Is it safe to remove one of the ERF's on a Lunt 100 mm DS?

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
OTangen
Im an EXPERT!
Im an EXPERT!
Posts: 335
Joined: Mon Sep 22, 2014 2:50 pm

Is it safe to remove one of the ERF's on a Lunt 100 mm DS?

Post by OTangen »

Hi!

I posted this on the SolarChat but was advised to try in this section:

Does anybody know if it is safe to remove the red ERF in front of the DS module on a Lunt100? Since I get so long exposures when double stacking (up to 30 ms with a Grasshopper3) I thought that I might get a brighter picture if I removed this filter. Or is it only reducing the infrared portion of the spectrum and does not affect the Ha band.

Most of all I want to have a safe setup that does not burn the camera. I never use it for visual.

Best regards
Oivind Tangen 60N, 10E


User avatar
Valery
Way More Fun to Share It!!
Way More Fun to Share It!!
Posts: 4059
Joined: Sun Nov 18, 2012 3:13 pm
Has thanked: 156 times
Been thanked: 893 times

Re: Is it safe to remove one of the ERF's on a Lunt 100 mm D

Post by Valery »

This will help only a little bit. May be your exposure will be 25ms or 20ms at best. If you can make the tube body like original, but without the filter itself (as I have made with my LS50F) then this has a sense and you need to remove the ERF at the bottom etalon. The front etalon must be protected from IR and other solar radiation by ERF and also from the dust.

If you not remove the ERF, to have the same effect of the exposure shortening, just add some gain. See that you will not see much of addition noise on the image on the screen. Record longer movies and stack more frames - your S/N will improves and will compensate the gain increase.
With a 100mm aperture you can record up to 60 or even 90 sec movies ( 1850 - 3000 frames) and select up 300 - 600 frames to stack them.

Hope this helps.


Valery.


"Solar H alpha activity is the most dynamic and compelling thing you can see in a telescope, so spend accordingly." (c) Bob Yoesle.

Largest full size 185 - 356mm Dielectric Energy Rejection Filters (D-ERF) by ARIES Instruments.
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: Is it safe to remove one of the ERF's on a Lunt 100 mm D

Post by swisswalter »

Hi Ovind

if the LUNT100 DS module has a removable ERF and is placed behind the first etalon with the ERF then you are on the safe side. I did this to a LUNT LS50 combo


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
Merlin66
Librarian
Librarian
Posts: 3970
Joined: Tue Dec 13, 2011 1:23 pm
Location: Junortoun, Australia
Has thanked: 173 times
Been thanked: 615 times
Contact:

Re: Is it safe to remove one of the ERF's on a Lunt 100 mm D

Post by Merlin66 »

IMHO the marginal improvement to the overall transmission isn't worth the effort and possible damage......


"Astronomical Spectroscopy - The Final Frontier" - to boldly go where few amateurs have gone before
https://groups.io/g/astronomicalspectroscopy  
http://astronomicalspectroscopy.com
"Astronomical Spectroscopy for Amateurs" and
"Imaging Sunlight - using a digital spectroheliograph" - Springer
User avatar
marktownley
Librarian
Librarian
Posts: 42272
Joined: Tue Oct 18, 2011 5:27 pm
Location: Brierley Hills, UK
Has thanked: 20437 times
Been thanked: 10245 times
Contact:

Re: Is it safe to remove one of the ERF's on a Lunt 100 mm D

Post by marktownley »

Post some pictures up so we can see it, will give us a better idea.


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