Second go at 150mm Mod
- solar
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Second go at 150mm Mod
Had another go at this contraption today. Extremely seeing dependent and wind is a major factor with the length of the scope.
Conditions were better today and seeing had improved a bit.
Not as good as Valery or Neo but I am getting there.
Conditions were better today and seeing had improved a bit.
Not as good as Valery or Neo but I am getting there.
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Vixen 130ss SolarMax 90 BF30 EQ6 Pro, LX200 14, C8 CG5, Megrez80, Lunt 100 DS. EQ 8
ASI 120mm 290mm 432mm Lunt B1800 Cal-K + other stuff.
Skywatcher 150mm PST Mod2
ASI 120mm 290mm 432mm Lunt B1800 Cal-K + other stuff.
Skywatcher 150mm PST Mod2
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Re: Second go at 150mm Mod
Looking good Ralph - I will look forward to your progress with this cannon!
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Re: Second go at 150mm Mod
Excellent Ralph the colour one is really good.You didn't nab any of that filament did you?
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Re: Second go at 150mm Mod
Yep, looking good ralph. I am intending to tinker with my DSII unit from my Lunt 80 and put it onto a 127mm unit to see what comes of it.
What ERF are you using?
Ted
What ERF are you using?
Ted
Lunt LS80THa DSII Quark Prominence ES127mm refractor
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Re: Second go at 150mm Mod
That's half your PST with a BF28 and barlow plus camera. No issues with flexing or sag as it is all top quality machined fittings.Asimov wrote:What's all that gear hanging off the arse end of it? You'll be getting flexure/sag from that surely...Nice work mate.
Vixen 130ss SolarMax 90 BF30 EQ6 Pro, LX200 14, C8 CG5, Megrez80, Lunt 100 DS. EQ 8
ASI 120mm 290mm 432mm Lunt B1800 Cal-K + other stuff.
Skywatcher 150mm PST Mod2
ASI 120mm 290mm 432mm Lunt B1800 Cal-K + other stuff.
Skywatcher 150mm PST Mod2
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Re: Second go at 150mm Mod
150MM full aperture ERF mount externally Ted.edobosz wrote:Yep, looking good ralph. I am intending to tinker with my DSII unit from my Lunt 80 and put it onto a 127mm unit to see what comes of it.
What ERF are you using?
Ted
Vixen 130ss SolarMax 90 BF30 EQ6 Pro, LX200 14, C8 CG5, Megrez80, Lunt 100 DS. EQ 8
ASI 120mm 290mm 432mm Lunt B1800 Cal-K + other stuff.
Skywatcher 150mm PST Mod2
ASI 120mm 290mm 432mm Lunt B1800 Cal-K + other stuff.
Skywatcher 150mm PST Mod2
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Re: Second go at 150mm Mod
Very good shots!solar wrote:Had another go at this contraption today. Extremely seeing dependent and wind is a major factor with the length of the scope.
Conditions were better today and seeing had improved a bit.
Not as good as Valery or Neo but I am getting there.
I belive that your mod is PST stage 2. Right?
The main difference with my mod is that my mod is designed for full solar disk at 0,7 - 0,8A and for half disk size at 0.5A.
PST mod allows barely 1/5 disk at 0,8-0,9A with 150mm telescope. Too small etalon size compare to the objective size.
Also, the optics in my mod is fully optimized for a given 150mm optics. Collimator and refocused lenses in PST are not
strictly designed for all other scopes even if they are close to F/10. This can soften images somewhat.
Regards,
Valery.
"Solar H alpha activity is the most dynamic and compelling thing you can see in a telescope, so spend accordingly." (c) Bob Yoesle.
Largest full size 185 - 356mm Dielectric Energy Rejection Filters (D-ERF) by ARIES Instruments.
Largest full size 185 - 356mm Dielectric Energy Rejection Filters (D-ERF) by ARIES Instruments.
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Re: Second go at 150mm Mod
Top shots Ralph, you'll get used to this new big gun!
Interesting info there valery...
