Large D-ERF "tri-band"
- Ronnie_Clayton
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Large D-ERF "tri-band"
Hello friends.
I would like to buy a large DERF ("tri-band") for a C9,25 Edge. Do you know some vendor or company to provide this size of D-ERF?
BR
Ronnie
I would like to buy a large DERF ("tri-band") for a C9,25 Edge. Do you know some vendor or company to provide this size of D-ERF?
BR
Ronnie
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Re: Large D-ERF "tri-band"
Ronnie.
I could be wrong, but I don’t believe believe that anyone is currently making anything larger than 180mm.
Valery of Aries Instruments was producing some, but the war in Ukraine has stopped that. (I had an order for exactly what you are wanting).
A couple of other companies have made them in the past, but I don’t believe anyone is currently doing so.
It could be that your only option at this point is to sell your current 9.25” and buy a tri-band 9.25” from Baader. I currently have one on order.
I could be wrong, but I don’t believe believe that anyone is currently making anything larger than 180mm.
Valery of Aries Instruments was producing some, but the war in Ukraine has stopped that. (I had an order for exactly what you are wanting).
A couple of other companies have made them in the past, but I don’t believe anyone is currently doing so.
It could be that your only option at this point is to sell your current 9.25” and buy a tri-band 9.25” from Baader. I currently have one on order.
- Ronnie_Clayton
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Re: Large D-ERF "tri-band"
Thanks DavidP!
I was checking and now Altair Astro is providing large ERF .
https://www.altairastro.com/altair-240m ... 2760-p.asp
But I didn´t find any reviews about this D-Erf...
BR
I was checking and now Altair Astro is providing large ERF .
https://www.altairastro.com/altair-240m ... 2760-p.asp
But I didn´t find any reviews about this D-Erf...
BR
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Re: Large D-ERF "tri-band"
Ronnie_Clayton wrote: ↑Wed Feb 22, 2023 1:42 pm Thanks DavidP!
I was checking and now Altair Astro is providing large ERF .
https://www.altairastro.com/altair-240m ... 2760-p.asp
But I didn´t find any reviews about this D-Erf...
BR
Interesting stuff.
30mm thickness.. holy moly. I wonder how much it weights with cell. If you come by a filter curve of it pls post it here.
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Re: Large D-ERF "tri-band"
Hi Ronnie.
Why does it have to be tri-band? CaK i'm presuming? You're going to get better results in CaK with your 6" APM than you ever will with a C9... Just my 2 cents...
Why does it have to be tri-band? CaK i'm presuming? You're going to get better results in CaK with your 6" APM than you ever will with a C9... Just my 2 cents...
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- Ronnie_Clayton
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Re: Large D-ERF "tri-band"
Many thanks for your 2 cents Mark .marktownley wrote: ↑Thu Feb 23, 2023 7:42 am Hi Ronnie.
Why does it have to be tri-band? CaK i'm presuming? You're going to get better results in CaK with your 6" APM than you ever will with a C9... Just my 2 cents...
I agreed with you about Cak! I´m thinking to buy a tri-band to use in both telescopes, to get more resolution in h-alpha and "continuum" with C9 and use with my APM to get Cak images.
Ronnie
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Re: Large D-ERF "tri-band"
Agreed. I don’t get the SCT tri-band thing, and while it’s difficult to imagine seeing conditions that would allow for. Ca imaging at 9” of aperture, I remember Christian saying that the 9.25“ can handle the blue end better than other SCTs. I don’t know if the difference is marginal or substantial.marktownley wrote: ↑Thu Feb 23, 2023 7:42 am Hi Ronnie.
Why does it have to be tri-band? CaK i'm presuming? You're going to get better results in CaK with your 6" APM than you ever will with a C9... Just my 2 cents...
Last edited by DavidP on Thu Feb 23, 2023 11:05 pm, edited 1 time in total.
- marktownley
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Re: Large D-ERF "tri-band"
Sensible!Ronnie_Clayton wrote: ↑Thu Feb 23, 2023 11:59 am I agreed with you about Cak! I´m thinking to buy a tri-band to use in both telescopes, to get more resolution in h-alpha and "continuum" with C9 and use with my APM to get Cak images.
