Search found 151 matches

by george9
Sat Jul 11, 2020 11:25 pm
Forum: Commercial Solar Filters/Cameras/Hardware
Topic: Polarizing filters : safe or not for solar observation
Replies: 4
Views: 100

Re: Polarizing filters : safe or not for solar observation

And thanks for the filter page. The Astrodon UV filter looks great. And not that much more expensive than filters with only 65% transmission.

George
by george9
Sat Jul 11, 2020 11:20 pm
Forum: Commercial Solar Filters/Cameras/Hardware
Topic: Polarizing filters : safe or not for solar observation
Replies: 4
Views: 100

Re: Polarizing filters : safe or not for solar observation

I think it is good that you have reminded people that polarizers are for viewing comfort and optimization, NOT eye safety. The rule of thumb is that the system should already be blocking sufficient UV and IR before you approach it with a polarizer. Once you know 200-400 and 700-3000 are safe, what i...
by george9
Fri Jul 10, 2020 3:57 pm
Forum: Commercial Solar Filters/Cameras/Hardware
Topic: Can I have an 2020 update on where we are with Ca-K filter controls.
Replies: 46
Views: 1076

Re: Can I have an 2020 update on where we are with Ca-K filter controls.

I wonder if my L-2c is a previous generation before the L-1, L-2, L-3 series. For example, I see no "c" mentioned anywhere any more. I got it about six year ago. It actually says:

L filter
UV IR cut
Type 2c

George
by george9
Thu Jul 09, 2020 8:56 pm
Forum: Commercial Solar Filters/Cameras/Hardware
Topic: Can I have an 2020 update on where we are with Ca-K filter controls.
Replies: 46
Views: 1076

Re: Can I have an 2020 update on where we are with Ca-K filter controls.

I did better measurements today, and I added tilting. Titling 3 degrees did little. But at 25-30 degrees, many of the filters passed a lot more light. At 30 degrees, I assume the image is degraded. This is all measured with a Lunt CaK B1200 and PST #1 yellow filter double stack on an ASI290, assumin...
by george9
Thu Jul 09, 2020 12:20 am
Forum: Commercial Solar Filters/Cameras/Hardware
Topic: Can I have an 2020 update on where we are with Ca-K filter controls.
Replies: 46
Views: 1076

Re: Can I have an 2020 update on where we are with Ca-K filter controls.

I stand corrected. I had a little time before sunset when the clouds cleared. In CaK: Baader blue-CCD - passed 33% Astronomik UV-IR cut L-2c - passed 50% Baader double stack K-line 8nm - passed 66%+ I didn't measure it, but my PST #1 yellow filter passes the least light, but that boosts contrast, so...
by george9
Wed Jul 08, 2020 6:09 pm
Forum: Commercial Solar Filters/Cameras/Hardware
Topic: Can I have an 2020 update on where we are with Ca-K filter controls.
Replies: 46
Views: 1076

Re: Can I have an 2020 update on where we are with Ca-K filter controls.

The other half of the equation, if you are using a Lunt CaK, is what it the transmission of its ERF? Depending on that profile, there may not be much to gain by adding another ERF in front. If the Lunt is already narrow and sharp, then adding another filter with high transmission in front of it ends...
by george9
Sun Jul 05, 2020 9:15 pm
Forum: Commercial Solar Filters/Cameras/Hardware
Topic: Baader Coronagraph
Replies: 5
Views: 138

Re: Baader Coronagraph

For the record, nope, not 530. More like 547nm. I looked at a reflection of the Sun off the floor in the spectroscope and logged the bands, and 530 was lower than the coronagraph line. I cannot find anything of interest at 547, so I suspect it is a degraded filter. A very narrow line though.

George
by george9
Sun Jul 05, 2020 3:57 am
Forum: Commercial Solar Filters/Cameras/Hardware
Topic: Baader Coronagraph
Replies: 5
Views: 138

Re: Baader Coronagraph

Or maybe that extra green band is 530nm for FeXIV in the hope to get that bright but low coronal emission over an active region (I just learned about it, so I may have it wrong)? I measured 540nm in my hand spectroscope, but it is not very accurate.

