Lunt B1200S2 BF produces a dark bar.

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Rusted
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Lunt B1200S2 BF produces a dark bar.

Post by Rusted »

I was back to my random barred sweet spot again this morning.
It defeated all my adjustments despite endless tilting and tuning.

Then I remembered being advised to "clock" my BF against the PST etalon.
It immediately became apparent that the Lunt BF produces a broad bar of darker detail.

Rotating the BF with the camera attached rotated the dark bar.
My PST BF does not produce a bar. Rotation has no obvious effect.

The Lunt BF produces ghost suns when looked through with the naked eye.

I remove the Lunt BF at the end of every imaging session.
Then take it and the camera back indoors in sealed plastic bags in plastic pots to avoid condensation.
Subjecting the BF and camera to overnight freezing in the observatory was considered a bad idea.

Removal means I return it to the telescope at completely random orientations each time.
I should probably mark it. To be able to return it to the same [best] orientation each time.

Is any of this normal? :D


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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: Lunt B1200S2 BF produces a dark bar.

Post by EGRAY_OBSERVATORY »

Hi Chris,
I have a BF1200 into the Lunt 60mm Ha as well as in the Lunt CaK scopes.

I haven't actually found that problem in the 10-years of usage.

I leave everything as-is between sessions (except to cover the objectives) and the observatory is de-humidified down to at least 40% all year round, so
if for any reason the internal temperature would drop below say about 10-degsC, there is a small oil-filled heater to keep away from freezing. In any case the de-humidifier requires a minimum temperature of +5-degsC to prevent possible freezing and damage.

I do also have the DS (not currently being used) and reading yours and previous posts about "clocking" - I might actually try various of those procedures and also with the BF too. Just to see if any improvements can be made.

Certainly to mark the favourite/sweet-spot for either end and the camera too, would certainly save much hunting and time...

Best Wishes
Terry


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Re: Lunt B1200S2 BF produces a dark bar.

Post by Rusted »

Sorry Terry,

I'm afraid your response missed my virtual in tray. :oops:

Any "bar" I noticed was probably due to tilting.
In my desperation to solve my PST issues I tried rotating the BF with camera still attached.
Even with three thumbscrews at 120° it is impossible to maintain the BF on axis during rotation.

Despite having an observatory I take the entire filter train indoors after every session.
Which means dismantling it to go into little storage tubs in the pockets of my laptop case.
Resulting in random rotation of the components when re-assembled.
So I have to adjust everything, including retuning the etalon, from scratch, every time.

Thanks
Chris


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: Lunt B1200S2 BF produces a dark bar.

Post by EGRAY_OBSERVATORY »

Hi Chris, sorry for the late reply..

I'm not sure whether transporting the components in-doors in sealed plastic-bags/containers is a good idea, as any humidity in/around those items will continue to be within those bags etc.

If you have mains electricity in the observatory, then consider purchasing a de-humidifier would help to keep the air dry down to say 40%-humidity and where the only snag would be that the water-bucket will need emptying - when required, or some have a water-pipe for passing that water outside automatically and which must be kept clear for such..

Desiccant as:- https://www.google.com/searchq=dessican ... e&ie=UTF-8

is an alternative solution to the problem...

Both could save you so much time on setting-up/re-tuning and allow you more-time for the real-purpose...

Could this be of help to your problem ?

Regards
Terry


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