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Light leak,.... any solution???


TareqPhoto

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Hi,

 

I tested my Newtonian scopes both i have, 6" F/4 and 8" F/5, and both simply have light leak, don't know from where, but most likely around the focuser chamber, and i am not interested to replace both to high end/quality ones such as FeatherTouch or MoonLite yet, so are anyone of you facing the same issue and fixed it without replacing the focuser if possible???

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It's not uncommon for Newtonians to leak light around the primary mirror.  Last year I lost a bunch of data to my laptop's keyboard light.

 

Edit:

 

The only real solution I found was to isolate the scope from local light sources. 

Edited by paulgrover68
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4 minutes ago, paulgrover68 said:

It's not uncommon for Newtonians to leak light around the primary mirror.  Last year I lost a bunch of data to my laptop's keyboard light.

 

Edit:

 

The only real solution I found was to isolate the scope from local light sources. 

 

I covered the back or rear of Newt where the primary mirror is and it is still light leak, same didn't change of light leak, i mean it didn't reduce it when i cover the back, so the primary mirror isn't the cause here.

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Try wrapping a thick dark cloth or towel around the focuser and see if that improves things. At least you'll find out if that is the issue.

 

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6 hours ago, MarkAR said:

Try wrapping a thick dark cloth or towel around the focuser and see if that improves things. At least you'll find out if that is the issue.

 

 

Ok, i will do that soon and see if that is the issue, then what? If that was the issue i will never go out with a wrapping whatever around the focuser all the time, not for both Newt, i want a better solution, so first i will see if the focuser is the issue then i will see how to replace it for a better solution.

 

I am wondering about others who are using Newt, aren't they facing this light leak with stock focuser, sometimes i feel like i am the only person who faces only issues in my astro imaging, i feel like i have to stop and shouldn't care anymore about doing astrophotography, i started in 2017 and still suffering, while others started in 2019 or 2020 and they are getting amazing results and winner shots, i am just wasting time with issues 😔😞😩

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Yes use the wrap to ascertain where the light leak is, then see if it can be fixed or a new focuser required. It might be around the base plate that holds the focuser in place.

 

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29 minutes ago, MarkAR said:

Yes use the wrap to ascertain where the light leak is, then see if it can be fixed or a new focuser required. It might be around the base plate that holds the focuser in place.

 

 

I didn't open the internal tube of the focuser without removing the base, and i can see there is gap, i mean when i move the focuser up and down there is slight gap, when i mount flashlight from any direction i can see it from the other side, so no wonder why there is light leak, and only when i use narrowbanding filters mainly Ha i barely see it, but it is there for sure, now if i take light frames in dark, doesn't light pollution or skyglow getting inside too? 

 

I am thinking about a focuser tube  i saw somewhere without base, but i can't be sure if that one is a light leak proof as well, funny why i see this with both of my Newt while with my Mak or even my ST80 which i replaced the stock focuser to 2" Crayford focuser same or similar to the ones on Newt, something wrong there.

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Finally i found the reason or cause of light leak with my 8" F/5, which is mainly the rear side where the primary mirror is, and i thought it was the focuser which has light leak also but very very minimal and slight, but that rear side didn't show light leak when i cover the scope to about 1/4 way of the scope OTA, i covered before but maybe only slight part, so all what i need to do is find kind of dark cloth to cover most of the rear part to make it completely covered and isolated from outside, and the focuser i can think about another solutions, i don't like to turn my scope into a Mummy.

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6 hours ago, MarkAR said:

Maybe something like a biscuit tin lid painted black to cover it.

 

Some will do it, i won't, i prefer a nice look or design or elegant solutions, i think i will give a try to something i saw, it is that hair cover which females use mostly to prevent it from water in shower or to keep whatever on hair away from air for example, it is also very like my Beauty Dish light sock, but i will go with a black color, i can always find a dark cloth large enough to wrap it around and use a stretching rubber to hold it there, i will make sure what option i choose is that it is securely locked tight, so it won't slip while the scope is moving around and the rear is all way down.

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23 hours ago, MarkAR said:

Something like the material they use to shroud truss tube dobsonians.

 

 

Yes, exactly

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