George
by george9
Sun Jul 05, 2020 1:17 am
Forum: Commercial Solar Filters/Cameras/Hardware
Topic: Baader Coronagraph
Replies: 5
Views: 138

Re: Baader Coronagraph

Thanks, Alexandra. I agree. My general rule is I don't view unless I have a complete commercial visual filter in series with whatever I come up with. The Prom15T will be for imaging only and sounds like so will be the original H-alpha filter. I guess I could try to find a commercial 2A prom filter t...
by george9
Sat Jul 04, 2020 3:05 pm
Forum: Commercial Solar Filters/Cameras/Hardware
Topic: Baader Coronagraph
Replies: 5
Views: 138

Baader Coronagraph

I acquired a Baader Coronagraph for fun, plus a matching Celestron (Vixen) 80mm refractor. The H-alpha filter is deteriorating, and the price reflected that. Normally when a filter deteriorates it gets darker, not lighter, so it is probably safe. But I was thinking of putting a Beloptic UV-IR KG3 cu...
by george9
Fri Jun 05, 2020 2:51 am
Forum: Solar Radio, Magnetometry and Spectroscopy
Topic: My smallest spectroscope first light
Replies: 6
Views: 152

Re: My smallest spectroscope first light

That's great. What approximate bandwidth are you achieving on each image, do you think? George
by george9
Thu Jun 04, 2020 4:03 pm
Forum: This is SolarChat !!
Topic: Fun with Ca K filters. First light of Alluxa Ca K filter, May 31
Replies: 27
Views: 469

Re: Fun with Ca K filters. First light of Alluxa Ca K filter, May 31

Excellent!

Is the Barr filter single cavity or multiple cavity? I wouldn't have thought the Alluxa would have made such a big difference in the two images (Barr versus Barr+Alluxa). But it must be multiple cavity or the Barr solo image wouldn't have looked so good.

George
by george9
Sun May 24, 2020 11:54 pm
Forum: This is SolarChat !!
Topic: Lunt Pressure Tuner
Replies: 13
Views: 240

Re: Lunt Pressure Tuner

Lunt uses Dow Corning High Vacuum Grease. They send some grease with new O-ring sets. I had cleaned the grease on one of my pressure tuners. Then I noticed it developed some hysteresis when tuning up and down. So I loaded more grease on the PT threads and it went back to normal. So some of the extra...
by george9
Sun May 17, 2020 12:32 am
Forum: This is SolarChat !!
Topic: 15May - C11 CAK Hi-Res Imaging - New images added on 20 May
Replies: 28
Views: 649

Re: 15May - C11 CAK Hi-Res Imaging - New image added and raw image for processing

Alfred, spectacular job in all cases. Visually, I prefer the first to the second even if it is less sharp because the second does not look real. When you blow it up, you see the entire image is made of dots and tubes that are all identical width, I guess based on the sharpening software because the ...
by george9
Tue Apr 14, 2020 10:50 am
Forum: This is SolarChat !!
Topic: Forum upgrades finally completed. sort of
Replies: 17
Views: 3140

Re: Forum upgrades finally completed. sort of

This is a unique resource. Thank you.

George
by george9
Fri Mar 13, 2020 1:59 am
Forum: This is SolarChat !!
Topic: Solar Spectrum filter for visual observation?
Replies: 6
Views: 5419

Re: Solar Spectrum filter for visual observation?

Very good. So you'll need to decide 0.3 or 0.5 . I would not go wider than that, though. As aperture increases (say for a future scope), I find the narrowness becomes increasingly important for visual.

George
by george9
Wed Mar 11, 2020 11:27 pm
Forum: This is SolarChat !!
Topic: Solar Spectrum filter for visual observation?
Replies: 6
Views: 5419

Re: Solar Spectrum filter for visual observation?

I love my Solar Spectrum RG32 0.3A. I use it on a 155mm, and now a 280mm, and sometimes on a 92mm but my LS80DS covers that. I got mine from Solar Spectrum but also configured through Bob at Alpine, and they both (collaboratively) walked me through the entire process. Prices in Europe may be higher....
by george9
Sat Mar 07, 2020 12:53 pm
Forum: Solar Scope Modifications
Topic: What is the cheapest mod to view details of the sun up close?
Replies: 20
Views: 11397

Re: What is the cheapest mod to view details of the sun up close?

