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Orion Sirius plossl worth keeping

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Those are better than most eyepieces thrown in with a scope.  Pretty good, actually.

You could use another one in between the 25mm and 10mm, like a 15mm.

The exact half-way point in magnification would be an eyepiece of 14-15mm.

You'll also find the 10mm might not give you a sharp image every night because of turbulence in the atmosphere (it's called Seeing).


In the long run, you'll want a lowest power eyepiece in the 40mm to 32mm range to get the widest field the scope can yield and the brightest image possible in the 90mm.

But in the mean time, the eyepieces you have are fine.  You'll use the 25mm more.  Planets and Moon are fine, but there are hundreds of nice star clusters that will be great in your scope.

I suggest you a. learn the constellations (if you don't already know them), b. get a decent star atlas to help you find more objects than just the ones visible to the naked eye

Here is a great one for free:


Mark on the pages all you want--it can be reprinted at will.

Then, learn how the scope works, learn how to star hp if the scope isn't computerized, and start with star clusters.  No two are alike and there are hundreds of them in reach of a 90mm scope.


And, I beg your forgiveness if you aren't a beginner, remember the following rules:

1) Don't even bother looking for these faint objects when the Moon is above the horizon.  Wait till after moonset or observe before moon rise.

2) Be dark adapted--that means 30-45 minutes outside away from lights before you start going for faint objects.

3) Don't bother if there are a lot of clouds in the sky because the uncloudy part of the sky is still hazy.  A few clouds on the horizon is no problem.

4) Start at low power until you identify the field, then increase the power until the object is visible.  You will probably find magnifications of 60x+ most useful for DSOs.  Remember, the image gets larger with magnification, but also gets dimmer.

5) Don't look for objects until it is completely dark.  The sun must be 18° below the horizon (90 minutes at 40° North on Mar21 and longer at 50° N).

6) Due to the atmosphere dimming objects when it gets thick, try to confine your observing of faint objects to nearer the N-S meridian, where objects are highest in the sky.

Avoid looking at faint objects below about 30° off the horizon if you can.

7) Use averted vision.  Instead of looking directly at the object, look 15° toward the side (right side for right eye, left for left) and let the area of the retina most sensitive to light see it first.

If it's bright enough you can then look at it with direct vision.  Some objects will only be seen well with averted vision.




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They're decent, entry level Plossl (symmetrical) eyepieces.  The older ones from the 90s like I have were made in Taiwan (by GSO?) and were MgF2 singly coated.  You can tell this because the only lens reflection is pale violet.  They're not quite as good as my GSO Super Plossls which do seem to have slightly better correction to the edge and are multicoated (several color reflections like green and red from the lens).

Those two eyepieces should serve you well for quite some time.

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