Search found 467 matches

by Bob Yoesle
Mon Nov 12, 2018 12:48 pm
Forum: This is SolarChat !!
Topic: Mg II in UltraViolet
Replies: 43
Views: 1053

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: 9
Views: 353

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: 43
Views: 1053

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: 43
Views: 1053

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: 43
Views: 1053

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: 43
Views: 1053

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: 43
Views: 1053

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: 43
Views: 1053

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: 24
Views: 784

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 160 times
by Bob Yoesle
Tue Nov 06, 2018 5:42 pm
Forum: Commercial Solar Filters/Cameras/Hardware
Topic: LS60 upgrade options
Replies: 13
Views: 597

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: 1117

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: 33
Views: 1344

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: 15
Views: 695

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: 15
Views: 695

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: 15
Views: 695

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: 15
Views: 695

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: 33
Views: 1344

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: 15
Views: 695

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: 18
Views: 597

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 :-)
by Bob Yoesle
Thu Oct 11, 2018 9:01 am
Forum: Solar Scope Modifications
Topic: Mersenne telescope design
Replies: 2
Views: 257

Re: Mersenne telescope design

I have considered this as well. There is a good discussion on the Mersenne design here: https://www.cloudynights.com/topic/392210-wide-angle-compound-telescope/ Would a Mersenne telescope in front with a h-alpha scope in the back attached achieve a higher resolution? There is significant potential f...
by Bob Yoesle
Fri Oct 05, 2018 6:30 pm
Forum: Solar Scope Modifications
Topic: ⚠️ ⚠️ Chroma 1.25” filter cell thermal fracture
Replies: 8
Views: 356

Re: ⚠️ ⚠️ Chroma 1.25” filter cell thermal fracture

Thanks for the heads up Apollo. I checked my filter and it uses a plastic retaining ring. I loosened it up when I got it and there is a slight rattle to it when gently shaken, so hopefully I'll have no issues. It is a hard coated filter on a fused silica substrate so it should be quite stable therma...
by Bob Yoesle
Thu Oct 04, 2018 5:11 am
Forum: Solar Scope Modifications
Topic: Narrowest 393.37 ever by Apollo Lasky
Replies: 210
Views: 7893

Re: Narrowest 393.37 ever by Apollo Lasky

I have asked Dick at Chroma Tech about the discrepancy of the data sets. So far, no answer. I did ask about the nomenclature difference; Apollo's files were labeled 393.37 0.1, the data sets Dick sent me were labeled 393.4 0.1. Dick stated it was just a labeling difference and that they indeed were ...
by Bob Yoesle
Wed Oct 03, 2018 7:10 pm
Forum: Solar Scope Modifications
Topic: Narrowest 393.37 ever by Apollo Lasky
Replies: 210
Views: 7893

Re: Narrowest 393.37 ever by Apollo Lasky

Single.

Chroma Tech said they could do a double cavity filter, but not a triple. I didn't ask what the price would be.
by Bob Yoesle
Wed Oct 03, 2018 5:01 pm
Forum: Solar Scope Modifications
Topic: Narrowest 393.37 ever by Apollo Lasky
Replies: 210
Views: 7893

Re: Narrowest 393.37 ever by Apollo Lasky

I don't know why there is a discrepancy, all I know is that this is the data Dick Stewart sent me. My filter also appears to need more than 1.5 degrees of tilt, but I have yet to calculate it from what I can measure in the Skybender - going to have to brush up on my trigonometry skills ;-) Dick did ...