Planetary eyepiece around 3mm?

[MortonH]

Last night I had great views of Mars in my SV110ED, but with my shortest FL eyepiece (4mm) the magnification topped out at 193x when I could have gone higher.

The next step up would probably be a Nagler 3.5mm but I'm also considering something around 3mm to give 257x. The problem is that there don't seem to be many options at 3mm.

I'd like to maintain the quality of my current eyepieces (TV, Pentax & Explore Scientific) and I'm not convinced about the Orion/William Optics 3mm planetary ep.

Any suggestions?

[brian nordstrom]

:thumbsup:Morton there is a 3mm radian on amazon. Com at the moment , under telescopes then Telvue .
Its a good price .
Brian.

[astro744]

3mm Radian if you can find one. Otherwise 4-2mm Nagler zoom or 6-3mm Nagler zoom or both as they really are excellent performers. 2.5mm and 3.5mm NT6 Naglers are very good especially if you need the extra AFOV due to drift but I use the zooms more.

Both zooms are variable but have click stops. The 4-2 every 0.5mm and the 6-3 every mm in focal length.

Note they were called 2-4mm and 3-6mm but I noticed Tele Vue recently renamed them to 4-2 and 6-3mm (makes sense).

[MortonH]

Should have mentioned that I used to own the 3-6mm Nagler zoom but sold it last year (doh!). Ideally I'd like more eye relief but the 2-4mm might be an option.

Brian, thanks for reminding me about Radians. I've owned a couple in the past and they were good performers.

[astro744]

Both Nagler zooms have 10mm eye relief which is way better than Plossls in that short focal length. The T6 Naglers have 12mm of eye relief.

If you want more eye relief then the Radian is the one to go with. Note the 3mm Radian is now the only one shown on Tele Vue's site and no longer listed on Bintel's site. You would have to ask if it was still available.

[Profiler]

Hi Morton

Although I wasn't expecting such results I was extremely impressed last night by the performance of a 5mm T6 Nagler coupled with a standard 2x TV Barlow.

This essentially replicated the 2.5 T6 Nagler. Keep in mind I was using a high end TV barlow as well.

I could discern no difference (other than slight increase in magnification) between this combination and my 3-6 Nagler zoom (set at 3mm).

However, it had the huge advantage of having 12mm ER (that 2mm really did seem to make a difference) but most importantly 82 fov! This is a huge advantage if you aren't using a motorised mount.

You mentioned the 3.5 T6 but I suspect that won't really give you the bump in magnification you are craving but at the same time when you get to these high powers keeping the target in the fov becomes a big problem unless you have a tracking mount.

I wouldn't recommend the 2.5T6 outright as the opportunity to use it consistently are likely to be few and far between but also the 3.5 may not give you what you really want in terms of magnification.

The 5mm T6 gives you good magnification which you can use for other targets, helps with initially finding objects and then can also be bumped up for additional power when you need it.:)

PS
Also keep in mind a good quality 1.6 barlow if you can find one.

[astro744]

This is a good combination and if you want to go down the Barlow/Powermate path as it opens many more possibilities.

e.g. with 900mm F.L. Note eye relief (E.R.) is increased when using Barlow hence the +.

7NT6 + 2x Barlow = 3.5mm/82deg/12+mm E.R., 257x
5NT6 + 2x Barlow = 2.5mm/82deg/12+mm E.R., 360x
9NT6 + 2.5x Powermate = 3.6mm/82deg/12mm E.R., 250x
7NT6 + 2.5x Powermate = 2.8mm/82deg/12mm E.R., 321x
16NT5 + 5x Powermate = 3.2mm/82deg/10mm E.R., 281x
13NT6 + 5x Powermate = 2.6mm/82deg/12mm E.R., 346x

There is also a 4x Powermate in the 2" size (heavy!) that will offer more combinations. One of the best views I ever had was of Saturn with a 35mm Panoptic + 4x Powermate; Huge eye lens, great eye relief and lots of magnification! Only problem was I needed a counterweight as it was that heavy.

All of the above eyepieces are excellent without any Barlows or Powermates for many objects on many different telescopes.

I prefer the Powermate to the Barlow as you never get any vignetting and the eye relief remains as with eyepiece alone. Note not all Barlow/eyepiece combinations vignette.

Note even a 0.5mm difference in focal length gives a big difference in magnification that is even more noticeable at the eyepiece than the numbers alone may indicate. This is why the Nagler zooms are so useful especially with short refractors.

