Search found 473 matches

by Bob Yoesle
Mon Dec 03, 2018 5:40 pm
Forum: Solar Scope Modifications
Topic: Dismantling and modification of a PST CaK
Replies: 29
Views: 1727

Re: Dismantling and modification of a PST CaK

"Painted the inside of the OTA with Berger Antireflexfarbe."

Unfortunately, can't be delivered to the States. Anyone know of a similar product available in North America?
by Bob Yoesle
Mon Dec 03, 2018 5:01 pm
Forum: Commercial Solar Filters/Cameras/Hardware
Topic: Internal vs. external Etalon placement question.
Replies: 2
Views: 223

Re: Internal vs. external Etalon placement question.

Ditto to what Mark has said ;-) Here's a little more detail as to why: All etalons are sensitive to the angle of light passing through them, and theoretically perform best with only parallel light passing at a 90 degree angle ("normal") to the reflective elements. The Sun, being an extended object i...
by Bob Yoesle
Wed Nov 21, 2018 4:02 pm
Forum: Solar Scope Modifications
Topic: optical contact experiments? Anybody?
Replies: 4
Views: 365

Re: optical contact experiments? Anybody?

"If an airspaced etalon is just two pieces of partially reflective glass contacted between mica spacers..." Not quite Apollo! Polishing to lambda/100 flatness across 25 mm is not too difficult using relatively standard production techniques, achieving this over the full area of a larger filter becom...
by Bob Yoesle
Mon Nov 19, 2018 3:16 pm
Forum: Commercial Solar Filters/Cameras/Hardware
Topic: Rust on either Lunt or Coronado
Replies: 7
Views: 391

As shown in Ken's pics, and as in the above Cloudy Nights link, the Lunt issue now appears to be "glass disease:" https://en.wikipedia.org/wiki/Glass_disease See the Stage 1 and Sage 2 descriptions. It is known the Lunt uses BG glass (verses an ITF), which is a simple soda lime glass. It seems the K...
by Bob Yoesle
Thu Nov 15, 2018 8:36 pm
Forum: This is SolarChat !!
Topic: Old Coronado BF30
Replies: 18
Views: 605

Re: Old Coronado BF30

Hi Bart, No doubt a killer deal, as the filter itself is probably worth 10 times the price advertised. I have 3 BF 30's and they all have different brightness levels. Sometimes darker is better... Your proposed ancillary filters should work well, as the DERF will block UV and near IR, the 35 nm H al...
by Bob Yoesle
Thu Nov 15, 2018 4:44 pm
Forum: This is SolarChat !!
Topic: Old Coronado BF30
Replies: 18
Views: 605

Re: Old Coronado BF30

I checked out this filter as well... The Isle of Man blocking filters were designed for an etalon with a higher finesse and narrower FSR than the later Coronado or Solar Scope etalons. As opposed to today's Coronado and Solar Scope BF's with about a 6-8 A FWHM, the one in question probably has a 2-3...
by Bob Yoesle
Mon Nov 12, 2018 12:48 pm
Forum: This is SolarChat !!
Topic: Mg II in UltraViolet
Replies: 31
Views: 1339

Re: Mg II in UltraViolet

" Here are the simulations for a re-spaced classic C8 :
http://astrosurf.com/viladrich/astro/in ... -Plate.htm "

Thanks so much for this Christian!
by Bob Yoesle
Mon Nov 12, 2018 12:41 pm
Forum: Solar Scope Modifications
Topic: Lunt CaK B1200 + PST #1 yellow
Replies: 6
Views: 470

Re: Lunt CaK B1200 + PST #1 yellow

Hi George, I don't know if you saw these, but here's my recent results using a $350 Chameleon CCD camera. I already knew from a few years ago that double stacking CaK filters provides a contrast improvement. Triple stacking CaK filters is useful for bringing out details near to the solar limb. The s...
by Bob Yoesle
Sat Nov 10, 2018 2:35 pm
Forum: This is SolarChat !!
Topic: Mg II in UltraViolet
Replies: 31
Views: 1339

