I want to buy a solar filter, which one?

[Tiny Clanger]

On 04/07/2021 at 15:31, Philip R said:

Avoid this type of screw-on filter like a pandemic/plague.

I just did some idle searching on the big river site, it seems some advertisers there are calling their dreadful eyepiece 'Sun' filters 'nebula' and 'not to be used for the Sun', despite the word 'Sun' apparently being printed on the filter ring ...  This particular specimen has a very appropriate brand name though, if it wasn't such a hazard to eyesight it would be funny  :

 

[Starwatcher2001]

On 08/07/2021 at 01:02, Lotinsh said:

I have a laser dot finder so I'm not sure if that can work for sun, but I'm pretty sure there is no need of a finder, as you can point your scope towards the sun until the shadow makes perfect circle (hard to describe). Still, thanks for advice, I can't wait to get my solar filter!

It probably wouldn't work against the glare of the sun. In fact I'd be tempted to cover it up or not fit it, along with any RDF or Telrad type finders people may have. While it's pointing at the sun, the sun is also pointing at it. Admittedly such finders are not getting a magnified view of the sun but I do know that direct sunlight is bad news for any reticle (warning that came with my Telrad).

 

[Tiny Clanger]

On 08/07/2021 at 01:02, Lotinsh said:

I have a laser dot finder so I'm not sure if that can work for sun, but I'm pretty sure there is no need of a finder, as you can point your scope towards the sun until the shadow makes perfect circle (hard to describe). Still, thanks for advice, I can't wait to get my solar filter!

I suspect that's a red dot finder, while it won't magnify , it would still need you to look at the  Sun to line it up , which wouldn't be wise. I roughly align my 'scope by using the shadow as you describe,  but take a bit of white card out to do that with, because I observe from the grass, where the shadow is not sharp ( my lawn being more 'rough pasture' than 'bowling green' ) .

It would be easy to make a solar finder , many work on the pinhole camera principle, so a tube or box (I'd go for smarties, purely to have the excuse to eat the contents) or even an open structure , all you need is a pinhole at the centre of the front end , and a screen at the rear. Foil with a pin hole and a tracing paper screen would be fine. You get a tiny (inverted) image of the Sun as a dot on the screen when you  are lined up. The length of the tube will affect the precision of the finder, a short tube will have a wider angle of view, so it might be necessary to fiddle around to find the optimum length. If there's no tracing paper handy, an open top side  tube projecting the Sun image onto the inside back end, like a projector screen, ought to work too .

The aperture of a pinhole is so small there shouldn't be a worry  about the Sun's image on the tracing paper getting hot, but I'd probably take the thing off the 'scope once the Sun was located .... just in case 🙂

Heather

[Stu]

On 08/07/2021 at 01:02, Lotinsh said:

I have a laser dot finder so I'm not sure if that can work for sun, but I'm pretty sure there is no need of a finder, as you can point your scope towards the sun until the shadow makes perfect circle (hard to describe). Still, thanks for advice, I can't wait to get my solar filter!

Don’t try to use the red dot finder, looking directly at the sun is not a good idea and you certainly won’t be able to see the red dot anyway.

The shadow method works pretty well, but even then it isn’t always trivial to find the sun, although it seems like it must be easy!

It is quite easy to make a cheap solar finder, plenty of tutorials or examples on the web and even here on SGL if you search. One here that I found quickly:

 

[johninderby]

Or if you have a small bit of Baader solar film laying around simply make a filter for your optical finder. 👍🏻

Edited July 9, 2021 by johninderby

[Tiny Clanger]

6 minutes ago, johninderby said:

Or if you have a small bit of Baader solar film laying around simply make a filter for your optical finder. 👍🏻

Would that work for an RDF ? That  is the finder the OP says they have ...

I don't think it would be possible to use safely.

Edited July 9, 2021 by Tiny Clanger

[Louis D]

2 minutes ago, Tiny Clanger said:

Would that work for an RDF ?

Probably a bad idea because you'll be looking in the direction of the sun to align it.  If you use a 6 inch or larger section to dim the whole region around the sun, that might work.

[Stu]

2 hours ago, Tiny Clanger said:

Would that work for an RDF ? That  is the finder the OP says they have ...

I don't think it would be possible to use safely.

No, I don’t think that would work and you would still get dazzled by the sun. There are some many easy diy alternatives, either covering an optical finder with solar film or making a simple pinhole device like you suggested. I think those are actually better than a covered optical finder because you can see more easily where the sun is before you are very close to it.

