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Planetary eyepiece upgrade


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If your 102mm F/8.6 refractor is of decent quality (is it a Tele Vue 102 perchance ?) you may well find that a 6mm eyepiece is barely pushing it.

With my 102mm and 100mm refractors I find that 5mm - 3mm focal length eyepieces get lots of use in planetary, lunar and double star observing.

Mine in that niche are:

Pentax XW 5mm

Tele Vue Ethos 4.7mm

Takahashi TOE 4mm

Tele Vue Nagler zoom 4mm - 2mm

Pentax XW 3.5mm

Frankly they all seem superb so I'm finding it difficult to pick between them 🙂

I'm sure the Delos and DeLite eyepieces are up there as well 👍

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I really like the Pentax XW 5mm and 3.5mm for planetary viewing, but even better, for me at least, is a binoviewer, 2X barlow, and a pair of 18mm plossl's. The 70° apparent field of the XW's also lends them to high power deep sky viewing. The 4.5mm Baader Morpheus is a nice eyepiece too!

Edited by mikeDnight
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Try the new Svbony 3-8mm zoom if eye relief isn't an issue for you.  I did a write-up on it here on SGL and have read lots of very positive reports both here and on CN.  It punches well above its price.  It's excellent from 5-8mm, and still pretty darn good from 3-4mm.  Add a quality 2x Barlow, and you'll have quite a range of high powers to choose from.

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4 hours ago, The Lapwing said:

In fact the more I think about it the more sense it makes. I had an early Baader, but it literally fell apart. I have had a morbid fear of zooms since then, but I am assuming a 6-3 zoom is, er…Tele Vue quality? 

The TV Nagler zooms are very good quality items. Their price is very high though.

The Svbony 3-8mm zoom is a very similar design, a lot less expensive and offers an even wider zoom range. It could cover all your medium/high/very high magnification needs in one eyepiece. 

I would like to try one of those myself - good call from @Louis D 👍

 

Edited by John
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14 hours ago, Louis D said:

Try the new Svbony 3-8mm zoom if eye relief isn't an issue for you.  I did a write-up on it here on SGL and have read lots of very positive reports both here and on CN.  It punches well above its price.  It's excellent from 5-8mm, and still pretty darn good from 3-4mm.  Add a quality 2x Barlow, and you'll have quite a range of high powers to choose from.

I use my 3-8mm zoom with a 130mm F5 and a 10" F5 and it is great in both scopes.  It takes a barlow very well.  Granted I can only compare it to BST Starguiders, but at 8mm, 6mm and 4mm it is much better than the Starguider (8mm,  12mm and 8mm with 2x ED Barlow).  The big advantage for me is that the one eyepiece covers pretty much every power that the seeing supports.  Having stumped out a couple times with magnification was intensely frustrating.  Now I just drop this in a get the ideal power for the seeing.

Edited by Ratlet
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2 hours ago, Ratlet said:

I use my 3-8mm zoom with a 130mm F5 and a 10" F5 and it is great in both scopes.  It takes a barlow very well.  Granted I can only compare it to BST Starguiders, but at 8mm, 6mm and 4mm it is much better than the Starguider (8mm,  12mm and 8mm with 2x ED Barlow).  The big advantage for me is that whilst I'll often 

Were you in mid-sentence? 😜

Edited by Philip R
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I’d suggest going the binoviewer route if you can - I find the improvement over mono for lunar and planetary viewing transformative and much more dramatic than swapping any single eyepiece in for another, assuming of course that both are of at least decent quality. I do have one each of Delos, Tak TOE and Vixen HR as well as 5 and 7mm Pentax XWs and all are terrific in different ways but the best planetary views - including with any of the above used singly - have been with the binoviewer and pairs of orthos and Televue Plössls .  And these are *relatively* inexpensive eyepieces. Something to consider, perhaps, before rushing out to spend the best part of £400 on a Delos, for example? 🙂

Edited by JTEC
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3 minutes ago, JTEC said:

I’d suggest going the binoviewer route if you can - I find the improvement over mono for lunar and planetary viewing transformative and much more dramatic than swapping any single eyepiece in for another

+1 to that. A binoviewer can be a little fiddly (achieving focus, merging the images) but once you have the hang of it the view is amazing, particularly of the Moon.

I also find them much easier on the eye(s), so that I am comfortable to gaze at the Moon for extended periods.

 

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BVs on Mars at opposition were transformative for me.  Mars went from being an overexposed orange-red blob to having a wealth of detail.  I suppose I could have tried a moon filter on it for monovision, but none was necessary for BV usage.  I was seeing detail in my Dob rivaling photographs.  In particular, one night, Mars looked very similar to the upper left image below:

spacer.png

I was able to easily discern the light/dark/light row of fine detail near the center of the image (Xanthe Terra region, I believe).  The best I've done in monoviewing has been to discern Syrtis Major in the lower right image, but only as a featureless dark marking.  That, and the polar caps are fairly easy, but featureless.

