Shapey Lens for Lunt LS60PT and DMK41

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
Gert
Ohhhhhh My!
Ohhhhhh My!
Posts: 54
Joined: Wed Nov 13, 2013 11:42 am
Been thanked: 1 time

Shapey Lens for Lunt LS60PT and DMK41

Post by Gert »

The DMK41 camera and the Lunt LS60PT are a popular combination to image the H-Alpha sun. The focal length of the Lunt LS60PT is specified at 500mm (measured 506mm) and that yields an image scale just a little bit too large for the full chip of the DMK41. There is always a little piece of the Sun cut off at the top or bottom. The usual solution is to make 2 images and combine them into a composite in image processing software. But using a weak Shapley lens is another alternative that scales the solar image to just fit the camera's chip size. A mild positive achromat positioned just in front of the camera will do the job. Calculations in OSLO raytracing software show that 300mm fl is just fine. Edmund optics makes just such a lens as catalog #45-215. Now we need a lens cell. A simple Barlow lens at Ebay is a welcome donor of a machined cell of just the right size.

Solar image with Lunt LS60PT and DMK41
Image

DMK41 Camera, Barlow Lens and Positive Lens from Edmund
Image

Camera now with all the Parts for the Shapley lens
Image

Camera with Mounted Shapley Lens
Image

Solar image with Lunt LS60PT and DMK41 with Shapley Lens
Image

Cheers,
Gert


User avatar
swisswalter
Way More Fun to Share It!!
Way More Fun to Share It!!
Posts: 17948
Joined: Thu Feb 06, 2014 4:28 am
Location: Switzerland
Been thanked: 1 time
Contact:

Re: Shapey Lens for Lunt LS60PT and DMK41

Post by swisswalter »

Hi Gert

that looks perfect, congratulations


Only stardust in the wind, some fine and some less fine scopes, filters and adapters as well. Switzerland 47 N, 9 E, in the heart of EUROPE :)

from 7 am - 7 pm http://www.nanosys.ch

from 7.01 pm - 6.59 am http://www.wastronomiko.com some times vice versa ;)
User avatar
marktownley
Librarian
Librarian
Posts: 42131
Joined: Tue Oct 18, 2011 5:27 pm
Location: Brierley Hills, UK
Has thanked: 20240 times
Been thanked: 10113 times
Contact:

Re: Shapey Lens for Lunt LS60PT and DMK41

Post by marktownley »

That is an excellent solution! great stuff!


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!
Post Reply