Optimum BF for 6" f/10 with PST etalon and ASI174?

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marktownley
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Re: Optimum BF for 6" f/10 with PST etalon and ASI174?

Post by marktownley »

Rusted wrote: Fri Mar 06, 2020 9:34 am I'd be using a Quark if it wasn't such a gamble buying a good one at very considerable expense. :roll:
In my experience there's plenty of variability with PST etaons too...


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Re: Optimum BF for 6" f/10 with PST etalon and ASI174?

Post by Rusted »

marktownley wrote: Fri Mar 06, 2020 3:58 pm
In my experience there's plenty of variability with PST etalons too...
Thanks Mark.

That sounds as if one can never be certain of a match made in heaven.
I'm using a Beloptik KG3 and Baader 35nm H-a after the full aperture Baader D-ERF.
So, presumably, have a better chance of avoiding problems with unwanted harmonics.
The downside is likely to be less than optimum bandwidth providing inferior H-a images.


http://fullerscopes.blogspot.dk/

H-alpha: Baader 160mm D-ERF, iStar 150/10 H-alpha objective, 2" Baader 35nm H-a, 2" Beloptik KG3,
Lunt 60MT etalon, Lunt B1200S2 BF, Assorted T-S GPCs or 2x "Shorty" Barlow, ZWO ASI174.
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Re: Optimum BF for 6" f/10 with PST etalon and ASI174?

Post by Merlin66 »

Rusted,
the ITF etc etc will have no impact on the H alpha bandwidth...this comes from the etalon.
The final sort/ blocking filter can affect the bandwidth if there is a serious miss-match by cutting off/ into the etalon bandwidth.


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Re: Optimum BF for 6" f/10 with PST etalon and ASI174?

Post by Rusted »

Merlin66 wrote: Sat Mar 07, 2020 9:49 am Rusted,
the ITF etc etc will have no impact on the H alpha bandwidth...this comes from the etalon.
The final sort/ blocking filter can affect the bandwidth if there is a serious miss-match by cutting off/ into the etalon bandwidth.
Thanks for the clarification.


http://fullerscopes.blogspot.dk/

H-alpha: Baader 160mm D-ERF, iStar 150/10 H-alpha objective, 2" Baader 35nm H-a, 2" Beloptik KG3,
Lunt 60MT etalon, Lunt B1200S2 BF, Assorted T-S GPCs or 2x "Shorty" Barlow, ZWO ASI174.
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Re: Optimum BF for 6" f/10 with PST etalon and ASI174?

Post by Rusted »

I ought to update this thread to say that my Lunt B1200S2 "straight through" blocking filter arrived.
Excellent service from Bresser.De and DHL for express delivery.
I didn't want to miss a deadline for closure of international postal postal packages due to the virus.

I quickly discovered that the new BF needed more inward focus than the PST BF.
So the previous fittings were removed. As was the 1.25" receptacle from the new BF body.

By sheer luck I had a T2 male threaded adapter which contained the BF's 2" barrel and fitted my camera.
While the female 2" thread fitted my 2" helical focuser. The new BF is invisible inside the adapter.

The immediate impression was of a much larger field of view on my monitor
The PST BF provided more even illumination on larger frame sizes in SharpCap.

I had some brighter corners and shaded rings from the Lunt BF. Probably from the PST etalon.
I could overcome these problems with flats but soon found 800x600 provided acceptably even brightness across the field.

Sadly I haven't had a continuously clear sky nor more than moments of a clear sun since the new BF's arrival.
There is definitely a real sense of 3D surface texture in iMPPG. Though not to the standard of the processing experts here.

Pictures are worth more than my usual excess of words:

P1410297 rsz 600.JPG
P1410297 rsz 600.JPG (138.43 KiB) Viewed 8287 times
P1410316 rsz 600.jpg
P1410316 rsz 600.jpg (104.41 KiB) Viewed 8287 times
P1410300 rsz 600.jpg
P1410300 rsz 600.jpg (122.07 KiB) Viewed 8287 times

My only capture shows the dying remnants of AR2758 near the limb.
Cropped from 800x600 to remove the brighter corners.
sun 17.3.20 11.07.jpg
sun 17.3.20 11.07.jpg (73.22 KiB) Viewed 8287 times


http://fullerscopes.blogspot.dk/

H-alpha: Baader 160mm D-ERF, iStar 150/10 H-alpha objective, 2" Baader 35nm H-a, 2" Beloptik KG3,
Lunt 60MT etalon, Lunt B1200S2 BF, Assorted T-S GPCs or 2x "Shorty" Barlow, ZWO ASI174.
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Re: Optimum BF for 6" f/10 with PST etalon and ASI174?

Post by marktownley »

Nice mod and looking promising with the results!


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Re: Optimum BF for 6" f/10 with PST etalon and ASI174?

Post by Rusted »

Thanks Mark.

I shan't be able to confirm any real improvements until I catch some clear sunshine with decent seeing.