[Renato1]

I've got a huge 2.5mm eyepiece that I never use, and two Televue Barlows which I very rarely use, mainly because I also have a 2.5X Televue Powermate which I always use now for higher power with other eyepieces than what my 4.7mm eyepiece can provide.
Regards,
Renato

[MortonH]

Lots of good info there - thanks guys.

I used to own a Powermate and was always impressed with the views, but that was when I didn't know much about contrast, light transmisison, etc. In recent years I've preferred to use a single eyepiece only and I've grown my collection accordingly. However, it seems I may have made a mistake selling the 3-6mm zoom!

I also have enough heavy eyepieces in my bag so ideally I'm looking for a smaller form factor like a Nagler or Radian. Shame there's no such thing as a Pentax XF 3mm!

[MortonH]

Can anyone comment on how a 19mm Panoptic would perform with a 5x Powermate? Just realised that the 19mm would convert to 3.8mm and my 14mm Explore Scientific would convert to 2.8mm. Then I wouldn't need my 4mm UWAN at all.

[PlanetMan]

On CN there is a very thorough review examining the performance of a 24 Pan with 5x powermate against a Tak 5mm LE - it gives high praise to the performance of the Pan + Powermate combo

[MortonH]

Just found that article. Sounds like the 5x PM is the way to go.

Anyone want my 4mm UWAN???

[AG Hybrid]

I was going to suggest a Nagler zoom. They seem to get good reviews.




YOU ALREADY HAD ONE!



Just grab yourself a 3.5mm Delos/Pentax XW. Job done Mort. Open and shut case Johnson.

That being said have you considered the exit pupil with a 3.5mm or less is? Its 0.50mm. You don't have a eye floaters problem do you?

[astro744]

It works very well with the 19mm Panoptic. I've not tried it with the ES14. Powermates are essentially invisible and the 5x is the smallest and lightest Powermate and can also be used for imaging, (T-Ring adaptor optionally available).

See http://www.televue.com/engine/TV3b_page.asp?plain=TRUE&id=143#.Uzoa5KiSy5I and also this review http://www.televue.com/engine/TV3b_page.asp?plain=TRUE&id=143#.Uzoa5KiSy5I

[astro744]

Good point! High power is better with larger aperture.

[MortonH]

Prefer something smaller than the Delos/Xw. My eyepiece case is already too heavy and cramped.

I do have some floaters in my eye. Occasionally they get in the way a little bit but if I adjust my eye position they go away. I've used the Nagler zoom at 3mm before and they weren't a problem.

[brunono2]

I looked at Mars last night with a 3 mm radian- fanstastic!
I WISHED I HAD A 2.5MM

Agena astro is selling a 3mm radian for USD $186 Agena are the best and quickest suppliers I have ever met with low postage costs

Cheers Brian

[Profiler]

+ The 3-6 Nagler Zoom is certainly nice and small and gives you sufficient power for what you are after.

- It is not necessarily the most comfortable ep to look through and only has a 50' fov - this is a real problem when using it at the 3mm click stop without a motorised tracking mount


+ The 3.5 Delos and XW provide 70' fov which is 'good' (not great) for following an object without a tracking mount and are supremely comfortable to look through for a protracted period of time

- These are probably the largest eyepieces in the Delos/XW range - not the biggest EPs in existence but they dwarf most other planetary EPs. Additionally, 3.5 in terms of magnification may not be sufficient for what you are after

+ Barlows/Powermates - Will certainly give you the power you desire dependent on what combination of EP you ultimately pick

- Tend to get a bit cumbersome and heavy having a train of EPs and barlows

It is little surprise that it is often commented that Astronomy is all about compromises in terms of getting one set of features for others:shrug:

[Kunama]

3.5mm LVW would give you 220X :question: 65º / 20mm eye relief / sharp across the full field.

[MortonH]

Coming round to the 3.5mm idea, since 220x is the "maximum useful" magnification for my scope. The 5x Powermate will give 275x with my 14mm eyepiece, which is probably too high.

[astro744]

For some reason I though you had a 900mm focal length telescope but I can only see an SV110ED as 770mm/f7.

That being the case there is an argument for both 6-3mm Nager Zoom and 4-2mm Nagler zoom in you arsenal. The latter for those exceptional nights and the former for most other nights. The image may be a bit dim at the 2mm setting but at 2.5mm you still get 0.35mm exit pupil.

I use both on my TV-60 and do not feel the image is too dim at 180x and 0.33mm exit pupil with the 2mm setting but my 'scope has only 360mm f.l. at f6.

On your telescope the 6-3mm would give 128x to 257x and exit pupil from 0.86mm to 0.43mm. The 4-2mm would give 192x to 385x and exit pupil from 0.57mm to 0.28mm.

