Lunt B1200S2 "straight through" blocking filter info?

[Rusted]

Hi,

Despite Peter's best efforts to dissuade me/us, a larger BF is in my stars. Well, the nearest one, anyway.
This is purely for solar imaging on my 6" f/10 H-a PST mod.

The Lunt 2" T2 B1200 comes in elbow [diagonal] and straight through S2 versions. The latter is of most interest to me.

I have very limited "elbow room" to fit a blocking filter in the light path before the camera.
I use a big, 2" helical focuser. Which eats up some focal length but is nicely long throw and has no flop. Unlike the 1.25" models I've tried and rejected.

My problem is that the images online, of the straight through B1200S2, are all identical, Lunt, sales website fodder and number precisely 1. No other images! 

Before I destroy my piggy bank I'd like to see what is involved. A diagonal version would arguably eat up far too much focal length after the PST etalon.

Does anybody have any better images of the Lunt 2" > T2 B1200S2? Perhaps in a state of undress?   Or even the B1800S2? Which must be quite similar.

Most importantly, I need to know what unscrews at the telescope end, the thread size and if/how it will fit into my PST mod.
I'll save on postage and/or delivery time wasted if I need to buy a suitable adapter as well. 

Thanks

[Davey-T]

Dunno about the 1200 but I think the bigger ones come in two pieces with a separate diagonal.

Dave

[Rusted]

Thanks Dave but this is definitely a straight object:

Linked to Optcorp B1200S2 sales webpage image:

I'm confused by the lower [?] end with the projecting thumbscrews.
It can't plug into a 2" socket with those in the way.
The other end has screws and a badge. That's won't fit a 2" socket either.
Is that a T2 male thread right on the bottom? Or just a bevel? 
Is it even the right way up? So many questions.
My piggy bank wants answers before giving up the struggle.

[Davey-T]

I think they do an optional diagonal to fit it, maybe there's a picture of it somewhere on their site, at least you could see how that attaches.

Dave

[Rusted]

Hi Dave,

The diagonal version has a great, long nose.
I'm worried that the B1200S2 is two widely separated units a bit like the PST but on steroids.
The PST has an ITF in front followed by the BF almost a couple of inches further back towards the EP.
If the diagonal version splits the units on either side of the optical flat then the unit could be slightly more compact.
Or much the same path length. Making the choice merely arbitrary based only on personal taste.
The same text is repeated, with the same image, on every sales website. Hardly helpful at this pricepoint.
I haven't found any amateur solar websites showing any greater detail. I may have to ask on Solar Chat.

 

[Peter Drew]

I'd be cautious about this. I've no direct experience but there have been comments on other solar forums questioning the compatibility of Lunt blocking filters and Coronado etalons.    🤔 

[Rusted]

1 hour ago, Peter Drew said:

I'd be cautious about this. I've no direct experience but there have been comments on other solar forums questioning the compatibility of Lunt blocking filters and Coronado etalons.    🤔 

Thank you Peter. It's lucky you responded! 
I had dismissed Coronado because Meade had filed for bankruptcy.

I know the dealer is directly responsible for sales and warranties.
It was just a concern which favoured Lunt. The Lunt is also a 2" > T2 fitting. Lunt only a 1.25".

I know of your recommendation for the 5mm PST BF with Barlow for visual.
This purchase was for imaging with a longer focal length OTA of 1500mm.
I'm now thinking about the BF15 at about the same price as the 12mm Lunt B1200.

 

[Peter Drew]

@Rusted.   I brought this up as I'm pretty sure that Lunt blocking filters do not work as well with Coronado etalons as Coronado blocking filters do with Lunt etalons.  I was suggesting that this possibility should be checked out to avoid disappointment particularly as they are so expensive.  A post to this effect would be worth raising on Solarchat.         🙂 

[Merlin66]

No experience with the 2" Lunt BF, but I have used the 1.25" Lunt diagonal BF (Ex-60m Lunt PT scope) successfully on my SM60/ ED80 set-up. No issues.

 

[Davey-T]

Presumably the optional diagonal goes in the end with thumbscrews.

Dave

[Rusted]

10 hours ago, Peter Drew said:

@Rusted.   I brought this up as I'm pretty sure that Lunt blocking filters do not work as well with Coronado etalons as Coronado blocking filters do with Lunt etalons.  I was suggesting that this possibility should be checked out to avoid disappointment particularly as they are so expensive.  A post to this effect would be worth raising on Solarchat.         🙂 

Thanks. I have taken up this very issue on Solar Chat.

[Rusted]

6 hours ago, Davey-T said:

Presumably the optional diagonal goes in the end with thumbscrews.

Dave

Thanks Dave,

I really don't think a diagonal is involved, at all, in these "straight through" models.
Those who want diagonals can have them at no extra charge.

Diagonals change image orientation. Which is a real nuisance while imaging.
Particularly when making manual adjustments with large image scales.
Even scanning the solar limb for prominences on the paddle becomes a chore.
Manually compensating for image drift during video capture is no longer familiar or logical.
Publishing images with "unlikely" orientations can cause an "image" problem.

[Rusted]

6 hours ago, Merlin66 said:

No experience with the 2" Lunt BF, but I have used the 1.25" Lunt diagonal BF (Ex-60m Lunt PT scope) successfully on my SM60/ ED80 set-up. No issues.

 

Thanks. Good to know.