Log in

View Full Version here: : DIY Rear Projection SOLAR TELESCOPE

Anil
06-01-2013, 09:49 PM
In this project i have used 60mm achromatic doublet lens with 25 mm metal eyepiece. Scope has a 3 inch by 3 inch secondary mirror. Casing is made of 25 & 12mm rubber wood. Lens is housed in a 70mm Aluminum tube. Here the image of the sun is projected on a white plastic sheet. Scope works on Alt-Azimuth wooden mount, movements are quite smooth as aluminum cradle runs on Teflon pads. There is a small maintenance hatch for focusing the image.

This is a useful scope for schools & colleges for Astronomy presentations. Projection method is safe & effective way to enjoy sun's features.
OICURMT
07-01-2013, 12:02 AM
Great idea / project!

So... the big question is.... if you put an etalon on the front, could you get Ha images on the screen... (black hood *MAY* be required....)

I don't see the need for a blocking filter, since it's a projection... (Merlin can chime in now :) )
Poita
08-01-2013, 05:24 AM
Without a blocking filter, you would get no detail as you are not removing all of the peaks that make it through the Ha filter.
brian nordstrom
08-01-2013, 09:17 AM
:thumbsup: Thats so cool , I like it and thanks for sharing.
Brian.
Poita
08-01-2013, 09:19 AM
I love your blog Anil, your machining skills are great!
OICURMT
08-01-2013, 01:14 PM
Excellent point...
asimov
08-01-2013, 01:20 PM
This is EXCELLENT!
originaltrilogy
10-01-2013, 11:40 AM
This is very good!

Do you make these for sale?

I can make wood parts but not metal.
Merlin66
10-01-2013, 12:05 PM
Peter beat me to it!
In the Ha scope the etalon must be matched with a very narrowband blocking filter...this "blocks out" everything other than the Ha wavelength.
originaltrilogy
10-01-2013, 12:08 PM
Does this mean blocking filter on its own can be used as Ha filter for DSO photo or is it too narrow?
Could Etalon be used for DSO?
Merlin66
10-01-2013, 12:15 PM
Petr,
The resulting bandwidth of the etalon/ blocking filter combo is only around 0.7 Angstrom (0.07nm).
The blocking filter on its own is about 8-10 Angstrom (0.8-1nm).
So the combo would be far too narrow for effective DSO work, but in THEORY the blocking filter COULD be used for extreme narrow band work.
Also, the small sizes of the available blocking filters (<12mm diameter) would certainly limit the field of view....