Note both 3.5mm and 2.5mm T6 Nagler eyepieces would complement each other with your telescope.

I find the zoom is ideal for fine tuning the magnification as it provides variable focal length between click stops. Some nights you can go higher and some nights not so. I also agree with a previous comment about 50 deg AFOV and 10mm eye relief being more than adequate, but of course that is a personal preference.

Note there are another couple of options.

8-24mm Zoom + 2.5x Powermate gives 3.2mm to 9.6mm.
8-24mm Zoom + 5x Powermate gives 1.6mm to 4.8mm.

There are a number of 8-24mm zooms on the market and are not all the same construction. The Tele Vue and Vixen are very nice.

[MortonH]

I have a real dilemma about this. Yesterday I was sold on the 5x Powermate option to get 3.8mm and 2.8mm. Then I got spooked about the exit pupil thing.

Tricky. I can afford a new Powermate but not a new Nagler zoom!

[Profiler]

The Nagler Zoom is a bit of a nightmare to clean and is only really suitable if you are using some sort of tracking/motorised mount that will maintain the target in the fov for you. Otherwise, it becomes a real problem trying to keep the target in position of the 50' fov especially when you start heading down from 4mm onwards.

Get a 5mmT6 and a good quality 2x barlow - you will be pleasantly surprised. Both the Televue Barlows and T6 Naglers are some of the few in the TV EP range which are still made with 100% Japan optics.

[astro744]

Nothing wrong with using your 19mm Pan and ES14 with a 5x Powermate.



Nothing wrong with this option either and if you ever get a 7NT6 you'll end up with both 2.5mm & 3.5mm combinations.

May I suggest you create a spreadsheet of the eyepieces you have in rows and then have separate columns for magnification, AFOV, TFOV, exit pupil and then also have multiple sheets for each Barlow/Powermate combination.

(2x & 3x Barlows and also 2x, 2.5x, 4x & 5x Powermates; note 2x & 4x Powermates are 2" only).

[MortonH]

Already have the spreadsheet!

Latest thought is a 2.5x Powermate to turn my ES82D eyepieces from 8.8, 6.7 and 4.7mm into 3.5, 2.7 and 1.9mm.

I find these quite comfortable to use and the wide field would be a big plus with my non-tracking mount.

[astro744]

Sounds like a plan. Note the 2.5x Powermate originally came out with an unusual barrel with the field lens protruding slightly below the 1.25" barrel and as a result there was no way of threading 1.25" filters. I know because I have one of these. The newer one as shown on Tele Vue's web site has a different barrel which I would think is threaded. (You would have to check with BINTEL).

Note although BINTEL still show an image of the previous version on their web site I would think you would now get the newer version but again if this is important to you then check with BINTEL when ordering.

If buying used beware of the two versions.

[MortonH]

Ended up getting the 2.5x Powermate and have just ordered the $59 Long Perng 3mm planetary from Andrews - it was too cheap not to try!

[omegacrux]

Hi Morton
Myself and another member ordered the same long pern 3mm , good value .
And they appear to be the same as William Optics 3mm

David

[MortonH]

Sounds good!

[brian nordstrom]

;) Sorry Morton , I forgot about my LP3mm , its that good I now use it as my dedicated high power white light solar eyepiece when viewing the sun in my SKY90 and hershell wedge . ( it has a variable polarising filter perminately screwed in , as well as my other solar eyepiece a 12.5 Saxon ED ) .

I did a few side by sides with my 3mm TV Radian and there was not much between them and at $59 from Andrews at the moment a bit of a steal .

Brian.

[MortonH]

Hi Brian, yesterday I found a thread from last year where you were singings its praises so thought I'd see for myself :D

[MortonH]

Last night I got some excellent views of Mars with my ES 82° 8.8mm and 2.5x Powermate (effectively 3.5mm together). In my SV110ED it gave 219x, which was usable for around 20 minutes of reasonable seeing. Mostly I used the Powermate with a 10mm XW at 193x.

I think I'm glad I didn't splash out on a new 3mm Radian as it wouldn't get much use.

[Regulus]

Morton I bought an LP 3mm and received it today and the general look and feel is quality.
On land use (it's raining to much to test it on the sky) it was sharp and had pretty good colour transmission (120x600SW refractor).
Here's the thing, and I would be interested in Brian's comment: it clearly says 20mm Eye Relief on the barrel but it has about the same ER as a GSO plossl. In fact it is the first time I have had to get so close that my eye lashes were in the way.
Luke at Andrews says he hasn't heard this complaint before so I wonder if mine's a bit odd.
A friend (Omegacrux) received his today as well too and I am waiting on his report re ER. Will be interested in your comments when you've gotten yours.
Trev

[brian nordstrom]

:) Trevor , I hope you enjoy yours , these are very good eyepieces will give about 200x in your frak ? high but usable on those nights that will allow this and your 120mm will easily take this ( my now sold 150mm f5 did ) .
Also with their huge eye lense and even at say , 15- 17mm eye relief these are a much easier eyepiece at 3mm than a plossl will ever be at that FL :thumbsup: .

