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GiovanniAprea

When is a 2" eyepiece desirable/better than an 1.25" one?

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When you want a wider field of view than the 1.25" format can deliver :smiley:

That is the primary benefit of the 2" fitting eyepieces.

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And when the EP in question is a monster.

The 2" fitting provides a bit more stability, so I have heard! ;D

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2" eyepieces provide better low power views of wide field targets like star clusters. An eyepiece like the Tele Vue Panoptic 24mm is about as wide as you can get with a 1.25" EP. Once you get to 30mm+, 2" eps and diagonals come into their own.

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When you want a wider field of view than the 1.25" format can deliver :smiley:

That is the primary benefit of the 2" fitting eyepieces.

As above but I would add that just because a 2" eyepiece allows for a wider field of view it doesn't necessarily mean the views will be any more desirable or better than a 1.25" eyepiece. This factor as with many other things in life is down to how much you are willing to invest. For example you may find that the views in a faster telescope with say a £230 1.25" 24mm Televue panoptic 68° far more pleasing to the eye than say a £30 2" 26mm revelation 70° as the correction and optics are far better in the one ep than they are the other.

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As above but I would add that just because a 2" eyepiece allows for a wider field of view it doesn't necessarily mean the views will be any more desirable or better than a 1.25" eyepiece. This factor as with many other things in life is down to how much you are willing to invest. For example you may find that the views in a faster telescope with say a £230 1.25" 24mm Televue panoptic 68° far more pleasing to the eye than say a £30 2" 26mm revelation 70° as the correction and optics are far better in the one ep than they are the other.

Agreed - thats why I just said "wider" :smiley:

You can simply fit more in. Whether what is in the field is well or pooly defined is subject to other factors than the size of the barrel.

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At this moment in time I have the two cheap EP which came with the ED80, they are LET branded, 20 and 5mm in 1,25" barrels, I added a TMB Optical 3.2mm and two Celestron X-Cel LX a 12 and a 25mm, all in 1,25", I was trying to figure it out if to look for a 30+mm in 2" for wide field even though I am more (when and if it happens that the scope will get out of home...) into planets and which would eventually be the advantages to compensate the heavy weight and cost of a 2 incher.

Thank you

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As said it depends on your budget. What kind of money did you want to spend?

At the budget ( noticeable improvement over cheap eyepiece) end I have found the 2" Sky-Watcher AERO £119 to perform well in scopes f/5 and slower http://www.firstlightoptics.com/skywatcher-eyepieces/skywatcher-aero-ed-swa-2-eyepieces.html then at the savings account destroying end is the Televue 31mm Nagler £500  http://www.telescopehouse.com/televue-nagler-31mm-eyepiece-2.html. This is in my opinion one of the best eyepieces there is. The views are quite simply stunning and the correction is excellent but this high quality lump of glass tilts the scales at 1000g. In the mid price range there is the 30mm Explore scientific £239 http://www.firstlightoptics.com/explore-scientific-eyepieces/explore-scientific-82-degree-series-eyepieces.html which some regards as very a good eyepiece. In my experience it was found to fall short of my expectations but then I may have found myself with a poor example ?? The ES 30mm is again a huge eyepiece weighing in even more than the Nagler at a whopping 1410g.

As always your going to get more for your money buying used.

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Don't do much observing nowadays due to failing eyesight in one eye, so have gone over to imaging.However at public events I find that visitors (non astronomers) find the 2in eyepiece much easier to see with.

Old Codger

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The two inch fitting is only needed by eyepieces which have too wide a field of view for the 1.25 fitting, as has been explained. It's usually claimed that a Televue 32 plossl will give all that can be given in terms of field of view in 1.25.

Don't do much observing nowadays due to failing eyesight in one eye, so have gone over to imaging.However at public events I find that visitors (non astronomers) find the 2in eyepiece much easier to see with.

Old Codger

Are you sure that this is not down to the eye relief offered by the particular eyepieces you are inviting the public to use? I don't think there is any reason to suppose that it's the 2 inch fitting which matters. I find that the 2 inch 13mm Ethos which is, for me, the greatest EP of all time, is not always preferred by beginners. Managing the position of your eye with regard to the EP is a skill which is soon learned but does need to be learned.

