What's wrong with my telescope?

[vlaiv]

1 minute ago, StuartT said:

thanks. I have never had a good experience trying to collimate. I always make things much worse. It's supposed to be simple, but it really isn't. Maybe I should stick to refractors. Only problem is, I need the long focal length for galaxies and planets. 

Maybe check out a video on youtube of look up a tutorial on how to collimate SCT?

[StuartT]

2 minutes ago, vlaiv said:

Maybe check out a video on youtube of look up a tutorial on how to collimate SCT?

oh believe me, I have watched them all. I even have a book about collimating SCTs!

[Ags]

26 minutes ago, StuartT said:

I even have a book about collimating SCTs!

A whole book on the subject? I think you should be able to fit the essential points on a sheet of A4. Sounds like a guide to overthinking... But Newts - I never could collimate mine.

Edited April 10, 2022 by Ags

[StuartT]

25 minutes ago, Ags said:

A whole book on the subject? I think you should be able to fit the essential points on a sheet of A4. Sounds like a guide to overthinking... But Newts - I never could collimate mine.

Precisely my point! Theoretically easy, practically impossible

Here's the book, by the way

https://www.goodreads.com/book/show/50622256-collimating-schmidt-cassegrain-telescopes

Edited April 10, 2022 by StuartT

[StuartT]

I think I'm just going to replace this telescope. Life's too short.

Edited April 10, 2022 by StuartT

[Elp]

Kind of get your position. My first proper telescope was a cheapish Newtonian of no major make, could I see anything through it, no. I ended up taking it completely apart trying to figure out why it wasn't collimating and ultimately sent it back (secondary fixings were dire). Stuck to refractors until I decided I wanted more aperture and FL for the same reason you do. 130pds later, collimation is a breeze with nothing more than a collimation cap. Maybe it's not perfect collimation, but it works for me and that's all that matters, I can always crop my images for edge of field distortion and coma is inherent.

Edited April 10, 2022 by Elp

[Stuart1971]

23 minutes ago, StuartT said:

I think I'm just going to replace this telescope. Life's too short.

I did say right at the start, it’s not a coma issue, it’s a flat field issue, a coma corrector was not what you needed IMHO, is was just an SCT field flattener….☹️

Edited April 10, 2022 by Stuart1971

[vlaiv]

1 minute ago, Stuart1971 said:

I did say right at the start, it’s not a coma issue, it’s a flat field issue, a coma corrector was not what you needed IMHO, is was just an SCT field flattener….☹️

It is SCT field flattener that has been used.

[Stuart1971]

Just now, vlaiv said:

It is SCT field flattener that has been used.

Thought it was a coma corrector, not a dedicated SCT filed flattener….?

[Stuart1971]

3 minutes ago, vlaiv said:

It is SCT field flattener that has been used.

Ok, I see it is sold as both…..flattener / coma corrector…..Hmmmm, well this is a strange one then….🤔🤔

[vlaiv]

1 minute ago, Stuart1971 said:

Thought it was a coma corrector, not a dedicated SCT filed flattener….?

It is dedicated SCT corrector - which corrects for all aberrations inherent in SCT design - which are coma and field curvature.

It is this one:

https://starizona.com/products/starizona-sct-corrector-63x-reducer-coma-corrector

 

[vlaiv]

1 minute ago, Stuart1971 said:

Ok, I see it is sold as both…..flattener / coma corrector…..Hmmmm, well this is a strange one then….🤔🤔

It's not - it is just specialty item for SCT - it corrects all aberrations in design which happen to be field curvature and coma.

It would not work as regular coma corrector on newtonian as it is specifically designed for SCT

[Stuart1971]

Taken from the advert page….so maybe an issue and spacing may be different for the Meade range….🤔

Additionally, even though the SCT Corrector is also an excellent fit for standard Meade f/10 Schmidt-Cassegrains, Starizona does not have precise data regarding the nominal designs of those scopes.

 

[vlaiv]

Yep, it is worth trying different distances as well if they can't be sure if 92mm is correct distance for Meade.

[StuartT]

46 minutes ago, vlaiv said:

Yep, it is worth trying different distances as well if they can't be sure if 92mm is correct distance for Meade.

Thanks. I shall try out a few different spacings, but I shall also look at the Celestron Edge HD 9.25" (I don't think my mount is accurate enough for the 11")

 

Edited April 10, 2022 by StuartT