11 replies to this topic

[Mattaeo]

Not sure if it's me or the telescope.  Lately, I've been looking at the sky at a bortle 7 under my 80mm refractor and 12" dob.  Both scopes still have very clear images when looking at stars and planets.

 

However, there's a lot of noise on the black background; like what you used to see on the old glass-tube TV when it loses signal and that static screen.  It's more obvious on the refractor than the dob.  I would see that static on the moon as well but more closer to the outer edge than anything.

 

Both are stored in the house and wheeled out to the back 10yds away.  The refractor immediately has this issue.  The dob has this issue 5min after wheeling it outside.

 

Is this what they mean to cool down the scopes and let it acclimate to the weather?  I've had mirrors and eyepieces dew over before and had to call it a night but never like this.  It is currently 75F inside during the day and about 70F at night when I watch.

[triplemon]

Its pretty unusual to talk about "noise" in visual observing. Its a term usually only used in imaging.

 

The sky isn't pitch black and in particular in Bortle 7 you can easily see that background brightness in a telescope, all the way to somewhat higher magnifications.

But its a very even and constant brightness. If you see any movement or brightness fluctuations in that background, its your eyes playing tricks on you. And that is normal - our brain constantly tries to detect motion and patterns and when confronted with none of either, its going to just make some up.

 

On the other hand, the atmosphere and even the air inside your telescope is as you suspect moving and creates distortions in what you see. But that won't create any visible movement on the dark background. On the high contrast moon and planets, this will create often quite notable movement, "boiling" or "fuzzyness", but no brightness fluctuations. Only for true point objects, i.e. only on the stars itself this can create flickering in brightness.

Edited by triplemon, 23 May 2025 - 01:25 AM.

[Tony Flanders]

A recent Cloudy Nights post mentioned Visual Snow Syndrome. That sounds vaguely similar to the symptoms you're experiencing. In any case, the problem certainly stems from your eyes and not from the telescopes.

[Keith Rivich]

Mirror temperature will not cause this. Your 5° is nothing. If I had to guess I would say it has something to do with the eyepiece, or as Tony suggest your eye itself. A quick check would be to rotate the eyepiece and see if the "static" rotates at the sane time. I suppose you could check your eye in a similar fashion by rotating your head and seeing if the static rotates. You my also be able to check your eyes by looking at a blank sheet of paper in low light and seeing if the static is present. 

[Mattaeo]

Mirror temperature will not cause this. Your 5° is nothing. If I had to guess I would say it has something to do with the eyepiece, or as Tony suggest your eye itself. A quick check would be to rotate the eyepiece and see if the "static" rotates at the sane time. I suppose you could check your eye in a similar fashion by rotating your head and seeing if the static rotates. You my also be able to check your eyes by looking at a blank sheet of paper in low light and seeing if the static is present. 

You're right!!!  I'll bet it's a medical reason because it's relatively new and an event happened not too long ago...

 

The reason why it didn't work on the dob right away is because the eyepiece I use have a brighter contrast on empty space.  Hence why when my eyes acclimated to the darkness, I began seeing the static.  When I cover my eyes after a bit, I start seeing them.

Edited by Mattaeo, 23 May 2025 - 10:06 PM.

[SeattleScott]

You're right!!! I'll bet it's a medical reason because it's relatively new and an event happened not too long ago...

The reason why it didn't work on the dob right away is because the eyepiece I use have a brighter contrast on empty space. Hence why when my eyes acclimated to the darkness, I began seeing the static. When I cover my eyes after a bit, I start seeing them.

Maybe this is floaters? Are you over 50?

[aeajr]

Floaters are particles that form in the eye gel as we age.  They become more prominent as we get older and become more apparent as you go to higher and higher magnifications. While they may be common, I would still advise a visit to the eye doctor to confirm that this is your situation.   Typically floaters are nothing to worry about, but you need a doctor to confirm that.

 

The exit pupil from the eyepiece becomes smaller as the mag goes up.  As the exit pupil gets smaller the more apparent the floaters.

 

I have experienced this for years.  Sometimes they pass directly into the light cone and I have to flick my eye to move them out of the way of what I am trying to see.  They never go away but I have learned to live with them.

 

Sometimes they even become apparent during normal vision, but again, I have learned to ignore them. 

[Sebastian_Sajaroff]

Floaters are evident when you observe a bright extended target at high magnification (>1.5x your telescope diameter in mm or >38x your telescope aperture in inches)
For example, when I observe the Moon on my 70 mm refractor at 120x I see tons of floaters strolling around, same for the Sun (with a white light filter).

[Mattaeo]

A recent Cloudy Nights post mentioned Visual Snow Syndrome. That sounds vaguely similar to the symptoms you're experiencing. In any case, the problem certainly stems from your eyes and not from the telescopes.

Funny thing…I spoke to a friend of mine who is a doctor and he said the same thing. It is indeed a visual snow syndrome. It’s not always a snowy effect but in my case, it’s light particles that appear sand goes throughout my visual effects. It’s very prominent when I’m looking at an all solid object or the sky in general.

He don’t have the issues I’m having so it’s definitely not my instruments.

It’s quite distracting to say the least but I’m not going to let this discourage me from enjoying the skies.

[Mattaeo]

Maybe this is floaters? Are you over 50?

Late 30s and I do have floaters. They don’t distract me one bit but this static snow effect fools me easily. I’m not sure what I’m seeing is an object or my eyes playing tricks on me.

[WillR]

By all means make an appointment with an ophthalmologist if you haven’t already done so. Your eyes are nothing to fool around with. 

[Mattaeo]

By all means make an appointment with an ophthalmologist if you haven’t already done so. Your eyes are nothing to fool around with.

After a few weeks, I finally got to see to an eye doctor. Don’t ask why but when one never had any visual issues, the scheduling gets weird. Doc said that the static is normal for my conditions because of the incident.

My eyes did indeed have gotten better little by little over time just as the doctor was suggesting. More rest and recovery will help with time.

Thanks for the input,
Matt