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1.25" or 2"?


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I'm looking to upgrade my standard ep's but there seems an awful lot to consider, can anyone tell me what advantages 2" eyepieces have (if any)? I understand the standard ep's are pretty rubbish but how much of an improvement can I expect? Thanks in advance. :hello2:

Phil.

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2" eyepieces only really have the advantage that they can produce a wider field of view because of their larger barrel diameter. For medium to high powers most folks use 1.25" eyepieces and have one or two 2" ones for low power, wide field of view viewing.

In the 1.25" fitting, the BST Explorers seem to deliver meaningful improvements over the standard supplied eyepieces at around £40 each. For a low power, wide angle eyepiece the Skywatcher Panaview 32mm is very popular. They do cost around twice as much as the 1.25" eyepieces though because there are more materials used in their manufacture.

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The 2" eyepieces allow you a bigger field of view at low power, long focal lengths, because the 1.25" barrel is a limiting factor. So if your scope allows it (with some of the small SCTs/MCTs the baffle tube limits you), then I'd go with a 2" for wide field views. For higher powers, you're only looking at the central part of the image, so 1.25" eyepieces are fine - although the ones that fit in both 1.25" and 2" focusers are a bit more convenient.

If you're using the eyepieces that came with the scope, upgrading will probably give you the option of a bigger apparent field of view (larger image circle), better eye relief at shorter focal lengths, and maybe better image quality, depending on what came with the scope.

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agree with what has been said above. even though your focuser will probably accept 2" eyepieces, another thing to consider is that your scope is quite fast at f5. this means that any 'budget' eyepieces will show a lot of mushiness in the outer third or more of the field of view. buying a good quality 1.25" eyepiece might be a better way to go than a poorer quality 1.25".

also, if you have some light pollution, the exit pupil might affect things and anything above about 5mm (e.g. 25mm eyepiece divided by f5 = 5mm exit pupil) might mean the sky will be somewhat washed out.

there are many factors to consider when buying eyepieces as you are beginning to find! one way to combat this is to buy used if you can. that way you can sell on again at not much loss if the eyepieces don't suit you/your kit. another option is attend star parties where your neighbour might allow you to use an eyepiece or two in your scope or you can at least look through other people's kit and see what a difference eyepiece quality makes.

if you are near Buxton in October, the Peak Star Party is a good one.

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