Jim's 7" refractor with 0.3A filter, or Frederic's 8" SCT with 0.3A How can I *cheaply* know the bandwidth of my quark? A lot of optimizing goes into producing great views. Apart from, say, add a beloptik UV/IR cut in front of the diagonal I don't know how else I can optimize Ha. I read that adding...
by george9
Fri Mar 06, 2020 8:58 pm
Forum: Solar Scope Modifications
Topic: What is the cheapest mod to view details of the sun up close?
Replies: 20
Views: 11397

Re: What is the cheapest mod to view details of the sun up close?

Heya, Daytime seeing is bad. Really bad. Relative to nighttime seeing. It's of course dependent geographically where you are. And typically its better in the morning hours, not afternoon. But that too is a generalization. Overall though, you would be hard pressed to find a typical location able to ...
by george9
Fri Feb 21, 2020 10:48 pm
Forum: This is SolarChat !!
Topic: Avoiding poor, local seeing conditions.
Replies: 22
Views: 7709

Re: Avoiding poor, local seeing conditions.

Cities can certainly have great seeing at night. My best night ever anywhere was in a city. I would think the 95F daytime temperature would have had roofs putting out heat all night, but the 85F night air was stationary. Not just great, but stationary. Textbook Airy disk in an 18", motionless and pe...
by george9
Fri Feb 21, 2020 1:29 am
Forum: This is SolarChat !!
Topic: Avoiding poor, local seeing conditions.
Replies: 22
Views: 7709

Re: Avoiding poor, local seeing conditions.

I didn't realize how big a difference the ground height can make. Thanks for that link. My tripod is somewhat tall, so the objective of the telescope is probably at 2 meters. I wish I had an observatory, but the up side is that I am set up on grass with no real buildings or roads to the south. I am ...
by george9
Thu Feb 13, 2020 10:43 pm
Forum: Commercial Solar Filters/Cameras/Hardware
Topic: Available external DS etalons??
Replies: 29
Views: 10913

Re: Available external DS etalons??

The pre-Meade Coronado were very nice but they varied just like today’s filters so be nice to try before buying. I have or had two 60s (astro buddy has them now). One was better than the other. They worked very well together. But my LS80 DSII actually has higher contrast and better sweet spot perfor...
by george9
Tue Feb 11, 2020 5:34 am
Forum: This is SolarChat !!
Topic: Some tests with double stack etalons (mica & FS) and the C8 EdgeHD
Replies: 20
Views: 7478

Re: Some tests with double stack etalons (mica & FS) and the C8 EdgeHD

Christian, yes my original blocking filter (for an ASP60) was also 2A (Prom15T), not because it needed 2A but I think because they simply repurposed their old prom filter. Nevertheless, if after tuning you still see a double limb, I would just try the 2A blocking filter and see if it eliminates it. ...
by george9
Wed Feb 05, 2020 12:31 pm
Forum: This is SolarChat !!
Topic: Some tests with double stack etalons (mica & FS) and the C8 EdgeHD
Replies: 20
Views: 7478

Re: Some tests with double stack etalons (mica & FS) and the C8 EdgeHD

I agree that with those two filters double stacked and centered, you should eliminate the double limb. If not, then something else is going on. Like leakage on a side spike through the blocking filter. If the space between spikes (FSR?) on one filter is narrower than the blocking filter is made for...
by george9
Mon Feb 03, 2020 4:56 am
Forum: Solar Scope Modifications
Topic: Newtonian vs SCT thermal handling with full aperture D-ERF
Replies: 25
Views: 8263

Re: Newtonian vs SCT thermal handling with full aperture D-ERF

Marty, sorry it hasn't worked out (at least yet) but thanks for posting as we learn how to use larger scopes. A Barlow high enough up the light cone might address it by increasing the focal ratio, but then might as well use the SCT. And you would have to make sure it works at 393nm for that work. A ...