Scope Eyepiece diameter for old eyes

In summary, the conversation is about a friend who wants to replace his scope for viewing the moon and terrestrial objects from his balcony overlooking a lake. He is interested in a refractor with 2" eyepieces, but they can be expensive. With a budget of $500, it may be difficult to find a scope with 2" eyepieces, but a long eye relief eyepiece may be more beneficial for extended viewing sessions. It is also suggested that a spotting scope with an adjustable zoom eyepiece may be a better option for terrestrial viewing. It is unlikely that a 1.25" scope with a 2" adapter would work effectively.
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DaveC426913
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TL;DR Summary
Are 2" eyepieces easier on aging eyes?
I have a friend who wants to replace his scope. Has a balcony overlooking the lake, so less about stars; more about Moon and terrestrial. So he's interested in a (right side up) refractor. He can save on the mount by getting an alt-az instead of an eq.

He's looking at this 4" Celestron:
https://www.amazon.ca/dp/B014EQ1LB2/

I've never explored 2" eyepieces. Would that be something that aging eyes would find easier?

Though 2" EPs are expensive, he probably only needs one.

His budget is $500. Is a scope with 2" EPs out of range? Would a 1.25" scope with an 2" adapter work? Is there such a thing?
 
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Two-inch eyepieces have an advantage in that they allow for a larger field of view, but that's it according to my limited understanding. If nothing else, I'd recommend a long eye relief eyepiece to make extended viewing sessions easier. But with a budget of only $500, including scope and mount, there's not a lot of choices available for eyepieces.

DaveC426913 said:
He's looking at this 4" Celestron:
Honestly, given that he's interested in mainly terrestrial viewing, I'd recommend a good quality 'spotting scope' with an adjustable zoom eyepiece. They are versatile, easy to setup and use, and uncomplicated.

DaveC426913 said:
Would a 1.25" scope with an 2" adapter work?
Probably not. The reason 2-inch eyepieces work is that the field stop, the thing that determines the maximum FOV, is often part of the eyepiece itself, and a larger field stop allows for a larger FOV. At least when the focuser tube and eyepiece are matched in size or the eyepiece is smaller. However, if you put a 2-inch adapter into a 1.25-inch focuser, the focuser tube itself might then become the field stop since it is so much smaller than the eyepiece tube. In other words, the focuser tube might be blocking rays that would otherwise pass through the field stop of the eyepiece, rendering the larger eyepiece size irrelevant.
 
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1. What is the purpose of the eyepiece diameter in a scope?

The eyepiece diameter in a scope is important because it determines the amount of light that enters the eye and affects the overall clarity and brightness of the image. A larger eyepiece diameter allows for more light to enter the eye, resulting in a brighter and clearer image.

2. How does the eyepiece diameter affect older eyes?

As we age, our eyes naturally lose the ability to adjust and let in as much light. This means that for older individuals, a larger eyepiece diameter is necessary to compensate for this decrease in light sensitivity. A larger eyepiece diameter can make it easier for older eyes to see and focus on objects through a scope.

3. What is the recommended eyepiece diameter for older individuals?

The recommended eyepiece diameter for older individuals varies, but generally a diameter of 1.25 inches or larger is recommended. This allows for enough light to enter the eye and can make it easier for older individuals to see and focus on objects through a scope.

4. Can the eyepiece diameter be adjusted for individual eyesight?

Yes, the eyepiece diameter can be adjusted by using different eyepieces with varying diameters. Some scopes also have adjustable eyepieces that can be customized to fit an individual's eyesight.

5. Are there any other factors to consider when choosing an eyepiece diameter for older eyes?

In addition to the eyepiece diameter, it is also important to consider the magnification power of the scope and the quality of the optics. A higher magnification power may require a larger eyepiece diameter to achieve a clear and bright image. It is also important to choose a scope with high-quality optics to ensure a clear and crisp image for older eyes.

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