The Quark,reducer and polarizer

[jetstream]

Yesterday I received my Quark back from Daystar and I'm happy to say the least. No banding with good even contrast across the whole disk. With above average seeing today Ha viewing was pretty darn good.... in the SW120ED/LZ/reducer the sky allowed 200+ mag  The 90mm was no slouch either.

The odd light cloud passed by and to my amazement increased the disk contrast- so out came the ND50 to try- mixed results with this one BUT I remember someone saying that polarizers work for Ha.... thanks to who ever posted this! Luke, Shaun?

The Baader single variable polarizer gave excellent flexibility for increasing disk contrast- it was startling actually. Just turning the EP allowed anywhere from zero (why?) light to full brightness, with the proms wanting more light and the disk less. The difference on the disk was large and combining the zoom EP with it gave super tunability.

My polarizer is now mounted on my reducer and will for sure be used on every occasion, it's funny how those few light clouds spurred on the filter try....

[Pig]

Great news Gerry, I think ED started the ball rolling about polarizing filters and how they enhance contrast with granulation  Its fantastic that you have your Quark back and that is performing as you expected   Maybe this will be good news for Gordon who has experienced similar issues.

Did you ever get your Zeiss zoom to compliment your Ha set up ?

[Floater]

That makes for great reading, Gerry! I'm pleased you have got a result and I'm encouraged to think that my problems will be sorted out, too. (Thanks for the thought, Shaun.)

I really do have high hopes for the Quark - and there are so many owners who are happy I'm sure that's the way it's going to go.

In the meantime, Gerry, your post has given me something else I need to research/learn about/have fun with - a polarising filter ... I'll introduce the subject quietly to Mrs Floater. I'm sure she'll be tickled to hear I'm buying another piece of kit.

Well of course she will ... Won't she?? Can I tell her to refer any comments to you??

Have fun.

[Luke]

Excellent news, Gerry

A bit different to your cloudy experience but the other day while I was imaging with the Quark it seemed to me that thin passing cloud steadied the view! My best guess to explain that one was that the cloud was taking a bit of sting out of the sun heating up the ground etc

[jetstream]

@ Shaun- The Zeiss zoom is in eastern Ontario and it will be here by Tuesday, I look forward to trying this EP. With a huge 7.3mm-25mm range and a nice small field stop(s) 19mm ish, it will work well with the Quarks aperture- and- the reducer.

@ Gordon- sure use me as an example! The Baader single polarizer is a VG filter... it also works in WL and on Jupiter in daylight. Keep working on your Quark issue, you will get it resolved. This is a new, innovative product that has opened the door to high contrast, high resolution Ha viewing. Let me know how its going if you like Gordon.

@ Luke- thanks! I'm happy!  The clouds seem to do strange things to Ha.... normally they kill the disk contrast, but these seemed to take enough of something away that helped... the polarizer does work well for me- no idea what such a precisely filtered view would respond to this. Any thoughts appreciated Luke!

[Stu]

Excellent news Gerry, really glad you are sorted at last.

I too have noticed the cloud effect of increasing contrast and do use a polarising filter though not every time.

The Zeiss sounds very attractive, particularly given the field stop. I look forward to hearing all about it!!

[Floater]

Thanks for your good wishes, Gerry.

The filter is now definitely on my list. As you point out, I see it is marketed with white light viewing as a major use - but good to learn of your experience using it in Ha. Hope to get similar.

Uh-oh. I'm salivating again ...

[Pig]

Oh yes Gerry nice new Avatar    I didn't realise it was you at first, am I the only one who initially recognises people by their avatar ?

[Al.Grant]

Good to hear about the polarizing filter.  

Rupert from Astrograph mentioned this in an email earlier in the week and I thought it must be worth trying at some point, hearing your views has reinforced that and I'm going to get one ordered today.

I have seen adapters to allow 2" ep's to be used with the Quark.  Anybody used one of these and is there much difference over 1.25" ep's ?

Al

[Stu]

Good to hear about the polarizing filter.

Rupert from Astrograph mentioned this in an email earlier in the week and I thought it must be worth trying at some point, hearing your views has reinforced that and I'm going to get one ordered today.

I have seen adapters to allow 2" ep's to be used with the Quark. Anybody used one of these and is there much difference over 1.25" ep's ?

