Recommended eyepieces to go with 80ED?

[Hipolito]

Hi There - I was just thinking of buying some additional eyepieces to make the most of the 80ED as I plan on using it mostly for viewing at the moment.

I already have a 25mm Plossl and a Ultima Barlow 2x piece. I was thinking in addition to get a 10mm and 6.4mm Plossl. The maximum power for the 80ED is 190x so I am guessing they are usable.

Any thoughts or suggestions?

Also, the Celestron X-Cel pieces seem quite expensive compared to the Skywatcher. Is there a hugh difference between the quality of the two?

Thanks

[kniclander]

Hipolito, see the recent thread on diffraction rings in the equipment forum - if you are using it at higher powers, it might be worthwhile investing in a better diagonal (unless you already have a better diagonal of course).

[John]

For wide angle, low power views you could think about getting a 32mm plossl which would barlow to 16mm so add some flexibility in the low to medium power range. The Ultima barlow is excellent BTW !. If you add a 10mm and 6.4mm to that they you would be well set up.

The Skywatcher plossls are quite decent as are those branded Antares and TAL. The Celestron X-Cel's are a different design which provide longer eyerelief and use ED glass which I assume is why they cost more. I don't think their actual optical performance is superior to standard plossls but the extra eye relief will make using them more comfortable, especially if you wear glasses when observng.

And do consider a change to a 90 degree mirror diagonal if you are still using the 45 degree prism one supplied with the scope - they are not good for astronomy - I think the ED80 has a 2" focusser so you could get a 2" diagonal which opens up the wonderful world of wide angle 2" eyepieces !.

John

[FLO]

... do consider a change to a 90 degree mirror diagonal if you are still using the 45 degree prism one supplied with the scope - they are not good for astronomy - I think the ED80 has a 2" focusser so you could get a 2" diagonal which opens up the wonderful world of wide angle 2" eyepieces !.

Definitely, it is better to upgrade to a 2" 90-degree diagonal first, even if you don't intend using a 2" eyepiece (everything else being equal a 2" diagonal will out-perform a 1.25").

HTH

[Hipolito]

Thanks guys

I still have the 45 deg diagonal supplied with the scope. I've not noticed any problems with it yet, but then again I haven't been using it at high magnification. However, I will replace it as the general consensus is that it is not particularly good.

Does buying a 2" diagonal means I cannot use my 1.25" Barlow? Also, the world of 2" eyepieces does seem a bit more expensive! Are the gains of 2" over 1.25 really that great? The costs may be a little beyond my pocket at the moment.

As mentioned in the other thread, the Skywatcher Deluxe looks like a decent option.

[John]

You can use your Ultima barlow between the diagonal and the eyepiece - the 2" diagonals come with 1.25" adapters and work great with 1.25" accessories.

2" eyepieces come into their own for low power, wide field observing but, using the adaptor mentioned above, the 2" diagonal will work very well with 1.25" eyepieces as well.

If you think you are only ever going to use 1.25" eyepieces by all means get a 1.25" diagonal but with a 2 incher you get the choice.

John

[Andrew*]

2" diagonals (almost?) always come with an adaptor to fit 1.25" accessories as well.

2" eyepieces are necessary to get larger FOVs than is possible with a 1.25" eyepiece. e.g. a 68° 24mm or a 52° 32mm eyepiece MUST use a 1.25" barrel, but if you want a wider FOV then you have to go 2".

A lot of people only have one or two 2" eyepieces but it's worth the larger diagonal for the nice big sweeping FOV!

Andrew

[Andrew*]

Ah, thought you might get there first John. Must take speed-typing lessons.....

[kniclander]

I went for the Stellarvue in the end. A 2" diagonal will do everything a 1.25" will do and is preferable because (if I understand correctly) the middle bit of the 2" mirror is likely to better than the outside edge of a 1.25" mirrorl. I avoided the 2" because I do not want to be tempted by 2" eyepieces:D. As always, I suspect that once you move beyond entry level stuff, the differences are quite marginal (only IMHO).

[Hipolito]

Great - thanks for clearing that up

If I can get confirmation that this Diagonals - Skywatcher Deluxe Di-Electric Star Diagonals does come with a 1.25 adaptor I may go for the 2" version and buy only one plossl at this point in time ... although that will definitely only be a 1.25 piece

[Jarndyce]

I use one of these with my C80ED and 6" SCT.

Diagonals - William optics 2" Dielectric Diagonal with CF Body and SCT Adaptor

Steve at FLO recommended one of these to me, and he was right - there is a noticeable difference over the supplied diagonal. It may not be the very best, but is several orders of magnitude better than the original.

[Hipolito]

Thanks - that one is about £20 more expensive than the 2" Stargazer model, but if it comes recommended ...

[John]

Thanks - that one is about £20 more expensive than the 2" Stargazer model, but if it comes recommended ...

I reckon you will not notice any difference in performance TBH - I reckon both diagonals come from the same manufacturer. I've owned a couple of William Optics diagonals and some clones of them and I really could not tell any difference between them in either performance or build quality - all very good

Thats just my viewpoint of course.

John

PS: I'm comparing the WO to the Skywatcher dielectric here - both are an improvement over the stock diagonals that come with the scope.

[Hipolito]

Thanks John - good to know.

[kniclander]

Hipolito, I changed my mind this morning and went for the 2" celestron XLT which is on special at telesope Plus (the David Hinds online shop) at about half price. Thanks to Johninderby for the tip.

for the spec it seems to be the best value by some way.

i will just have to be rigidly disciplined and not buy any 2" e/ps (although recent form suggests I may fail )

[John]

i will just have to be rigidly disciplined and not buy any 2" e/ps (although recent form suggests I may fail )

2" eyepieces are not necessarily more expensive than 1.25" ones and, for low power, wide field viewing, offer much more capability.

John

[FLO]

FLO has also acquired a number of the Celestron 2-inch diagonals at clearance price (I won't mention it in the sponsors section as there are only a handful).

[kniclander]

FLO has also acquired a number of the Celestron 2-inch diagonals at clearance price (I won't mention it in the sponsors section as there are only a handful).

Steve, I hope you won't mind me spreading my funds amongst your astro-retailing brethren...

ps - did you see my query about the vertical bars in the out of focus diffraction rings? (I think the post was headed "diffraction rings" in equipment help) Any ideas?

thanks

Dan

[FLO]

You must be using the image-erecting prism. If you hold it in front of you and view into it you will probably see the thin line along the prism edge - that will be the culprit.

Most image erecting prisms are intended for daytime terrestrial use where it rarely shows.

[Hipolito]

Thanks Steve - does the celestron diagonal also come with the 1.25" adaptor?

[kniclander]

cheers Steve - you are right that is with the erecting prism. Presumably it won't be there with the star diagonal.

thanks again

Dan

[Hipolito]

i will just have to be rigidly disciplined and not buy any 2" e/ps (although recent form suggests I may fail )

Hah, good luck!

[FLO]

Thanks Steve - does the celestron diagonal also come with the 1.25" adaptor?

Yes, it is shown fitted in the picture below (see long chromed thumbscrew and bronze compression-ring):

HTH

[Hipolito]

Great stuff. In that case, I shall be ordering one

[FLO]

Presumably it won't be there with the star diagonal.

No, it won't be there with the 2-inch diagonal and you will notice an appreciable increase in overall performance.