[johninderby]

Actually with a 9x50 finder you have a wide field of view and so can be quite a way from being centered on the sun and still have the sun in the fov. It simply works. 👍🏻

[RT65CB-SWL]

On 07/07/2021 at 23:23, Stu said:

I would probably get the A4 sheet so you have some spare depending on the size of your scope. If you have an optical finder you could cover that too.

Apologies to @Stu but... you should or would cover that too.

If you have an RDF fitted as well; remove it or cover it. I got a nasty rash on my forehead/temple during 1999, a few days prior to the solar eclipse and it stung for weeks, when I forgot to remove mine.

[Tiny Clanger]

12 minutes ago, Philip R said:

Apologies to @Stu but... you should or would cover that too.

If you have an RDF fitted as well; remove it or cover it. I got a nasty rash on my forehead/temple during 1999, a few days prior to the solar eclipse and it stung for weeks, when I forgot to remove mine.

Don't think it was Stu who said that, and it certainly wasn't me either 🙂

Heather

[Stu]

14 hours ago, Philip R said:

Apologies to @Stu but... you should or would cover that too.

If you have an RDF fitted as well; remove it or cover it. I got a nasty rash on my forehead/temple during 1999, a few days prior to the solar eclipse and it stung for weeks, when I forgot to remove mine.

Of course any optical finder or RDF  should either be removed or capped if not being used, that is standard practise. My point was that the optical finder could be used if covered with solar film.

I’ve never found the need for an optical solar finder. Pointing using a covered RACI finder is actually more difficult to get aligned initially. I have a Televue Sol Searcher which I got free with a scope ages ago, and my PST mod has a gun sight type arrangement, small hole towards the front of the OTA and a small screen at the back. They simply work 😉, and they are cheap!

[Stu]

14 hours ago, Tiny Clanger said:

Don't think it was Stu who said that, and it certainly wasn't me either 🙂

Heather

I did say ‘that’, but my ‘that’ was misinterpreted by Philip. I was simply saying that you could use an optical finder is it were covered with solar film.

Everyone should know to remove or cap unused or unsafe finders when solar observing, or to ensure they are safely protected using film. Whilst it is good practise to emphasise safety when discussing solar observing, people are ALWAYS responsible for their own safety and of those observing with them, and to make sure they are fully informed of how to observe safely. We can’t expect every post to cover all the aspects of safety.

[Tiny Clanger]

2 hours ago, Stu said:

I did say ‘that’, but my ‘that’ was misinterpreted by Philip. I was simply saying that you could use an optical finder is it were covered with solar film.

Everyone should know to remove or cap unused or unsafe finders when solar observing, or to ensure they are safely protected using film. Whilst it is good practise to emphasise safety when discussing solar observing, people are ALWAYS responsible for their own safety and of those observing with them, and to make sure they are fully informed of how to observe safely. We can’t expect every post to cover all the aspects of safety.

Ah,  sorry Stu,  my mistake, I conflated Phillip's answer with the reply which seemed to suggest somehow using a large filter sheet around an RDF .

An abundance of caution is what I feel , as a beginner in solar observing on a budget.

Heather

[Stu]

28 minutes ago, Tiny Clanger said:

An abundance of caution is what I feel , as a beginner in solar observing on a budget.

I totally agree on caution, but would encourage people not to be scared of solar observing as it is a wonderful aspect of the hobby which has sustained my interest in astronomy during times when night time Astro is not possible.

Educating yourself about what is needed, and then taking a careful, methodical approach are keys to safe observing, as well as always understanding you are fallible so double check key safety elements each time.

[Barry Fitz-Gerald]

I have 2 filters for a 130mm refactor, one is a Seymour glass solar filter (about £75) and the other is a DIY job using the Baader Safety Film (£18 plus a couple of quid for cardboard and glue).

I was surprised at the difference.

The Seymour filter provides a nice (to me) yellow solar disc and black sky background, but the detail visible, in particular the surface mottling, granulation and the detail in the sunspots was not distinct as I expected. So aesthetically nice but a bit fuzzy.

The Baader solar film, which cost a fraction of the price shows sharp detail in terms of mottling, penumbra and faculae. The film does not lie flat in the filter, and has a few small ripples - makes no difference to the view. And of course with the Baader film you can use s Baader Solar Continuum filter which really enhances the contrast on all features, but does give the disc an appearance akin to a lime flavoured boiled sweet, which I quite like as well (but the boiled sweets) but some might not.