Interesting info there valery...
http://brierleyhillsolar.blogspot.co.uk/
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Re: Second go at 150mm Mod
Yes Valery it is the Mod 2. Not sure I am following you with your setup. Can you post some shots an a bit more info please.Valery wrote:Very good shots!solar wrote:Had another go at this contraption today. Extremely seeing dependent and wind is a major factor with the length of the scope.
Conditions were better today and seeing had improved a bit.
Not as good as Valery or Neo but I am getting there.
I belive that your mod is PST stage 2. Right?
The main difference with my mod is that my mod is designed for full solar disk at 0,7 - 0,8A and for half disk size at 0.5A.
PST mod allows barely 1/5 disk at 0,8-0,9A with 150mm telescope. Too small etalon size compare to the objective size.
Also, the optics in my mod is fully optimized for a given 150mm optics. Collimator and refocused lenses in PST are not
strictly designed for all other scopes even if they are close to F/10. This can soften images somewhat.
Regards,
Valery.
Vixen 130ss SolarMax 90 BF30 EQ6 Pro, LX200 14, C8 CG5, Megrez80, Lunt 100 DS. EQ 8
ASI 120mm 290mm 432mm Lunt B1800 Cal-K + other stuff.
Skywatcher 150mm PST Mod2
ASI 120mm 290mm 432mm Lunt B1800 Cal-K + other stuff.
Skywatcher 150mm PST Mod2
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Re: Second go at 150mm Mod
Ralph, the resolution you are getting is just awesome - all stunning images.
George
George
DS External SM90 Etalons, Single External SM40 Etalon, BF30, WO FLT98 f/6.3, Tak FS-102 f/8, Tak FS-60C f/5.9, DMK51, DMK21
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Re: Second go at 150mm Mod
Geez,
Not bad for a 20mm PST etalon!!
Great set up.....
I'm sure, given the good seeing conditions you usually get, that you'll soon be posting even more exciting images.
Well done!
Not bad for a 20mm PST etalon!!
Great set up.....
I'm sure, given the good seeing conditions you usually get, that you'll soon be posting even more exciting images.
Well done!
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Re: Second go at 150mm Mod
Valery,
Why do you say the PST etalon is not so hot with larger scopes even at f10....the etalon doesn't know what's up front, only that the "usual" f10 beam is entering and it's in its "usual" position 200mm inside focus....
Why do you say the PST etalon is not so hot with larger scopes even at f10....the etalon doesn't know what's up front, only that the "usual" f10 beam is entering and it's in its "usual" position 200mm inside focus....
"Astronomical Spectroscopy - The Final Frontier" - to boldly go where few amateurs have gone before
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Re: Second go at 150mm Mod
Impressive HR images for a 20mm PST etalon mod. Nice work Ralph
Pedro Re'
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Re: Second go at 150mm Mod
Several things:Merlin66 wrote:Valery,
Why do you say the PST etalon is not so hot with larger scopes even at f10....the etalon doesn't know what's up front, only that the "usual" f10 beam is entering and it's in its "usual" position 200mm inside focus....
1. Acceptance angle of any etalon is about 1 degree if the etalon works in quazy parallel light beam. in a front of an objective.
2. For internally working etalons there is a rule: acceptance angle = d/D degree where d is etalon diameter and D is objective diameter.
For a given case, 20mm etalon in a 150mm scope the acceptance angle is about 1/3,5 - 1/4 of the sun disk if the band wide is 0,7A.
For wider band wide, say, typical 0.9, acceptance angle can be even solid 1/3 of the sun disk.
3. PST etalons are quite vary in band wide - some of them are even at 0,7A, but most are around 0,9A.
4. Even if the collimator-refocused optics in the PST is F/10, this does not necessary mean that it will not add some aberrations or will not undercompensite some aberrations of another systems F/10 different to what it was designed for. SA in Ha, field curvature, astigmatism are different for 40mm F/10 and 150mm F/10 objectives and may between. So, the PST optics does not work at best in another F/10 systems, not say in F/X systems which are not F/10.
Of course, image processing and contrast increasing makes this problem less noticeable, but absolutely not fix it and PST etalon itself will works better with specially designed optics for larger donor objective.
If to take as an example the mod by ARIES, the etalon is 2,5x larger and the optics is FULLY optimized for a given 150mm F=750 SW refractor.