Re: Mg II in UltraViolet

Without the optical prescriptions of the lens system, it is impossible to know. The respaced SCT corrector probably does a better job of coma reduction, while I believe a separate system would be required for chromatic spherical aberration correction at 393 nm. For CaK work, the PST filters will be ...
by Bob Yoesle
Sat Nov 10, 2018 12:27 am
Forum: This is SolarChat !!
Topic: Mg II in UltraViolet
Replies: 31
Views: 1339

Re: Mg II in UltraViolet

Hi Christian, It's the standard (not the Edge-HD) C8. Any chance you could "cook up" a spherical aberration corrector using COTS fused silica len(es) from Edmund, Thor Labs, etc? That seems like it would be an ideal CaK imaging platform and relatively less expensive compared to a custom CaK refracto...
by Bob Yoesle
Fri Nov 09, 2018 4:50 am
Forum: This is SolarChat !!
Topic: Mg II in UltraViolet
Replies: 31
Views: 1339

Re: Mg II in UltraViolet

Hi Christian,

Thanks you very much - that would be wonderful :-) I have seen your C14 re-spaced write up and have purchased a carbon fiber tube towards the implementation...
by Bob Yoesle
Thu Nov 08, 2018 4:47 pm
Forum: This is SolarChat !!
Topic: Mg II in UltraViolet
Replies: 31
Views: 1339

Re: Mg II in UltraViolet

Hi Valery, Do you have a transmission plot for the C8 DERF? I also would like to know the physical dimensions, and if it is possible to put a central hole in the filter. I'm considering a re-spaced SCT mod and would prefer to mount the secondary mirror to the DERF if it could be made to replace the ...
by Bob Yoesle
Wed Nov 07, 2018 5:13 pm
Forum: This is SolarChat !!
Topic: Mg II in UltraViolet
Replies: 31
Views: 1339

Re: Mg II in UltraViolet

Thanks for that Peter ;-) OK, so now we add a sounding rocket to the equipment list: https://www.youtube.com/watch?v=sQw_C5KLhFM Alternatively, one could always move to Antarctica: Solar-Spectrum-GballEditz.png https://www.youtube.com/watch?v=fzN0LbZXX1s&feature=youtu.be But you'll probably also nee...
by Bob Yoesle
Wed Nov 07, 2018 4:15 pm
Forum: This is SolarChat !!
Topic: Mg II in UltraViolet
Replies: 31
Views: 1339

Re: Mg II in UltraViolet

An interesting research paper - thanks for sharing it Valery. "If one will go this way, he should not save money on a too small telescope. 100mm is a minimal size I would say. Minimal SA is a must for such a telescope. A must have also a SSM. The main price driving factor is an etalon with a 0,5A ba...
by Bob Yoesle
Wed Nov 07, 2018 2:49 pm
Forum: Solar Scope Modifications
Topic: Pst Cak filter secret -
Replies: 10
Views: 905

Re: Pst Cak filter secret -

Hmmm - this is a notch filter (not bandpass), hence the NF prefix. What would it be useful for in a CaK solar filter?
NF405-13_Transmission_780.gif
NF405-13_Transmission_780.gif (17.05 KiB) Viewed 281 times
by Bob Yoesle
Tue Nov 06, 2018 5:42 pm
Forum: Commercial Solar Filters/Cameras/Hardware
Topic: LS60 upgrade options
Replies: 12
Views: 712

Re: LS60 upgrade options

Hi Dano, If at all possible, for whatever you decide to buy, make sure you can return it if you are not pleased with the performance. Even the very most highly regarded manufacturers can have a lemon slip through, and with commercial production pressures, overall quality has seemed to slip from what...
by Bob Yoesle
Tue Oct 30, 2018 11:09 pm
Forum: Commercial Solar Filters/Cameras/Hardware
Topic: ITF filter on the way out?
Replies: 5
Views: 1171

Re: ITF filter on the way out?

