JUNE 10TH - PARTIAL SOLAR ECLIPSE UK - SOME SOLAR FILTERS IN SHORT SUPPLY!

[paulastro]

I know it's a bit early, but Im bringing this up now as some filters are in short supply if you need one.  I ordered one myself for my 102mm refractor a few weeks ago and it took over two weeks to arrive. Just checked and there is only one in stock of the one I needed. 

https://www.firstlightoptics.com/solar-filters/astrozap-baader-solar-filter.html

There are other types and suppliers of course. If you are willing to make one yourself, there doesn't seem to be a problem in buying single sheets of Baader Solar Film.

Here's a brief resume of the eclipse taken from the 2021 Philips Stargazing Guide To The Night Sky.

 

[bish]

I booked the day off work for this, so expect cloud. Sorry.

[Mark at Beaufort]

I have arranged an event for Herefordshire Astronomical Society at a park on the edge of the City. Hope to use the PST plus another scope for white light.

[John]

8 minutes ago, Mark at Beaufort said:

I have arranged an event for Herefordshire Astronomical Society at a park on the edge of the City. Hope to use the PST plus another scope for white light.

Are you going to project the image via a laptop screen or similar Mark ?

 

[Mark at Beaufort]

1 minute ago, John said:

Are you going to project the image via a laptop screen or similar Mark ?

 

We have a meeting this Thursday to discuss arrangements. Hopefully we will try and organise something on these lines.

[paulastro]

1 hour ago, bish said:

I booked the day off work for this, so expect cloud. Sorry.

I am prepared to travel on the day, or stay with accommodating friends in various locations, if the wheather prospects are noticeably better else where. 

I'm also hoping that there may be some nice sunspots.  If there is no activity then you can't readily tell eclipse photos taken at different eclipses.

[paulastro]

1 hour ago, Mark at Beaufort said:

I have arranged an event for Herefordshire Astronomical Society at a park on the edge of the City. Hope to use the PST plus another scope for white light.

I hope your event goes well Mark 🙂.

[Tiny Clanger]

3 hours ago, paulastro said:

I know it's a bit early, but Im bringing this up now as some filters are in short supply if you need one.  I ordered one myself for my 102mm refractor a few weeks ago and it took over two weeks to arrive. Just checked and there is only one in stock of the one I needed. 

https://www.firstlightoptics.com/solar-filters/astrozap-baader-solar-filter.html

There are other types and suppliers of course. If you are willing to make one yourself, there doesn't seem to be a problem in buying single sheets of Baader Solar Film.

Thanks for the heads - up, I seldom look forward further than the next week  , so hadn't noticed that .

I just made some A4 ish Baader film my first ever panic buy of lockdown , it was already on my FLO wishlist , may as well beat the rush ! 🙂

Heather

Edited May 4, 2021 by Tiny Clanger

[paulastro]

1 minute ago, Tiny Clanger said:

Thanks for the heads - up, I seldom look forward further than the next week  , so hadn't noticed that .

I just made some Baader film my first ever panic buy of lockdown , it was on my FLO wishlist , may as well beat the rush ! 🙂

Heather

Thanks Heather.  I realise you probably know this, but do make sure the filter you make is secure.  I hope you have clear skies on the day.

[Tiny Clanger]

Just now, paulastro said:

Thanks Heather.  I realise you probably know this, but do make sure the filter you make is secure.  I hope you have clear skies on the day.

Believe me, I'm suitably neurotic about the risk to eyesight ! The warning does bear repeating often though .

Back before buying a telescope, I projected last century's total eclipse visible from the UK through one side of some old binos onto a bit of white card , but I feel I should take proper advantage of the instruments I have now.

However, I think I'll most likely use my ST80 and utilise the central hole in the objective cap to fix the filter material , intellectually I know the filter material properly mounted and secured would be fine on my 150mm dob or 127 mak, and the st80 is not really less hazardous  , but, as I say, I'm neurotic   Another factor is that the only finder I have on the st80 is an RDF , so there's no chance of forgetting to be sure an optical finder is safe too.