All aberrations are nullified and 0,8 degree field is really ideal in Ha. This is one of the main factor of good images this system produce.
But, of course, PST mod, especially mod-2 is a very cost effective mod for Ha telescopes, just with it's native limitations. And this images in this thread show it's potential which is high enough within smaller FOV.
Regards,
Valery.
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Re: Second go at 150mm Mod
Valery,
Thanks for that.
I think the only difference, possibly, could come from the change in objective. The PST has a very basic achromat and I'd assume a similar achromat in the donor would give similar performance.
Your rule:
For internally working etalons there is a rule: acceptance angle = d/D degree where d is etalon diameter and D is objective diameter
I haven't heard this before...could you give more details?
Thanks for that.
I think the only difference, possibly, could come from the change in objective. The PST has a very basic achromat and I'd assume a similar achromat in the donor would give similar performance.
Your rule:
For internally working etalons there is a rule: acceptance angle = d/D degree where d is etalon diameter and D is objective diameter
I haven't heard this before...could you give more details?
"Astronomical Spectroscopy - The Final Frontier" - to boldly go where few amateurs have gone before
https://groups.io/g/astronomicalspectroscopy
http://astronomicalspectroscopy.com
"Astronomical Spectroscopy for Amateurs" and
"Imaging Sunlight - using a digital spectroheliograph" - Springer
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http://astronomicalspectroscopy.com
"Astronomical Spectroscopy for Amateurs" and
"Imaging Sunlight - using a digital spectroheliograph" - Springer
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Re: Second go at 150mm Mod
There is NO such basic achromat as a 40mm F/10. An 80mm F/10 achromat will have 2x larger spherical aberration at 656nm than a 40mm F/10.Merlin66 wrote:Valery,
Thanks for that.
I think the only difference, possibly, could come from the change in objective. The PST has a very basic achromat and I'd assume a similar achromat in the donor would give similar performance.
A 150mm achromat F/10 will have almost 4x larger SA at 656nm. So, images in these telescopes will be aggravated by a larger, uncorrected SA.
Also, the collimation-refocusing block of the PST corrects a field curvature of a 40mm F/10 achromat - the radius of curvature of the focal plane of a 40mm F/10 achromat is about 140mm, while radius of curvature in 150mm F/10 achromat is about 545mm. So, the field in PST mod with 150mm F/10 will not be flat and will have negative field curvature - images at the edge will be softer. And so on and so on.
If you don't believe, you can check this will optical design software.
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Largest full size 185 - 356mm Dielectric Energy Rejection Filters (D-ERF) by ARIES Instruments.
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Re: Second go at 150mm Mod
fantastic ralph good job
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Re: Second go at 150mm Mod
Valery,
OK I see your point!
What about the d/D rule??
OK I see your point!
What about the d/D rule??
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https://groups.io/g/astronomicalspectroscopy
http://astronomicalspectroscopy.com
"Astronomical Spectroscopy for Amateurs" and
"Imaging Sunlight - using a digital spectroheliograph" - Springer
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http://astronomicalspectroscopy.com
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Re: Second go at 150mm Mod
Without wanting to hog this thread, or send it off in another direction, i'm really interested in further understanding the issue of spherical aberration in our mod scopes and how we can improve matters optically. I will start a thread in the mod section, I do hope you can join us there Valery!
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Re: Second go at 150mm Mod
Me too Mark, very interested, and thanks.marktownley wrote:Without wanting to hog this thread, or send it off in another direction, i'm really interested in further understanding the issue of spherical aberration in our mod scopes and how we can improve matters optically. I will start a thread in the mod section, I do hope you can join us there Valery!
Vixen 130ss SolarMax 90 BF30 EQ6 Pro, LX200 14, C8 CG5, Megrez80, Lunt 100 DS. EQ 8
ASI 120mm 290mm 432mm Lunt B1800 Cal-K + other stuff.
Skywatcher 150mm PST Mod2
ASI 120mm 290mm 432mm Lunt B1800 Cal-K + other stuff.
Skywatcher 150mm PST Mod2
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Re: Second go at 150mm Mod
Hi Ralph
wonderful results and great discussions on that thread
wonderful results and great discussions on that thread
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