What would be the next logical eyepiece to get?

[crazzy88ss]

Hi, newbie here.

I have an Orion Skyquest 8XT 1200mm on a basic Dobsonian mount with 10, 20 and 25mm 1.25" eye pieces. 

To get some additional magnification, would a barlow lens be the next purchase to make?  If so, what features should I look for?

What about size of the eye pieces/barlow? The focuser will take 1.25" or 2" pieces.

I'm generally looking at planets.

Edited July 19, 2020 by crazzy88ss

[PaulM]

ive just ordered a 6mm eyepiece i have a 4mm which doesnt work well and an 8mm which is fine so hoping a 6mm gives me closer views of Saturn and Jupiter

[jetstream]

9 minutes ago, crazzy88ss said:

Hi, newbie here.

I have an Orion Skyquest 8XT 1200mm on a basic Dobsonian mount with 10, 20 and 25mm 1.25" eye pieces. 

To get some additional magnification, would a barlow lens be the next purchase to make?  If so, what features should I look for?

What about size of the eye pieces/barlow? The focuser will take 1.25" or 2" pieces.

I'm generally looking at planets.

How is your seeing ie steady skies?

[bingevader]

If you are thinking of a 2x barlow, then I'm not sure it would be the best investment with the eye pieces you have.

The 20 mm and 25mm with a 2x barlow would be too close in magnification to the 10 mm without and the 10mm with a 2x barlow would be good only on the moon most of the time.

As Jetstream is hinting at, your next move depends on how steady your views are.

I have a 6mm and from semi-rural skies and when the conditions are good it gives splendid views of the planets at 200x.

However, I can't say I am able to use it every time and less so atm, with Jupiter and Saturn still being low in the sky.

An 8 mm or possibly a 7 mm might be a better place to start.

[crazzy88ss]

Good point on a 2x barlow.

What exactly does "steady view" mean?  The scope itself is pretty solid on its mount.

[Louis D]

1 hour ago, crazzy88ss said:

Good point on a 2x barlow.

What exactly does "steady view" mean?  The scope itself is pretty solid on its mount.

How steady is the seeing in your area?  If the atmosphere is turbulent, there isn't much point in increasing your magnification because all you'll be doing is getting a closer look at blurry details.  Do stars twinkle at night or do they hang there in the sky like little Christmas lights on a tree?  Do bright stars show color flaring that rapidly varies at modest magnifications?  Those are signs of atmospheric turbulence.

[jetstream]

18 hours ago, PaulM said:

ive just ordered a 6mm eyepiece i have a 4mm which doesnt work well and an 8mm which is fine so hoping a 6mm gives me closer views of Saturn and Jupiter

Your 1650mm fl scope will give 412x mag with a 4mm eyepiece. This is quite a bit for Jupiter even with good seeing, reasonable on Saturn and Mars under vg seeing. The 350mm of aperture can be affected by sub par seeing a fair bit.

In general I use about 150x mag as a default for the planets regardless of seeing and aperture. If I cant observe using this mag I pack it in.

[jetstream]

13 hours ago, crazzy88ss said:

Good point on a 2x barlow.

What exactly does "steady view" mean?  The scope itself is pretty solid on its mount.

http://www.damianpeach.com/pickering.htm

[jetstream]

For a bit of a reference my TSA120 will go 375x mag + under Pickering 8 and the 15" over 700x. The TSA 120 goes much more but I'm limited by my lowest focal length EP, 2.4mm.

For a start a nice 7mm-8mm eyepiece will give you a very useable 150x to 170x mag in your XT8. Your scope will support much higher mag if well collimated and under good seeing.

Vixen SLV?- nice eye relief with excellent optics?

[bingevader]

The 7mm OVL Nirvana-ES UWA-82º Ultrawide Eyepiece is also very good indeed.

Couldn't resist getting the 150mm dob out to have a look at Jupiter and Saturn whilst comet spotting last night!

Not great seeing, but the 7mm gave just over 100x in this 'scope.

4 moons and 2 faint bands on Jupiter and a very distinctive Saturn with rings.

[John]

1 hour ago, jetstream said:

For a bit of a reference my TSA120 will go 375x mag + under Pickering 8 and the 15" over 700x. The TSA 120 goes much more but I'm limited by my lowest focal length EP, 2.4mm....

 

A couple of the finest scopes of their aperture made under probably some of the best observing conditions that any member of this forum has

It is worth knowing what is possible when it all comes together though

[crazzy88ss]

Is there an advantage to using 2" eyepieces over 1.25"?

[John]

48 minutes ago, crazzy88ss said:

Is there an advantage to using 2" eyepieces over 1.25"?

Only in the width of the field of view. The 1.25" barrel size restricts the maximum size of the field of view with longer focal length eyepieces so going to the 2 inch format is needed when eyepieces get to around 20mm in focal length AND the designer wants a large field of view.