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Johan03

Eyepiece for Televue TV-60?

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Hello,

Newbie here with a TeleVue TV-60. I wonder what the maximum useful magnification would be with this refractor?

I need a high power eyepiece mainly for carbon star and double star observation.

My only eyepice now is a TV Panoptic 24mm for wide field/large exit pupil.

Would a TV Delite 4mm eyepiece Yield to small exit pupil (0,67mm) at 90x magnification?

Best regards / Johan

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2 hours ago, Johan03 said:

Would a TV Delite 4mm eyepiece Yield to small exit pupil (0,67mm) at 90x magnification?

That is going to depend on how many floaters you have in your observing eye.  I find that exit pupil to be right at the limit for my eyes.  Below that, I have to keep flicking my eye to move the floaters out of the way for a second or so to see something clearly.

There are folks using Vixen HR eyepieces down to 1.6mm in APO refractors, so it really depends on the person and the scope how low you can go on exit pupil.

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I have owned a TV60 for over 10 years. It is a wonderful scope for travel and quick look viewing. 

If you only want three eyepieces for the TV 60, I recommend the Panoptic 24mm, the Nagler 9mm and the 3-6mm Nagler zoom.

The 3-6mm zoom covers all high mag conditions and allows you to get the best out of the situation. I have used a Vixen HR 2.4mm but there is little gain unless the conditions are absolutely perfect. I think the 4mm Delite would be fantastic however the 3-6mm zoom is just more versatile.

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Thanks for the input!

Plyscope: Do you use the zoom Nagler 3-6? Have you tried it at 3mm in TV-60? Good for double stars?

Louis D : I have not seen any floaters when observing the night sky but I only have a low magnification eyepiece. When I observe the bright and clear sky a sunny day without telescope I can notice some floaters. Might be a problem when observing faint carbon stars and splitting double stars or just when observing the bright moon?

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5 hours ago, Johan03 said:

Might be a problem when observing faint carbon stars and splitting double stars or just when observing the bright moon?

Not much of an issue on the moon because it is an extended object of considerable size and high contrast.  It is an issue with low contrast planetary features for me.  I can't recall it being an issue for double stars since they tend to be fairly high in contrast.  It might be an issue if you're trying to detect a faint companion next to a bright star.

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I also have a TV-60 and think that it is a great little scope. 

I second the suggestion for: Panoptic 24mm, the Nagler 9mm and the 3-6mm Nagler zoom, which is what Al Nagler recommends on his website. The Vixen HRs are terrific eyepieces (have 3 of them) and to my eye they outperformed the Vixen SLVs and Delos eyepieces when barlowed with the superb Baader VIP barlow (which I consistently found to sharpen the views a bit). With a 6 and 5mm, the TV-60 does not deliver enough magnification power for planetary observations, therefore to me you will end up using the zoom at 4 and 3mm most of the time. As an alternative to the zoom, you could get the vixen HR 3.4mm and 2.4mm, delivering ~100x and 150x, both handy mags with the TV-60 for planetary, lunar and double star observing. 

One notice though, the Vixen HR have been discontinued. Apparently, here you can still find a 2.4mm: https://okularum.eu/Vixen/Vixen_HR_eyepiece_2-4mm . For the 3.4mm, you might have to research a bit, but I believe there is still some online shop in the UK / EU selling them.

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Is the TV Nagler 3-6mm zoom compatible with the Dioptrx lens? Found no info on TV website but maybe that is because they are not compatible. Website only states Dioptrx fit on all focal length Type 6 Naglers. Do the 3-6mm zoom belong to the type 6 serie?

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1 hour ago, Johan03 said:

Is the TV Nagler 3-6mm zoom compatible with the Dioptrx lens? Found no info on TV website but maybe that is because they are not compatible. Website only states Dioptrx fit on all focal length Type 6 Naglers. Do the 3-6mm zoom belong to the type 6 serie?

The Nagler zoom is a 5 element design with a 50 degree apparent field of view across it's zoom range. It is not related to the 82 degree Naglers apart from that it was designed by Al Nagler.

Not sure about Dioptrix compatibility :icon_scratch:

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The 3-6mm TeleVue Nagler Zoom is NOT compatible with the DioptRx corrector.

Even if it were, it would reduce the eye relief to less than the depth of the pupil below the cornea of the eye.

The DioptRx sacrifices about 8mm of eye relief.  On an eyepiece with 10mm of eye relief, that's a No-Go.

Edited by Don Pensack

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I’ve had a variety of small apo scopes, including a Tak FS-60C which I imagine is similar to the TV-60. I frequently used my Nag Zoom in these scopes, and often found myself down at the 4mm and 3.5mm range on good nights, occasionally 3mm. This gives a 0.5mm exit pupil and I used to find this quite manageable, although the dreaded floaters now make it more challenging. I think it is less of an issue on stars, more so on Planets. I did also use a 2.5mm Type 6 Nagler for the best nights, which still worked well but probably diminishing returns over the Nag Zoom.

I’m sure the Delite would be, err, a delight 😉, but the ability to fine tune the magnification to the seeing conditions and target so easily is very useful, and the quality is excellent. I do think the Vixen HR Planetaries are a smidge ahead so perhaps worth considering too.

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On 12/11/2020 at 12:03, Johan03 said:

Is the TV Nagler 3-6mm zoom compatible with the Dioptrx lens?

