View Full Version here: : Recommendation for 5mm eyepiece
10-05-2012, 08:49 PM
I have a Black Diamond ED 120MM Refractor, looking for some ideas for a 5mm eyepiece, eye relief isn't an issue.
Also is a 3.5mm too much for this scope ?
11-05-2012, 12:19 AM
I don't know what type of eyepiece you like but for me it has to be 60 to 68 degrees. 70 is ok too, plus lots of eye relief... so many to choose from, read the thread on LVW or NLV, so much good stuff in there specially the Hyperion/Stratus/ LVW review somewhere on page 2. I learnt massive amounts 'bout eyepieces in there.
11-05-2012, 07:11 AM
5mm is a safer choice on most nights, when you get really good seeing with steady atmosphere you might be able to use a 3.5mm at over 200x mag but not that often
11-05-2012, 09:31 AM
I use a 4.7mm Explore Scientific 82 degree with my 120 Tak which I like.
Wide field high power eyepiece, nitrogen purged and waterproof, comfortable 14mm eye relief. It'll give you 230x which is about as high as you'd want to go 90% of the time. Good value too.
11-05-2012, 09:49 AM
Dennis, it really depends on which BD120 you have, they come in 600, 900, or 1000mm focal lengths.
I suspect you have the 900? If so, Daniel is pretty right, any shorter than 5mm will rarely give you a good quality view.
What other eyepieces do you currently have? And how much are you willing to spend?
11-05-2012, 05:44 PM
Yes Jason it's the 900mm focal length, i do have a 25 mm old meade plossal,i do like it, probably came with the LX 50 SCT which i still have. A 9mm Vixen LV,13mm Televue plossal and a 2inch 28mm which came with the Skywatcher .
I had visions of a 20mm 2inch Nagler and 5mm Nagler VI ;)
Do those 82 degree fields make that much difference?
What is a good range to have Jason?
12-05-2012, 08:34 AM
The 5mm Nagler is a great eyepiece but I sold mine when I found that I used the 3-6mm zoom more often. The Nagler 3-6mm zoom is very versatile and I decided I didn't need both.
12-05-2012, 09:41 AM
Dennis, going from 100x (9mm) to 180x (5mm) is a big jump in magnification.
If you go for 30x per inch of aperture, which is reasonable, that's about 140x.
900/140 gives us 6.4mm so a 6 or 7mm would get a lot more use, and is a good step from 9mm.
If you're considering Nag20+Nag5, then you don't mind spending on a good eyepiece.
Around 7mm there is the Nagler Type VI 7mm, the Pentax XW 7mm, the Tak LE7.5mm
I have the Nag and the Tak, both are very good. I've not tried the Pentax but it is supposedly great. I like the Nag for night time astro and the Tak for daytime nature stuff. The Tak is also great on the moon.
There's not nearly as much at the 6mm mark, then at 5mm again you have the Nag, Pentax and Tak.
Whether you go for the 5mm or 7mm, I'd stick with one of these three brands. Nag will be the widest, then Pentax, with the Tak the narrowest, which will mean moving the scope more often.
Yeah, I'd look more around the 6 or 7mm mark as suggested by others.
Dennis, how happy are you with the 13mm TV Plossl and 9mm Vixen LV, both which are around 50 deg FOV? With a 120mm/900mm ED refractor, I'd be considering a quality ~17mm/70 deg FOV EP first, but that's just me...
12-05-2012, 07:43 PM
Others have steered you down the right path.
5mm gives you 180X which depending on your prevailing local seeing conditions you may not get use on a fair number of nights. I had very good local seeing on the Central Coast and could have used 180X at least 9 nights out of 10. But that's pretty rare for most topographical conditions.
A 7mm eyepiece gives you 128X which to be honest I don't think is quite enough.
That leaves you IMO trying to find something decent at the 6mm focal length. Unfortunately pentax don't make a 6mm XW but a 6mm Televue Delos would easily be your best option. You could also go for a 6mm Nagler T6 or hunt around for a 2nd hand 6mm TV Radian. Other options are 6mm Clave if you can find one or 6mm UO ortho or 6mm UO HD ortho or the Baader 6mm genuine ortho. There are also a number of high quality 6mm japanese plossls you could raise 2nd hand. There are quite a few options 2nd hand where you will get an excellent eyepiece for not a lot of money. The new options are great eyepieces but not cheap. The cheap new 6mm eyepieces IMO aren't as good as some of the older stuff in the lower price brackets.