The eternal optimism of the apprentice, solar imager. ;)


http://fullerscopes.blogspot.dk/

H-alpha: Baader 160mm D-ERF, iStar 150/10 H-alpha objective, 2" Baader 35nm H-a, 2" Beloptik KG3,
Lunt 60MT etalon, Lunt B1200S2 BF, Assorted T-S GPCs or 2x "Shorty" Barlow, ZWO ASI174.
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Re: Optimum BF for 6" f/10 with PST etalon and ASI174?

Post by Solar-Cologne »

Hi Rusted,

Coronado and Lunt are not the best BFs.

I am tested the BFs from Wolfgang Lille Heinbokel / Germany.......they are the best

I use an Lille 30mm and 50mm Blockingfilter.

http://sonnenfernrohr.de.w0199a68.kasse ... a-systeme/

Sorry, Wolfgangs Website is only in German.

If you have Questions, pleas ask me.


Best Regards
Achim


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Re: Optimum BF for 6" f/10 with PST etalon and ASI174?

Post by Merlin66 »

The Ha systems are listed and documented, but I can't see any specifics on the BF (LS1800 is mentioned), there no information on compatibility with other etalon suppliers (ie Lu,t Coronado, Solar Spectrum, SolarScope etc.)


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Re: Optimum BF for 6" f/10 with PST etalon and ASI174?

Post by Rusted »

Solar-Cologne wrote: Mon Mar 23, 2020 5:34 am Hi Rusted,

Coronado and Lunt are not the best BFs.

I am tested the BFs from Wolfgang Lille Heinbokel / Germany.......they are the best

I use an Lille 30mm and 50mm Blockingfilter.

http://sonnenfernrohr.de.w0199a68.kasse ... a-systeme/

Sorry, Wolfgangs Website is only in German.

If you have Questions, pleas ask me.


Best Regards
Achim
Hi Achim,

Many thanks for that information and link.

Google auto-translate solved any problems.

I didn't see any price list for Lille's products
What does such a large BF cost in Euro?

There is an English saying: "If you have to ask the price, then you can't afford it!" :shock:


http://fullerscopes.blogspot.dk/

H-alpha: Baader 160mm D-ERF, iStar 150/10 H-alpha objective, 2" Baader 35nm H-a, 2" Beloptik KG3,
Lunt 60MT etalon, Lunt B1200S2 BF, Assorted T-S GPCs or 2x "Shorty" Barlow, ZWO ASI174.
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Re: Optimum BF for 6" f/10 with PST etalon and ASI174?

Post by Rusted »

Merlin66 wrote: Mon Mar 23, 2020 6:10 am The Ha systems are listed and documented, but I can't see any specifics on the BF (LS1800 is mentioned), there no information on compatibility with other etalon suppliers (ie Lu,t Coronado, Solar Spectrum, SolarScope etc.)
Thank you for that.

I am very happy with my new Lunt B1200S2 BF so far. After making repeated back and forth comparisons the Lunt easily wins over the BF5. There is a difference in focus between the two. So one of them must have some optical power.

The Lunt BF image is very much duller but there is none of the obvious vignetting of the BF5. I often ran into minimum exposure with zero gain with the PST BF5 in SharpCap with my 6" and the ASI174! Now I have a much wider, safety margin to play with and must adjust gain upwards to have enough light at 1-2ms exposures. With the BF5 I would always be on zero gain and under 1ms on a clear sun!

You may remember that I had motorized my PST etalon which was discussed in another thread here. That worked rather well with the BF5. With the Lunt the looseness of the thinner packing rings I had used, meant very non-optimum, brightness levels across the much larger field on the monitor.

I removed the rubber band and thin metal shell and played with the PST etalon's tuning with a rod in the tuning holes. Naturally there was a lot of play and this changed the "lighting" across the field.

So, I have returned to the original, ridiculously stiff, O-rings and was pleased to see much larger fields of smooth surface detail with much more even brightness.

Downside is I now have to manually tune the etalon again. Even with thin and very grippy, industrial, rubber gloves it is hard work turning the PST tuning band smoothly. Which is what drove me to motorize the etalon in the first place. Except it was far too stiff to turn with a motor as standard.

Despite considerable expense and many trials with different materials [all bought online] at 1.5-1.7mm Ø I never found a perfect match between freedom [i.e. desirably low friction for driving] and the necessary stability of the PST etalon in rotation.

I've had a couple of days of sunshine between cloud now but with rather indifferent seeing conditions. I shall continue to experiment and will report any useful improvements. My blog shows some of the images I have been capturing. I don't think the experts here have much to worry about! ;)

Sorry for this long winded update. :oops:


http://fullerscopes.blogspot.dk/

H-alpha: Baader 160mm D-ERF, iStar 150/10 H-alpha objective, 2" Baader 35nm H-a, 2" Beloptik KG3,
Lunt 60MT etalon, Lunt B1200S2 BF, Assorted T-S GPCs or 2x "Shorty" Barlow, ZWO ASI174.
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