I tried both filters one after the other on the same telescope many times, always with the same result, the Baader film was always far superior.

I used a Baader Cool Ceramic wedge (visual version) for some time, much less faff but not cheap,  probably optically better than the DIY film version, but for someone new to solar or just a casual interest the film gives you almost the same result, but for a fraction of the cost.

 

[johninderby]

I bought a sheet of Seymour solar film once to try it out. Used it once and then tossed the filter in the bin and threw away the rest of the film as well. So disappointing compared to the Baader film.

The film used in the solar filters supplied with many Bresser scopes is also very poor. Better than nothing I suppose and as they are included for free can’t really complain. 

Edited July 11, 2021 by johninderby

[Stu]

15 minutes ago, Barry Fitz-Gerald said:

I have 2 filters for a 130mm refactor, one is a Seymour glass solar filter (about £75) and the other is a DIY job using the Baader Safety Film (£18 plus a couple of quid for cardboard and glue).

I was surprised at the difference.

The Seymour filter provides a nice (to me) yellow solar disc and black sky background, but the detail visible, in particular the surface mottling, granulation and the detail in the sunspots was not distinct as I expected. So aesthetically nice but a bit fuzzy.

The Baader solar film, which cost a fraction of the price shows sharp detail in terms of mottling, penumbra and faculae. The film does not lie flat in the filter, and has a few small ripples - makes no difference to the view. And of course with the Baader film you can use s Baader Solar Continuum filter which really enhances the contrast on all features, but does give the disc an appearance akin to a lime flavoured boiled sweet, which I quite like as well (but the boiled sweets) but some might not.

I tried both filters one after the other on the same telescope many times, always with the same result, the Baader film was always far superior.

I used a Baader Cool Ceramic wedge (visual version) for some time, much less faff but not cheap,  probably optically better than the DIY film version, but for someone new to solar or just a casual interest the film gives you almost the same result, but for a fraction of the cost.

 

Very interesting Barry. That does back up my previously unsubstantiated views on the comparison between glass solar filters and Baader solar film which is one of the best Astro bargains out there really. It’s a little counter-intuitive really, and I think people probably expect glass filters to be better but they are not!

[Barry Fitz-Gerald]

2 minutes ago, Stu said:

people probably expect glass filters to be better

I did, cost me £75 - expensive mistake.

[johninderby]

For me it’s Baader film or a wedge. 👍🏻

Would love to compare a Zeiss glass filter to a wedge to see which is better. However given the prices being asked for the Zeiss filters when one comes up for sale not likely. 

Edited July 11, 2021 by johninderby

[saac]

I managed to escape threats of alien abduction and got around to making up a filter holder for the Baader film and also a little pin hole solar finder;  so ready to go to do the comparison between the glass and film filters.  Still waiting for clear weather - the sun is making intermittent appearances today .  Probably just as well , busy watching Richard Branson making history - first commercial flight operation into space  - good luck team Virgin Galactic 

Jim 

Edited July 11, 2021 by saac

[saac]

Ok so managed a quick low power (32mm eyepiece)  visual test of the filters.  The foil filter produces a white image at the eyepiece which gave me a little fright , thinking that the filter wasn't fitted properly; by comparison my glass filter produces a subtle yellow coloured disk.  Anyway, all was well and a quick check confirmed the filter was fitted and working correctly.   The simple solar finder worked well placing the sun's disk in the centre of the eyepiece - no more peering squint eyed to locate it   This was just a quick test , the mount wasn't powered up so manually recentering every so often . Both filters easily picked out  2842 and 2841 and both showed subtle granulation effects particularly noticeable around the larger sun spot 2842.  The film filter produced what appeared to my eye a brighter image and I'm wondering if it would benefit from a further filter at the eyepiece to help with contrast and make it more comfortable.  Do people normally use a neutral density eyepiece filter with this type of filter ?   Anyway both performed well, no optical aberrations as far as eye could see from either.  This was of course just a quick visual first light so no real comparative test as yet; hopefully later on in the week I'll set up the camera and have a further play.  How do people normal take solar images , video then stacking.  I've only ever taken single sub images  so any hints/tips in that direction would be appreciated - I will be using a OSC camera ZWO ASI 183 MC Pro . 

Jim 

Edited July 12, 2021 by saac