effect
Replies: 3
Views: 624

Re: Fulvio Mete - Zeeman effect

That's a huge amount of splitting. The Zeeman effect is quite a weak phenomenon. Very good measurement to see it at all.
by thesmiths
Sat Jul 02, 2016 8:28 pm
Forum: Solar Radio, Magnetometry and Spectroscopy
Topic: "Imaging Sunlight - Using a Digital Spectroheliograph"
Replies: 55
Views: 8273

Re: "Imaging Sunlight - Using a Digital Spectroheliograph"

I just received my copy today from Amazon. What an amazing amount of time and dedication to detail to produce such an impressive volume. I have copies of Ken's other two books on astronomical spectroscopy, which I bought and read mainly to understand solar spectroscopy (despite their being mainly or...
by thesmiths
Mon May 09, 2016 7:03 pm
Forum: This is SolarChat !!
Topic: Mercury Transit in CaK, 9 May 2016
Replies: 9
Views: 471

Re: Mercury Transit in CaK, 9 May 2016

Maybe we were under the same clouds? I add a final one which is 150% cropped at 12:09 UTC. I think it's the one where Mercury itself looked the sharpest. Click to see in full size. What a tiny little planet Mercury is!
Sun_120926_150.jpg
Mercury Transit 150%
by thesmiths
Mon May 09, 2016 5:49 pm
Forum: This is SolarChat !!
Topic: Mercury Transit in CaK, 9 May 2016
Replies: 9
Views: 471

Re: Mercury Transit in CaK, 9 May 2016

Another one taken slightly earlier at 11:31 UTC (click on picture for larger view). Unfortunately, earlier than this suffered from clouds and after 13:26 UTC some trees became a factor. Then came the rain! Nevertheless, I'm pleased with what I got as the weather forecast for London looked truly omin...
by thesmiths
Mon May 09, 2016 5:22 pm
Forum: This is SolarChat !!
Topic: Mercury Transit in CaK, 9 May 2016
Replies: 9
Views: 471

Mercury Transit in CaK, 9 May 2016

I haven't pulled out the telescopes for quite awhile -- but Mercury Transit is a worthy reason. Taken with a 106mm APO triplet, 700m FL, 2X Barlow. Using a Lunt CaK [Mark/Walter] mod (Herschel wedge plus Baader K-line filter). ZWO 174MM, 2.5ms, 126 fps. Best 50% of 300 frames in AS!2, RegiStax 6 wav...
by thesmiths
Tue Nov 10, 2015 9:26 am
Forum: Solar Scope Modifications
Topic: From 50 to 60 DS?
Replies: 23
Views: 2788

Re: From 50 to 60 DS?

I have a 60/60 Lunt DS and in retrospect I think upgrading to a 80mm or 100m SS would be a more satisfying investment (assuming financial constraints).
by thesmiths
Mon Sep 28, 2015 11:50 pm
Forum: This is SolarChat !!
Topic: A quick Lunar Eclipse image
Replies: 8
Views: 469

Re: A quick Lunar Eclipse image

Pedro, your eclipse photos are lovely. In retrospect, I wish I had brought out my 4 inch APO and GEM. The weather conditions were very good here. I just hadn't appreciated how interesting a Lunar eclipse would be. [I sent you a PM just now, by the way, with some interesting photos]
by thesmiths
Mon Sep 28, 2015 5:38 pm
Forum: This is SolarChat !!
Topic: A quick Lunar Eclipse image
Replies: 8
Views: 469

Re: A quick Lunar Eclipse image

As I understand it, this was a particularly dark and intense eclipse due to it being a "Super Moon"; i.e., the Moon was near its closest approach so the Earth's shadow blocked more light. The shadow on the Moon at the beginning of eclipse was really startling and I could imagine ancient peoples gett...
by thesmiths
Mon Sep 28, 2015 11:48 am
Forum: This is SolarChat !!
Topic: A quick Lunar Eclipse image
Replies: 8
Views: 469

A quick Lunar Eclipse image

I actually never witnessed a Lunar Eclipse before. It's quite amazing to watch. Most photos can't really capture the huge dynamic range during the eclipse and the unusual colours. I didn't put much effort into the photography: 200mm Canon f2.8L lens with Canon 40D camera on a camera tripod. Photo ta...
by thesmiths
Tue Aug 11, 2015 11:48 am
Forum: Solar Radio, Magnetometry and Spectroscopy
Topic: Tailor made glass optical slits
Replies: 13
Views: 1526

Re: Tailor made glass optical slits

If you have a chance to make another run of slits, I'd recommend getting a batch of 1 inch c-axis sapphire wafers . They are very commonly used in the semiconductor industry and are reasonably priced (maybe around $10 each these days?). As stated by Thorlabs: "sapphire provides exceptional surface h...
by thesmiths
Tue Aug 11, 2015 12:53 am
Forum: Solar Radio, Magnetometry and Spectroscopy
Topic: Tailor made glass optical slits
Replies: 13
Views: 1526

Re: Tailor made glass optical slits

Wah, your comments made me look at the Thorlabs metal slit that I have been using for SHG. These are stated to be: "302 Stainless Steel w/ Black Oxide Finish". I have actually not used it a huge amount but I notice that the "black oxide" has been completely burned off in an oval shaped pattern due t...
by thesmiths
Tue Jun 23, 2015 1:35 am
Forum: Solar Radio, Magnetometry and Spectroscopy
Topic: its it safe to say a SHG is born?
Replies: 18
Views: 1931

Re: its it safe to say a SHG is born?