I hope we all have clear skies on the day ... 🙂

Heather

[Size9Hex]

Thanks Paul, I had somehow missed that this was happening. Great reminder 🙂

[SuburbanMak]

58 minutes ago, Tiny Clanger said:

use my ST80 and utilise the central hole in the objective cap to fix the filter material

This is an idea so good I’ll have to steal it... 

Edited May 4, 2021 by SuburbanMak

[Paul M]

Looking here: http://xjubier.free.fr/en/site_pages/solar_eclipses/ASE_2021_GoogleMapFull.html?Lat=54.15589&Lng=-3.84681&Zoom=2&LC=1  I see it's about 28% at maximum.

If you click on your location it will display your local circumstances.

Stellarium view:

 

Edited May 4, 2021 by Paul M

[SuburbanMak]

1 minute ago, SuburbanMak said:

This is an idea so good I’ll have to steal it... 

I am thinking Velcro may be involved here.

[Tiny Clanger]

Just now, SuburbanMak said:

I am thinking Velcro may be involved here.

I'm not sure, and won't be until the film arrives , but I'd vaguely thought of sticking in on the central hole of the cap from the inside, (possibly with a sandwich type card ring mount too )and with a lot of duct tape, which I think (I've not checked ) might mean the small cap can be replaced without any risk of harm to the film or mounting .  To be absolutely, neurotically sure of the main cap not falling off, I'll probably add some strips of masking tape from it on to the dew shield as well ...

Heather

[SuburbanMak]

5 minutes ago, Tiny Clanger said:

I'm not sure, and won't be until the film arrives , but I'd vaguely thought of sticking in on the central hole of the cap from the inside, (possibly with a sandwich type card ring mount too )and with a lot of duct tape, which I think (I've not checked ) might mean the small cap can be replaced without any risk of harm to the film or mounting .  To be absolutely, neurotically sure of the main cap not falling off, I'll probably add some strips of masking tape from it on to the dew shield as well ...

Heather

Similar thinking - the Baader film as the filling of a gaffer tape covered cardboard disc sandwich, probably leave enough diameter free at the outside so the cap still fully fits. 
Held in place with sticky Velcro to make it reusable. Likewise a bit of extra gaffer tape to prevent accidents seems a wise move. 

[Stu]

34 minutes ago, Tiny Clanger said:

I'm not sure, and won't be until the film arrives , but I'd vaguely thought of sticking in on the central hole of the cap from the inside, (possibly with a sandwich type card ring mount too )and with a lot of duct tape, which I think (I've not checked ) might mean the small cap can be replaced without any risk of harm to the film or mounting .  To be absolutely, neurotically sure of the main cap not falling off, I'll probably add some strips of masking tape from it on to the dew shield as well ...

Heather

If you just use the small central hole, you will have limited resolution as you are not using the full aperture of the quote. I would definitely make a holder which allows full, or almost full aperture use. They are quite simple to make, in a way which ensures they won’t fall off. The view will be better with full aperture/resolution than just using the small hole.

[AstroNebulee]

3 hours ago, bish said:

I booked the day off work for this, so expect cloud. Sorry.

Same here 

[John]

I'd better dig out my Lunt Herschel Wedge. I've not used it for some time

 

Edited May 4, 2021 by John

[Tiny Clanger]

4 minutes ago, Stu said:

If you just use the small central hole, you will have limited resolution as you are not using the full aperture of the quote. I would definitely make a holder which allows full, or almost full aperture use. They are quite simple to make, in a way which ensures they won’t fall off. The view will be better with full aperture/resolution than just using the small hole.

Good point, thank you.

The 'scope in question is a cheapie ST80 , and rife with CA when pointed at the Moon , but with slightly less purple halo when used with the reduced diameter cap/mask . Will there be a similar CA fest with the Sun ?  I'm not expecting fabulous detail from the little frac. , but would prefer to use it over the 127 mak out of an excess of caution ... I also suspect that the irregular shape of the front of my heritage dob , where the extension rods fix to the front section , make it a poor candidate for a safe solar filter, even with the decent opaque shroud I have on it.

Heather

[Stu]

3 minutes ago, Tiny Clanger said:

Good point, thank you.

