televue eyepieces panoptic nagler

[umadog]

Gaz, I reckon 4 mm as your largest exit pupil is a little conservative. I have a couple of eyepieces which give me an exit pupil of about 5 to 6 and those get used a lot. Even your 6.4 mm will be useful. Wide field eyepieces of this sort are nice for open clusters and for framing galaxy groups. Also useful for finding stuff. Perhaps you'll loose a little light with a 6.4 exit pupil, but I wouldn't worry about that. You won't be loosing much and the wide true field of view makes up for it.

[GazofCorra]

That makes good sense, so i will keep the 2" 38mm PanaView for open star clusters etc and i especially like the fact that it will make finding stuff a bit easier as that is half the battle with me.

Cheers

[Rui]

You did the right thing. EP's are always a good investment because telescopes come and go, but the good eyepieces stay for good.

About Barlows, if you can do without them, it's always better. No matter how good the quality of the barolw lens, it will take a small share of light. Personally I prefer to have dedicated EP's to fill the gaps in the magnification range. So, below the 13mm Nagler I have a 9mm Nagler, a 8mm Radian and a 6.8mm UWA Meade.

[GazofCorra]

You did the right thing. EP's are always a good investment because telescopes come and go, but the good eyepieces stay for good.

About Barlows, if you can do without them, it's always better. No matter how good the quality of the barolw lens, it will take a small share of light. Personally I prefer to have dedicated EP's to fill the gaps in the magnification range. So, below the 13mm Nagler I have a 9mm Nagler, a 8mm Radian and a 6.8mm UWA Meade.

I would love to have a dedicated 9 & 6mm EP, but in the last 2 weeks i have spent nearly £800 on new kit, so until i can build my reserves back up i am going to buy the TV 2x barlow so at least i can up the power a bit when needed and it will give me a good idea of what viewing is like in the higher power band, as soon as i have some more spare cash i will buy a dedicated EP under 10mm.

Thanks for all the advice guys it has been a great help.

[jonstarrysky]

What mag do you get from your 10" dob with the 8mm ethos, as for planetary viewing i here of people using 200x plus, but if i used an 8mm with my 8" f5.9 dob i would only get 150x or 133x with a 9mm nagler?

What is one to do?

The 8Ethos with paracorr gets me around 173x mag. If I go higher there will not be any real benefit, you wont see more, you'll just see the same thing but it will look bigger and more blurry and the field of view will be smaller. Thats UK seeing for you ! Others will claim differently. But seeing is the limiting factor for magnification in my scopes, not the theoretical liimit of the scope based on aperture (eg 50x per inch). Personally 20-30x per inch makes more sense anyway. Going above 200x isnt my cup of tea.

[GazofCorra]

That is sound advice coming from another UK dobsonian user and your 10" dob gets more light than mine, so resolving power if i am not mistaken will be better in yours and to quote you - "you wont see more, you'll just see the same thing but it will look bigger and more blurry and the field of view will be smaller".

As i have bought my scope for observation work only, seeing any of the starry delights at there best is all i am after, and i have now realised that this boils down to my scope, eyepiece and the conditions, so finding a maximum limit based on these 3 factors makes good sense to me. I thought if the stars were visible on a clear night then i could use up to 200x for observation especially on planets, not taking into account where we are (the UK weather is appauling most of the time, so it makes sense that the atmoshere will always be a bit bubbly) even when it looks clear to the naked eye.

I think i am learning....lol

[jonstarrysky]

Just remember the highest power thing is subjective ! You may wish to experiment with cheap plossls before splashing out on a top-end eyepiece for high mag work. You'll see a fair amount of planetary detail with your 13mm Nagler and the mag that gives you will always be within UK seeing conditions, be it a good night or a bad night for seeing. 8mm EP should be safe enough for most nights. Below that is getting into subjective territory were opinions will differ - even between ppl observing at the same site on the same night, as to what ppl enjoy looking at.

[pvaz]

The Ethos 13mm with a quality barlow will offer images very close to what you get with a quality stand alone planetary EP.

My Ethos 10mm + Antares or Big barlow is almost as good as my single BGO 5mm. I can only notice the BGO gives a bit more contrast on very faint details such has the great red spot in Jupiter. The difference is minimal, sometimes, as hard as I try, I can't see a difference.