Perhaps, but the only difference may be image brightness (peak transmission), not resolution or ability to magnify the image. A brighter image does make higher magnifications easier to be able to see detail with. Check with Oliver at BelOptik. If the PST has another RG630 filter in the filter system...
by Bob Yoesle
Tue Oct 30, 2018 10:57 pm
Forum: Commercial Solar Filters/Cameras/Hardware
Topic: Experimenting calcium imaging with small refractors
Replies: 28
Views: 1544

Re: Experimenting calcium imaging with small refractors

Hi George, Not sure my results will be that informative - although I am looking forward to getting things up and running with a new CaK module. My circa 1996 130 EDT f/8 uses an oil-spaced glass combination of ZKN-7 crown sandwiching an FPL-53 center element. The later f/8.35 EDF scopes used FPL-53 ...
by Bob Yoesle
Thu Oct 25, 2018 8:48 pm
Forum: Commercial Solar Filters/Cameras/Hardware
Topic: BF30 ITF replacement
Replies: 10
Views: 791

Re: BF30 ITF replacement

Individual biological tissue susceptibility, dose, exposure time, and recovery time, are all variables which need to be accounted for with any kind of energy exposure, whether it is electromagnetic, acoustic, or kinetic. With IR there seems to be a paucity of data related to optical instruments in g...
by Bob Yoesle
Thu Oct 25, 2018 1:54 am
Forum: Commercial Solar Filters/Cameras/Hardware
Topic: BF30 ITF replacement
Replies: 10
Views: 791

Re: BF30 ITF replacement

Image re-proportioned from here:

https://www.phys.ksu.edu/personal/macf/ ... aining.htm

Original figure source document described here:

https://www.lia.org/resources/laser-safety-information
by Bob Yoesle
Wed Oct 24, 2018 4:15 pm
Forum: Commercial Solar Filters/Cameras/Hardware
Topic: BF30 ITF replacement
Replies: 10
Views: 791

Re: BF30 ITF replacement

Hi Ken, "Why do we think blocking IR beyond 1400nm is an important issue in solar filter design?" For one reason it seems most of the solar filter manufacturers think it's important, and spend additional funds and increase the costs of their products to provide blocking to 3000 nm or beyond. https:/...
by Bob Yoesle
Sun Oct 21, 2018 3:59 am
Forum: Commercial Solar Filters/Cameras/Hardware
Topic: BF30 ITF replacement
Replies: 10
Views: 791

Re: BF30 ITF replacement

The ITF of the solar blocking filters do not fail from lamination separation or de-contacting between the filter components, they fail from thermal cycling and loading. This compromises the edge seal, which results in atmospheric moisture being able to penetrate the filter and degrade the silver lay...
by Bob Yoesle
Sat Oct 20, 2018 1:13 am
Forum: Commercial Solar Filters/Cameras/Hardware
Topic: Experimenting calcium imaging with small refractors
Replies: 28
Views: 1544

Re: Experimenting calcium imaging with small refractors

"An exceptionally detailed image posted somewhere in this forum (I have been unable to locate it again, may be from Bob Yoesle) made me curious to image the Sun in Ca-H light with a 100ED f/9 refractor. In the used market I could find one that accidentally was already mine five years ago :lol: and n...
by Bob Yoesle
Thu Oct 18, 2018 6:09 pm
Forum: Commercial Solar Filters/Cameras/Hardware
Topic: BF30 ITF replacement
Replies: 10
Views: 791

BF30 ITF replacement

I just got a note from Oliver Smie that he can now provide his drop-in replacement for the ITF in the BF30 size: "After endless time I have also durable ITF replacement filters for the Coronado BF30 in stock, a batch of 18pcs. Filter design is the same to my smaller ones for PST, BF10... https://bel...
by Bob Yoesle
Mon Oct 15, 2018 5:20 pm
Forum: Solar Astronomy Shop and Swap
Topic: "Astronomie Solaire" - New (French) book on Solar Observation now available
Replies: 14
Views: 697

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

So, we have to get working to get this English version available ASAP ;-)
Yeah! Looking forward to it Christian :-)