I'll believe Don when he says it's, but why would you need a Dioptrx at such small exit pupils?  How much astigmatism are you dealing with in your observing eye?  I have 2.0 diopters, and below a 1mm exit pupil, it isn't much of an issue.  I still prefer long eye relief at shorter focal lengths just for viewing comfort and consistency across my eyepieces, but it's not essential as it is at low powers.

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4 hours ago, Louis D said:

I'll believe Don when he says it's, but why would you need a Dioptrx at such small exit pupils?  How much astigmatism are you dealing with in your observing eye?  I have 2.0 diopters, and below a 1mm exit pupil, it isn't much of an issue.  I still prefer long eye relief at shorter focal lengths just for viewing comfort and consistency across my eyepieces, but it's not essential as it is at low powers.

Same correction here on my observing eye. Other eye does not need correction but I am not comfortable observing with left eye. Glad to here it is not a problem with small EP. Really appreciate the information. A lot to learn when new to this fantastic hobby.

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You've probably already seen this chart on Tele Vue's Dioptrx webpage; but in case you haven't, I've found it to be pretty accurate about when astigmatism becomes intrusive:

spacer.png

That's not to say it's undetectable right on the line between regions.  It's just unobtrusive enough there for most folks that the benefits of shorter eye relief, planetary specific eyepieces outweighs it.

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I second Louis.

If you just use the defocused star test to see if astigmatism is visible in the defocused star image, you'll detect astigmatism down to about 1/2 the exit pupil in the TeleVue chart.

But if you evaluate astigmatism based on whether you see it in the focused star images, the TeleVue chart is very apropos.

My coma-corrected dob is f/5.75, and 11-12mm is almost exactly the point where I start noticing it in the in-focus star images.  I have 1.0 diopter of astigmatism in my observing eye,

and the chart suggests I should start seeing it at a 2mm exit pupil.  Bingo.

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Appreciate your replys!
 

Actually, I just ordered the Pentax XW 5mm. I read some reviews that Pentax XW have a more neutral color tone then Televue. I think that is important when my main observing interest is in double and variable stars like ruby carbon stars.

Now I am searching for a eyepiece with a focal lenght that fit between 24mm Panoptic and 5mm XW. 

I will observe for some months before I decide if I need to buy another short focal length eyepiece, maybe a 3mm, for higher power.

I did not go for the Nagler zoom because I think the small AFOV may be a problem as I use a manual alt az mount. 

 

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3 hours ago, Johan03 said:

Now I am searching for a eyepiece with a focal lenght that fit between 24mm Panoptic and 5mm XW. 

Something around 12mm, give or take a few millimeters, would probably be ideal.  It's going to come down to your preferences for apparent field of view, eye relief, weight/size, 2" vs. 1.25", budget, etc.  I really like my 10mm Delos and 12mm ES-92 in this range.  There are so many choices, though.  Perhaps you could start with your budget and barrel size preferences?

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On 16/11/2020 at 09:56, Johan03 said:

Appreciate your replys!
 

Actually, I just ordered the Pentax XW 5mm. I read some reviews that Pentax XW have a more neutral color tone than Televue. I think that is important when my main observing interest is in double and variable stars like ruby carbon stars.

Now I am searching for a eyepiece with a focal lenght that fit between 24mm Panoptic and 5mm XW. 

I will observe for some months before I decide if I need to buy another short focal length eyepiece, maybe a 3mm, for higher power.

I did not go for the Nagler zoom because I think the small AFOV may be a problem as I use a manual alt az mount. 

 

My daylight comparisons showed a bit more yellow in the field of the XWs than in the comparable TeleVue Delos.

I think both are indistinguishable at night, though, in regards to tint.

My comments about color tints in eyepieces can be found here:

https://www.cloudynights.com/topic/739868-best-eyepieces-diagonals-for-keeping-bright-whites-pure-white/?p=10658910

The point is, only believe about 10% of what you read about color tints in eyepieces.

Believe 0% of comments about tints if the reviewer's scope is a refractor.

And look at this to get an idea why the age of the reviewer counts too:

http://people.brandeis.edu/~sekuler/SensoryProcessesMaterial/eyesGetOld.html

The process of lens coloration in the eye is called brunification.  That "coffee color" is probably not in the eyepiece.

No one has defined a "neutral" tone in eyepieces.  Many observers identify it as a cooler tone, with less warmth to the image.  The truth is, that may be quite far from neutral.

The eyepiece may be filtering out the longer wavelengths.

Look t this test from several years back:

http://www.amateurastronomie.com/Astronomie/tips/tips3.htm

Notice how many of them peak at long wavelengths and yet most do not have reputations for being "warm" in tone.

My advice: get the eyepiece you want and can afford in the focal length you need and pay zero attention to comments about tint in the eyepiece.  You won't see it unless you start doing my daylight test to detect it.

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Would the 24mm Panoptic with a 2.5x TV Powermate be a good option for a dedicated 10mm eyepiece?
 

Not sure if I am fully understanding the information correct on TV web site about Powermates. Will the AFOV, ER and field correction be the same with Powermate combo with Panoptic serie eyepieces? 
 

I really like the the ergonomics of the Pan 24mm 🙂

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17 minutes ago, Johan03 said:

Will the AFOV, ER and field correction be the same with Powermate combo with Panoptic serie eyepieces? 
 

Yes, unless you have an exceptionally fast telescope in which case adding the powermate could improve correction. 

Personally I would go for a 10XW instead of buying a powermate to use with just one eyepiece. 

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