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

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

Post by OTangen » Thu Apr 30, 2015 8:13 pm

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.

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

Post by Valery » Fri May 01, 2015 1:17 am

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.


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

Post by swisswalter » Fri May 01, 2015 4:16 am

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

Post by Merlin66 » Fri May 01, 2015 6:45 am

IMHO the marginal improvement to the overall transmission isn't worth the effort and possible damage......
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Re: Is it safe to remove one of the ERF's on a Lunt 100 mm D

Post by marktownley » Fri May 01, 2015 7:35 am

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