Al

Al, I'm willing to be corrected on this, but I really can't see the point of using 2" eyepieces in the Quark.

The 32mm (1.25") Televue Plossl has a field stop of 27mm which is bigger than the 20mm clear aperture of the Quark etalon. You basically see the etalon field stop within the eyepiece field stop and I imagine going to 2" will just make this more obvious.

You would not gain any additional fov, and using wide field eyepieces is not recommended anyway so I can see no further benefits.

As said, if anyone disagrees please let me know!!

[Pig]

The only reason I would buy one is if I wanted a Quark and didn't own any 1.25" eyepieces, even then the cost of the adapter is half the price of a suitable eyepiece..... bit of strange one to me

[jetstream]

Stu is absolutely right.

The Quarks aperture -about 22-23mm- is a big limiting factor on EP selection. 27mm field stop is "gotten away with"( vignetting from Quark) using the 32mmTV plossl but there is also the reducer involved. I think that a RIGHT 40mm EP could work, but the fs and eyerelief (exit pupil disk) location must be chosen wisely.

Reducers only like reducing so much and so does any individual eyepiece (which varies) so matching all these factors can reap big rewards. This is why these small FOV zooms can work so well- small fs dia, they work well with reducers and of course they zoom- allowing us to easily catch the seeing instantly. The Baader MK3 zoom become a 48mm-16mm zoom effectively which greatly increases the useabilty of some 70mm-90mm f7 scopes for use with the Quark.

[Pig]

The Vixen 40mm Plossl work very well with the Quark in both the Equinox & Esprit, I am unable to find the field stop diameter published anywhere but I suspect it is approx. 25mm

[Floater]

Hi again, Gerry.

Have done some reading on polarising (spell check keeps changing the z in that word) filters and am curious about the single/double aspect of these. You write that just turning the EP changed the brightness; how does that work? I can figure out how a double filter does that trick - one cell on diagonal, the other on EP, for example - but how can that be achieved with a 'single'?

Yours,

Confused

[Pig]

Gerry I hadn't thought about using the variable polaris(z)ing filter with the zoom   I will now though.

[Stu]

Hi again, Gerry.

Have done some reading on polarising (spell check keeps changing the z in that word) filters and am curious about the single/double aspect of these. You write that just turning the EP changed the brightness; how does that work? I can figure out how a double filter does that trick - one cell on diagonal, the other on EP, for example - but how can that be achieved with a 'single'?

Yours,

Confused

Gordon, I believe the light coming out of the Quark is polarised already so this does the job of the first filter. Same with a Herschel wedge.

[Peter Drew]

Further interesting info re polarisors on Solarchat today.   

[Al.Grant]

Al, I'm willing to be corrected on this, but I really can't see the point of using 2" eyepieces in the Quark.

The 32mm (1.25") Televue Plossl has a field stop of 27mm which is bigger than the 20mm clear aperture of the Quark etalon. You basically see the etalon field stop within the eyepiece field stop and I imagine going to 2" will just make this more obvious.

You would not gain any additional fov, and using wide field eyepieces is not recommended anyway so I can see no further benefits.

As said, if anyone disagrees please let me know!!

The only reason I would buy one is if I wanted a Quark and didn't own any 1.25" eyepieces, even then the cost of the adapter is half the price of a suitable eyepiece..... bit of strange one to me

Thanks for the comments on the use of 2" ep's.  The main reason for asking was that I have a bigger choice of 2" ep's between 28-40mm.

My current 1.25" ep's jump up from 25mm straight to 40mm but it makes more sense to get some new 1.25" ep's to fill the gaps rather than swapping between 2" & 125" and adapters etc.

Al

[jetstream]

Maybe if my Quarks blocking filter worked better there would be no need for the polariser?

[Peter Drew]

If you can see Ha detail then your blocking filter is working fine. It's not there to reduce the brightness by design but to block wavelengths other than Ha. 

[jetstream]

What did the member on SC mean by "if the axes is not fully blocked (misalign) then the HW will look broader". I took it to mean one of the etalon "combs" is intruding a bit on the one that is supposed to be centered in the blocking filter, excluding the others, if this makes any sense. Any input is appreciated Peter.

[jetstream]

May I retract my previous post since reading further?

[Peter Drew]

That's a relief!