A quality barlow works well. The main problem with it is the extra weight and the extra length which may be too much for stock focusers. My focuser been handling the abuse but I reckon at some point it will need replacing for something sturdier.

Regarding the highest useful power, I find 250x is usable on about 50% of the clear nights here in Portugal. I do most of my planetary observations in the 7 to 5mm range.

[John]

The Ethos 13mm with a quality barlow will offer images very close to what you get with a quality stand alone planetary EP.

My Ethos 10mm + Antares or Big barlow is almost as good as my single BGO 5mm. I can only notice the BGO gives a bit more contrast on very faint details such has the great red spot in Jupiter. The difference is minimal, sometimes, as hard as I try, I can't see a difference.

A quality barlow works well. The main problem with it is the extra weight and the extra length which may be too much for stock focusers. My focuser been handling the abuse but I reckon at some point it will need replacing for something sturdier.

I echo this 100%

With the Antares 1.6x barlow my 8mm and 6mm Ethos work exceptionally well at 5mm and 3.75mm focal lengths - actually a tiny bit better than classic University Optics orthoscopics which is impresssive when you consider the 11 glass elements that the Ethos / Barlow combo contains

The focusser / diagonal does need to be up to the task though, as Paulo says

[GazofCorra]

Thanks guys this thread is definately pointing me towards a barlow or a cheaper plossl to start with, i notice that Paulo & John you both use the Antares 1.6x barlow with your TV EP's, so you obviously class this as good barlow lens.

If i use the Antares with my 13mm nagler i would then have a 8mm equivilent focal length and this seems an ideal choice.

Regarding my focuser on my 200P dob i know it has a Dual-Fit 1.25"/2" Crayford Focuser, so do you think this is up to the job? BTW all my TV EP's are 1.25" and i went for the type 6 nagler over the type 4 due to the difference in weight.

Is the Antares 1.6x barlow useable with 1.25" EP's? and finally where is the best place to get one from here in the UK, i was thinking of FLO.

Gaz

[pvaz]

Is the Antares 1.6x barlow useable with 1.25" EP's? and finally where is the best place to get one from here in the UK, i was thinking of FLO.

Yes, but it comes in 2" format. You then need a standard 2" to 1.25" adapter. The one that came with your scope should do it.

The only flaw in the antares is that it comes with screws instead of compressing brass ring. This will leave marks in your EPs' barrel.

PS-> If the adapter moves the EP far from the barlow's Lens then it will magnify more. It's possible it will work as a 1.8x barlow with the adaper. The TV BigBarlow 2x comes with a recessed 2" to 1.25" adapter to reduce this effect.

This is noticeable but not a problem, as long as you realize you're getting a bit more then 1.6x. If you use an extension tube between the EP and barlow, you may easily make it behave as a 2x+ barlow, if you don't mind the extra length and weight.

Here's a graph for TV barlows and the extra mag they provide as you increase the distance: http://www.televue.com/engine/TV3_page.asp?id=52&Tab=_dev&plain=TRUE&preview=TRUE

I have used my Ethos 10mm + 50mm extension + TV BigBarlow to get 320x on the moon. It's only usable on the moon with good conditions and the setup is so big, it looks like I have another scope sticking out of the scope.

[GazofCorra]

Paulo, thanks for the information and after your explanation about having to use a reducer so it can take the 1.25" EP's and also if the adapter moves the EP away from the barlow it might become 1.8x and finally that it has screws which leave marks on the EP barrels.

It seems i will be paying over £100 for the Antares 1.6x barlow with the 2" - 1.25" adapter, so i might as well save my money and buy a dedicated high power EP.

Just have to decide which one is worth my investment.

Gaz

[pvaz]

Your focuser is 2". Did it came with a regular 2" to 1.25" adapter? I believe they all do so you can use that one.

Stock focusers usually come with screws as well so marks will probably be there anyway.

Buying a dedicated high power EP is a good idea if you're not saving much with the barlow. With the Ethos the Antares 1.6x is really a money saver. I got mine for about 75£ from the US at: Antares 2" 1.6x Barlow Lens

So I get a 19mm Nagler (31mm + Barlow), a 13mm Ethos (21mm + barlow) and a 6mm Ethos (10mm + barlow). Buying these 3 dedicated EPs would cost me over 1000£.

