Barlowing the Lunt LS50Tha (Experimental!)

[Macavity]

Been a while since I did anything here! Was trying to think of something
new to try with the Lunt 50Tha? Try "nailing" the Barlowing? Previously
I only had a Skywatcher 2x, so bought myself a 3x Antares Twist Lock!

OK, I "should've gone to Teleview", but I once had an Antares 2" 1.6x
which was good... and 1.25" Twist Locks come in a "set" of 2x, 3x & 5x!

Amidst the clouds I tried a few quick and dirty experiments! There is no
drifting to remove the Newtons Rings on the Barlowed images but...

First with NO Barlow:

Then with the Skywatcher 2x Barlow:

Then with the Antares 3x Barlow:

And finally the Antares 3x with "kitchen sink" (processing) thrown at it:

Whether the Barlowed images "show more" is naturally moot! But I don't think they are WORSE? 
Obviously this has to be repeated under easier skies and with greater care (and minus the NRs!!)
But I'm not completely discouraged?!? Might even go the whole hog and get an Antares 5x too? 

[xtreemchaos]

i think the difference is impressive, your deff on the right track. well done. thanks charl.

[Davey-T]

Looks like it should be capable of some pretty impressive images when / if we ever get some nice weather, been one downpour after another here today.

Dave

[laudropb]

Looks like there is a definite improvement. Well worth the experiment.

[David Smith]

Promising images.

[Macavity]

Thanks Folks! No Rain, but I can well empathise with those finding the
weather "challenging". Competing clouds at two or more levels here? 

I sense there is no real substitute for additional aperture and inherent
contrast with double stacking? But it's fun to play (I think?!?). 

Here's looking forward to imaging over a consistent 60 sec? 

[cshahar]

The Newton Rings make it hard to really assess the barlows for detail. I think good seeing is a factor as well, with magnification holding up much better under good seeing. These are good efforts though!

-Charles

[Macavity]

"But these go up to Eleven"? 
https://youtu.be/KOO5S4vxi0o
True enough though...

Maybe, I can catch a bit o' Sun today, and "drift away" my NRs!
Try to "equalise" the image sizes to better check the quality...

FWIW, The Lunt 50Tha works "more easily" with *shorty* Barlows
(limited helical focussing etc.). So I have hopes for the Antares...
I actually "steal" the lens element from the Barlow housing. 

With the particular setup, I measure 2.7x with the Antares. (1.75x
for the Skywatcher). I have a hunch that 3x Barlows are about right 
for this sort of stuff? I could even put in the effort re. a mosaic. The
3x3 format would at least make the additional effort worthwhile! 

Overall, I'm trying to work out a "future strategy" for all this? lol
With this scope I think I will concentrate on simple full disks...
and use a 3x Barlow for any "interesting" stuff.

[michael.h.f.wilkinson]

There is certainly some gain, but it is hard to judge due to the Newton rings. Much depends on the pixel size of the camera you are using. If you are using the ASI120MC F/16-F/20 is the ball-park range I would use. With the LS50 at F/7 I would go for something between 2.5 and 3x

[Pete Presland]

Interesting comparison I only ever really use my TV x2 Barlow or x2.5 Powermate.

[Lowjiber]

Very interesting comparisons.  Thanks for sharing.

I've never had success using much over a 1.5x lens (bottom lens from a Shorty Barlow) with my 120MM.  I have a tilt adapter, but it didn't make enough differences.  I think it's because the chip is so small.

Clear Skies

[Macavity]

2 hours ago, michael.h.f.wilkinson said:

There is certainly some gain, but it is hard to judge due to the Newton rings. Much depends on the pixel size of the camera you are using. If you are using the ASI120MC F/16-F/20 is the ball-park range I would use. With the LS50 at F/7 I would go for something between 2.5 and 3x

Thanks Michael (and ALL!) - Interesting / useful as ever. 

Strictly the ASI120MM...  But that's what I was kinda thinking out loud!
If it delivers a nice 2.7x (minus NR!) image, I shall be happy enough...

FWIW, the Antares 3x allows one to play with a nifty negative doublet...
complete with blackened edges. Wouldn't DARE "mess" with a Teleview!

[Pete Presland]

I do like the difference I get in image scale between the Barlow and Powermate. I struggle with the maths, but when the conditions seem right I like to use the Barlow as it gives me much more "close up" view.  The difference is nicely shown in the 2nd and 3rd images I took this morning. 

 

 

[cshahar]

At this point, I would only buy barlows from Baader or Televue. To really get the full magnification without degradation these are of superb quality.  Did you know there is software that eliminates newton rings, and the developer is looking for beta testers? Please pm me for further details.

-Charles