DIY Solar filter advice sought

Hi ,
I've also used the Baader to make filters for my camera lens and etx 90.
It's perfect and it doesn't have to be very tight so your image won't be affected.
Used it at Solar eclipses myself and its spot on.

Mark

Dave - I made a solar filter for my 8" Newt. Its actually very easy and it does a great job. Your major expense will be the solar film.

As Mark says, the film doesn't have to be ripsnortingly taut - mine has a few wrinklles in it and there's no distortion whatsoever.

I used a sheet of card (the type used for making picture frames) from Eason's (about 7 quid). Make 2 circles just ( a couple of mil) larger than the scope tube diameter. Cut a hole in each circle so you have a border of about 1 or 2 cm. Sandwich the film in between and glue. I used superglue and it worked fine. Cut a rectangular piece of card that'll wrap around the end of the OTA (2 to 4 cm will do for the width) and cut tabs into one side. Bend over the tabs, join the two ends then glue the film onto this tube. I also covered the join with electrician's tape to make sure. Voila.

An A4 sheet of film was big enough to cover the 8" aperture so you'll probably have a good bit left over. There might be someone else in KAS who'll spilt the cost with you - I think its around 20 or 30 quid a sheet....

Cheers

Dave McD

Thanks for the advice lads- Dave, hope you had a good holiday!!
John O'Neil had some surplus film and he's been kind enough to give it to me. Will be interesting to see how his works out- he purchased a wall clock in woodies that should fit neatly over his etx-125- should be able to use the glass to keep it relatively smooth. Both of you dont seem to have any trouble with distortion though.
Since I posted this I found instructions on www.astro-physics.com under the Baader film section funnily enough. :D

Hi Dave,
All good advice from the lads ,BUT the only thing I have a BIG reservation with the Baader film is that after a while having used it the creases start to apesr due to wind and just movement effects,I would try to get it as tight as possible IE sandwich it between 2 pieces of card boardand pull it taut.
A sure test is to hold the filter up to the sun (without the scope)and if you can see light spots blacken them out with a marker.If they are very obvious use patches of masking tape ...You only have ONE set of eyes.
If you are really into Solar do as I did and buy a glass one'cause you'll be conctantly replacong the film one.
Regards
Eugene

Hi all,
I purchased a Kendrick Baader Solar Filter for a 500mm Mirror "Lens" recently. Gives a good image. From reviews I read for best results it
should not be pulled taut. I inspected mine and found no pinholes. I have also a Thousand Oakes solar glass filter, I found quite a nimber of pinholes, which I patched them all up with tippex.

When doing a do it yourself job - remember it must be securely
attached to the front of the telescope. I have heard stories of solar filters been blown off in the wind.

I have a number of BAA Eclipse Viewers available at cost (€1.50). I will have them along at tonight's IAS Meeting (Ely House at 8pm).

John

Hi again,

Just to further add to your confusion(!) and to further on a comment made by Eugene, after a bit of use and some mishandling the creases CAN become worn and let in UNFILTERED light IF you're not VERY careful. The way around this in the past for me was to generally just make a new one for every trip and Pack it carefully. I'll never forget the fright I got on a trip to the 2001 eclipse trip when at the start of the trip I was testing out the filter and luckily enough it was evening as I looked through it and noticed the worn patches creases!
I obviously stopped looking immediately and discarded it as I had a spare sheet with me to make a new one. I have the thousand Oaks filter now too which does give a more aesthetically pleasing Yellow colour to the images too.
Other than that...no worries!

Mark