Jump to content

 

1825338873_SNRPN2021banner.jpg.68bf12c7791f26559c66cf7bce79fe3d.jpg

 

Solar filter or projector


malc-c
 Share

Recommended Posts

Hi,

My scope (Explorer P200 on a EQ5 pro goto) arrives tomorrow, and I'm looking at starting with the Moon and Sun to get used to using the scope, but noticed that there seems to be a lack of sun projection screens on the market.

I know that there is some A4 film that cost around £20 that can be used to make a filter, but how safe is it to use, and can it be used in conjunction with a NexImage CCD or DRSL body to take pictures. Or is there a commercially available clamp on projection plate available for this scope which might be safer ?

Link to comment
Share on other sites

The 200p OTA dust cap has a removable 2" cap that baader film can be taped to the inside of. Make sure you use a hi-tack adhesive tape and make sure you check the film before every session.

The black marks and brown tape are covering suspected holes that I didn't want to risk.

SPACEBOY

Link to comment
Share on other sites

Thanks for the suggestions and links.

Looking at the notes, and the images, I'm thinking of making a filter that fits over that removable 2" cap. If the foil is sandwiched between two thin circles of glass would this have any negative effects. My thinking is that the glass would protect the foil from damage between uses.

Link to comment
Share on other sites

Thanks for the suggestions and links.

Looking at the notes, and the images, I'm thinking of making a filter that fits over that removable 2" cap. If the foil is sandwiched between two thin circles of glass would this have any negative effects. My thinking is that the glass would protect the foil from damage between uses.

I would advise against placing glass any where in direct sun light. The film is pretty tough stuff and if you are careful where you place the cover when using the scope at night the film will last ages. The only problem is if you have not confidently looked after the film you will doubt its performance and end up taping suspect holes. The trouble is that when you check the film up to the sun you will see what looks like pin pricks. These are normal and as long as there is no actual break or scratch in the film it should be safe to use. Baader film is coated on both sides so the pin ***** you see is actually where one side has not been covered and is allowing through more light but the other side should be coated and so "should" be safe to use. The theory is that to get a pin ***** miss in the coatings on both sides in the same spot is a million to one. If you have ANY doubt you can drop a small bit of tape on the suspected pin hole.

Link to comment
Share on other sites

Just noticed that no-one has advised that projection using a reflecting scope (of any size or design) is a no-no - the concentrated heat will destroy the secondary mirror.

Edited by brianb
Link to comment
Share on other sites

There are purpose made projection boxes that project the image on to paper so that a sketch of sun spots can be made safely. I came across one last year on a site for £39 (basically a cardboard box) but having done a quick search I can no longer find it. This kind of projection dose allow you to see sun spots reasonably well and very safely but using a telescope allows you to use magnification and this allows detail of the filaments around sun spots to be seen.

This is a capture with my webcam through the 2" dust cover, not the best but you will get the idea. http://stargazerslounge.com/observing-lunar-solar/116396-sun-spot-10-10-10-a.html

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share

  • Recently Browsing   0 members

    • No registered users viewing this page.
×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue. By using this site, you agree to our Terms of Use.