Search found 560 matches

by Bob Yoesle
Thu Mar 05, 2020 6:26 am
Forum: This is SolarChat !!
Topic: Outreach
Replies: 6
Views: 1852

Re: Outreach

Hi DT6,

I do a lot of outreach in the PNW, feel free to PM me for advice or a gettogether. The only real issue now is the solar minimum and paucity of continuum activity. Otherwise you tailor your outreach to the age/audience.
by Bob Yoesle
Thu Mar 05, 2020 3:31 am
Forum: Commercial Solar Filters/Cameras/Hardware
Topic: SM2 Etalon, Primary vs Double Stack Module?
Replies: 7
Views: 3202

Re: SM2 Etalon, Primary vs Double Stack Module?

Hi Marty, you can not rely on retail vendor advertising images to reflect the current model production. Many of them show previous generation models for the current version. I would stick to the manufacturers site for the correct image of the filter production - and this is not even 100% reliable.
by Bob Yoesle
Thu Mar 05, 2020 3:27 am
Forum: Solar Scope Modifications
Topic: Optimum BF for 6" f/10 with PST etalon and ASI174?
Replies: 35
Views: 3659

Re: Optimum BF for 6" f/10 with PST etalon and ASI174?

Unfortunately, Christians' experience with Omega filters is also my experience. FYI - Not all blocking filters are 0.6 nm - it depends on the etalon and blocking filter generation. Some of the early Coronado BFs were closer to 0.2-0.3 nm, and the etalons themselves had a narrower FSR. Using a Lunt B...
by Bob Yoesle
Mon Feb 03, 2020 4:18 am
Forum: This is SolarChat !!
Topic: Some tests with double stack etalons (mica & FS) and the C8 EdgeHD
Replies: 20
Views: 3031

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

Very nice references Christian :-) Bray and Loughhead noted the photospheric limb begins to manifest itself at +/- 0.65A off the center line, which seems to be essentially confirmed and refined by the higher resolution SST CRISP double stack to be +/- 0.6A. They also noted - and the CRISP images cle...
by Bob Yoesle
Sun Feb 02, 2020 6:29 am
Forum: Commercial Solar Filters/Cameras/Hardware
Topic: "New" PST comes with a 30mm etalon??
Replies: 12
Views: 1942

Re: "New" PST comes with a 30mm etalon??

Hi Ken,

I suspect Meade is stating the physical diameter to the entire etalon plates, not the effective diameter of the reflective coated portion of the etalon itself.
by Bob Yoesle
Sun Feb 02, 2020 6:24 am
Forum: This is SolarChat !!
Topic: Some tests with double stack etalons (mica & FS) and the C8 EdgeHD
Replies: 20
Views: 3031

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

Hi Christian, Very nice images! ;-) I'm thinking one or both of the filters is slightly off-band, and hence the double limb is still present. Alternatively, even at f35 you may not be getting the theoretical 0.5A and 0.6A FWHM of either filter, especially if your telecentric optics are not optimized...
by Bob Yoesle
Fri Jan 17, 2020 2:12 pm
Forum: Commercial Solar Filters/Cameras/Hardware
Topic: Meade / Solarmax Etalon Future?
Replies: 20
Views: 3466

Re: Meade / Solarmax Etalon Future?

There's the Celestron brand owners perhaps...

Wouldn't it be poetic justice if Lunt bought back their original patents and possibly production infrastructure for pennies on the dollar at auction?
by Bob Yoesle
Tue Jan 14, 2020 2:56 pm
Forum: Commercial Solar Filters/Cameras/Hardware
Topic: Meade / Solarmax Etalon Future?
Replies: 20
Views: 3466

Re: Meade / Solarmax Etalon Future?

Yes, exactly. At sea level, over 50% of the energy from the Sun lies in the near IR. The combination of the two ERF's essentially removes everything out to 2500 nm, where the atmosphere then blocks most everything beyond. Solar Energy Distribution.png The larger Solar Scope filters - lacking a centr...
by Bob Yoesle
Mon Jan 13, 2020 7:49 pm
Forum: Commercial Solar Filters/Cameras/Hardware
Topic: Meade / Solarmax Etalon Future?
Replies: 20
Views: 3466

Re: Meade / Solarmax Etalon Future?

