Sub 3.5mm eyepiece for planetary/lunar

[Slawomir]

Hi all :hi:

Recently I started enjoying visual astronomy a bit more often and thought that I would like to see if a tad more planetary/lunar detail can be squizzed out of my 105mm f/6 triplet. My shortest FL eyepiece is 3.5mm Delos, which I like for its FOV (I track manually) and ease of viewing through. But it is a large eyepiece as well. My next one up is 5mm Delite and I really like how it performs with my small refractor on the planets and the moon, and it is very easy to look through.

Would a 3mm Delite be too close to 3.5mm Delos on the planets/lunar? I was also thinking perhaps 2.5mm TOE could be a good candidate as well, but not sure if I would like such short eye relief and narrow FOV with manual alt-az, and also doing 630/2.5=252x might be a bit over the top with such small aperture on the planets for a reasonably comfortable viewing. I observe without glasses.

I would appreciate any comments and advice :help:

[glend]

I guess the only question is just how often do Seeing conditions allow the use of such an EP? I doubt a change from 3,5 to 3,0mm is going to give you much any way. Just my opinion. Going to a longer focal length scope is going to give you much more impact.

[astro744]

Get a quality 2x Barlow and use with your 5mm DeLite. A Powermate would be better to maintain eye relief but there is none at 2x in 1.25” size so you need a different focal length eyepiece to start with if using a 2.5x or 5x Powermate.

2.5mm at f6 gives 0.42mm exit pupil which for me personally is the smallest I prefer before the image starts looking dim. 252x is a nice power for Mars.

Note 0.5mm increments in focal length of the eyepiece are noticeable even at 630mm focal length.

Between 3.5, 3 and 2.5 you go from 180x, 210x and 252x and seeing will determine which yields the best image. On my TV-101, I use the 6-3mm and 4-2mm Nagler zooms for variable magnification. If seeing is superb, I use the 4-2 zoom for 135 to 270 magnification. Then again when seeing is superb I often switch to a larger aperture (Newt) for a lot more light at the same magnification, (achieved with differing focal length eyepieces).

[bigjoe]

Seeing is the big thing at ultra high powers I feel Slawomir..I have one Tak Toe left a 4mm .The 4mm and 3.3mm I had bested the 4mm delite not by much just a little contrast wise..it is a narrow field though ..you would go mad with non tracking..I tried the Delites,still have some 98 % as good with great sharpness and contrast; a 3mm would be great on Saturn or Mars but NOT Jupiter in your scope except a few rare nights a year.

Jupiter is a real PAIN at taking Mag usual 175 to 250 max on most good nights..contrast just gets washed out.

Its up to you screw on a good Barlow for 1.5x extra? But that can wash out contrast on Jove too..very difficult if you like observing Jupiter most nights a 3mm delite not worth the rare use of it BUT great for DOUBLES; split Pi Aquillae in your Delos youll love that one at 1.4"!
Hope that helps a bit.

BTW Baader CONTRAST Booster is amazing on planets in so so seeing.

Cheers Bigjoe.

[Atmos]

From my experience I’d say there is a bit of a visual difference between 180x and 210x, especially on nights of better seeing. For me it may even be my astigmatism makes it easier for me at higher mags. I know others with better eyes have had an easier job seeing details at lower mags that I need higher ones for.

Of course, that could also be simply more observing experience as that also plays a big role.

[Slawomir]

Thank you all for advice and comments. Much appreciate it.

A larger scope is at of question for the time being, and I'm quite happy at the moment with the short tube and performance of my small fast refractor on a manual alt-az.

I have TV 2x Barlow but feel that although it works nicely with my 13mm Nagler, for high resolution planetary observing (as high as one can expect from a 4" glass) I prefer to keep it simple and without a Barlow. Will think of Powermate though.

I did notice slightly more detail with 3.5mm Delos than with 5mm Delite, so perhaps a bit more magnification with a 3mm Delite might be the way to go for Mars, Saturn and the Moon, to test the waters, before I consider a 2.5mm TOE.

Thank you all again :hi:

[N1]

Hi Slawomir, another low cost option you might consider are the TMB planetary knock-offs available on alixpress and elsewhere. I got the 2.5mm to use in my FS60 a few years ago and was very pleased with the results. Alex (mental4astro) thought it did alright to, versus an XO2.5 no less...

[Slawomir]

Thank you for your suggestion Mirko :thumbsup:

[N1]

I understand the ES 2x focal extender currently for sale on the classifieds would be the next best thing to the non existent 2x 1.25" Powermate... Just another option to consider

[Slawomir]

Thanks Mirko.

Would it be any better than my 2x televue Barlow?

[N1]

Probably not as far as image quality (though not far off), but the ES extenders are said to behave like a Powermate in that they don't alter the eye relief of the EP like a barlow does.

[Wilso]

Hi Suavi,
I personally wouldn’t go to any higher powered eyepiece than you have without tracking. I use a good quality barlow or extender to try first as these are always useful when the conditions permit ( which aren’t that often) but will give you a better eye relief and possibly fov. If available get the dedicated extender for the scope.
Cheers :thumbsup:

[astro744]

There is a 3mm Orion Planetary in the classifieds for a reasonable price may be worth a try. If you do want to go lower than 3mm may I suggest you put a wanted ad for a 2.5mm Tele Vue Nagler. This will give you a much wider apparent field for longer viewing when not tracking.

Your 5mm DeLite with 2x Tele Vue Barlow is a fine combination to give you an idea of what 2.5mm will show you in terms of magnification. When not using the 4-2 Nagler zoom I use both 3.5 and 2.5 Naglers on the TV-101. A 3mm Radian fills the gap in between and this is where the Nagler zoom is so useful for it is an infinite number of focal lengths between two limits with click stops every 0.5mm, (1mm click stops for the 6-3mm Nagler zoom).

