Something melting inside of scope? (1 Viewer)

[Anhinga882]

Hello all!

New here and longtime lurker.

I've been having issues with a month-old spotting scope. I've been more than happy with the image quality, but when birding recently on a hot and muggy day, I noticed the edges of the view-field warping -- it almost looks as though something is melting inside the scope's eyepiece. The distortions were small at first, but they've grown and become quite ugly.

It hasn't necessarily affected the image quality, but I feel that this should not be happening in a month-old scope. I've been taking excellent care of it and I figure that the ambient air temperature shouldn't be enough to build up enough heat inside of the scope to warp the eyepiece (though I definitely don't know enough about optics to tell).

I've attached an image to give you folks an idea of what I'm describing.

Does anybody have any insight into what's happening here? Thank you so much for your time!

 

[Binastro]

Hi and welcome.

Normally this is because of direct Sun's heat.

However, if not the scope should be returned for a replacement.

What make is the scope?

B.

 

[Anhinga882]

Hi and welcome.

Normally this is because of direct Sun's heat.

However, if not the scope should be returned for a replacement.

What make is the scope?

B.

Hi! It's a GoSky ED scope.

When you say "direct Sun's heat", what exactly is happening here? I presume that this isn't normal behavior for a scope. Is there any way to prevent this in the future?

 

[Binastro]

It looks like a plastic field stop has melted.

If this is the case, then don't leave the scope pointed at the Sun.
Or cap the objective.

I think it was in New York that a home burned down because of a glass ornament left on the window shelf. $250,000 at the time.

Awful 'Sun filters' have cracked while being used.
The Sun is powerful.

Regards,
B.

 

[Anhinga882]

Hmm...I never pointed the scope directly at the sun, but it's possibly the sun was angled directly over the eyepiece behind me (I assume this would yield the same results).

 

[wllmspd]

Yep. A friend once watched the focal spot from his 18” telescope burn a hole inside his telescope dome. I’ve melted a plastic “solar funding aid” I designed (made from dark plastic so it heated up badly - rookie error!)
You’d need to have had it pointed not too far from the sun, maybe leaving it unattended and the sun got closer. If so it won’t get worse if you don’t repeat the experiment. Glad your eye was nowhere near at the time… need to keep good care of eyes.
Peter

 

[Binastro]

Possible, I suppose, or maybe the plastic could melt in high temperatures.

Usually, it is the objective's concentrated heat that melts the plastic.

B.

 

[Anhinga882]

I'll note I never had the actual scope pointed anywhere near the sun. I suppose it was just a combination of VERY hot outside temps combined with the sun being at just the right angle to enter the eyepiece.

Does this speak to the cheapness of the scope or is this something that can occur even with more expensive optics?

 

[Binastro]

An expensive scope probably has metal field stops.

It will also depend on the design of the optics.

It is possible that expensive scope makers consider this type of damage when designing the optics.

The balsam in cemented pairs will also fail due to solar heating, although this might not impact the image much.

But probably partly down to luck.

Maybe the eyepiece can be changed on this scope.

B.

 

[Binastro]

For solar projection with long focus or stopped down telescopes two element Huyghenian eyepieces are recommended.

I use 10x25 low priced roof prism binoculars for solar projection and a low priced Kowa 20x50 scope.
I wouldn't use expensive or large optics.

B.

 

[richard866945]

I've seen similar damage in a number of binoculars and if the owner wanted, I have simply removed the melted plastic component.
The irregular shape can be annoying / distracting.