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1.25" and 2" scopes


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I was finally starting to make up my mind about which scopes I wanted. An 8" Dob for now, and a C9.25 when I can afford it for imaging. I just noticed that the Celestron one takes 2" EP's though, which is pretty ****. I planned to start building up my eye piece collection soon, going for good quality and more expensive ones so I wont need to reinvest in the future, but obviously I'll have to start a new collection with my new scope.

I assume that the adapters you can get aren't very good? So it'd be pointless to buy 2" EP's to use with my Dob, and 1.25" EP's would obviously be pointless with a 2" scope.

As I read back through this, I realise it doesn't make much sense and I'm just rambling on, so my question is... Is this a common problem that people have? Is there an effective solution to it other than having 2 EP collections? And is it standard for the better scopes to take 2" EP's, or could I find a C9.25 equivilent that would be compatible with my 1.25" EP's and filters?

Thanks.

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I think what you'll find is the Celestron also takes 1.25" EPs, all scopes take both 2" and 1.25" EPs. The 1.25" adapter can be removed to accomodate 2" EPs.

What Celestron scope are you looking at?

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Just to clarify for you - 2" ep's afford wider views than 1.25" ep's purely by nature of their size. As such they are typically used for low power wide views of the larger dso's. Views that you can't get with 1.25" ep's that tend to be used for higher power magnifications of planets. It's only a general rule because there's a big overlap between the two sizes - i.e. you can get 40mm and 5mm in both 2" and 1.25".

You can also get 1.25" and 2" diagonals and the better one's usually come supplied with an adaptor and compression ring fittings so you can use both ep sizes with them. So in terms of a "solution" to your percieved problem - there really is no "problem" at all and neither colection will be wasted :(

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I think what you'll find is the Celestron also takes 1.25" EPs, all scopes take both 2" and 1.25" EPs. The 1.25" adapter can be removed to accomodate 2" EPs.

What Celestron scope are you looking at?

Ahh cool, that's good to know. Explains why I was confusing myself. I thought it was either one or the other. The one I want when I can spare the cash is a C9.25-SGT XLT. Maybe the C11 if I can stretch the budget.

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Just to clarify for you - 2" ep's afford wider views than 1.25" ep's purely by nature of their size. As such they are typically used for low power wide views of the larger dso's. Views that you can't get with 1.25" ep's that tend to be used for higher power magnifications of planets. It's only a general rule because there's a big overlap between the two sizes - i.e. you can get 40mm and 5mm in both 2" and 1.25".

You can also get 1.25" and 2" diagonals and the better one's usually come supplied with an adaptor and compression ring fittings so you can use both ep sizes with them. So in terms of a "solution" to your percieved problem - there really is no "problem" at all and neither colection will be wasted :(

So do more experienced people generally have both 1.25" and 2" for different things, or is it doable to just stick with all 2's and simply switch the EP for more magnification when the wider FOV isn't required. Hope that makes sense.

Thanks.

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Yes your "question" is making sense lol. But the answer largely depends on what your objectives are, and what type of scope you have. It's all down to wether you are an observer only, or if you intend some astro photography. Also what sort of objects you are looking at or photographing, and how the ep matches up to your scopes characteristics (especially focal length).

It's also down to what suits your eyes and what you feel comfortable with - bit of a personal thing really - get to try some before you buy in order to acquaint yourself with what's available :(

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Thanks for the advice. I really just want good all around stuff, as I'm probably always going to be on a budget. I'm getting a 200/250P Dob soon, but I'm thinking ahead and wanting to invest in decent EP's that will be effective for photography on a scope like the Celestron C9.25.

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Below about 17mm you can't 2" ep's you can get some dual skirt ep's such as the 13, 10, 8 and 6mm Ethos' and the Nagler 12T4. These will all fit in a 2" focuser without need for adapter but will also fit in a 1.25" focuser. I use 2" (including 2 dual skirt models) for all but one of my ep's and it makes switching between ep's a lot easier.

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So do more experienced people generally have both 1.25" and 2" for different things, or is it doable to just stick with all 2's and simply switch the EP for more magnification when the wider FOV isn't required. Hope that makes sense.

Thanks.

The higher power (low focal length number eg: 5mm, 9mm etc.)eyepieces are 1.25" and the lower power wide field eyepieces (25mm, 35mm etc.) are usually 2" so to have a usable range of eyepieces you would want both 1.25" and 2" eyepieces. I have mostly 1.25" eyepieces and a couple of 2" eyepieces for low power use.

John

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Most ep's have a filter thread at the end of the barrel whatever the size. For those you would buy the size filter that matches (1.25" or 2").

However - if you are using draw tube extenders, photographic items, reducers, flatteners, or other items in the train then you may have to ensure threads are available at the point you want to place a filter, and match that size. :(

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I suppose for most filters that wouldn't matter anyway. For example, a moon filter would only really be used with the higher power EP's which would be the 1.25" ones so a 1.25" filter would be all I needed. And an OIII filter would be used for DSO's which a 2" EP would be best for, so it's only really standard light pollution filters that I'd need to be able to use with both sizes. As long as I'm understanding it right.

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