Solar Film & An Open Dob - Safe??

[Paul73]

Hi Guys

Inspired by some, quite frankly amazing solar views at SGLX, I've ordered some solar film.

Then I thought..... I have a 250mm FlexTube (semi truss dob). Would having the sides open to sunlight be a issue?

Paul

[Kropster]

You shouldn't get any unfiltered light fed through the eyepiece, but I wonder if some off-axis sunlight might get directed somewhere and burn something a bit when swinging the scope about.

Seems unlikely, but you never know.

[Steve Ward]

You definitely need to shroud the open truss section well in order to prevent sunlight striking the primary , even a 'glancing blow' will result in an accident.

[michael.h.f.wilkinson]

I have seen some images of the damage done by sunlight entering through the side of a truss tube. Not pretty at all. Shrouding is a must.

[DRT]

I agree that a shroud is a must - it is just not worth taking the risk.

Also worth noting that it is not necessary to have a large aperture for solar viewing. You can save yourself some money by taking the small cap off the top cover of the scope and applying a filter to that rather than trying to cover the full aperture. A common way to do that is to place a square of solar film on the inside of the lid covering the 2" hole that will be exposed when you remove the small cap. Make sure you use good quality sticky tape to secure it all the way around the edge of the square with no gaps. Electrical insulation tape works well. Also make sure the hole in the cover isn't sitting over one of the struts holding the secondary to avoid interference in the light path and you should get some stunning views.

Be safe and good luck

[Steve Ward]

Report here from Squeaky from 2012 on said subject ... http://stargazerslounge.com/topic/148838-off-axis-baader-film-and-fire-hazard/

Pictures are no longer available nor is his website , I fear Richard is no longer with us , I have not been able to contact him for a couple of years now ...   

[Paul73]

Thanks guys. Shrouding it is!

Paul