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20 minutes ago, Louis D said:

BVs on Mars at opposition were transformative for me.  Mars went from being an overexposed orange-red blob to having a wealth of detail.  I suppose I could have tried a moon filter on it for monovision, but none was necessary for BV usage.  I was seeing detail in my Dob rivaling photographs.  In particular, one night, Mars looked very similar to the upper left image below:

spacer.png

I was able to easily discern the light/dark/light row of fine detail near the center of the image (Xanthe Terra region, I believe).  The best I've done in monoviewing has been to discern Syrtis Major in the lower right image, but only as a featureless dark marking.  That, and the polar caps are fairly easy, but featureless.

I love seeing the light cloud on Mars , amazing we can see it. My 10" years ago gave me a similar view to your description. IIRC I was using a 3-6 Nagler zoom.

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4" f/8.6 = FL of 875mm, I would round off.

If it's a decent instrument, and it is, magnifications up to 240x are possible.

That is a 3.6mm eyepiece.

 

If you have the scope mounted on a tracking mount, the 3-6mm TeleVue Zoom is a strong possibility.  It's not just a single eyepiece, it's a whole set of planetary eyepieces in one because all the in-between magnifications can be used.

 

If you have the mount on a non-tracking mount, then I would not recommend a 50° eyepiece.  I would try to go wider--at least to the 62° of the TeleVue Delites (which come in 3mm, 4mm, 5mm, 7mm, etc.)

or to even wider apparent fields like 68-80°.  You may hear endless comments about how this eyepiece or that eyepiece is a better planetary eyepiece, but if you have to push the mount so often you only have a few seconds

when the scope has settled down to yield a sharp steady image before you have to push it again, those super-high magnifications will not be enjoyable to use.

It's a reason I use a 3.7mm 110° eyepiece a lot for planetary and lunar observing in my 4" refractor.  If the seeing supports such a high magnification, the eyepiece in the focuser will give a great view, even if it's not a Zeiss, or Takahashi.

 

All that presumes you don't need glasses at such small exit pupils, and few observers do.

What may be the case, however, is that the really small exit pupils might start showing you floaters in your own eye.

My 4", for instance, has great optics and can easily support a 3mm eyepiece, but my vision cannot.  Floaters interfere seriously when the exit pupil gets smaller than ~0.6mm (roughly a 4mm eyepiece).  I can only go smaller on double stars.

So that is the one caveat I would mention for using eyepieces shorter than, say, 4.5mm in your scope.  For double stars, the limit is only determined by seeing and telescope optical quality.

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9 hours ago, Philip R said:

Keep an eye open for TeleVue Radian’s too. I have a 6 & 8mm. They are now discontinued and were superseded by the DeLite’s a few years later.

Radian are a great eyepiece in my opinion, I have had a few of them. They get a bad press on some, er… forums for reasons I don’t fully understand. One woman on there said she was doing the astronomy community a favour by binning the ones she owned….seriously. 
 

As it happens I am looking for a 12 mm Radian at the moment. 8 mm seems to be everywhere 

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Thanks for the comments. In the end I bought a 5mm Delite I came across on eBay literally seconds before its time was up for 175 quid. It’s supposed to be as new so for that money it would have been silly not to, well I think so anyway. 
 

I have my TV 102 on a Gibraltar HD4 and after consideration I thought 50 degrees was just a little too tight to live with so I discounted the zoom. 
 

Thanks for your input

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I tried Radians in an astro shop in 1998 when the first came out.  They had terrible SAEP (kidneybeaning) in daytime usage.  The Vixen LVs and Pentax XLs did not and had equivalent correction, so I went with a 9mm LV and 5.2mm/14mm XLs.

I'm glad I did because strong SAEP limits using these types of eyepieces from being used for solar or lunar observing in my experience with other eyepieces with strong SAEP like the TV NT4 line.  If you back off and lose some field, then they become usable again on bright targets that cause your eye's pupil to constrict.

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On 01/05/2023 at 17:49, Louis D said:

I tried Radians in an astro shop in 1998 when the first came out.  They had terrible SAEP (kidneybeaning) in daytime usage.  The Vixen LVs and Pentax XLs did not and had equivalent correction, so I went with a 9mm LV and 5.2mm/14mm XLs.

I'm glad I did because strong SAEP limits using these types of eyepieces from being used for solar or lunar observing in my experience with other eyepieces with strong SAEP like the TV NT4 line.  If you back off and lose some field, then they become usable again on bright targets that cause your eye's pupil to constrict.

That’s an eye opener [pun unintended] as I purchased my 6mm Radian during early 1999 and 8mm Radian [secondhand] during late 2022.

I admit, I was a little dubious about using the 6mm when I first used the 6mm in my ETX105 as I was getting ‘blackouts’. This was because I did not fully understand the use of the supplied exit pupil guide* and did not use it, or I had temporarily mislaid it! 

This was before the plastic rear end got damaged following an accident/incident and had replaced the backplate with one that I had made for me by a local engineering workshop [and before Jim Wegat https://wegatoptical.com/shop/ made them].

 

 

 

* How use the TeleVue Radian & Nagler/type 4 exit pupil guide... TV Radian Eyepiece Instructions.pdf

Edited by RT65CB-SWL
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