On the 20mm ER I found that in a direct side by side with my 3mm Radian that mine is that close to the advertised 20mm that I did not notice a difference , hence it became my solar high power EP , and at that it is very good as well .

Look forward to Yours , Morton's and Omegacrux's reviews , this will give some idea on their QC that LP employ with their eyepieces :question: .

I also believe these are WO's 'planetarys' and Orion's 'edge on?' eyepieces minus the brand name .

Brian.

[Regulus]

Finally got around to trying the LP 3mm tonight and very disappointed.
Like it's got a soft focus filter built in and my budget Celestron 4mm Plossl remarkably sharp by comparison. In fact my 9mm GSO through a GSO 2x barlow was much sharper than the LP 3.
I am waiting for a friend to give me his thoughts on the one he bought to see if mine is just 'wrong'.
It will be returned and Luke at Andrews has one put aside to swap back to me, but is that just a big risk? I will have paid $20 in postage by the time I return it and gained no value, so not happy.
Would be interested in comments if others have this EP so I can decide whether to replace or refund.
(Your comments are noted Brian, but one more favourable would be encouraging)
Trev

[omegacrux]

Hi all
Well I tried the LP3mm in my ed80 (i purchased off Baz great scope)
Focus was not good but I put it down to seeing , there was a lot of twinkling in the stars !
I haven't tryed it in the 10in dob yet , I think it might be too much , unless its an exceptional night , and then it'll zoom out of the ep FAST

David

[PlanetMan]

Unfortunately at these Fl's the "quality" and "observing conditions" are absolutely critical and must be carefully gauged and kept in mind. Whereas you have no control over the sky the choice of EP can be critical

IMHO the absolute best pound for pound planetary eyepiece suited for "refractors" is the [B]TELEVUE NAGLER 3-6 ZOOM/B]

5 element design made in Japan with the amazing ability to fine tune magnification dependent on the sky conditions. They are readily available to buy and have much better ER in comparison to some of the other elite planetary EPS (XO, ZAO). Their only downside of course is cost at around $500 at Bintel. However when you realise they represent potentially 7 eyepieces in one package (ie 6, 5.5, 5, 4.5, 4, 3.5, 3) not to mention the smaller gaps in between they are well worth it as a genuine lifetime investment.

So - if you are daunted by the prospect of a $500 outlay for a new zoom I recommend anyone to don't hesitate for a moment if one comes up 2nd hand. They seem to rarely come up for sale 2nd hand but they are IMO well worth the money and I haven't meet anyone who has been disappointed with one

[omegacrux]

PlanetMan
Good idea , taken onboard
Il keep an eye out

David

[MortonH]

Mine seemed ok in my 110mm scope but the mag was too high for the seeing to be sure. Will try again with a smaller scope tonight if I can.

[MortonH]

I've had my 80mm f/7 scope out for the last hour or so. Mars is still not high enough to push the magnification very high, and the seeing might not be the best, but this is what I think so far:

With my 4mm UWAN, the view is not steady yet but I can clearly see the polar cap and surface markings, and this is the less well-defined face of Mars tonight.

Switching to the LP 3mm, I can still clearly see the polar cap, and I can see some of the surface features that were visible in the 4mm. But the whole image is less sharp.

The deterioration in image between the two eyepieces is exactly what I'd expect from pushing the magnification too high for the current seeing conditions. If it stays clear I'll keep monitoring every 15 minutes or so for a while but there's nothing about the LP's performance that tells me it's a dud. However, I may never find out unless I get really good conditions one night!!!

Bear in mind that going from a 4mm eyepiece to a 3mm is a 25% increase in magnification, which is a lot. This is why the Nagler zoom exists, as PlanetMan says above - because the optimum focal length tonight might be 3.8mm, or 3.2mm, or anywhere in between 3mm and 4mm. But if we only have 3mm and 4mm to choose from, the 3mm might be a step too far nearly every time. That's why I'm glad the LP is so cheap, because it might only get used twice a year!

[MortonH]

Update:

After my previous post I went back outside and the seeing had steadied a bit. I was now able to see the same detail in the LP 3mm that I'd seen in the 4mm UWAN, although the optimal magnification for the seeing would still have been a little bit lower.

