Search found 534 matches

by Bob Yoesle
Sat Jun 15, 2019 5:34 pm
Forum: Commercial Solar Filters/Cameras/Hardware
Topic: Help me to know what is that...
Replies: 3
Views: 93

Re: Help me to know what is that...

Those appear to be either Newton's rings or FP etalon interference fringes: https://en.wikipedia.org/wiki/Newton%27s_rings https://en.wikipedia.org/wiki/Fabry%E2%80%93P%C3%A9rot_interferometer They could be an internal reflection issue with your imaging system, or there might be something amiss with...
by Bob Yoesle
Fri Jun 07, 2019 4:36 pm
Forum: Solar Scope Modifications
Topic: Relation between BF size and the PST Sweet Spot
Replies: 8
Views: 140

Re: Relation between BF size and the PST Sweet Spot

No, not true. The "sweet spot," technically known as the Jacquinot spot, is generated by the field angles (and for the mica filters - instrument angles) produced by the optical configuration within which the etalon is placed. For collimator based etalon systems, it has little to do with the f ratios...
by Bob Yoesle
Sun Apr 28, 2019 12:18 pm
Forum: This is SolarChat !!
Topic: Hydrogen Alpha Upgrade
Replies: 19
Views: 534

Re: Hydrogen Alpha Upgrade

Good luck with your journey David - but I did want to get back to you about your question: " Fascinating Bob. So a question then, of the front mounted etalons on the market are some generally better than others e.g. Coronado vs Lunt vs Solarscope vs ?? Or do the variations in each make it pretty muc...
by Bob Yoesle
Sun Apr 28, 2019 11:52 am
Forum: This is SolarChat !!
Topic: Photographic Benefits of UV/IR Blocking Filter
Replies: 10
Views: 404

Re: Photographic Benefits of UV/IR Blocking Filter

I have seen first hand that if something can go wrong, it will eventually actually go wrong - at least for someone. So when it comes to safety, I'm pretty conservative. I also believe there is a reason most solar telescope OEM's incorporate IR blocking as a safety AND liability issue. Here's a slide...
by Bob Yoesle
Fri Apr 26, 2019 9:53 pm
Forum: This is SolarChat !!
Topic: Hydrogen Alpha Upgrade
Replies: 19
Views: 534

Re: Hydrogen Alpha Upgrade

" Front mounted etalons are fickle and unreliable in terms of their performance - I have been through and own quite a few; a couple of them are lovely and flat, and show no banding etc due to needing excess tilt. Then there are quite a lot that do have banding and especially with imaging more so sho...
by Bob Yoesle
Wed Apr 24, 2019 5:35 pm
Forum: This is SolarChat !!
Topic: Lunt CaK module testing 22nd April
Replies: 24
Views: 579

Re: Lunt CaK module testing 22nd April

Hi Valery, I don't think it is valid to apply processing to only one image and not the other to come to a conclusion that the questionable filter has no faults. Under the circumstances of using identical scopes, camera, and processing to obtain the images, the significant differences between the two...
by Bob Yoesle
Wed Apr 24, 2019 11:37 am
Forum: This is SolarChat !!
Topic: Lunt CaK module testing 22nd April
Replies: 24
Views: 579

Re: Lunt CaK module testing 22nd April

Hi Alexandra, I noticed you called yours a "Lunt CaK wedge." I'm assuming that means it's the B1800 diagonal, and therefore the diagonal mirror itself might be a part of the problem. If you are beyond the Lunt 5 year warranty and end up stuck with it (and since you likely do only imaging for CaK any...
by Bob Yoesle
Wed Apr 24, 2019 11:10 am
Forum: This is SolarChat !!
Topic: Hydrogen Alpha Upgrade
Replies: 19
Views: 534

Re: Hydrogen Alpha Upgrade

You've covered all the bases David.

Front etalon(s) will generally give you the best performance - especially for full disc views/imaging, and of course will cost the most...
by Bob Yoesle
Sun Apr 21, 2019 7:29 pm
Forum: Solar Scope Modifications
Topic: PST Etalon with a Quark, Log & Results
Replies: 115
Views: 6584

Re: PST Etalon with a Quark, Log & Results

That's really very good Marty, and better than a lot of others I've seen with the more recently made filter systems.
by Bob Yoesle
Mon Apr 15, 2019 1:19 am
Forum: This is SolarChat !!
Topic: When I win the lottery
Replies: 18
Views: 572

Re: When I win the lottery

Here's the skinny from Lunt: https://mailchi.mp/luntsolarsystems/join-us-at-neaf-and-double-stack-your-savings-save-10-off-gift-cards-starting-now-2205613?e=657ad57360 Intriguing for the ability to do "full disc" imaging - which indeed would require very large etalons to keep the Jacquinot spot larg...
by Bob Yoesle
Mon Apr 15, 2019 12:57 am
Forum: Commercial Solar Filters/Cameras/Hardware
Topic: First solar shot ASI290
Replies: 10
Views: 369

Re: First solar shot ASI290

Looks great George!
by Bob Yoesle
Sun Apr 14, 2019 7:22 pm
Forum: Commercial Solar Filters/Cameras/Hardware
Topic: Help tweak this PST + SM40II Double Stack?
Replies: 20
Views: 474

Re: Help tweak this PST + SM40II Double Stack?

