Adaptors

[REG78]

Can I get an Adaptor so my telescope takes 2" EPs

[Cornelius Varley]

What telescope do you have ?

[Knighty2112]

Depending on the make and model of your telescope, you may be able to upgrade the focuser to a 2" one if the one you have currently fitted only takes 1.25" EP's.

[REG78]

Have a skywatcher 300mm by 900mm

[REG78]

Sorry have a 130-900

[Cornelius Varley]

12 minutes ago, REG78 said:

Have a skywatcher 300mm by 900mm

is that correct ? Shouldn't that be 130x900.  There are adapters available but you probably won't be able to use them , 2"-1.25" eyepiece adapter.

Quote from site:-

"Please note that the use of extension/conversion tubes such as this item requires additional in-focus travel. If your eyepiece is fully seated in the 2" upper barrel, then you will require 1.53" of additional in-focus travel. If your eyepiece does not fully seat in the barrel and extends out, then you will require additional in-focus travel by the amount the eyepiece extends out. As in the case of barlows, focal reducers, diagonals, and other accessories, your telescope may or may not be able to accommodate this additional travel requirement, so you may not be able to reach focus with all eyepieces and configurations. That is technically a limitation of the mechanical design of the telescope and not a shortcoming of the product itself.

Also, it is possible that your view through some 2" eyepieces might be vignetted when used with this adapter because of the smaller 1.25" barrel in the light path. This will depend on your telescope and eyepiece combination and cannot be predicted in advance. However, many customers have successfully used this adapter with many 2" eyepieces, especially in the Meade ETX line of telescopes"

[Star Lord]

Excellent, that's the first 1.25-2" adapter I've seen. To answer in another way, 2" focusers typically need a 8" tube in my experience (203mm) due to the curvature of the tube. Cornelius's idea seems very agreeable, though the focus travel issue probably does limit you as well. It sounds like your telescope is a Reflector, is that correct?

[REG78]

Yea skywatcher 130-900

[John]

The vendor says:

"Also, it is possible that your view through some 2" eyepieces might be vignetted when used with this adapter because of the smaller 1.25" barrel in the light path."

The primary advantage of a 2" eyepiece is that it can deliver a larger field of view than the same focal length eyepiece in the 1.25" format. The 2" - 1.25" adapter will effectively add a 1.25" barrel to the 2" eyepiece so the field of view will (rather than might) be reduced / vignetted to that which a 1.25" format eyepiece in that focal length could produce,

Add to this the strong possibility that a 2" eyepiece in this adapter will be able to be brought to focus, I can't see the point of using a 2" eyepiece in such an adapter

 

 

[Cornelius Varley]

7 hours ago, Star Lord said:

Excellent, that's the first 1.25-2" adapter I've seen. To answer in another way, 2" focusers typically need a 8" tube in my experience (203mm) due to the curvature of the tube. Cornelius's idea seems very agreeable, though the focus travel issue probably does limit you as well. It sounds like your telescope is a Reflector, is that correct?

The problem with using the adapter is that you need sufficient back focus to accommodate the adapter and you will also get vignetting. Basically being able, maybe, to use 2" eyepieces but also being restricted by the vignetting so not getting the benefits of the larger size.

[Ricochet]

It would be better to get a 32mm Plossl or 24mm 68 degree eyepiece I think.

[Dave In Vermont]

If it's a wider FOV you're looking for in a 2" format, there are some 1.25" EP's with an 80° FOV out there. Examples are on this page - the two in 11mm and 16mm respectively:

http://www.universityoptics.com/125inch.html#80

With 5 lens-elements, they may work alright in your scope. But I'd ask before 'pulling the trigger' to be sure.

Dave