Hi Rainer, It means I added a Baader DERF to the etalon assembly, which already included the Solar Scope OEM RG630 ERF with some IR blocking. DSF100 v SM90DS DERF comp.jpg The OEM Solar Scope ERF apparently has significant IR leakage, which exacerbates the thermal instability of the 100 mm etalons (...
by Bob Yoesle
Mon Jan 13, 2020 4:41 pm
Forum: Commercial Solar Filters/Cameras/Hardware
Topic: Meade / Solarmax Etalon Future?
Replies: 20
Views: 3466

Re: Meade / Solarmax Etalon Future?

Hi James, At 60-70 mm, an unobstructed etalon can perform quite well. But your minimally obstructed 60 mm will likely do just as well, and the wavefront effects of the obstruction will likely be indistinguishable from an unobstructed etalon, especially given daytime seeing rarely gets to diffraction...
by Bob Yoesle
Sun Jan 12, 2020 9:58 pm
Forum: Commercial Solar Filters/Cameras/Hardware
Topic: Meade / Solarmax Etalon Future?
Replies: 20
Views: 3466

Re: Meade / Solarmax Etalon Future?

It does quite well but I never have liked the idea of the central obstruction it has in the light path. A refractor should be unobstructed. An etalon is a filter, not a telescope. Etalons are quite sensitive to thermal variations of both the gap spacers and etalon plates themselves. A central (or o...
by Bob Yoesle
Sun Jan 12, 2020 9:15 pm
Forum: Commercial Solar Filters/Cameras/Hardware
Topic: Blocking filters and wintertime
Replies: 20
Views: 2774

Re: Blocking filters and wintertime

My gut is telling me that the original Coronado blocking filters may have been a bit more temperature stable. Then again I'm a lightweight and don't really enjoy cold weather observing in the middle of deep solar minimums, so my experience level may not be valid. The OEM's face a tough niche competi...
by Bob Yoesle
Sun Dec 15, 2019 3:53 pm
Forum: Solar Scope Modifications
Topic: D-ERF in converging beam?
Replies: 26
Views: 2401

Re: D-ERF in converging beam?

Just as a FYI, Brian Stevens at Lunt did mention the issue of tube currents was one of the reasons their 30 cm scope uses a open truss design. The other issue I want to highlight is that etalons are very sensitive to temperature changes. My Solar Scope DSF100 etalons suffered greatly from thermal in...
by Bob Yoesle
Sat Dec 14, 2019 4:27 pm
Forum: Solar Scope Modifications
Topic: D-ERF in converging beam?
Replies: 26
Views: 2401

Re: D-ERF in converging beam?

Hi Ken, You are of course correct in that 18 W in remains the same (conservation of energy), it is the energy density per unit area which has increased ~ 188 times at the focus. Therefore the 18 W falling over the surface area of the objective can be converted to heat through warming would be equiva...
by Bob Yoesle
Fri Dec 13, 2019 4:01 pm
Forum: Solar Scope Modifications
Topic: D-ERF in converging beam?
Replies: 26
Views: 2401

Re: D-ERF in converging beam?

Now I am seriouly beginning to wonder whether I wasn't cooking my old ASI120MC when it began to show a film of solar-surface like artefacts in the field of view. Though it seems unlikely given the Maier ITF and PST IBF5 in series. Is this likely given the extreme exposure in my case? I doubt it, as...
by Bob Yoesle
Thu Dec 12, 2019 5:50 pm
Forum: Solar Scope Modifications
Topic: D-ERF in converging beam?
Replies: 26
Views: 2401

Re: D-ERF in converging beam?

