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...

Hmmm - this is a notch filter (not bandpass), hence the NF prefix. What would it be useful for in a CaK solar filter?

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...

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...

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 ...

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...

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

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:/...

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...

"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...

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...

So, we have to get working to get this English version available ASAP ;-)

Yeah! Looking forward to it Christian :-)

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...

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...

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 ...

Single.

Chroma Tech said they could do a double cavity filter, but not a triple. I didn't ask what the price would be.

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 ...

Greatly appreciated Peter!

Bob

Hello all, Spoke to Dick Stewart at Chroma Technology about the CT 392.37 0.1bp filter's tilt performance, and he provided me the following data: 0.0 degree tilt peaks at 393.999 nm 99.69% 1.0 degree tilt peaks at 393.386 nm 99.69% 1.5 degree tilt peaks at 393.371 nm 99.70% 2.0 degree tilt peaks at ...

Maybe the PST filter is natively narrower and the quoted 2.2a is the bandpass in the f/10 beam? Perhaps a multiple cavity filter with steeper transmission sides, which may make it less susceptible to light ray incident angle effects(?) Bob, if you have a TZ-2, you might give it a try. They are desi...

Hi Bob, Thanks for your test. The incraese of contrast from the Chroma filtre, PST single stacked, PST double stacked and triple stack is clearly appearant. BTW, I have probably overlooked the information ... what F/D ratio did you used with the Chroma filter in this test ? Best regards Hi Christia...

Thank for posting your results Raf ;-) Great images Pedro! The only drawback of the TOA 150 is its the price and ... its aperture. I wish I have a TOA 200 ;-) Hi Christian, my thought is that this seems to be pointing perhaps to using a reflector telescope such that you already have with an appropri...

Hi Apollo, Hoping to get out for another run for prominence imaging this coming Monday the 24th... hoping some prominences will cooperate !-) Hi Mark, Brilliant no - just results of being a bit obsessive compulsive ;-) As you know, one must reduce the variables as much as possible, and it's impossib...

A little better seeing today, so here are my latest test images for the CT 393.37 (used in Skybender tilt unit) - ED100/900, FireCapture set at minimum gain (160), gamma 700, histogram max ~ 190 +/- 10. All used a Baader B CCD and KG3 sub-aperture ERF's. All are 30 sec. captures @ 18 fps, aligned an...

Had another chance to try some imaging before the weather deteriorated. The imaging train consisted of a Orion ED100/900, Baader Blue CCD and KG3 for ERF duties, Baader K line used as a blocker, a ND 0.6 for image brightness control, and finally either the PST CaK or CT 393.37 0.1 filter. All images...