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Managing stray light and NV

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#1 GOLGO13

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Posted 02 September 2020 - 11:46 AM

One issue I have fairly often is stray light from neighbors. When I use the unit at 1x with a filter, stray light is an issue. I also have this issue with my 50mm guide scope. And sometimes I have this issue through the telescope if enough is getting through. 

 

Looking for suggestions, but here are a few things I can do.

 

1) A while ago I made these panels made out of PVC and has black material on them. I have 4 panels which can make for a little observatory when tied together. Or I can use one panel by itself to block a specific light.

2) I did flock the inside of the 6 inch F4 and my 10 inch F4.7 was already flocked. This helps greatly for planetary work, but also should help with this situation.

 

Unfortunately I live in one of those neighborhoods where they want everyone to have a front light on. Mine doesn't work and I don't put it on...but almost everyone else does. Blah.

 

For the 1x capability I'm thinking maybe I could switch over to using camera lenses which already have light shields I can put on. I still have not installed a filter holder in my c mount camera adapter...I just need to get some sort of silicon to hold that in place. I don't know if that would be better than the Envis lens or not. But for stray light it should be better.



#2 Eddgie

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Posted 02 September 2020 - 12:11 PM

I have issues with glare and reflection off of the filter glass sometimes so I know what you mean.  The challenge with 1x is the very wide 40 degree viewing angle.

 

My guess is that the best way to combat this would be with a lens hood.   The ENVIS is an excellent lens and you will struggle to find SLR lenses that are as good for 1x so the solution I would recommend would be to find someone around you with a 3D printer and ask them to print a lens hood for you.   This is something on my own list of things to do, but that list is long and this is one of those things near the bottom.  Still, it should be easy for someone with Fusion 360 (or whatever they use) and a 3D printer to knock out a lens hood. 

 

It might even be possible to make a hood from PVC pipe fittings or other common materials. 


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#3 PEterW

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Posted 02 September 2020 - 02:19 PM

For my 80mm scope I have a 40cm long internally flocked black plastic tube that I hold in place. It’s invaluable to remove the effect of local streetlights. I can use it with 1/3x, but it will vignette if I don’t poke it down the tube far enough. I made a conical shield for my SQM to reduce local lights affecting it, so could “botch” Together with an adapter for the 1x lens.... though I tend to push for a 2”filter adapter to the 1x, so maybe I just make the cone wide at the bottom to hold the filter.... saves tryi Goto be too clever. Could have a filter less one or one for a 1.25” filter if people want.....

Peter

#4 GOLGO13

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Posted 02 September 2020 - 04:36 PM

I have issues with glare and reflection off of the filter glass sometimes so I know what you mean.  The challenge with 1x is the very wide 40 degree viewing angle.

 

My guess is that the best way to combat this would be with a lens hood.   The ENVIS is an excellent lens and you will struggle to find SLR lenses that are as good for 1x so the solution I would recommend would be to find someone around you with a 3D printer and ask them to print a lens hood for you.   This is something on my own list of things to do, but that list is long and this is one of those things near the bottom.  Still, it should be easy for someone with Fusion 360 (or whatever they use) and a 3D printer to knock out a lens hood. 

 

It might even be possible to make a hood from PVC pipe fittings or other common materials. 

If you come up with a 3d print design please share it. I have a friend who does 3D printing and can probably make it for me.



#5 a__l

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Posted 02 September 2020 - 05:48 PM

I bought a kit from AliExpress with a 48mm ring, compatible with the 2" filter thread (which in turn screw onto the lens). They are cheap.

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  • hood_.jpg

Edited by a__l, 02 September 2020 - 05:48 PM.

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#6 Dale Eason

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Posted 02 September 2020 - 09:37 PM

I tried an experiment with a cardboard tube about 2inches long in front of my Nikon 1.8 mm 55mm lens on the front of my Mod3C.  It did not help.  Perhaps because the inside was just cardboard brown and allowed the IR to reflect several times off of its surface.



#7 GeezerGazer

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Posted 10 September 2020 - 10:02 PM

There are a couple of ways to shield an Envis lens discussed in this thread from last year, including two images to show how shielding can block glare from street lights and/or moon light.  I still use the simplest version when direct light is a nuisance... the plumbing tail pipe with a very short extension beyond the front of the lens.  The others work very well too, but require the threaded connection.  The tailpipe just slides on and stays put until I slide it off... a perfect fit. 

Ray


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#8 PEterW

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Posted 11 September 2020 - 10:29 AM

Keep the shield out the lens field of view, make it long enough and paint it as black as you can. Wide angle lenses are the worst to suffer from nearby lights, best to find a way to hide from them.

Peter
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