Olly

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Eye position for the best view is very important when dealing with non astronomers or children attending outreach events, bear this in mind if you are doing anything to support the BBC "Stargazing Live" later this month. We often employ a sub-optimal eyepiece just on the basis of it being easier to use.  :smiley:

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When I've taken my scope along to star parties which are outreach type events I use eyepieces that have good eye relief, large eye lenses, soft rubber eyecups and moderate fields of view (ie: 60-70 degrees). They are 1.25" eyepieces that happen to have these characteristics and also have good optical quality as well - I don't really want someone to look through my scope and comment "why do those stars look like seagulls ?" :smiley:

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An eyepiece like the Tele Vue Panoptic 24mm is about as wide as you can get with a 1.25" EP. Once you get to 30mm+, 2" eps and diagonals come into their own.

Actually 32mm gives the widest view possible in the 1.25 format. (Sorry Olly, you already mentioned this)

Edited by Mr Fiery Jack

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The 32mm TV Plossl and the 24mm Panoptic both have field stops of 27mm.

'This Sky & Telescope "Hot Product" is designed to produce the largest true field possible in a 1¼" eyepiece. (Its 27mm field stop is the same as the 32mm Tele Vue Plössl). The higher power darkens the sky background while the greater magnification yields more details on extended objects.' ~ TeleVue 24mm Panoptic http://www.televue.com/engine/TV3b_page.asp?id=22&Tab=EP_EPO-24.0

http://www.televue.com/engine/TV3b_page.asp?id=51&Tab=EP_EPL-32.0

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The 32mm TV Plossl and the 24mm Panoptic both have field stops of 27mm.

'This Sky & Telescope "Hot Product" is designed to produce the largest true field possible in a 1¼" eyepiece. (Its 27mm field stop is the same as the 32mm Tele Vue Plössl). The higher power darkens the sky background while the greater magnification yields more details on extended objects.' ~ TeleVue 24mm Panoptic http://www.televue.com/engine/TV3b_page.asp?id=22&Tab=EP_EPO-24.0

http://www.televue.com/engine/TV3b_page.asp?id=51&Tab=EP_EPL-32.0

Thanks for pointing out, and I see you are supremely qualified to judge as owner of both eyepieces.

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Thanks for pointing out, and I see you are supremely qualified to judge as owner of both eyepieces.

They are both great eyepieces, I think the 24mm Panoptic is TeleVue's biggest selling eyepiece. On my small Mak I struggle to get low enough magnifications for the occasional use of a UHC filter.

The 24mm Pan will give me around 54x but I get a slightly brighter image with M42 plus a filter sometimes with a 25mm TV Plossl. The 32mm TV Plossl gets a little better and I've recently acquired the TV 40mm Plossl. I haven't had chance to see M42 with it yet due to inclement conditions but I got first light with it the other night. The eye relief is a little long for me and I've ordered the TeleVue eyeguard extender to help with this. 

In a couple of months I plan to get a much bigger SCT (235mm). I will seriously consider a 2" diagonal and the 55mm TV Plossl if it will work with it. I think it will be the only way I'll get a 5mm or more exit pupil on an SCT. 

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I had a 40mm TV plossl for a while but I found it less effective than the 32mm or the 24 Panoptic. Perhaps under really dark skies it might have had some benefits but not from my back yard !

It's also not par-focal by quite a way from the other TV plossls. Thats a minor annoyance though. It's a good eyepiece if you wear glasses when observing - I believe Al Nagler said thats why they introduced it to the TV plossl range.

I found the TV Eyeguard Extender a very valuable addition to the 32mm TV plossl because I really don't like having to "hover" my eye over the top of the rubber eyecup to find the "right place".

The 24mm Panoptic was regarded as possibly the best 1.25" eyepiece made by a number of experienced observers a few years back. It's a lovely piece of kit, thats for sure :smiley:

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I had a 40mm TV plossl for a while but I found it less effective than the 32mm or the 24 Panoptic. Perhaps under really dark skies it might have had some benefits but not from my back yard !

It's also not par-focal by quite a way from the other TV plossls. Thats a minor annoyance though. It's a good eyepiece if you wear glasses when observing - I believe Al Nagler said thats why they introduced it to the TV plossl range.

I found the TV Eyeguard Extender a very valuable addition to the 32mm TV plossl because I really don't like having to "hover" my eye over the top of the rubber eyecup to find the "right place".

The 24mm Panoptic was regarded as possibly the best 1.25" eyepiece made by a number of experienced observers a few years back. It's a lovely piece of kit, thats for sure :smiley:

I'm OK with the TV 32mm Plossl and I can deal with the eye relief. The 40mm is weird though at first. I definitely think the eyeguard extender will help.  Although I don't tend to use the 24mm Pan with the Powermate or Barlow with the Mak, it is light enough to use it with them easily. It really is a superb eyepiece. 

