Baader HA 35nm as D-ERF in 60mm PST Mod?

Frankenscope? Let's see it!***be advised that NOTHING in this forum has been safety tested and you are reading and using these posts at your own peril. blah, blah, blah... dont mess around with your eyesight when it comes to solar astronomy. Use appropriate filtration at all times...
Post Reply
moonshane
The Sun?
The Sun?
Posts: 4
Joined: Fri Apr 15, 2016 12:30 am

Baader HA 35nm as D-ERF in 60mm PST Mod?

Post by moonshane » Fri Apr 15, 2016 12:43 am

Hi all
I have a larger 100mm stage 2 PST mod and use a 90mm Baader DERF in the light cone for this but want something smaller to take on holidays etc. I have found a suitable donor scope, a 60mm f10 cheapie refractor.
Rather than try to find a DERF I have been offered a Baader 35nm Ha 2" filter which I understand has a similar make-up to the Baader DERF but is thinner glass (2mm vs 8mm or so).
However, the one I have been offered has a slightly odd specification in that although it has the correct product code on the filter housing edge for the 35nm filter in 2", it contradicts itself by stating "Baader H-alpha 45nm Passfilter 2" w-IR Cut (Optically polished) #2458380"
My question is therefore, will this filter being a 45nm and not a 35nm still be suitable and safe to use visually to reduce heat/IR/UV by attaching it to the nosepiece of my PST mod i.e. in the chain between the objective and the etalon and subsequent blocking filter?
Looking at the graphs, the DERF seems to reject all but 50nm either side of 650nm (so as I understand it is actually closer to the filter I have been offered than the standard 35nm)

http://www.teleskop-express.de/shop/Bil ... filter.jpg

where the 35nm filter as described above rejects all but 35nm either side.

http://www.baader-planetarium.de/sektio ... _gross.gif

Logically, it seems suitable but given the potential risks, I wanted to check first
Any advice greatly appreciated.

Best wishes
Shane
UK

User avatar
marktownley
Librarian
Librarian
Posts: 24536
Joined: Tue Oct 18, 2011 5:27 pm
Location: Brierley Hills, UK
Contact:

Re: Baader HA 35nm as D-ERF in 60mm PST Mod?

Post by marktownley » Fri Apr 15, 2016 5:34 am

Hi Shane, it will work just fine! :)
Image
http://brierleyhillsolar.blogspot.co.uk/
Solar images, a collection of all the most up to date live solar data on the web, imaging & processing tutorials - please take a look!

moonshane
The Sun?
The Sun?
Posts: 4
Joined: Fri Apr 15, 2016 12:30 am

Re: Baader HA 35nm as D-ERF in 60mm PST Mod?

Post by moonshane » Fri Apr 15, 2016 6:53 am

Cheers Mark
is my logic of how these filters work sound? I.e. The reference to e.g. 45nm means all wavelengths other than 22.5nm either side of optimal are rejected?

User avatar
marktownley
Librarian
Librarian
Posts: 24536
Joined: Tue Oct 18, 2011 5:27 pm
Location: Brierley Hills, UK
Contact:

Re: Baader HA 35nm as D-ERF in 60mm PST Mod?

Post by marktownley » Sat Apr 16, 2016 9:49 am

Yeah, that's right.
Image
http://brierleyhillsolar.blogspot.co.uk/
Solar images, a collection of all the most up to date live solar data on the web, imaging & processing tutorials - please take a look!

moonshane
The Sun?
The Sun?
Posts: 4
Joined: Fri Apr 15, 2016 12:30 am

Re: Baader HA 35nm as D-ERF in 60mm PST Mod?

Post by moonshane » Mon Apr 18, 2016 11:22 am

Cheers Mark
Your previous comment gave me the confidence to try the filter on the end of my stage 2 pst modded focuser/BF/Etalon and to insert the lot into the 60mm tube to test for the correct focus /etalon position and I am pleased to report that it seems to work perfectly and allows full disk at 60mm.
This will be a great Ha travel scope once completed.

Post Reply

Who is online

Users browsing this forum: No registered users and 1 guest