Marty, I would be very careful about compression Richview tuning. 1) The DS etslons sometimes are farther to the red wing, and may require more compression to come on-hand with no tilt. 2) Going to the blue wing could apply too much pressure, stressing or fracturing the ERF (there are no collimating...
by Bob Yoesle
Sun Apr 14, 2019 3:20 am
Forum: Commercial Solar Filters/Cameras/Hardware
Topic: Help tweak this PST + SM40II Double Stack?
Replies: 20
Views: 474

Re: Help tweak this PST + SM40II Double Stack?

I would try the SM40 on its own on another small refractor. Leave the tilt alone (e.g. no tilt) and use the Richview only (compression - tightening) to tune the etalon. Add the etalon to the pre-tuned PST, and tilt the etalon just enough to get the reflections of the disc far enough to get the full ...
by Bob Yoesle
Sat Apr 13, 2019 1:11 am
Forum: Solar Scope Modifications
Topic: Tilt needed on a front ERF?
Replies: 2
Views: 257

Re: Tilt needed on a front ERF?

I recall the general parameter for both external and internal filter tilts is about 2 degrees.
by Bob Yoesle
Sat Apr 06, 2019 9:14 pm
Forum: Solar Scope Modifications
Topic: Crazy Idea...?
Replies: 4
Views: 306

Re: Crazy Idea...?

Removed.
by Bob Yoesle
Sat Apr 06, 2019 3:04 pm
Forum: Solar Scope Modifications
Topic: Crazy Idea...?
Replies: 4
Views: 306

Crazy Idea...?

Removed.
by Bob Yoesle
Sat Apr 06, 2019 2:02 pm
Forum: This is SolarChat !!
Topic: When I win the lottery
Replies: 18
Views: 572

Re: When I win the lottery

I think the price tag will be scary when it is released too.
A poster on CN stated it was "six figures," and this might be true given the cost of the LS230 (DS).
by Bob Yoesle
Wed Apr 03, 2019 10:43 pm
Forum: Commercial Solar Filters/Cameras/Hardware
Topic: Experimenting calcium imaging with small refractors
Replies: 44
Views: 3470

Re: Experimenting calcium imaging with small refractors

I have not measured it or taken one of the objective out of it's cell. The value is based solely on Mike Jones penciling it out theoretically. That said, a general rule for Achromats may apply for the curves and spacings being scalable to a percentage of the focal length, and therefore if the actual...
by Bob Yoesle
Wed Apr 03, 2019 12:21 am
Forum: Commercial Solar Filters/Cameras/Hardware
Topic: Experimenting calcium imaging with small refractors
Replies: 44
Views: 3470

Re: Experimenting calcium imaging with small refractors

When increasing the lens spacing is there any negative effect on other wavelengths? Increasing spacing works for achromats too but improving blue-violet correction has an adverse effect on H alpha. Raf is correct, but it might not be as bad as it sounds. I think the acid test is needed in the form ...
by Bob Yoesle
Sat Mar 30, 2019 4:20 pm
Forum: Commercial Solar Filters/Cameras/Hardware
Topic: Experimenting calcium imaging with small refractors
Replies: 44
Views: 3470

Re: Experimenting calcium imaging with small refractors

Hi everyone, It seems in general that f-ratio for f-ratio, achromatic refractors have better longitudinal chromatic aberration control, while APO's have better lateral chromatic aberration. However, even my lowly Synta ED100/900 semi-APO doublet does well at CaK, which is one of the most difficult w...
by Bob Yoesle
Sun Mar 24, 2019 1:09 am
Forum: This is SolarChat !!
Topic: Latest Cycle 25 Prediction
Replies: 6
Views: 203

Re: Latest Cycle 25 Prediction

Hi everyone: indeed this is both potentially good news and very interesting science. And here's another piece of independent supportive data: "The development of the solar polar field strength throughout a solar sunspot cycle can be used to predict the magnitude of the next cycle and the peak of the...
by Bob Yoesle
Sat Mar 23, 2019 2:21 am
Forum: This is SolarChat !!
Topic: Latest Cycle 25 Prediction
Replies: 6
Views: 203

Latest Cycle 25 Prediction

This past December 6, 2018, the Center of Excellence in Space Sciences India (CESSI) reported that two of its scientists have made a prediction for the upcoming sunspot cycle. Solar physicist Dibyendu Nandi and his PhD student Prantika Bhowmik devised a new prediction technique, which simulates cond...
by Bob Yoesle
Thu Mar 14, 2019 11:11 pm
Forum: Commercial Solar Filters/Cameras/Hardware
Topic: Help me decide on solar setup
Replies: 8
Views: 928

Re: Help me decide on solar setup

For narrow-band imaging (e.g. H alpha and CaK), the 102 f10 achromat will be superior to a shorter focal ratio ED refractor telescope due to generally better spherochromatic aberration performance. For white light continuum viewing/imaging, the chromatic aberration will not be too obtrusive, and can...
by Bob Yoesle
Sun Feb 24, 2019 8:29 pm
Forum: This is SolarChat !!
Topic: Saturday Sunshine - 23rd February
Replies: 15
Views: 453

Re: Saturday Sunshine - 23rd February

Hi Mark,

The DS w Quark/SM90 is amazingly good!

I'm also envious you have such good weather. We're not going to get much above freezing for another two to three weeks...

Driveway snow.jpg
Driveway snow.jpg (281.88 KiB) Viewed 379 times
by Bob Yoesle
Sun Feb 24, 2019 8:21 pm
Forum: This is SolarChat !!
Topic: CaK, 24022019, second try telecentric beam
Replies: 12
Views: 440

Re: CaK, 24022019, second try telecentric beam

Hi Bart,

Right now (when the sun comes out), I'll be using my Chameleon w 3.75 um pixels... may get something different in the future.