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Re: Large D-ERF "tri-band"
I would say it depends on each C9 sample, and many scts have their optimum towards the red for whatever reasons. I doubt that those would give decent results @393nm for WL or Ca k imaging. On the other hand im quite satisfied with the results i got with my sample of C9 and the antlia 393nm filter. Therefore i dont see a reason why it would be much worse with the lunt cak module im going to try soon. If it doesnt i will use a small and slow refractor for it.DavidP wrote: ↑Thu Feb 23, 2023 2:50 pmAgreed. I don’t get the SCT tri-band thing, and while it’s difficult to imagine seeing conditions that would allow for. Ca imaging at 9” of aperture, I remember Christian want to say that the 9.25“ can handle the blue end better than other SCTs. I don’t know if the difference is marginal or substantial.marktownley wrote: ↑Thu Feb 23, 2023 7:42 am Hi Ronnie.
Why does it have to be tri-band? CaK i'm presuming? You're going to get better results in CaK with your 6" APM than you ever will with a C9... Just my 2 cents...
Triband C9.25
H-a: Quark Chromosphere with BF mod
WL: Antlia 500nm/ 3nm, 393 nm/ 3nm
Ca-K: homebrew (includes 2x 1.5A filters, thanks Apollo)
Player One Apollo Max + Mars MII
Barlows:
-2x Gerd Düring 2.7x
-2x TMB 1.8x
H-a: Quark Chromosphere with BF mod
WL: Antlia 500nm/ 3nm, 393 nm/ 3nm
Ca-K: homebrew (includes 2x 1.5A filters, thanks Apollo)
Player One Apollo Max + Mars MII
Barlows:
-2x Gerd Düring 2.7x
-2x TMB 1.8x
Re: Large D-ERF "tri-band"
Hi Group,
My concern is that these filters are ion assisted e beam . Which is really not that much different then e beam. Which come down to the coating. I don't think you can get a 1/4 wave on transmission with this coating method. So the filter will work for heat, but it will not be diffraction limited. Sputtering coating is the only way to get there. So being in front of the objective it may soften the image. Now if you go with the idea that the seeing during the day is never diffraction limited. Then it will be fine for you.
The coating of a soft coated filter is never diffraction limited. It doesn't matter how the good of windows you mount it in.
Mark W.
My concern is that these filters are ion assisted e beam . Which is really not that much different then e beam. Which come down to the coating. I don't think you can get a 1/4 wave on transmission with this coating method. So the filter will work for heat, but it will not be diffraction limited. Sputtering coating is the only way to get there. So being in front of the objective it may soften the image. Now if you go with the idea that the seeing during the day is never diffraction limited. Then it will be fine for you.
The coating of a soft coated filter is never diffraction limited. It doesn't matter how the good of windows you mount it in.
Mark W.
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Re: Large D-ERF "tri-band"
Mark, your insights are always helpful.
Thanks
Thanks
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Re: Large D-ERF "tri-band"
mdwmark wrote: ↑Fri Feb 24, 2023 8:41 pm Hi Group,
My concern is that these filters are ion assisted e beam . Which is really not that much different then e beam. Which come down to the coating. I don't think you can get a 1/4 wave on transmission with this coating method. So the filter will work for heat, but it will not be diffraction limited. Sputtering coating is the only way to get there. So being in front of the objective it may soften the image. Now if you go with the idea that the seeing during the day is never diffraction limited. Then it will be fine for you.
The coating of a soft coated filter is never diffraction limited. It doesn't matter how the good of windows you mount it in.
Mark W.
Hi, thank you for your insights.
Baader states on their website that their D-ERFs are made with ion assisted beam tech, they claim they reach up to l/10 surfaces. So i think i dont understand.
Triband C9.25
H-a: Quark Chromosphere with BF mod
WL: Antlia 500nm/ 3nm, 393 nm/ 3nm
Ca-K: homebrew (includes 2x 1.5A filters, thanks Apollo)
Player One Apollo Max + Mars MII
Barlows:
-2x Gerd Düring 2.7x
-2x TMB 1.8x
H-a: Quark Chromosphere with BF mod
WL: Antlia 500nm/ 3nm, 393 nm/ 3nm
Ca-K: homebrew (includes 2x 1.5A filters, thanks Apollo)
Player One Apollo Max + Mars MII
Barlows:
-2x Gerd Düring 2.7x
-2x TMB 1.8x
- marktownley
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Re: Large D-ERF "tri-band"
I see Altair says their filters are L/8.
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Re: Large D-ERF "tri-band"
For the record, here the test of my 160 mm Baader D-ERF with a Schack-Hartmann wavefront analyzer (Imaging Optics HASO) :
http://astrosurf.com/viladrich/astro/in ... /tests.htm
It is lambda/9.6 P-V wavefront in Ha and lambda/41 rms. So quite within Baader spec.