[GazofCorra]

WOW! you have some superb eye pieces and that combination with the 1.6x barlow makes a superb set indeed.

I do not have my scope as yet (still waiting for it to come back in stock) but it has the crayford 2" focuser with a 1.25" adapter supplied with it.

I cannot afford a 8mm ethos so have a list of 3 EP's i am considering buying to complete my set.

1. Pentax XF 8.5mm - 141x

2. Antares spear waller 7.2mm - 166x

3. Baader Hyperion 8mm - 150x

I did consider the 8mm radian but have heard mixed reviews and also the eye relief seems very high at 20mm, not sure that will be very useful as i do not wear glasses and the 9mm nagler would also cost a bit more money than the other EP's and it would only give me 133x so not really a high power EP, i do not want to go nearer the 200x limit i have read about on Dob's as our conditions for viewing here in the UK are not that good and i would rather have a smaller, clearer object to look at rather than a bigger blurrier one.

[umadog]

If your scope is under F5 you might want to stay away from the Hyperions. It has been the experience of both me and a few others that these eyepieces play badly with faster focal lengths. There's lots of astigmatism. If you can get hold of Explore Scientific, those would work much better and not cost much more.

[John]

I tend to agree with umadog on Hyperions in fast scopes. The Speers-Waler could be good but they do have issues with needing more inward focuser travel than other eyepieces so it's worth checking that it would work OK with your scope before committing. I've not used a Pentax XF but Russ on this forum has and speaks very highly of it I seem to recall.

Personally, I would have an eyepiece capable of delivering 250x with an 8" scope. OK you will not use it that often but, when conditions are good, pushing past the 200x barrier is needed to tease out the finder details of the smaller worlds such as Mars. It's also very useful for tight double stars and closer views of the lunar surface.

[GazofCorra]

That is good to know about the hyperions, i might as well spend a bit more money and buy a 8mm radian whilst the sale is still on but the 60 degree fov worries me more at higher powers.

I would like the pentax XW 7mm with 70 degree fov, maybe it is worth saving for a few more months?

Gaz

[pvaz]

My personal opinion is that you already have good gear to get started. Take it easy, do some sessions, compare the stock EPs to the premium ones and then make your mind.

In your 1st post you talk about photography. In photography the image is recorded and the differences between a bad lens and a high quality one are obvious.

In EPs they are obvious too but not nearly as much. You pay 10x more for details. I seen people getting a Nagler with their 1st scope and then complain they don't see enough difference to justify the expense.

Some beginners also expect a level of detail they are use to see in images. Most DSOs will be gray fuzzy blobs, planets will be small and hard to observe when conditions aren't right, stars are so far away they will still be single points, so you may actually be a bit disappointed depending on how realistic your expectations are.

Another important thing is that everyone haves different opinions on how to observe. Some here like to stay bellow 200x. I, personally, don't like to do planetary observations below 200x. When conditions aren't good enough for that I simply pick other targets. My most used planetary EPs are the 5mm BGO and the Ethos 10mm barlowed to 6mm or 5mm.

Your main problem now will be to get to grips with the scope and locate objects. Then use all your gear, find out what works for you and base your future purchases on those experiences.

[GazofCorra]

Great advice Paulo, i am going to use the EP's i have to start with and see how things go, i might add a 2x barlow and use it with my 13mm Nagler before i decide on a dedicated high power EP.

Gaz

[Adz]

This thread has been of great help to me, Gaz I am in a very similar situation to you with the same scope

I was thinking of a wide panaview and a 24mm panoptic, 14mm radian and a planetary something. I hope to see how you get on matey.

[GazofCorra]

Hi Adam,

I am still waiting for my Skyliner 200P dob to arrive from FLO and in the meantime i bought a SW Skymax 127 auto which arrived yesterday and now it is blumming cloudy - figures.

Good thing buying good EP's from the start is you will get the best views possible, so will avoid buying loads of different makes and models working your way through a labyrinth of this vs that.

I have the 24mm Panoptic as i have only ever heard rave things about this eyepiece on here and in books.

I went for the 13mm Type 6 Nagler over the 14mm Type 4 due to the weight of the 14mm.

I have also bought the televue 2x barlow to use with my 13mm Nagler.

Hopefully soon i wil get to use the EP's and my scope and i will post the results.

Cheers!