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Dusk cover white-light filter, Yes or No?

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#1 cpsTN

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Posted 16 April 2021 - 01:17 PM

I have the Celestron Omni 150, 6" f/5 Newt. I have used strong spray adhesive to adhere a square of AstroSolar film over the hole in the dusk cover, on the inside. I asked about this in a FB group and thought I would get your opinions too. I have used three layers of adhesive onto the inside of the dusk cover and mashed the edges of the film flat against the edges of the hole. I have run tests with the cover both on and off the scope while pointing it toward the Sun. I am getting temperature readings of 130*F (55*C) on the surface of the cover, even after 30 minutes of exposure. Should this be safe? 

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Edited by cpsTN, 16 April 2021 - 01:24 PM.


#2 havasman

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Posted 16 April 2021 - 02:09 PM

That appears to be well executed. Be sure that your dust cover is securely in place. The one on my XT10i has always been on the loose side. Maybe a couple of lengths of gaffers tape might be good cheap insurance.



#3 cpsTN

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Posted 16 April 2021 - 05:10 PM

Thank You. It's very snug. I have to nudge my way around it to loosen it enough before comes off.



#4 NorthernlatAK

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Posted 16 April 2021 - 05:54 PM

Why not go full aperture? Works great on my 8". You can make a mask if conditions don't allow for full aperture, which I've never had to do. Just use less magnification. Heat is a non issue if using full aperture as light is reflected off the filter. Looks like a good job btw.

Edited by NorthernlatAK, 16 April 2021 - 05:57 PM.


#5 cpsTN

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Posted 16 April 2021 - 09:27 PM

I have enough filter material to do a full aperture on the stove I wasn't going to try this and see if it works because I'm not a great solar Observer but I do like to view Transit an eclipse Isn't So for but I don't do the viewing everyday. One thing I do like to do though is use the viewing glasses and just to watch clouds moving front of the sun that's cool. And I occasionally take videos and I capture the Silhouettes of birds across the Sun. This is the only 42mm in diameter, so this will severely restrict my highest magnification but with it being daytime anyway they seeing isn't going to be fantastic. I posted the same picture and explanation on one of the Facebook astronomy sites that I'm part of and nearly everyone said it was too dangerous. ???


Edited by cpsTN, 16 April 2021 - 09:29 PM.


#6 Gregory Gross

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Posted 17 April 2021 - 12:57 AM

Ehhh... I would be more than a little uncomfortable with this.

 

I am getting temperature readings of 130*F (55*C) on the surface of the cover, even after 30 minutes of exposure. Should this be safe? 

What happens at minute 31? Or 40? Or even later? Are you absolutely 100% sure the adhesive won't begin to soften and fail on the inside of a black plastic cover as the Sun beats down on the other side? Are you sure the dust cover itself won't fall off?

 

I don't mean to sound like a curmudgeon, but... your eyesight is at stake.

 

I would look for something that is far more secure than spray adhesive making contact with only one side of the filter film. I'm thinking of the kind of sandwiched DIY filter cell that Baader describes on their AstroSolar.com website.



#7 cpsTN

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Posted 17 April 2021 - 05:07 AM

This is why I'm doing the tests. It hasn't gotten really really warm here yet a but it's been in the the 70s almost 80s already but not much. During the summer it'll get into the 80s and maybe the 90s with a decent amount of humidity. I already have a well-built, long tested (10 years) solar filter for my little 70 mm refractor so I could easily just use that. As far as the dust cover falling off, it fits so snuggly I usually have to pry it off from around the edge before it even comes loose. So that it isn't an issue at all. But as the temperatures rise during the season I will do more tests with it on the scope without viewing through it and over time test the adhesive which is quite a strong bond that I use for nearly everything so it should be OK. If there becomes any question of safety, I will do the other way because I do have enough to create a full-aperture filter with cardboard as it "should" be done. 


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#8 philmor56

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Posted 17 April 2021 - 09:06 AM

Thank You. It's very snug. I have to nudge my way around it to loosen it enough before comes off.

 

Ehhh... I would be more than a little uncomfortable with this.

 

What happens at minute 31? Or 40? Or even later? Are you absolutely 100% sure the adhesive won't begin to soften and fail on the inside of a black plastic cover as the Sun beats down on the other side? Are you sure the dust cover itself won't fall off?

 

I don't mean to sound like a curmudgeon, but... your eyesight is at stake.

 

I would look for something that is far more secure than spray adhesive making contact with only one side of the filter film. I'm thinking of the kind of sandwiched DIY filter cell that Baader describes on their AstroSolar.com website.

 

This is why I'm doing the tests. It hasn't gotten really really warm here yet a but it's been in the the 70s almost 80s already but not much. During the summer it'll get into the 80s and maybe the 90s with a decent amount of humidity. I already have a well-built, long tested (10 years) solar filter for my little 70 mm refractor so I could easily just use that. As far as the dust cover falling off, it fits so snuggly I usually have to pry it off from around the edge before it even comes loose. So that it isn't an issue at all. But as the temperatures rise during the season I will do more tests with it on the scope without viewing through it and over time test the adhesive which is quite a strong bond that I use for nearly everything so it should be OK. If there becomes any question of safety, I will do the other way because I do have enough to create a full-aperture filter with cardboard as it "should" be done. 

 

Hi Charles:

You seem to be on the right track with a proper attitude, but sometimes it's easy to overthink the details.

I would strongly suggest that you find a better method.

If you can nudge it to come off, then assume it will.

Adhesive tape is not a secure method, and gravity is your enemy here.

I would suggest that you find another dust cap for your aperture opening, cut out the centre bit, and sandwich the film between the dust cover and the front collar of the dust cap.

Much like a collared full aperture cover (make one if you have the film!), it puts the film in the front of everything else.

It sounds like the caps are snug but...  try to use some Velcro tape at this point for your new "collar" , and make sure that you secure the larger dust cap to your main scope as well.

Solar observers generally have Velcro dots and strips hanging off of their scopes and dew shields for just this reason. Not attractive, but necessary.

Always assume something will go wrong, check and check again.

Sorry to sound like I'm preaching gramps.gif , but we have to be careful out there.

Besides, you'll want to share what your seeing, and you will benefit from the longer f/l with your new mask.

Hope this helps.

 

Cheers



#9 cpsTN

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Posted 17 April 2021 - 09:49 AM

I believe you got the wrong idea when I said nudge. I probably shouldn't have used that word anyway. I mean that I generally have to use both hands to losen the dusk cover then actually pull it off. It won't, at all, move unless I do that. It is very well fitting. 


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