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 (As avatar)]

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]

Originally Posted by 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.

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 (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]

Originally Posted by Profiler

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 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 (Renato)]

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]

Originally Posted by 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

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

Anyone want my 4mm UWAN???

[AG Hybrid (Adrian)]

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]

Originally Posted by 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.

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_p...3#.Uzoa5KiSy5I and also this review http://www.televue.com/engine/TV3b_p...3#.Uzoa5KiSy5I

[astro744]

Originally Posted by AG Hybrid

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?

Good point! High power is better with larger aperture.

[MortonH]

Originally Posted by AG Hybrid

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?

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 (Brian)]

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 (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

[Kunama]

3.5mm LVW would give you 220X 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.