Baader solar film

[Davie]

Since tomorrow is fathers day the boss has been asking if theres anything I'd like to do, but since shipping the kids out for the day to get some peace and quiet was frowned upon :blink:I thought that if its sunny I might give my solar film a go and try imaging/observing the sun.

Now for the question, the film will be fitted to a Blue Peter style holder but how big should I make the actual filter itself? Should I go full size, a smaller one to fit inbetween the secondary mirror vanes or would 4 smaller ones for each part between the vanes work?

Oh it will be fitted to a 200pds

Thanks in advance

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[Bizibilder]

I would go for one around 100mm diameter and position it so it allows the filtered sunlight to pass between the secondary vanes. If you make it central the secondary will be a very large obstruction!! Make sure the finder is covered or removed!!!!!!!!!!!!

[Steve Ward]

A smaller one fitted to miss the spider vanes would be best on two counts ,

1. You won't see any great difference between full aperture and a 100mm filter due to the atmospherics .

2. You'll get two filters from the A4 sheet ...

[Merlin66]

If the Baader solar film sheet will allow a full aperture filter - that's OK.

Otherwise check the maximum diameter you can squeeze between the edge of the secondary and the edge of the primary mirror diameter, and go for that.

Based on average seeing conditions, 100mm to 125mm diameter seems to be the optimum.....

[DrRobin]

Hi,

I would agree a 100mm or there abouts will work just fine. You won't see the secondary vanes, but if you can avoid them it would be better. My 200mm has a cut out in the front cap, I just made the filter cover this aperture, saved on making a full aperture cardboard.

I made a very small filter for my finder, about 8mm in diameter for a 25mm finder, it works very well. I align the finder and main scope of a distant tv aerial or mast and then put the filters on, makes a great sun finder, very useful if you use high magnification.

Robin

[Davie]

Thanks for the replies

Managed to get a cardboard cap with a bit of film on it but by the time I managed to get it done the sun had taken the huff and was hiding

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[michael.h.f.wilkinson]

Shame to hear you missed out. Allegedly, the sun can appear more than once each summer, so there is still hope