[Slawomir]

Thank you all for your suggestions, all are very helpful :thumbsup:

I know that going lower than 3.5mm with such small aperture is perhaps a little over the top. I tried both 5mm Delite and even 3.5mm Delos with my 2x Barlow with manual tracking to get some idea, but I feel, perhaps wrongly, that less glass is better when going for such high magnification with such small aperture.

I have a very good goto equatorial mount that I will ocassionally set up for longer sessions.

Anyway, I made my decision and pulled a trigger on 2.5mm TOE. If this eyepiece will not sit well with me, someone may get a bargain on classifieds in the near future :lol:

Thank you all for sharing your experience and for suggestions :hi:

[Atmos]

I’ve comfortably used around 250x with my 4” when looking at Jupiter, Mars, Moon and stars clusters so it’ll be good with yours I’d say. Too high for Saturn though with 4”; dims a bit too much for my liking.

[Slawomir]

Thanks Colin for confirming that :thumbsup:

Just managed to see Dione and Thetys with both 5mm and 3.5mm eyepieces. Ganymede's shadow on Jupiter was a highlight of tonight's short and sweet viewing session. Seeing looks below average tonight.

[Don Pensack]

105mm, f/6 = 630mm focal length.
3.5mm = 180x.
3.0mm = 210x. That is a fair increase.
2.5mm (Vixen SLV, Skywatcher planetary) = 252x That is a big increase.
So I agree, a 2.5mm is too much. A 3mm is the next logical choice. TeleVue, Orion, Explore Scientific. There are choices if you look around.
But you won't find a better eyepiece than the Delite.

[Slawomir]

Thank you Don for your reply.

I have already ordered Tak TOE 2.5mm, if anything to satisfy my curiosity.

I really love the performance of 5mm Delite - easy to use, very sharp and shows pretty much the same detail on Saturn and Jupiter as 3.5mm Delos perhaps it even has a bit less scatter than 3.5mm Delos on bright planets with my diagonal, my scope and my eyes.

3mm Delite is definitely on the cards.

[Slawomir]

Hi all,

My 2.5mm Toe arrived yesterday, and I was able to take advantage of a few hours of clearish skies before it got more humid and cloudy last night.

It is a very nice eyepiece, and surprisingly still quite comfortable to look thought, in spite of working with only 105mm aperture at 630mm FL (mag 250x). Last night I set up a mount with tracking to allow for comfortable observations with higher magnifications.

To my eyes, I did not see any more detail with 2.5mm Toe than with my 3.5mm Delos, and perhaps even with 5mm Delite, but the image was larger and it has made seeing some of Saturn's moons a bit easier (but some were easier in 5mm Delite).

Overall - I like how it worked last night on Saturn and Jupiter.

Splitting Rho Capricorni (1.7" separation) confirmed that this eyepiece works just fine with my telescope.

And yes, I went silly and barlowed 2.5mm Toe and 2x TV barlow on Saturn (mag. about 500x with 105 mm). Still could clearly see all 5 moons (not at once of course as they didn't fit into the view) and the image held together well, which is a testimony to the quality of glass in the light path.

[The Mekon]

Interesting report Suavi,
I observe a lot with my 106mm F6.5 (I take the FL as 700mm) using both a 5mm Nagler (140x) and a 4mm DeLite (175x). Mostly I find that the 4mm does not show better resolution than the 5mm, just makes it a little easier on the eye. By this I mean that if I can detect a double star's companion at 175x, it will also show at 140x. If seeing allows I will push to 280x with a barlow, but using the barlow for 350x is futile and the view is always better at 280x.
The same eyepieces give 185x and 230x in my 132CFF. I have barlowed to give 370x with this scope but never used the 460x option.
I will say that the 132 at both 185x and 230x is superb and the use of the 4mm in this scope makes more of a difference than the jump from 5mm to 4mm than in the 106.

[Slawomir]

Thank you John for sharing your observations.

After another session with 2.5mm Toe and comparing planetary and lunar views with 3.5mm Delos and 5mm Delite, I think 5mm Delite shows every detail that there is too see with 105mm aperture (mag 126x), but the two shorter FL eyepieces make seeing some aspects and structures easier to observe, especially the 3.5mm with its 20mm eye relief and its large lens. Having said that, I feel that 2.5mm Toe will become my favourite eyepiece when chasing doubles on a goto mount with tracking.

[bigjoe]

.
Slawomir..
The Toe 4mm is my go to doubles EP in my 115mm 805 Very little LIGHT SCATTER or any other annoying abberations as in most widefields; the 3.3mm is the same too...The Delites are outstanding too ..use em for all else.
Bigjoe

[jamespierce]

Chiming in late on this thread. The Nagler 2-4mm zoom is a very good eyepiece (so is the 3-6) having the ability to tweak the magnification quickly, and push up to the seeing limit is a big benefit over having to switch between eyepieces. The only real downside is the small FOV.


The Tak EPs are really nice too, but end up being much more expensive to have an equivalent set, my sense is the quality is much the same.

[Slawomir]

I was worried that 2.5mm Toe will be too much for my eye(s) with 105mm f/6, but surprisingly it is still quite comfortable to look through, and as you wrote, optically Toe are excellent and fantastic on doubles. I also really like how 5mm Delite works with my small telescope - currently it is my favourite planetary eyepiece.




Thank you James for sharing your impressions - I thought of Nagler 2-4mm but I believe those are unavailable any more. I wanted as simple eyepiece as possible below 3.5mm, and 2.5mm Toe seems to present a good balance in terms of optical performance and ease of use. Would be cool though to easily adjust magnification, so perhaps I will try a TV zoom eyepiece one night :thumbsup: