please critique my eyepiece collection

Hello,

I'm relatively new to the hobby (less than a year) and am still learning to see, etc. The planets and the moon are my main targets.

The following eyepieces are used with an Orion ED80 and an Orion XT10.

XT10 ED80
30x 15x 40mm Plossl
48x 24x 25mm Plossl
86x 43x 14mm TV Radian
120x 60x 10mm TV Radian
170x 85x 7mm TV Nagler
240x 120x 5mm X-cel
324x 162x 3.7 ED-2

My criteria for the above were developed using Ultima and Plossl EPs and a barlow:
1) High quality, minimum distortion EPs for most frequently used XT10 magnifications (85x, 120x, 170x).
2) Maximize eye relief.
3) Avoid barlow.
4) Minimize cost.

All but the plossls were purchased via Astromart classifieds.

Any suggestions (e.g. gaps to fill, additional purchases,etc.) or comments?

Thank you for your time.

Jack

P.S. You can't hurt my feelings, so fire away if I'm out in left field. I'll check for replies once a day.

You've got some great eyepieces there--and good spacing. It matches my sequence for a 10" Discovery dob. Is yours an f/4.7?

OTOH, there's no reason to avoid a barlow--and it does offer incredible versatility and even better views. I would get a 2x barlow, say an inexpensive Orion shorty barlow. That would let you double up the power on your Radians (and maybe the 7mm Nagler, but I don't know that eyepiece). You might find that the planetary views are better through the barlowed Radian than the Epic/X-cel, but others who have done that should chime in. If the views are better, you simply sell out the redundant eyepieces.

Do you have a 2" focuser? If so, then I'd recommend a wide field low power 2" eyepiece for star hopping, framing larger DSOs, and sweeping the Milky Way.

Otherwise, you'll be the best judge of whether there are gaps... when you're out observing do you often wish for a little more or a little less power? If so, you've got a gap. If not, forget about it!

A few comments:

The 40mm eyepiece is too large of an exit pupil for the 10". Also, if it is a 1.25" plossl, it is giving the same true field as a 32mm plossl would (i.e. narrower TFOV). So I would dump that one for either a 32mm plossl (cheapest option) or a 2" widefield eyepiece in the 30-35 range. If you want to stick to 1.25" eyepieces than maybe swap both the 40mm and 25mm for a 24 pan.

You might find that the 10mm radian is a bit redundant with the 7mm nagler (about the same TFOV), so if you notice that it doesn't get much use, I would consider selling that one. I found this to be the case when I had both a 13 nagler and an 18 radian (same TFOV, 18 didn't get used any more).

The spacings look good at the high end. If you find it hard to track with the 5mm and 3.7mm, you might consider upgrading them to naglers or Pentax XW's someday for the wider FOV. Not urgent, and pricey, so only do it if the narrow FOV bothers you in terms of tracking the dob.

Lastly, I know you said you wanted to avoid barlows, but I find that using a 2.5x powermate with my nagler T6s works very well. I have the 13, 9 and 7, which with the powermate gives 5.2, 3.6, and 2.8. It allows you to get the wider FOV without costing quite as much (3 naglers plus a powermate vs. 6 naglers).

Hope this helps,

Jarad

My thoughts as the owner of an 10 inch F5 Newt.

1, A widefield 2 inch eyepiece somewhere around 32mm. This will make finding stuff much easier and give some nice views if the eyepiece is a good one.

2. A decent widefield eyepiece around 20-24mm or so. This would be around 50-60x, some very nice views here of open clusters and the like.

3. I had a 5mm Excel, mine was not a good eyepiece. (I gave it away rather than selling it because I did not feel comfortable selling it) I have not heard good things about these in general.

You have a 10mm Radian and 7 mm Nagler. Add a 2X barlow and you will essentially duplicate the Excel and ED-2 but with much better optics.

Barlows are good things, especially in fast Newtonians where the increase they effective focal ratio of the scope so that astigmatism and coma from the eyepiece are reduced significantly (even drastically.) The Excel and ED-2 both have some sort of barlow or barlow like front section so there is not need to use them just to avoid using a barlow.

Last but not least... At F4.7 your are getting into Paracorr territory. Find a used one for $150 or so and it would be a nice long term addition.

Just my thoughts...

jon

I will echo the others comments on Barlow/Powermate - no need to avoid if you get a good one. You might want to try the TMB 1.8X Barlow - one of the very best, and only about $180.

First, I'd say that you have a collection vastly superior to all but the very best equipped amateurs of the pre-Tele Vue era! We live in a golden era of eyepieces. So don't worry too much, and enjoy the views.

I'm actually with you on the avoiding a barlow - not because of optical issues, but convenience issues. I just don't like fidgeting with the things. A personal issue. I do have a marvelous 2.5x Powermate, and I do use it but I've been building up my short focal length collection, so I may in fact sell it some time in the future. It's a magnificent gadget, though.

40mm 1.25" barrel Plossls are an odd historical relic that really shouldn't be built anymore. I think people were accustomed to using 40mm Kellners as a low power eyepiece, and wanted 40mm eyepieces, but a 32mm Plossl will show just as much sky as a 40mm Plossl.

Especially if you want to stay with 1.25 inch eyepiece, you should definitely consider replacing the 40mm and 25mm Plossls with a 24mm Panoptic. Really. Think about it - you'll see just as much sky as the 40mm, but at about the same magnification as the 25mm Plossl! It's a beauty.

So much for me telling you to be happy with what you have...

Hi Jack,
I'll echo the sentiments regarding a 1 1/4" 40mm Plossl concerning TFOV. Personally I don't particularly like using Barlows although I don't knock any of the comments here. A Quality Barlow can be a great investment to reduce costs.
I'm fortunate enough to own an extensive set of all types of EPs. As indicated the 10mm Radian and 7mm Nagler are somewhat redundant as far as FOV. On nights of excellent viewing I find the Radian provides only slightly better planetary viewing.
Personally I suggest you look at selling the 40mm plossl and 10mm Radian. If finances permit you should look at the TV 24mm Panoptic. I love mine enough that I bought a second one to use in my binoviewer & Vixen binoculars.
Since you indicated you like planetary & moon viewing I'd suggest you look at a 10mm and/or 4 or 6mm Ortho of some type. Especially through the 80mm ED they do provide great detailed images. UO Orthos (& HD Orthos) are a good value for the price and can be found through AstroMart with some patiences. A step up for considerably more $$ are the TMB Super Monocentrics but they have a Very narrow FOV which would be a problem with the 10". To be honest, on a non-motorized mount they're a pain.
Anyway, just thought I'd throw in my 2 cents. Whatever you wind up with, Enjoy!
Clear Skies, Bill

Hi Everyone,

Thanks for all the great input.

Remember, I'm a newbie.

1) There's a 24mm panoptic in my future. You're logic makes perfect sense for low magnification in a 1.25" EP.

I use the 40mm to find the Sun in the ED80 (can't use my finders!). The 24mm Pan has nearly the same TFOV (2.72 vs 2.86) so away goes the 40mm. The 25mm plossl provides 1.08 TFOV in the XT10 which I was using for star hopping. I bet I can learn to use the 24mm even though it's 1.36*.

2) I find using a barlow to be a pain (previously owned the Ultima, the views were fine, but...). Maybe improved views via barlowed TVs vs the 5mm and 3.5mm Xcel/ED Epic will make it worth the effort and the pain will go away. I'll borrow some barlows and make a decision.

3) Speaking of the X-cel/Epic, I don't see a great deal of difference between them and the TVs for near edge coma, flat field, etc. when using the ED80 (I think it is f7.5).

*Does that make sense or is it my inexperience?

4) I'm still a little confused about choosing an EP based upon true FOV vs. magnification vs. a combination of both.

*Does the following 'justify' the 120x Radian or is my inexperience showing?

On *some* nights the 120x gives a much clearer view of Jupitor than 170x. The 170x seems to wash out. Backing down to the 86x is clearer yet, but the larger planet at 120x seems to be a better compromise.

5) It sounds like Orthos may add detail to the views of planets and the moon. I have heard that small differences in magnification around 100x often increase detail while not sacrificing contrast (the most prominent person I've heard say this is Ed Ting). Of course, I don't know what a small difference is.

*Based upon these two ideas, would adding a 100x Ortho be justified?

*Or would a different magnification for an Ortho make sense based upon the following (50x (24mm Pan), 86x, 120x, 170x, 240x, 340x).

Thanks again for all the great input.

Jack

It's a terrible collection!! you should send them to me and start over.

I won't tell anyone about how bad your original collection was.

Hi Jack,

I'd ditch the 40mm plossl and get a 32. My dob is similar to yours and the 40 had too much eye relief and exit pupil with only a 43 degree f.o.v. Otherwise I like your selection.

IMHO you could spring for a 22mm Panoptic or Vixen LVW. 1.2 degrees @ 54x on the XT10.