When specifying quality of an optical window, it is important to know whether it is about :
- transmitted wavefront or surface (and remember there are two surfaces ...),
- peak-to valley (P-V) or rms,
- what is the lambda used (red, gree, , etc..).
http://astrosurf.com/viladrich/astro/in ... /tests.htm
It is lambda/9.6 P-V wavefront in Ha and lambda/41 rms. So quite within Baader spec.
When specifying quality of an optical window, it is important to know whether it is about :
- transmitted wavefront or surface (and remember there are two surfaces ...),
- peak-to valley (P-V) or rms,
- what is the lambda used (red, gree, , etc..).
Christian Viladrich
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Editor of "Solar Astronomy"
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Co-author of "Planetary Astronomy"
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Re: Large D-ERF "tri-band"
Here is the image taken with full size 280mm DERF and additional 7nm Ha filter.mdwmark wrote: ↑Fri Feb 24, 2023 8:41 pm Hi Group,
My concern is that these filters are ion assisted e beam . Which is really not that much different then e beam. Which come down to the coating. I don't think you can get a 1/4 wave on transmission with this coating method. So the filter will work for heat, but it will not be diffraction limited. Sputtering coating is the only way to get there. So being in front of the objective it may soften the image. Now if you go with the idea that the seeing during the day is never diffraction limited. Then it will be fine for you.
The coating of a soft coated filter is never diffraction limited. It doesn't matter how the good of windows you mount it in.
Mark W.
This is a SINGLE frame shot. So, no lucky imaging and deep deconvolution were applied. Just a little noise reduction after a bit of sharpening.
Right click on the image and open it in a separate window to see it in a full resolution. Look at the details inside the larger spot and bridges there.
So, here is the image forming train: atmosphere + DERF + telescope optics + small 50mm H-a filter + Barlow lens.
Does anybody think that diffraction limit was not reached in this image? What is the part of the image destruction was introduced by the coating layers of the DERF?
The world changes. And what were not possible yesterday is possible today.
Valery
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Re: Large D-ERF "tri-band"
Altair best of the best for big aperture!
https://www.facebook.com/oleg.lavigne/
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https://www.astrobin.com/users/RamonLviv/
https://www.astroclub.kiev.ua/forum/ind ... ic=46758.0
Telescope: TS 152/900/Bresser 102/1350
Baader D-ERF 160MM
2xBaader 1.25 GPC
2xLunt 50mm
Lunt Cak B1200
Coronado BF15
Camera: Apollo Max 432M/ Apollo Mini 429M/Player One Mars II 462M/QHY 290MM
Mounh: 2xSky Watcher AZEQ6
Telecentric Lense: Televue Powermate 2/2.5x/4X/5X
Re: Large D-ERF "tri-band"
HI group
So ion assist is used with e- beam and also sputtering. The idea is that helps with the stress of the coating and reduces the substrate temperature. With e-beam the crystal formation will be larger. This is what degrades the transmission wavefront . While with sputtering the crystal should be smaller and less degrade of the wavefront on transmission. If you want to get fancy . Then Plasma-assisted sputtering deposition if done right, would give us the best wavefront error on transmission. But this would cost much more then the others.
I talked to my friend that has machines that use a planetary to keep uniformity. They can do 4 -24" at one time ( that would be 4 -24" uniform filters narrow enough for an ERF). He didn't think with that many layers for an ERF design that the crystal formation with ion assisted e- beam could get you to diffraction limited on transmission.
But there are companies out there that can coat any size you would want for a price. ( Barr has a machine to make large narrow custom filters for the telescopes in Hawaii and Chile. I was told that $50,000 each would be a good starting price)
Mark W.
So ion assist is used with e- beam and also sputtering. The idea is that helps with the stress of the coating and reduces the substrate temperature. With e-beam the crystal formation will be larger. This is what degrades the transmission wavefront . While with sputtering the crystal should be smaller and less degrade of the wavefront on transmission. If you want to get fancy . Then Plasma-assisted sputtering deposition if done right, would give us the best wavefront error on transmission. But this would cost much more then the others.
I talked to my friend that has machines that use a planetary to keep uniformity. They can do 4 -24" at one time ( that would be 4 -24" uniform filters narrow enough for an ERF). He didn't think with that many layers for an ERF design that the crystal formation with ion assisted e- beam could get you to diffraction limited on transmission.
But there are companies out there that can coat any size you would want for a price. ( Barr has a machine to make large narrow custom filters for the telescopes in Hawaii and Chile. I was told that $50,000 each would be a good starting price)
Mark W.
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Re: Large D-ERF "tri-band"
Thanks for the information Mark
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