PST / Double Stack - Getting the best views?

[Paul73]

Hi Guys

My solar set up is finally complete....

The latest purchase is the double stack filter which I collected from its former owner on Monday. Incredibly, first light was yesterday.

What a fantastic piece of kit!!!! Detail jumping out!! I was one happy happy camper! ??? - must be getting excited about SGLXII - sorry...

Tuning the two etalons seemed to be trial and error. Much enjoyable fiddling about with some lovely views, but no method.

My question is a simple one. Is there a better way to get the best out of this setup?

Any hints & tips greatly appreciated.

Paul

[michael.h.f.wilkinson]

Congrats on getting that double stack unit. I got a double stack unit for  my SM-II-60 and it just transforms the views. What I generally do is first tune the SM-II-60 single stack, then attach the DS unit, tilt it so that the reflected image is far enough away from the disk not to bother me, and then tune the etalon for maximum contrast. There is a degree of sweet-spotting in my set-up, so the image is not perfect over the entire disk.

[Paul73]

Thanks Micheal.

I thought that tilting was the same as tuning? My Double stack unit just has a thumb wheel that tilts the filter.

Paul

[michael.h.f.wilkinson]

I see your double stack unit is a tilt-tuned one. I have one with two adjustments: tilt with a thumb wheel and tuning by rotating the black ring surrounding the front ERF.

 

[Paul73]

It would be interesting to see if just rotating the whole filter, once tilted, makes any difference. 

Paul

[cdd2455]

Hi Paul

Congratulations on the Double Stack, I've often thought of going that route.

Regarding rotating the whole filter once tilted : in my experience it most definitly makes a difference even for single stack.

I think this is refered to as " Clocking " and has been discussed on CN with regard to double stacking.

I have both a SM40 and SM90 and there is the temptation to thread them snuggly to the matching TMax tuner and the TMax snuggly to the scope, but over time I found that a better view could be obtained by rotating the SM to TMax ( unthreading it ) by an eigth to a quarter turn.

Why it should show a benefit in single stack is not clear to me, I think there may be a relationship between the orientation of the etalon and the one or other element in the BF but thats as far as I've got.

Best Regards

Carl

 

 

 

[jabeoo1]

Paul, 

As you probably know a few of us use the Lunt 50 & DS.  

I realise some of the following may not be the same on your PST but I will explain my approach. 

Clocking is essential,  to achieve a decent view the DS on mine likes to sometimes (but not always) be half-way out along its thread + some. Remain vigilant about how close to the end of the travel they are ! 

I notice whilst in this 'half way out' position the DS loosens, leading to some play/slop.  Depending on the viewing angle this slop is effected in different ways.  If the scope is aiming high the DS rests on the ERF and the slop is all but eliminated, if looking at a sunrise/set then the slop can sporadically shift the reflected image by the dramatic effect on the light path, so it can be some skill getting this to rest in the sweet spot.  The sweet spot does not always show a uniform full disc. I scan to get the best snippets of the full disc/picture, however on really good days where all the factors come together I have had some amazing full disc views!??  I have not yet understood this really.  

I think 'perfection' is only a combination of obvious stuff like excellent seeing, finely tuned etalons & focus, relaxing the eye and feeling like being able to concentrate, covering the head to block the glare, and having a dynamic sun with lots of contrasting features to observe.  I am sure at times I have everything set up perfectly but the view just is not too gripping.  I always check the latest GONG hydrogen alpha images once I have set up to see if I am getting the view well enough, if its not a worthy representation I sometimes go back to single stack and really get that tuned up, then add the DS over that again. Then fine focus and fine scan and hone in on the sweet spot.  A session can be cycles of these micro tasks, and different sessions for me can vary in how rewarding they are and also how task orientated they are.  When everything just all falls into place and the fiddly activity is minimal, its a nice feeling however this does not happen much for me.   

I am still learning generally & am still picking up very subtle techniques to achieve consistent views.  

 

[The Head Gardener]

On 24 August 2016 at 10:44, Paul73 said:

Hi Guys

My solar set up is finally complete....

Many congratulations.. With tongue firmly in cheek. I'd cheekily suggest there is no such thing as a 'complete' set up, but what the heck do I know?. That is a lovely looking set up though

Jayne

 

[Paul73]

Thanks guys. I'll look forward to trying all of this advice tomorrow.

Jayne - You are so so right. There is no such thing as complete!! There is such a thing as being happy with the kit you have; until a) more Astro budget appears. Or, b ) I see or read about some fantastic piece of kit that I just can't live without.....

I'm not good with temptation.

Thanks again.

Paul

[michael.h.f.wilkinson]

Interesting point about clocking. Might try that on top of the tuning I already do

[Highburymark]

Great set up Paul - congrats.

With the Lunt 50 DS unit, clocking is essential to get the best out of all those variables - solar features, seeing, sweet spots, EPs etc - jabeoo's post above perfectly sums it up. Sometimes it's frustrating but other times everything comes together. 

[Paul73]

Thanks guys. I had a really good play with the little PST+DS today.

The results were great. Micheal's tuning method removed a lot of the initial setup headache. And then Clocking really made a difference. It only took about 1/4 turn to get the best all round view, but tinkering a bit to the left and a bit to the right brought different features into crisper focus. True, there was a definite "sweet" band where the view was much much crisper. I guess that it will take a fair bit of practice to get the very best out of this kit.

Ha observing, even at the budget end, isn't cheap. But it is certainly rewarding.???

Paul

[Stu]

Great looking setup Paul, very jealous. My PST used to give great views so I know what you are experiencing.

I had (probably stil have) an understanding that double stacking a comparitively small scope was good for imaging but lead to dim images for visual, it sounds like that is definitely wrong info?

[jabeoo1]

46 minutes ago, Paul73 said:

Thanks guys. I had a really good play with the little PST+DS today.

The results were great. Micheal's tuning method removed a lot of the initial setup headache. And then Clocking really made a difference. It only took about 1/4 turn to get the best all round view, but tinkering a bit to the left and a bit to the right brought different features into crisper focus. True, there was a definite "sweet" band where the view was much much crisper. I guess that it will take a fair bit of practice to get the very best out of this kit.

Ha observing, even at the budget end, isn't cheap. But it is certainly rewarding.???

Paul

Todays features were outstanding Paul, it was a fantastic time to practice using the new toy as it was a rich view.  I did not get out early enough really, and by midday seeing was mostly turbulent with only occasional glimpses of good seeing.   I am sure before Bristol warmed up it would have been great.  

I like taking the solar scope into the countryside, in fact it goes everywhere in the UK with me.  Not long ago I stopped at the cafe next to Hardy's Monument (well worth a visit) in Doret overlooking the south coast.  I decided off the cuff to set up & the owner of the Cafe was fascinated with the views.  Two other girls who were from Belgium were touring the south coast on mountain bikes and stopped for a drink, they both also looked and were also very interested.  

Theres something great about letting strangers see the views, I feel no guilt owning this gear on the basis its never just kept to myself.   

[Paul73]

8 hours ago, Stu said:

 

I had (probably stil have) an understanding that double stacking a comparitively small scope was good for imaging but lead to dim images for visual, it sounds like that is definitely wrong info?

Plenty bright enough. It is dimmer than the PST by itself and is definitely harder work for the observer..

Paul

[andre2]

Looks like the double stack is really worth if you OWN a pst. My guess that a 12 mm eyepiece should works just fine with the 40mm stack. That alone will be make the double stack a “ welcome kit”?  Ooh yea i forget the 3D effect.i think it will be cool for the first time fewing. I am beginning to save....and hope that i will love the double stack as i love the single stack for what it is. Thanks!