Planetary Eyepiece 8 inch dob

[beachbum]

I'm having trouble deciding which planetary eyepiece to get for my 8 inch dobsonian, my budget is around 150$ and I was wondering whether a good amount of eye relief is too much of a quality sacrifice.

The four that I have been looking at are;

Celestron Ultima LX - 5mm

Vixen NLV Lanthanum - 5mm and 6mm

Baader Hyperion - 5mm

Baader Genuine Orthoscopic - 5mm and 6mm

Any advice for about these or suggestions for others in my budget?

[dweller25]

For the most comfortable planetary views in a Dob I found wide angle eyepieces with long eye relief to be the best.

The 5mm is a good size, of the four you mention the Celestron Ultima would be my choice.

The 5mm Baader Ortho is VERY sharp and has good contrast but you will have to nudge a lot more.

I saved up a little longer and bought a 5mm Pentax XW which is superb in the Dob.

[beachbum]

Thanks, this is the first eyepiece that I will be buying, does a longer eye relief effect the sharpness or quality of the view?

[dweller25]

Thanks, this is the first eyepiece that I will be buying, does a longer eye relief effect the sharpness or quality of the view?

I have directly compared the 5mm Baader Ortho with a 5mm Pentax XW, sharpness and contrast are the same but the Pentax is MUCH more comfortable to use.

[johninderby]

A second hand 5mm Nagler would be about £150.00 and would make a great planetary eyepiece in an 8" dob.

John

[John]

I used to use a 5mm Nagler Type 6 in my dobs and it was an excellent eyepiece. It's eye relief is 12mm. The Pentax XW is also superb and, while having a slightly narrower field of view than the Nagler, has even more eye relief, 20mm I believe. My current 5mm is an Ethos / Antares 1.6x barlow combination when I want ultra-wide field or a 5mm Baader Genuine Ortho whan I want minimum glass simplicity. The tight eye relief, small eye lens and small field of view of the latter does make it more challenging to use but optically it's fanatastic and, in my opinion, the best optical performance you can buy for under £100.

You will gather from this and the other posts that the choice is wide at this focal length !.

[solarwallace]

I can second that the Baader is good but difficult to use due to the pin head sized viewing.

Not sure if this is within your budget but you could use a x2 Barlow with a 10mm ortho for more comfortable viewing. I'm using a 9.5mm volcano topped ortho for this purpose.

Regards

Steve

[Mr Spock]

This is where dob owners make compromises. Ideally, for planetary use an orthoscopic will give the best detail and contrast. But, it's a case of nudge, nudge, nudge due to the 40° field. So, people use Naglers with their 82° field. A good eyepiece, but pants compared to an ortho.

Other choices? I have a few eyepieces of different designs, so here goes.

TMB planetary: 60° field, 20mm eye relief, but not as sharp in short focal length Newts as SCTs. A good inexpensive choice.

Vixen NLV: 50° field, 20mm eye relief. Sharp and contrasty as an ortho despite having eight elements! The 20mm isn't really usable though as the field closes in as you move your eye closer.

Nagler: 82° field, shorter eye relief and sharp to the edges. Not as sharp as orthos and suffers from black outs/kidney beans. On uniform bright objects such as the moon this gives some weird shading effects. Too expensive when new so secondhand only.

Orthoscopic: 40° field. The planetary eyepiece of choice but that field is limited for a Dob. At short fl eye relief is miserable.

Plössl: 50° field. Inexpensive compromise. Not that good at f5, very usable at f8 and above. Short fl eyepieces have poor eye relief.

Vixen LVW: 65° field. My personal favourite. Very sharp edge to edge. 20mm eye relief and it's all usable, you can put your eye anywhere! Very expensive when new so it would be secondhand only. Oh, and they are big!

Radian: 60° field, 20mm eye relief and very sharp. Another one with odd blackout effects.

[John]

... So, people use Naglers with their 82° field. A good eyepiece, but pants compared to an ortho....

Our "mileage varies" here Mr Spock:).

I tried a BGO 7mm back to back with a Nagler Type 6 7mm for several sessions last year and the differences in contrast and sharpness were virtually undetectable.

Underwear just didn't come in to it !.

Just my experiences of course

[beachbum]

Thanks everyone, I decided to go with the Vixen NLV Lanthanum - 5mm

[stolenfeather]

I have always heard good things from Celestron. I just purchased a Barlow from that company myself. I guess I'll put it to the test!

Isabelle

[spaceboy]

Nagler: 82° field, shorter eye relief and sharp to the edges. Not as sharp as orthos and suffers from black outs/kidney beans. On uniform bright objects such as the moon this gives some weird shading effects. Too expensive when new so secondhand only.

Radian: 60° field, 20mm eye relief and very sharp. Another one with odd blackout effects.

Sorry to question this given you have more experience than me but I have to disagree with some points here. Naglers although I say myself are over rated IMHO, do require a certain finesse when using which if ignored can result blackouts by the user. Its all about the users awareness to utilize the exit pupil light cone entering your retina at the end of the day not the abilities of the EP. This is also true with radians. When purchased new radians and Nagler T4's they came with donuts to place over the lens to aid eye placement for non spectacle wearers to avoid BO & KB. Once gotten the hang of there is no need to the placement circle. I am assuming the weird shading effect on the moon is simply down to the obtuse curve require on the optics which is an unavoidable compromise made for a wide FOV to be achieved. I have only noted this problem with the shorter 7mm in my collection. I am unsure if this is common to the shorter FL Nags but I have not seen any issue with the longer FL ones.