New Lunt 60mm MT. Good or bad etalon?

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Rusted
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New Lunt 60mm MT. Good or bad etalon?

Post by Rusted »

Hi,

After waiting over four months for a Lunt 60MT it has finally arrived.
Visually, with a T-S binoviewer, the sun is superbly crisp. Mesmerising!
A 1.6x GPC and a pair of Meade 4000 20mm brings the magic used straight through on the low, sinking sun.
The T-S 1.25" star diagonal needs a 2x WO Barlow on its nosepiece with 26mm EPs to reach focus.
It would not reach focus with the 2.6x GPC on the binoviewer nose.

Fast forwards to today: How does it behave with a camera?
A short extension brought my ASI174 to focus. Not the ideal camera but it's what I have.
Lunt B1200S2 straight through BF.

I centred the sun in SharpCap at 800x800 to almost fill the frame.
High cloud teased all afternoon at 80F.
Just after 18.00 locally I had a few brief cloudless moments.

Mono 16 2.25ms 100fps 0 Gain.
AS!3 at finest settings. 50/500 stacked.
ImPPG required Lucy Richardson be reduced to 0.5! Coarse grain!
Default everything else. Saved as 16-bit TIFF.
Converted to JPEG in PhotoFiltre. Auto levels.

Not sure about perfect focusing or tuning.
The scope is well out of reach from the 27" HD monitor.

Is this Lunt [35mm] etalon a keeper for a 150mm Marty Mod?
There is some obvious and uneven roughness around the limb on the image.
Could this simply be a tuning issue?

Please note: Only the quality of the etalon is of interest.

There are some cosmetic issues with the scope itself.
It may have been returned to the dealer without my being informed.
Had somebody rejected the etalon as unworthy?

14.08.2022 18.08.46  Lunt 60mm B1200S.tif ASI174.jpg
14.08.2022 18.08.46 Lunt 60mm B1200S.tif ASI174.jpg (103.64 KiB) Viewed 1616 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: New Lunt 60mm MT. Good or bad etalon?

Post by marktownley »

Looks ok to me, the right hand side of the disk is offband though. Did yoiu take any other images with it you can share?


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Re: New Lunt 60mm MT. Good or bad etalon?

Post by Rusted »

marktownley wrote: Mon Aug 15, 2022 7:19 am Looks ok to me, the right hand side of the disk is offband though. Did yoiu take any other images with it you can share?
Thanks Mark.

All my videos and pictures are on the observatory laptop.
I have been out all morning. I'll get back to you when I find more images.
I was dodging cloud most of the time.


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: New Lunt 60mm MT. Good or bad etalon?

Post by Rusted »

Two more images: I was struggling to avoid ImPPG over-sharpening AS!3 output on steroids.


14.08.2022 13.09 Lunt 60mm B1200S.jpg
14.08.2022 13.09 Lunt 60mm B1200S.jpg (107.49 KiB) Viewed 1543 times
14.08.2022 18.00  Lunt 60mm B1200S.jpg
14.08.2022 18.00 Lunt 60mm B1200S.jpg (70.54 KiB) Viewed 1543 times
Today's hot sunshine 83F has turned to cloudbursts and possible thunder.
So little chance of any more captures today.

I am probably premature in asking for judgment of the etalon quality on so little data.
All because I am desperate to upgrade my problematic PST etalon! :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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Re: New Lunt 60mm MT. Good or bad etalon?

Post by marktownley »

Neither addition looks tuned evenly to me Chris.


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Re: New Lunt 60mm MT. Good or bad etalon?

Post by Rusted »

marktownley wrote: Mon Aug 15, 2022 2:42 pm Neither addition looks tuned evenly to me Chris.
Thanks Mark.

Is this something I can adjust? Or is it a feature of this particular etalon?
This supposedly brand new instrument has a serious cosmetic issue.
So timely return to the dealer may be the wisest choice.
Even if it means more time waiting for a replacement.


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: New Lunt 60mm MT. Good or bad etalon?

Post by marktownley »

It should just be a case of tuning it to get it even across the disk.


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http://brierleyhillsolar.blogspot.co.uk/
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Re: New Lunt 60mm MT. Good or bad etalon?

Post by Rusted »

marktownley wrote: Mon Aug 15, 2022 3:49 pm It should just be a case of tuning it to get it even across the disk.
Thanks Mark. Good to know. :bow
I had automatically assumed asymmetrical tuning across the image was bad news.

I really need to be in the shade of the dome in the morning.
With a huge sun on the big 27" HD monitor to see precisely what is happening when I tune.
Afternoon means I can't see the monitor from the scope as I tune and focus from a ladder.
I can't see a thing on the laptop screen out of doors. Even with a box shade.

The Lunt PT knob is surprisingly hard work turning inwards and moves the scope all over the place!
Probably best to be too far in and slowly unscrew the knob to reach optimum tune. It is much easier to unscrew the PT knob.

I'll leave you in peace until I have some hours of imaging with the 60mm MT under my belt. Give me enough sunshine!
Only then will I attempt to mod the 6" if the etalon proves to be a good one.


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: New Lunt 60mm MT. Good or bad etalon?

Post by marktownley »

You need to make sure the sun is in the centre of the field of view when you tune.

Might sound counter intuitive, but make the sun as small as possible on your monitor, zoom down to 10% in firecapture it will make it much easier to see the gradient caused across the disk when it is not properly tuned.


Image
http://brierleyhillsolar.blogspot.co.uk/
Solar images, a collection of all the most up to date live solar data on the web, imaging & processing tutorials - please take a look!
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Re: New Lunt 60mm MT. Good or bad etalon?

Post by Rusted »

Thanks. I'll try that. I usually zoom right in for a huge disk.


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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