250px stock eyepiece spec.

[urchin]

Hi all

Recently got myself my 1st real scope, 250px. I've read a lot on here about how much the stock eyepieces can be improved upon.

My question is what kind of eyepieces are they, how much eye relief do they provide and what is the AFOV. Is there a spec or do these need to be measured/worked out.

I only ask because while looking for possible upgrades, the spec is always provided and I need to compare, what I'm using with what I could be using.

Don't get me wrong I've already had some WOW moments. Like moon shadows on Jupiter. But am I still missing out on what the 250px can really show me.

[John]

When I had a 250PX the stock eyepieces supplied were a 25mm and a 10mm. The 25mm was labelled "Super 25 Wide Angle Long Eye Relief" I seem to recall. That was a 3 element design based on the Kellner eyepiece type sometimes also known as an Achromatic Hugens (AH) as well. It was not particularly "super wide" having an apparent field of around 50-55 degrees I recall. The 10mm was labelled "Super 10mm" and seemed to be a similar 3 element design to the 25mm but with a smaller field of view, perhaps 45 degrees, and quite tight eye relief.

The 10mm was not a very good performer and easily bettered by a standard plossl. The 25mm was better and tolerable as long as you did not look too closely at the shape of stars in the outer half of the field of view.

These things cost around £5 each on the used market so they are about getting you started. The next step up comes at around £30-£50 per eyepiece (new, less on the used market) and the scope will acquit itself much better if you can make such an upgrade and increase your range of focal lengths from the 2 supplied to 3/4. A barlow lens can be a helpful way to do this to save buying 3/4 eyepieces although a decent barlow costs as much as an eyepiece.

As Sir Patrick Moore once said, eyepieces are like gears in a car. One or two gets you going along but three or four are somewhat more useful !

Hope that helps

[ronin]

If I recall from the assorted posts the eyepiece's supplied with that scope are often "undefined". Meaning it is a bit of pot luck as to what is included.

Usually the eyepiecees are MA's, Kelners or Huygens, but on some 250's the people have had plossl's as the supplied items. However I thing the 250 is fast and plossl's may well be out of their comfort zone.

Usually there is a letter or two on the eyepiece, indication what they are, anything on yours?

P, PL, MA, RK, SR, R - anything anywhere ??

Upgrades depends on budget and what you look at in the majority.

[urchin]

John has them correct the 25mm is marked up as "super 25 wide angle long eye relief" and the 10mm just has "super 10" on it. No extra letters that I can see.

I'm quite taken with Jupiter just now its in a good position and is easy to find from my garden. I can easily loose an hour watching it cross the sky.

[John]

It's good to spend a good chunk of time observing a planet like Jupiter - you get to see more details as your eye gets "tuned in" to the brightness and contrast.