12-05-2012, 08:59 PM
:) Hi Dennis , I got me one of the 3mm Planetary eyepieces from Andrews ( Long Perng ) and for the asking price its really very good , it gives me 166x in my LP 90mm f500 LP apo .
It has 20mm eyerelief as the whole range does has , so its easy to look thru and for the $59 ( the rest are $99) its definatly a keeper , very well made with no suprises when I use it , it just gets on with high powers , verty nice .
These are William Optics eyepieces made in the same factory , but dont have any brand name printed on them , :hi: .
Here is it in my TV Pronto to give you an idea of its quality build and size.
Highly Reccomended .
13-05-2012, 12:12 AM
I agree with John but would also add the TMB Planetary eyepiece on to the good value list. While not the same league as the Delos/Pentax gear they are pretty nice and good calue for money...nice eye relief and physically small...Cheers...
13-05-2012, 08:03 AM
I forgot about the TMB planetary's. They very good performers for the price with good eye relief and they have a 6mm variety.
13-05-2012, 01:51 PM
Pentax xo 5mm or televue 3-6mm zoom. Personally I'd go with the Pentax.
17-05-2012, 11:30 AM
I'm just wondering if anyone has views on the trade off between the 50 degree field of view on a nagler zoom EP vs the ultimate convenience of having a single EP that handles (what would be for me) the main focal lengths for planetary viewing.
Would it be better to barlow up a longer nagler and keep the 82 degree FOV, or have the convenience of a zoom nagler that is adjustable to the conditions on the night and keep bumping the scope along for the planetary viewing session?
I have a 4.8mm TV Nagler. I think that is pushing it. I wish I had of got around 7mm. Few nights can handle something 5 or under well.
18-05-2012, 08:43 AM
I can send you my 5mm TMB planetary for you to try out if you like. Just drop me a PM with your address.
19-05-2012, 08:39 AM
The Pentax XW's in general have a very good reputation although I have never looked through one myself. Having stated this caveat I have looked through both the 5mm T6 Nagler and 3-6 Nagler zoom - both of which struck me as exceptionally good EPs.
When looking at Saturn and keeping all elements constant (scope, diagonal etc) the Zoom at the 5mm setting (and all other settings for that matter) had a slight but clear edge in terms of contrast, clarity and crispness of what I could see. So, for pure optical performance the zoom was better than the standard 5mm Nagler. Additionally, the zoom is brilliant in being able to fine-tune the magnification to whatever increases or decreaes you think your equipment can handle on any particular night and whatever you might prefer in terms clarity versus magnification. The big stumpling block for the zoom is the fov. This is not however a problem if you have a tracking mount in which case the problem is nullified as the mount will simply maintain the target in the fov for you and thus you get all the benefits of the zoom with none of the disadvantages.
Having stated all of this the 5mm T6 Nagler is by no means an optically shabby EP either and is also amazingly clear and sharp when you appreciate that it is an 8 element design versus 5 in the zoom. However, where the 5T6 really excels is naturally in the fov if you are not using any sort of tracking mount. The object remains in the fov for sometime and you will find yourself using this EP alot for its ease and comfort and quick pragmatic set-up.
Finally, with respect to ER both are roughly the same and ironically not too bad at all in terms of comfort. I find them both easier to look through than Tak LE's which are meant to be the ER eyepieces by Tak. In terms of comfort for pure extended observing I would probably tip my hat towards the 5T6 but the zoom is still pretty good
01-06-2012, 03:58 PM
I would say, go for the 6mm TMB Planetary.
They are so affordable and light on your wallet.
For less then $60, it is hard to beat and the optics are good enough for most viewing.
They are very popular due to its incredible affordability and very often appears on the For Sale section.
Of course if you have a golden wallet buy the Nagler,the Pentax.
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