The 'scope in question is a cheapie ST80 , and rife with CA when pointed at the Moon , but with slightly less purple halo when used with the reduced diameter cap/mask . Will there be a similar CA fest with the Sun ?  I'm not expecting fabulous detail from the little frac. , but would prefer to use it over the 127 mak out of an excess of caution ... I also suspect that the irregular shape of the front of my heritage dob , where the extension rods fix to the front section , make it a poor candidate for a safe solar filter, even with the decent opaque shroud I have on it.

Heather

Why not try the Mak? With a full frontal filter there is no risk to the scope and the resolution would be significantly better than the ST80.

I can’t answer the question about what would give the best results between a full aperture ST80 vs one stopped down. There are two (probably more) factors in play; resolution due to aperture vs CA and SA (spherical abberation) from the faster focal ratio of the full aperture ST80. SA kills fine detail more than CA which can be filtered out with a narrow band filter such as a Baader Continuum filter. Perhaps try both and see what the best result is, but I still think full aperture is likely to be best. A lot depends on the quality of the figure of the scope which may vary sample to sample.

[AstroNebulee]

2 hours ago, Tiny Clanger said:

I'm not sure, and won't be until the film arrives , but I'd vaguely thought of sticking in on the central hole of the cap from the inside, (possibly with a sandwich type card ring mount too )and with a lot of duct tape, which I think (I've not checked ) might mean the small cap can be replaced without any risk of harm to the film or mounting .  To be absolutely, neurotically sure of the main cap not falling off, I'll probably add some strips of masking tape from it on to the dew shield as well ...

Heather

I have used the baader solar film for all my homemade solar filters and just sandwiched between two rings of card and a tight fitting cardboard collar works a treat and can always tape the collar to provide an even tighter fit. 

Edited May 4, 2021 by AstroNebulee
Spelling

[Tiny Clanger]

32 minutes ago, Stu said:

Why not try the Mak? With a full frontal filter there is no risk to the scope and the resolution would be significantly better than the ST80.

I can’t answer the question about what would give the best results between a full aperture ST80 vs one stopped down. There are two (probably more) factors in play; resolution due to aperture vs CA and SA (spherical abberation) from the faster focal ratio of the full aperture ST80. SA kills fine detail more than CA which can be filtered out with a narrow band filter such as a Baader Continuum filter. Perhaps try both and see what the best result is, but I still think full aperture is likely to be best. A lot depends on the quality of the figure of the scope which may vary sample to sample.

Why not try the mak ? Well, as I said above, I'm a bit neurotic about pointing an optical instrument at the Sun, decades of dire warnings have had their intended effect .

So I was thinking of a somewhat over cautious approach , try the  st80 small aperture mask first, (the solar equivalent of a toddler on a tricycle). If that works OK , and assuming we actually get any daytime clear skies anytime soon to try it out, I will make the ST80 a whole aperture filter,(the equivalent of stabilisers on a bicycle 🙂 ). If I'm happy with that, there should be sufficient Baader film left I think to make a suitable filter for the mak ... proper cycling on two wheels !

I shall report back any conclusions I reach 🙂

Heather

 

[Stu]

9 hours ago, Tiny Clanger said:

Why not try the mak ? Well, as I said above, I'm a bit neurotic about pointing an optical instrument at the Sun, decades of dire warnings have had their intended effect .

So I was thinking of a somewhat over cautious approach , try the  st80 small aperture mask first, (the solar equivalent of a toddler on a tricycle). If that works OK , and assuming we actually get any daytime clear skies anytime soon to try it out, I will make the ST80 a whole aperture filter,(the equivalent of stabilisers on a bicycle 🙂 ). If I'm happy with that, there should be sufficient Baader film left I think to make a suitable filter for the mak ... proper cycling on two wheels !

I shall report back any conclusions I reach 🙂

Heather

 

Always worth being cautious when observing the sun, making sure you know what you are doing and taking a methodical approach 👍. Don’t forget to remove or cover finders! Or if you have a right angle finder, put a piece of film over that too, finding the sun can be surprisingly tricky!!

Whilst understanding your caution, so long as you have a secure and safe front filter, the Mak is not at risk of damage any more than the ST80 is.

I look forward to hearing how you get on 👍🌞

[Mark at Beaufort]

You may find this video useful in making a solar filter. Pete Lawrence is using a Meade Mak/Cass.

https://www.bbc.co.uk/programmes/p014hpkh