42 replies to this topic

[kgb]

Woah. Does that ring appear visually or only photographically? Is that being taken through an eyepiece? How long is your exposure?

Edited by kgb, 28 September 2023 - 06:51 PM.

[Santola]

Maybe it is internal reflections. Could be in the Eyepiece. The Moon is very bright.

Does this ring show with a different eyepiece?

Yes.

[Santola]

Woah. Does that ring appear visually or only photographically? Is that being taken through an eyepiece? How long is your exposure?

I think it's even stronger visually, I used my 23mm aspherical eyepiece

Exposure 1/40.

I'm worried about it being a defect in the mirrors...

[kgb]

It definitely doesn't appear as if this is an atmospheric or an alignment problem. Do you have the ability to place a camera at prime focus by attaching the camera directly to the telescope with no eyepiece in between? There is something introducing color into the mix and possibly reflections too. It may be the eyepieces or the camera lens. Are there any lenses located inside the focuser body itself? You said this is happening in both of your eyepieces?

[Santola]

It definitely doesn't appear as if this is an atmospheric or an alignment problem. Do you have the ability to place a camera at prime focus by attaching the camera directly to the telescope with no eyepiece in between? There is something introducing color into the mix and possibly reflections too. It may be the eyepieces or the camera lens. Are there any lenses located inside the focuser body itself? You said this is happening in both of your eyepieces?

I wasn't able to take a photo, but I can see these rings even without an eyepiece. I pointed it at the Moon and moved away a little so I could see the Moon.

My telescope does not have lenses inside the focuser.

Edited by Santola, 28 September 2023 - 07:26 PM.

[briansalomon1]

"My mirror is parabolic, and I use Celestron's aspherical eyepieces. (23mm | 10mm)"

 

Most of what I see online shows this model comes with a spherical mirror. Unless it's been replaced, it's probably spherical.

 

If what you're seeing is caused by spherical aberration from your primary mirror, it should be greatly diminished in the center 1/3rd of your field of view. Using the your 23mm eyepiece, with The Moon centered in the field of view, this will represent 0.5 deg out of 1.5 deg total.

 

If what you're seeing is spherical aberration (from the primary mirror) the effect should be noticeably less than when you're using the 10mm eyepiece.

 

(Note: If the mirror has been replaced, please ignore this)

Edited by briansalomon1, 28 September 2023 - 09:19 PM.

[kgb]

"My mirror is parabolic, and I use Celestron's aspherical eyepieces. (23mm | 10mm)"

Most of what I see online shows this model comes with a spherical mirror. Unless it's been replaced, it's probably spherical.

If what you're seeing is caused by spherical aberration from your primary mirror, it should be greatly diminished in the center 1/3rd of your field of view. Using the your 23mm eyepiece, with The Moon centered in the field of view, this will represent 0.5 deg out of 1.5 deg total.

If what you're seeing is spherical aberration (from the primary mirror) the effect should be noticeably less than when you're using the 10mm eyepiece.

The OP indicated that this was made by an expert ATMer in Brazil. And that the mirror is parabolic.

Edited by kgb, 28 September 2023 - 09:11 PM.

[kgb]

Santola- can you determine if the reflective coating is on the front side of the mirror or on the back side? Absent any refractive surfaces, you should not see any prismatic effects that show the constituent colors of light separated out like you do in the most recent images that you provided. When you said that you can see these rings without an eyepiece in place, do you also see the colors?

[Santola]

The OP indicated that this was made by an expert ATMer in Brazil. And that the mirror is parabolic.

 

 

Santola- can you determine if the reflective coating is on the front side of the mirror or on the back side? Absent any refractive surfaces, you should not see any prismatic effects that show the constituent colors of light separated out like you do in the most recent images that you provided. When you said that you can see these rings without an eyepiece in place, do you also see the colors?

Yes, the mirror is parabolic. He said that in 20 years of experience he has never seen a report like this with his telescopes. I'm talking to him directly these days and we're trying to figure out what it is, the support he offers is great. I was very unlucky unfortunately lol, but in the end it will serve as a learning experience.

I will test tonight to see if I see colors in the rings without the eyepiece.

[kgb]

Glad to see that you were able to go back to the source for help resolving your problem. If you could, please, report back with what you find. I'd be interested to know what the nature of this problem was.

[rgk901]

interesting.. I'd like to know the outcome myself.

Edited by rgk901, 29 September 2023 - 02:14 PM.

[walt r]

Odd thought but need to ask:

Is the secondary mirror have the mirrored side toward the primary & eyepiece? If not then there will be two reflections.

 

The multiple 'rings' seem to sharp to be reflections off internal parts of the scope. These tend to simply cause loss of contrast.

 

The sharpness seems to indicate it is in the optics somewhere.

[Santola]

We are working with the hypothesis that it is the atmosphere. Another person from the same region also reports the same problem. We have to consider that here in Brazil we are suffering a very strong heat wave with temperatures reaching more than 40 degrees Celsius in several regions of the country. But there is also the fact that I have already observed this effect for more than a month.

I was also instructed to replace the glue that holds the mirror to the support, which could be causing stress. We have also ruled out that it is a problem with collimation or with the integrity of the mirrors. Despite this, the mystery has not yet been definitively solved. But I feel more relieved to know that everything seems to be ok with the mirrors.

When possible I will bring more updates. 

[Santola]

Odd thought but need to ask:

Is the secondary mirror have the mirrored side toward the primary & eyepiece? If not then there will be two reflections.

 

The multiple 'rings' seem to sharp to be reflections off internal parts of the scope. These tend to simply cause loss of contrast.

 

The sharpness seems to indicate it is in the optics somewhere.

Yes. We also made a projection of a light bulb here at home onto cardboard and the image formed was perfect, without these "rings", which I believe that really rules out a problem with the optics.

Edited by Santola, 29 September 2023 - 03:03 PM.

[rgk901]

apsherics have a plastic lens.. I know you said you used other eyepieces but where they also aspherics? maybe the batch is somehow compromised or by chance did you clean them with something that could have clouded the plastic lens? just thinking out loud and throwing stuff out there

Edited by rgk901, 29 September 2023 - 03:22 PM.

[Santola]

apsherics have a plastic lens.. I know you said you used other eyepieces but where they also aspherics? maybe the batch is somehow compromised or by chance did you clean them with something that could have clouded the plastic lens? just thinking out loud and throwing stuff out there

Yeah, they're all aspherics and I didn't do anything to damage the eyepieces.

[briansalomon1]

Yeah, they're all aspherics and I didn't do anything to damage the eyepieces.

Thanks for all the feedback. It's an interesting puzzle....
 

[rgk901]

just looked at the moon with my aspheric 10 and no rings..decollimated the mirror and gets fuzzy but still no rings... but tonights's sky wasn't hazy.