I have discovered some serious downsides: A hot exit beam from the empty focuser despite the D-ERF! This suggests the PST etalon is being baked for hours every day when I am imaging all day. Quite often! The smaller D-ERF is also being cooked by the same converging beam. A fierce, re-focused beam j...
by Bob Yoesle
Wed Dec 11, 2019 1:32 am
Forum: Solar Astronomy Shop and Swap
Topic: "Astronomie Solaire" - New (French) book on Solar Observation now available
Replies: 29
Views: 6683

Re: "Astronomie Solaire" - New (French) book on Solar Observation now available

I checked with Christian on this; here's his reply:

"The work of the book is advancing at a slow pace for a number of reasons. I think we will have it ready by the end of the first semester of 2020... We have included a lot of new stuff compared to the French version."
by Bob Yoesle
Sun Dec 01, 2019 12:28 am
Forum: This is SolarChat !!
Topic: Coronado PST testing
Replies: 31
Views: 3631

Re: Coronado PST testing

Hi Alexandra, I too think I prefer the old PST image, even though it is dimmer - it appears a bit more uniform. Just a thought - have you checked the ITF for rust? Replacing it in the older PST might give you a considerable bump in brightness. Better yet, using a Baader 35 nm Ha filter as an objecti...
by Bob Yoesle
Fri Nov 22, 2019 2:40 pm
Forum: Solar Scope Modifications
Topic: Removal of lunt erf double stack possible?
Replies: 3
Views: 1090

Re: Removal of lunt erf double stack possible?

Double stacking reduces the overall transmission of the filter system, but also removes the parasitic continuum from the photosphere itself. Both contribute to the overall perception of reduced image brightness, but vastly improved disc contrast. For two Lunt etalons in series with a transmission of...
by Bob Yoesle
Fri Oct 25, 2019 4:28 pm
Forum: Commercial Solar Filters/Cameras/Hardware
Topic: Lunt monster
Replies: 14
Views: 2704

Re: Lunt monster

Agreed Mark, Indeed it would theoretically be even smaller, since the FWHM of the PST is generrally closer to 0.1 nm, and a double stacked air spaced etalon is less than 0.05 nm; the Jacquinot spot is proportional to the square root of 2 x the FWHM.
by Bob Yoesle
Wed Oct 23, 2019 1:55 pm
Forum: Commercial Solar Filters/Cameras/Hardware
Topic: Lunt monster
Replies: 14
Views: 2704

Re: Lunt monster

Just visited with Brian at Lunt where this telescope is located... an impressive instrument when seen up close and personal. Objective has ERF coatings. Middle section has a large tilted precision polished optical window with additional ERF coatings. Open tube design in order to prevent build-up of ...
by Bob Yoesle
Wed Oct 23, 2019 1:28 pm
Forum: This is SolarChat !!
Topic: When I win the lottery
Replies: 20
Views: 1793

Re: When I win the lottery

Just visited with Brian at Lunt where this telescope is located... an impressive instrument when seen up close and personal. Objective has ERF coatings. Middle section has a large tilted precision polished optical window with additional ERF coatings. Open tube design in order to prevent build-up of ...
by Bob Yoesle
Wed Oct 23, 2019 1:01 pm
Forum: Commercial Solar Filters/Cameras/Hardware
Topic: Time for selling...
Replies: 11
Views: 1937

Re: Time for selling...

That is indeed a rather old citation, and one must take most predictions with a grain of salt. One of the most respected sources for solar information is Dr. David Hathaway, who is now retired from NASA, but who maintains an active solar prediction interest with solar physicist Lisa Upton: We predic...
by Bob Yoesle
Mon Aug 19, 2019 9:57 pm
Forum: Solar Scope Modifications
Topic: Blocking Filter In a Collimated Beam?
Replies: 10
Views: 1515

Re: Blocking Filter In a Collimated Beam?

"Anyone ever tried placing a Coronado / Lunt blocking filter in a collimated beam to see if it trims down continuum leakage in the wings?" Hi Mark, not sure this would get much improvement. If the BF has a Lorentzian profile - just as with FP etalons - the main effect would be to improve field angl...
by Bob Yoesle
Wed Jul 31, 2019 5:47 pm
Forum: Solar Scope Modifications
Topic: asi120mm-s DIY cooling
Replies: 6
Views: 1337

Re: asi120mm-s DIY cooling

Did this with my Chameleon a few years back:

https://www.cloudynights.com/topic/3266 ... chameleon/

I would consider active cooling for about any camera employed during the day for solar imaging.