10 replies to this topic

[murray.collingwood]

 Hi there, first time poster.

 

I have a Meade 395 and have been looking at the moon lately.

The image I'm looking at is okay, however it looks like a second reflection of the moon slightly offset from the real one I'm looking at.

I don't have any flash equipment so I can't take any photos or anything, so I googled for a similar image and it is attached so you get an idea of what I'm seeing.  REPEAT: the image attached is not my image, it's to give you the idea that I'm seeing the moon, but there is a faint reflection also visible.

 

1. I can see the moon quite clearly.

2. When I look to the to the top edge of the moon I can see a second outline of the moon edge as though in a reflection from a window (not a mirror).

3. I wondering if it was because I was behind our double glazed windows, so I took the telescope outside, but unfortunately I'm getting the same result without any windows.

 

Can this be fixed?

Is it my eyes?

Is it the telescope?

Is there actually a second ghostly moon behind the one we see?

 

Cheers

Murray

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[SeattleScott]

First of all, I have to ask, are you viewing the Moon through a double pane window?

If not, this sounds like ghosting . This is caused by the moon reflecting off your eyeball back onto the eyepiece. Better eyepieces with anti-reflection coatings can help with this some, but this is not unheard of, even with premium eyepieces.

[oldphotonm]

Absolutely.

Prolly not.

Depends.

Oh heck no.

 

Are you using a camera of any kind or just your eyeball to capture the "image" you mention?

 

Do you wear glasses when observing?

 

When you say "top edge", how much of an offset? Is the ghost image slightly offset or grossly offset like the example image you posted?

[michael8554]

What OTA and eyepiece ?

[JOEinCO]

I believe the Meade 395 comes with an erect-image prism diagonal. My guess is you are seeing reflections caused by that diagonal. 

 

Try looking at the Moon tonight with just the eyepiece in the focuser. Angle might be odd and a bit awkward with the Moon so high right now, but you just want to eliminate the diagonal as the source of the double Moon reflection.

[Echolight]

Some binoculars with prisms will do this.

 

It's called a ghost image.

 

I've only seen it when viewing the Moon.

Edited by Echolight, 14 November 2024 - 05:36 PM.

[triplemon]

What type/brand of diagonal are you using ?

I've seen an uptick of ultra-cheap diagonals using second surface (aka bathroom) mirrors. They cause ghosts similar to that. One indication of that is the ghost image is just a bit out of focus compared to the main image. If you can focus sharply on either one but not both at the same time - that a is dead giveaway for this.

 

Poorly made image errect diagonals can also cause similar.

 

In either way - try to see if you can get to a fcous without the diagonal to check.

Edited by triplemon, 14 November 2024 - 06:53 PM.

[murray.collingwood]

WOW!  Awesome to get so many replies.  Thanks everybody.

 

@SeattleScott initially we were looking through double glazed windows, which is why I took it outside, there was no improvement.  Reflection from my eyeball, not something I have noticed before when using other telescopes.  However, I did recently have cataract surgery and new lenses inserted (in my eyes).  Unfortunately this is not the solution as my wife who has normal eyes (whatever normal is) also sees the 'ghostly' image.

 

@oldphotonm No camera - just my eyes.  If I could get a photo of it I would post the actual photo.  I might try that tonight.  No glasses, however I've got new lenses in my eyes, however as mentioned to Michael, my wife with normal eyes sees the same thing.  The top edge, it's probably about 1/3 of the moon, same size.

 

@michael8554 OTA - no idea.  What would an OTA look like?  The eye piece, there seems to be two.  First in line is a Meade 2x telenegative followed by a Meade MA25mm.

 

@JOEinCO  I will try just the eye piece tonight and see what that looks like.  It could well be any piece of glass or reflection in the telescope.  I have no idea of the history - whether it was dropped at some time before I took possession.

 

@Echolight  I had another telescope in Australia and didn't see reflections like this.  Also, I'm getting a similar issue looking at stars, although the offset is much greater, and there are two reflections instead of one.  I'm hoping it's something simple that can be fixed.

 

@triplemon Would I have to disassemble the telescope to find this?  My guess is that it is the original that came with the telescope.  I have nothing to suggest that anything has changed from the original product, but maybe something has moved inside.  I will check in the focusing makes any changes to the ghost image tonight and let you know.

 

Is there a simple method of getting a photo of what I can see through the telescope.  At this point I'm thinking I will just stick my iphone camera over the eye piece and see if something appears that I can capture.  If you have any other suggestions I'm all ears.

 

Cheers

Murray

[SeattleScott]

If you are seeing multiples with stars, that’s concerning. My guess would be the diagonal. I don’t think the barlow and eyepiece alone could do this. Granted lack of anti-reflection coatings can contribute to ghosting, but this sounds more serious than the usual faint ghost image.

[SeattleScott]

OTA is optical tube assembly. Basically the telescope tube.

[oldphotonm]

Murray-

It sounds suspiciously like something is slightly wonky (out of alignment) with your objective lens or the focuser body, especially since you see double images of the stars and your sweetheart (with OEM eyeballs) sees the same thing.

From what I've read so far, the objective lens cannot be collimated (aligned) in its cell.

But what can be checked is if the objective cell is properly attached to the main tube and not cross-threaded or otherwise mis-aligned.

Same thing for the focuser body.

 

Do you have only the single MA25 eyepiece?

 

Another question: if you take the diagonal out and gently shake it, do you feel and/or hear a rattle? If so, that's likely your problem. Otherwise, what triplemon notes is also a likely suspect.

Also try the shake test with that 2x barlow (telenegative) lens. A loose element there could also cause the mis-alignment.

 

Finally, a most important question:

Do you belong to a local astronomy club where you live? If so, attend a club meeting and talk to some of the members and see if someone in the group can assist you.

Good-sized clubs have a wealth of knowledge in the "collective" membership and makes for a very good reason to join a club.