B400 for visual observation?

[tico]

Hello,
Really in a Lunt LS50 have the B400 for visual observation (strictly) there is much difference with a B600 in this same solar telescope?
Thanks in advance.
Greetings.
Nebu,

 

[joe aguiar]

I used a bf5 which is 5mm 4 being 4mm 6 is 6mm.

I dont think u should consider 400 at all even the 600 would be boaderline. 

Pay extra get the 1200mm or 12mm since lunt doesnt have a 10mm.

If if your budget really really cant handle the 1200 then get 600 but it's almost like a pinhole sight through.

I mean I used a bf5 on my first scope and lasted a yr but I then sold it used and bought the bf10.

So the 600 could work  BUT if u also find it hard to look through and do what i did sell 600 u will lose 30 to 35% then u have to buy the 1200 anyway.

When u just upgrade from the store or manufacturer its norm like 250 difference from bf5 to bf10 etc

So u save alot more by just getting the bigger one right from the start

Joejaguar 

[Peter Drew]

My experience has been that larger blocking filters only enlarge the field of view, they don't increase the "sweet spot" of good Ha on band performance, this is determined by etalon diameter and focal length of the telescope.  I have 5mm, 10mm and two 15mm blocking filters, the 5mm gives the best image in conjunction with a 2x Barlow and binoviewers at a minimum magnification of 150x on my 150mm solar refractor.     🙂

[NGC 1502]

I’ve used several Ha solar scopes from Lunt (L35 & L60), Coronado, Solar Scopes Isle of Man, with various blocking filters, for visual use only.

I think the more expensive blocking filters are nicer to use with a less restrictive field of view. But the actual detail seen with a more expensive blocking filter seems the same to me.

The more expensive Ha scopes seem to give a noticeably better view of solar surface detail, but for prominences the difference between the cheapest and more expensive is much less.

Hoping that helps your decision, Ed.

[Rusted]

There seems to be some variation in user's experiences here.

Can I try to expand the discussion slightly?

Are there alternatives to these "dedicated" diagonals + blocking filters to obtain considerably more, clear filter aperture?

I'm thinking of 1.25" or 2" filters which can be placed further upstream.

A Baader D-ERF energy rejection filter is assumed as standard up front. 

UV and IR blockers like the Baader H-alpha 35nm and Beloptik's IR KG3?
About 250 Euros for the pair in 2" ahead of the etalon.
Could use multiples of each and stacked in series for greater reduction outside the nominal passband?

How much more blocking is needed for visual [or imaging] H-alpha beyond these three filters?

[Merlin66]

Rusted,

Doesn't work like that.... The typical "blocking filter" is actually made up of at least two elements.

There are two factors to consider

1. The reduction in heat/ energy load

2. The "sort filter" required to suppress all the etalon "bands" other than the one at Ha

The ERF combo etc will look after #1 but does nothing for #2

A sort filter requires a very narrow bandwidth (typically <10A) and be set/ tuned to the Ha CWL (central wavelength)

[Rusted]

Thanks Merlin.

I thought it was a bit too easy.

Hope all is well in your area Down Under?
The fires have been dominating the global headlines.

[joe aguiar]

On 15/01/2020 at 18:17, Peter Drew said:

My experience has been that larger blocking filters only enlarge the field of view, they don't increase the "sweet spot" of good Ha on band performance, 

hi peter yes that is correct.

I guess on a video I made about the Coronado solar max11 with bf10. I kinda explain its kinda like viewing through a 4mm plossl ep which is pretty hard, but viewing through a 10mm plools even tho its still small is much better then the 4mm version. Just an example I think gives people a good idea what to expect.

so in this case if you can and its between the bf4 or bf6 then get the 6 as its kinda like a 4mm pl vs a 6mm pl the 6mm will be a tad easier to look through, and it shouldn't cost much more since its only a 2mm difference.

joejaguar

[Highburymark]

I don’t think it makes much difference to the view. You need a B600 if you want to use a binoviewer or image - and it’s easier to sell the scope with a B600 blocking filter. Otherwise a B400 is fine. 

[daslolo]

On 15/01/2020 at 15:17, Peter Drew said:

My experience has been that larger blocking filters only enlarge the field of view, they don't increase the "sweet spot" of good Ha on band performance, this is determined by etalon diameter and focal length of the telescope.  I have 5mm, 10mm and two 15mm blocking filters, the 5mm gives the best image in conjunction with a 2x Barlow and binoviewers at a minimum magnification of 150x on my 150mm solar refractor.     🙂

My experience too with the 5mm bf of the stock PST and 1.85x barlow in binos, large field of view. i don't understand why you wouldn't gain afov with a larger bf (all them acronyms)

[Peter Drew]

A larger blocking filter does increase the Actual field of view but not the sweet spot, a benefit for imagers who want a full disc image.  The small blocking filter in combination with a Barlow increases the Apparent field of view whilst retaining the original sweet spot which now covers the whole field albeit a smaller Actual field.  Horses for courses.  🙂

[Look left]

Thanks for all the advice guys.

i,m going to be imaging and not much visual does this effect things?