Enhanced Ha Solar viewing

[NGC 1502]

Hi all.    My Lunt 35ha gets used on almost every occasion I can.   Being retired helps with that of course 

I've had my Lunt 35 for over 5 years, and learned that surface detail on the Solar disc is more apparent at very low power, prominences better seen at higher powers. 

Generally, the best viewing is done when the Sun is well above the horizon, and with a clear haze free sky.

However, even if it's a bit hazy, I usually can't resist a look, and under these conditions I began to suspect that more surface detail on the Solar disc could be seen.    I realise that's counter intuitive, but I do mean very slight haze, what's often called a 'milky' sky when the Sun is still casting very obvious shadows, and that only seems to work at very low power with my 26mm Plossl at 15x.   

At higher powers, haze free is best, and at all powers prominences are best seen in a gin clear sky. 

Of course I only suspected this, you cannot turn the haze off and compare the view without, until on one day I had patchy haze drifting across my location.  I took particular note and decided that my suspicion was right.

So I obtained one of these  http://www.firstlightoptics.com/moon-neutral-density-filters/baader-neutral-density-moon-filters.html  It's the ND = 0.6 weakest version.

I've tried the filter on several occasions when conditions were good, including around midday today, when I had a lovely clear blue sky.  At 15x with my 26mm Plossl plus the filter, letting my eye adjust to the view and with careful focusing, surface detail was great, particularly filaments, dark and easy to see.  I removed the filter to compare the view, then replaced it.........

Just to repeat, it's only worth using the filter if conditions are excellent  ( clear and obviously blue sky ) and only at very low power for detail on the Solar disc. At higher powers, no filter is best, and if I want to see prominences at any power, no filter is best.

I think what's happening is that at very low powers the Lunt 35 gives a very bright view that makes low contrast surface detail harder to see, and the slightly dimmer view with the filter helps with better apparent contrast.

I do fully accept that you may find different, this could just be a unique combination of my eyes and my scope......

IMPORTANT  -  for anyone reading this who is not familiar with observing the Sun, the neutral density filter is absolutely not to be used in isolation.  I'm using my filter together with a dedicated scope designed for viewing the Sun.

Opinions and comments welcome, Ed 

[Pig]

Ed,

I too have also noticed this and have had very similar experiences with surface detail, I also think the same happens when very thin clouds sail past the objective whilst observing. Finding a filter that can replicate this effect is excellent news for everyone and I thank you for posting.

[Pig]

Ed,

Just a quick follow up to you first post,

Out of curiosity I tried my variable polarising filter with the Quark and with some fine maneuvering with the rotation of the eyepiece surface detail was enhanced. The effect also dimmed the prominences as you described.

I do not know the range the polarising filter gives but it must be similar to the 0.6 value you mentioned. Thanks for the tip  every little helps.

[Stu]

Good post Ed, I quite agree with your findings.

Coincidentally I tried a similar thing with a Polarising filter after the Quark and by turning the eyepiece was able to arrive at an optimum brightness to show the surface detail.

In line with your thinking, I tend to use a x0.5 focal reducer after the Quark to optimise the contrast for surface detail. Proms, as you say are great at higher power and unfiltered.

Thanks for the post!

Stu

[michael.h.f.wilkinson]

Curiously, I found that I could pick out more surface detail at higher magnifications with my old LS35 (often using the WO zoom at around 11-12mm, so around an exit pupil of 1mm, or 35x). I also went up to 47x with a Pentax XF8.5mm, or used 40x with the XW10 to great effect. Proms showed up well and with rich detail, but I use low magnification to spot the fainter proms, especially rare detached proms sitting at a good distance of the disk. I even had to use averted vision to spot some. I do agree that the surface also looks spectacular at low magnification (MaxVision 24mm 68 deg as a rule). The hazy conditions you describe often coincide with better seeing, so that might be an explanation.

I did use a B1200 rather than B600 or B400 blocking filter, and my immediate impression was it has a much higher transmission than the B400 I had before. This might have allowed me to throw more magnification at the disk before contrast suffered due to lack of light. I had the same effect with my SM-II 60mm, where the BF5 showed much dimmer images than the BF15 I have now.

[Stu]

I knew I remembered a similar thread from a while back.

http://stargazerslounge.com/index.php?/topic/229473-Moon---ND-filter-for-Ha-scope-%28PST%29%3F

Peter mentions that the effect is strongest with a layer of moving thin cloud which may narrow the bandpass.

This certainly seems to match what I've seen. I have experimented with Polarising filters and think they can help, but not as much as cloud!! (Of the right sort!)

[NGC 1502]

Thanks for the latest posts and the link in #6

Interesting to hear of peoples differing findings, seems like the best idea is to experiment with magnification, filters, time of day, etc

Solar viewing is great for those of us living in a large town, no worries with light pollution

Regards, Ed.

[Solar_observer]

Hmmmm interesting post guys,might give the polariser a wiz.

[jabeoo1]

Thanks Ed, Will be trying out some combinations now.   

[Gazabone]

I tried a polariser on my PST and thought it detracted but I'll try some of the combinations mentioned in this thread. Thanks.

[NGC 1502]

I tried a polariser on my PST and thought it detracted but I'll try some of the combinations mentioned in this thread. Thanks.

I've used my club's PST a number of times, sometimes alongside my L35.   One of the differences between them was the brighter view in the Lunt, and this may be masking low contrast detail which I felt was just a bit better in the PST.

So I'm thinking that dimming the view with a filter may help the Lunt but not help the PST with its inherently dimmer view.

May be wrong on this, so I think that experiment is good, and of course an individuals eyesight could play a part with perceived detail.

Regards, Ed.

[Dave In Vermont]

Regards a polarizing-filter set: I have one I purchased through Orion some years back, and I have noted they are slightly different today. Whereas mine have a range of 3% - 40% reduction of light, the newer ones claim 1% - 40% darkening:

http://uk.telescope.com/Accessories/Telescope-Eyepiece-Filters/125-Orion-Variable-Polarizing-Filter/pc/-1/c/1308/sc/1374/p/109834.uts

It would be interesting to hear what they do with Ha - filtered views. Many extoll their virtues for both glass solar-filters, as well as Baader solar-film. As is, the white solar-view is too bright for many people. I'm using the Thousand Oaks solar-film - Orion branded - and the orange-yellow image is fine as is regards brightness. But I'll try it anyway.

Sunny Skies,

Dave