Some clouds covered Mars so I moved over to Alpha Centauri. The view of this double star was as perfect as I could hope for with my equipment and the conditions. I had viewed it a couple of nights ago at virtually the same magnification in my 110mm ED scope (with the 4mm UWAN) and if anything the view tonight was better. The airy disks were well defined and there were quite a few faint stars visible in the field. There's definitely no "soft focus" effect with this eyepiece.

The other interesting thing I found is that the 55-degree field of view didn't annoy me. Most of my shorter eyepieces are 82 degrees and my mount is undriven, so I though a 'narrow' 55-degree field might bother me. I think the excellent eye relief compensates for the narrower field, so in real world use it's fine.

So I guess I'm with Brian on this one. Quite possibly the best value eyepiece I've ever owned!

[omegacrux]

Yup seeing has a lot to do with it
I split the same double tonight mine you could see a definite gap the stars had quite an airy disc around them
Just have to be patient
Trev you must have a dud il bring mine over try it in your scope

David

[PlanetMan]

For anyone who might be interested a 3-6 Nagler Zoom has just come up for sale in the classifieds

[Wavytone]

Morton, seeing has nothing to do with it. 3mm equates to 190X on your scope, which is considerably higher than what the diffraction limit suggests as useful for any 80mm scope.

If you look carefully at the detail you can actually see on say Jupiter or the moon I think you'll find 4-5mm will be optimum. 3mm is not helpful, the image will be bigger but dimmer and fuzzier and you won't see any more detail.

FWIW I had my 180mm Mak out tonight too and mars was ok at 220X, good seeing here. The darned clouds refused to cooperate though and after an hour Saturn was still a no show so I packed it in.

[Regulus]

Hmmmm Seems like mine is a dud then.
The lunar view last night was sharp as in the little celestron 4mm and looked like I had gladwrap over the objective with the LP3mm in the SW120 f5

[MortonH]

Ah, yes. Forgot about diffraction. Maybe once a year in my 8" Newt for the 3mm then!

[PlanetMan]

The alternative would be to buy yourself a refractor with a very short focal length - ever thought about a TV-60 FS-60, Sky90 or Genesis/TV101/NP101 - you will get plenty of use out of a 3mm eyepiece - mind you the old expression of 'putting the cart before the horse' does seem to spring to mind:rofl:

[MortonH]

In light of the diffraction issue, I dragged my 8" f/5 Newt onto the balcony last night instead of the refractors. Turned out to be a good decision as the seeing was decent and Mars put up a good show before I lost it behind the roof around 10pm. I briefly had the LP 3mm in the scope (at 333x) and although it was definitely too much, there was one moment when the polar cap froze in the seeing and the black band that surrounds it was clearly visible. A memorable view for sure.

With Mars lost to view I turned to Saturn. Being lower down the best views were around 213x (4.7mm) and 250x (4mm). As it climbed higher in the sky and the view became more stable, I started to notice something strange about the edges of the rings. It was like they were 'rough' or something. I moved up to a 3.5mm eyepiece and realised I was seeing the Encke division for the first time! Tried the LP 3mm but it didn't improve the view.

The point of all this? Well, the LP 3mm is a very decent eyepiece in my opinion, and worth having since it's ridiculously cheap, but 3.5mm is probably enough for 99% of the observing I'm likely to do.

I should mention that the 3.5mm in question is a Vixen LVW. It was offered to me after I had ordered the LP 3mm. It's a big, heavy eyepiece (like the XW and Delos 3.5mm models) but significantly cheaper and a great performer. If I hadn't already bought the LP 3mm I would have been happy for the LVW 3.5mm to be my highest power eyepiece. It will see MUCH more use than the 3mm.

[Wavytone]

Great, 3.5mm on your 8" gives 286X or 1.4X per mm of aperture which confirms what I would regard as the ideal highest power f.l. for an f/5 scope with photopic (colour) vision, i.e. 1.5X per mm of aperture.

[brian nordstrom]

:thumbsup:Yes , my 3mm Radian gets lots of use in my SKY90 , a nice easy 166x that the Takahashi takes with ease .
I looked at Mars last night with this combo and I was rewarded with some excellent views , like Morton says , when the seeing steadied for those few seconds at a time , nice combo .
For a lark I tried my 5mm Radian and 2x powermate giving 200x and it was even better , but only fleetingly , as 166x was cleaner almost constantly .

Morton I am glad you like your LP3mm , they are a good high power eyepiece for sure , off the top of my head I think its about 4 positive reviews and 1 so-so report , Trevor seemed to have lucked out .

Brian.