It's definitely working. I assume one issue is that the slit is not perpendicular to the scan direction. I don't think that's absolutely necessary but it's obviously helpful if it's not too far off. The current data can be fixed by a transformation in Photoshop (rotate and then resize). Your slit lo...
by thesmiths
Fri Jun 19, 2015 11:56 pm
Forum: Commercial Solar Filters/Cameras/Hardware
Topic: First light for a "new" CaK PST (and 1st attempt to mod it!)
Replies: 12
Views: 1577

Re: First light for a "new" CaK PST (and 1st attempt to mod

Thanks for the suggestion to look up info on "Loctite". I found the following interesting info: "What is the difference between the Red and Blue threadlocker? Red Threadlocker is the highest strength. This product cures fully in 24 hours and is available in both a liquid and as a semisolid anaerobic...
by thesmiths
Fri Jun 12, 2015 1:40 am
Forum: Solar Scope Modifications
Topic: CaK module ERF
Replies: 18
Views: 3079

Re: CaK module ERF

Bob, the solar Newtonian concept seems to work best with a metalised secondary. For CaK, there is not enough light if both mirrors are uncoated. But even with WL, I've noticed there can be strange ghost reflections from the back on an uncoated secondary. My original idea was that a Newtonian would h...
by thesmiths
Wed Jun 10, 2015 10:28 pm
Forum: Commercial Solar Filters/Cameras/Hardware
Topic: First light for a "new" CaK PST (and 1st attempt to mod it!)
Replies: 12
Views: 1577

Re: First light for a "new" CaK PST (and 1st attempt to mod

Mark, so you mean remove the #1 filter via the front of the gold tube? Sounds a bit like endoscopic surgery! I may first actually try the old hair-dryer trick. I've found with stuck microscope parts, heating with a hair-dryer will partially melt any old grease and differential expansion (e.g. betwee...
by thesmiths
Wed Jun 10, 2015 10:18 pm
Forum: Solar Scope Modifications
Topic: CaK module ERF
Replies: 18
Views: 3079

Re: CaK module ERF

Bob, if the image reversal bothers you, I believe Firecapture has a toggle to invert the x or y directions! In my setup, I built a pair of inserts that drop into the Lunt wedge. One is a stack of ND filter, Baader contiuum and IR cut. The other is Baader K-line, Lunt CaK stack and polarisation filte...
by thesmiths
Wed Jun 10, 2015 1:26 am
Forum: Solar Scope Modifications
Topic: CaK module ERF
Replies: 18
Views: 3079

Re: CaK module ERF

Bob, I'm curious why you don't want to use a wedge? I'm using a Lunt wedge (1.25 inch), Baader K-line, followed by the Lunt CaK stack (from my B1200). It works really well (and I hope to eventually add a PST CaK filter #1 to double stack it). My motivation was also to go up in aperture to 150mm, as ...
by thesmiths
Mon Jun 08, 2015 11:38 am
Forum: Commercial Solar Filters/Cameras/Hardware
Topic: First light for a "new" CaK PST (and 1st attempt to mod it!)
Replies: 12
Views: 1577

Re: First light for a "new" CaK PST (and 1st attempt to mod

Mark: yes, I have a camera lens spanner, a crucial tool for any telescope and microscope servicing (or modding!). Were you trying to suggest this could be used to remove the #1 filter? But I would still first need separate the gold tube, as far as I can see. Below is a photo of my lens spanner (from...
by thesmiths
Sat Jun 06, 2015 11:25 pm
Forum: Commercial Solar Filters/Cameras/Hardware
Topic: First light for a "new" CaK PST (and 1st attempt to mod it!)
Replies: 12
Views: 1577

First light for a "new" CaK PST (and 1st attempt to mod it!)

I finally managed to find a CaK PST here in the UK. It is of course "used" since they don't make them any more. But I'm calling it "new" since I've never seen one myself before. When it arrived, it brought back many memories since one of my first telescopes was a H-alpha PST many years ago. I had ta...
by thesmiths
Sun May 31, 2015 1:04 am
Forum: This is SolarChat !!
Topic: Long V-Filament spotted today
Replies: 9
Views: 577

Re: Long V-Filament spotted today

I think image 1 has been flipped along the horizontal axis, hasn't it? That explains the apparent "lift off" mentioned by Alexandra. I believe all the other images are in the correct relative orientations (including the mosaic).
by thesmiths
Sat May 23, 2015 10:34 pm
Forum: Commercial Solar Filters/Cameras/Hardware
Topic: Best camera?
Replies: 12
Views: 1566

Re: Best camera?

I personally think the search for an all-in-one camera will lead to disappointment. Planetary imaging and solar imaging have quite different limiting factors. I would recommend having a different camera for each. Typically for planets, you need only a very small chip and actually not that many pixel...
by thesmiths
Fri Mar 27, 2015 1:26 am
Forum: This is SolarChat !!
Topic: First shot eclipse
Replies: 34
Views: 2345

Re: First shot eclipse

Jesus, that CaK swirl is great.