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I had a 40mm TV plossl for a while but I found it less effective than the 32mm or the 24 Panoptic. Perhaps under really dark skies it might have had some benefits but not from my back yard !

It's also not par-focal by quite a way from the other TV plossls. Thats a minor annoyance though. It's a good eyepiece if you wear glasses when observing - I believe Al Nagler said thats why they introduced it to the TV plossl range.

I found the TV Eyeguard Extender a very valuable addition to the 32mm TV plossl because I really don't like having to "hover" my eye over the top of the rubber eyecup to find the "right place".

The 24mm Panoptic was regarded as possibly the best 1.25" eyepiece made by a number of experienced observers a few years back. It's a lovely piece of kit, thats for sure :smiley:

I guess if you had shorter focal length scopes John then the 40mm doesn't have much value, but as Mak says, in a longer focal length Mak or SCT it can be useful to achieve lowest mag/larger exit pupil?

The eye relief can be challenging. I used the 32mm with a Daystar Quark and at times I had two eyeguard extenders stacked I order to shield the view from reflections and glare because you stand so far off the eyepiece to view.

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Has anyone had any experience with any of the 70° or 80° eyepieces offered here by University Optics?

http://www.universityoptics.com/125inch.html#80

I've never had a bad EP from UO, but I wish they'd offer a bit more nuts & bolts on their offerings. At the price and the track-record I've had with them, that 16mm 80° is looking like a good experiment.

Thanks in advance,

Dave

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Has anyone had any experience with any of the 70° or 80° eyepieces offered here by University Optics?

http://www.universityoptics.com/125inch.html#80

I've never had a bad EP from UO, but I wish they'd offer a bit more nuts & bolts on their offerings. At the price and the track-record I've had with them, that 16mm 80° is looking like a good experiment.

Thanks in advance,

Dave

They are chinese clones of the Japanese KK Widescan series. They work well in F/10 and slower scopes but in my F/7.5 they showed lots of edge of field astigmatism.

The UO branded orthos are good but many of their other lines recently have been rather "so so" and can sometimes be bought for less under other branding. Here is OWL's take on the 80 degree series:

http://www.owlastronomy.com/ultrawide.htm

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I bought the 35mm Panoptic a couple of months ago. Had high expectations, but it delivers on every level - best views of clusters I've ever had - only disadvantage is it's over three times the weight of the 24mm. The eyepiece gricers on SGL might be able to say whether that's the biggest weight difference between two EPs in the same range separated by just one other - ie in this case the Pan 27mm.

(I should explain, the word "gricer" is an affectionate term for an anorak/trainspotter/someone who is absorbed in the study of a hobby, invariably male, - also a verb - to "grice" something, is to partake in the act of gricing, to add to one's already extensive knowledge of trivia/facts in one's chosen interest. I should add that I have long considered myself a gricer - ever since the age of ten when I used to spend days at Manchester Airport ticking off aircraft numbers in my book. Now I am in the process of becoming more of an eyepiece gricer, but I have a very long way to go to reach the levels of many distinguished SGL members)

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Ooooh - I'm definitely an eyepiece "gricer" then :grin:

On the difference in weight thing, the 16mm T5 Nagler (a 1.25" eyepiece) is separated by just one eyepiece from the 26mm T5 Nagler. Their respective weights are 7.1 and 25.6 oz. Maybe the 24 / 35 Pan difference is larger though ?

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Ooooh - I'm definitely an eyepiece "gricer" then :grin:

On the difference in weight thing, the 16mm T5 Nagler (a 1.25" eyepiece) is separated by just one eyepiece from the 26mm T5 Nagler. Their respective weights are 7.1 and 25.6 oz. Maybe the 24 / 35 Pan difference is larger though ?[/quote

A brilliant repost, and evidence of gricing excellence

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Well, as only a novice 'gricer' I can say that the 16mm T5 Nagler and the 19mm Panoptic are very similar (201 & 187 grammes respectively) in weight, dimensions and even their field stops (both around 21-22mm).

TV%20Pan%2019mm%20%20Nag%20T5_zpst0qdcsm

This makes them both ideal to use with a Powermate/Barlow on a small scope. Which could be a factor even on scopes that can utilise 2" EP's. I've seen 6" Dob's with 2" adaptors and I'm guessing that the weight of a 2" EP plus a Barlow/amplifier would be quite noticeable. 

Edited by Mak the Night

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