Other focal lengths needed?

[gooseholla]

Hello there.

I have some plossls at 6.5, 9, 12, 15, 20, 32 and 40mm as well as 9,m, 15, 25mm Kellners and a 3.6 super MA. Also have a 2x and 1.5x Barlow. Are there any other focal lengths that I should consider for my collection? Or any other type of eyepiece design?

I use a 8 inch Newtonian made by Celestron.

Thanks

[Ags]

You have a very good selection of focal lengths. Perhaps consider a few shorter focal lengths for viewing planets, such as a 5mm or 4mm. The TS Planetaries (and similar TMB clones) are often recommended, as are BST Explorers. Both these designs offer short focal lengths with good eye relief and a wider field of view than a plossl, and are relatively affordable.

If your newt is F6 I think your 40mm plossl is not useful - the 32mm shows the same amount of sky while the 40mm will probably make views dimmer as it gives an exit pupil of nearly 7mm so if you are not in your twenties then the light cone will be larger than your eye pupil.

[rwilkey]

Sticking to Plossl's does not make for a varied selection, go for wider angles, the BST's are in between, great quality and 60 degrees, better eye relief than your shorter f/ratio plossl's. The BST Explorer 5mm would be a useful addition if you want to view the planets better and with more precision.

[newman]

You already have more than enough of a selection of various magnifications. Probably more than you'll effectively use. So I don't see a point in getting any more budget eyepieces, you're pretty much covered. Unless you're willing to invest in something that would bring a marked improvement in quality, such as premium wide fields, I don't see much of a point in getting more ep's.

Best way to shape your collection is to look through what you do have as much as possible. You'll get a much better idea of what you actually do need, which focal lengths are useful, which are less useful for you, etc.

[John]

I think your Kelners are redundant to be honest. Can't see the MA 3.6 getting a lot of use either. The 40mm plossl shows no more sky than the 32mm and is more "tube like" to view though so that's probably redundant as well.

So that's thinned your herd out by 5 eyepieces

You might want to think about moving to the 2" barrel size for the 32mm - that would give you a larger field of view.

[gooseholla]

Nah kellners do get use sometimes. Those and the MA were my first eyepieces before the plossls. They still get regular use. The 40mm also came before the 32, as it was cheap. They aren't necessarily redundant in my observations, but granted, they do get less use than the plossls.

[NGC 1502]

Your signature in post #6 asks why Chelmsford does not have an astronomical society. North Essex Astronomical Society

is not far away. Or my own club, Castle Point AC, meets near Rayleigh. I'm sure you would be most welcome at either.

Regards, Ed.

[gooseholla]

Your signature in post #6 asks why Chelmsford does not have an astronomical society. North Essex Astronomical Society

is not far away. Or my own club, Castle Point AC, meets near Rayleigh. I'm sure you would be most welcome at either.

Regards, Ed.

Thank you, but both are too far for me.