Explore Scientific Eyepieces for Orion XT8

[Dan Watts 13]

Hi all,

I have finally decided on starting building a fixed focal length collection.

I settled on the Explore Scientific 82° range but due to only having a Baader Zoom 8-24mm and a couple of cheap EP's that came with the scope, i just wondered due to starting from scratch, what selection of EP's would be the best?

I'm thinking starting with 3 EP's from the range, but really can't decide...If anybody has any guidance or suggestions to make this easier, that would be great

Thank you for reading this and I appreciate any feedback.

Dan.

@Spanners360

[Stargazer_00 749]

Hi there.

Good choice, you won't be disappointed. Are you planning on using a barlow or focal extender at all?

What is the focal length of the XT8, 1000mm or 1200mm?

A good spread would be 6.7 for planets, lunar and high power DSO viewing. 11 or 14 for most DSO work & 18,24 or 30 for widefield and large DSO viewing.

I find the 4.7 quite useful, and the 8.8.

Once you asnwer the first two questions I can give you a better steer I think also what do you prefer to look at or do you want an all round set? Are you intending to grow once you have the 3 or stop there?

[rwilkey 1,328]

I prefer wide starfield viewing and DSO's and so have got the 11mm and 14mm ES82's and would like to add the 18mm when it appears in the s/h lists, already have an Axiom LX at 23mm so the 18mm ES would be perfect.

[Stargazer_00 749]

The 18mm is very good but has a notably short eye relief for the focal length. I love the 18mm in all my scopes.

[Dan Watts 13]

Hi,

Thank you so much for your valued info! The focal length is 1200mm for the XT8. Yeah, I was looking at starting with 3 EP's then gradually increasing the collection. I have a x2.5 Baader Barlow at the moment...I have also heard of these focal reducers, what exactly do these do?

I am really getting into DSO hunting of recent so would be nice to have something to have something to bring that out for sure! Def a planetary and there is always the Barlow for the 2" EP route I could go down as well, that gives a few options

Thank you for your time answering, I really appreiate it

[Stargazer_00 749]

Great, the same focal length as my dob then so I have an even better idea what to suggest!

The barlow you have is the 2.25x 1.25" barlow which pairs with the zoom eyepiece I assume. I hear this is a good barlow so should work well with the 1.25" ES options.

The 2" ES eyepieces do ramp up in price significantly between 18mm, 24mm and 30mm, so bear that in mind.

I would recommend, with the use of that barlow a 8.8mm and 14mm initially. To give you 136x and 86x respectively. Barlowed; 307x and 193x. With a bit of creative round you get approximately 80x 140x 200x 300x. So good medium to high power range there.

The low end is a question. Many people go right for the hand grenade 30mm and then later pick up a 18mm, i'd suspect many skip the 24mm altogether. I feel that this is a shame and very much enjoy the 24mm I have and in fact question if i need a 30mm at all (yet). Let me explain. The people that I've seen that say they love their 30mm's all have 12" or larger telescopes as well. Take the 12" dobsonian as the most common scope for people who like this FL of eyepiece. Those have 1500mm focal lengths and therefore with a 30mm ultra wide give a magnification of 50x and show 1.64 degrees true field of view.

In a 1200mm focal length telescope with a 24mm ultra wide you get 50x magnification and 1.64 degrees true field of view, so you have to consider that when reading the comments. A 24mm UWA in a 1200mm FL is the same mag and tfov as the much praised 30mm offerings in a 1500mm/12" (ignoring light grasp of aperture, obviously).

A 30mm is much more expensive, perhaps as much as £100 more. You have to question if this is worth it. Looking at in a 1200 FL scope again (both your 8" and my 10") the 30mm would provide a 40x magnification and 2.05 degrees true field of view, and likely introduce significantly more coma for that extra field - meaning you'd more obviously require a coma corrector. For me the 24mm I own is already introducing enough coma that I feel I need a corrector soon and I'm sure a 30mm may even disappoint if I didn't own a coma corrector before I bought it.

So on that rationale, I'd actually recommend a 24mm as your low end EP. It'd give still very nice views (my 24mm frames the entire double cluster and quite a good deal of space outside of it at 50x with this AFOV) and have the advantage of offering slightly darker backgrounds over the 30mm and being way more affordable at the same time.

There is a deal currently all over the american dealers for a meade 24mm uwa bunbled with their top of the range dielectric diagonal for $159. After import tax and so on I landed this deal at my door for £160. I used both parts of the bundle but if you had no use for the diagonal you could sell it as new (UK price for the diagonal alone is £145 - see telescope house) and basically get the 24mm uwa for a considerable discount, assuming you could sell the diagonal for a moderate cost.

If you are interesed in that meade deal then either google for it or state it here and I'll search for it for you. It is a nice eyepiece but does not match the other eyepieces in my case. For what I paid for it though I can't argue.

[Dude_with_the_tube 542]

meade 5000 UWA series are awesome and equal to ES 82 deg range. also they require only very little focuser adjustment when you change the EP to another.ES dont pop up that often on s/h market where meades do time to time and you can get a good bargain if you have the patience.Only 2 out of the lot where bought new (14mm and 24mm from states) where all the others are s/h and costed on average 70-80 quid.For starters get one high power :6.7mm or 8.8 ,one in the middle 14mm and 24mm for low power DSO hunting.afterwards you can always top up with other ranges or just get a good quality barlow.I agree with Stargazing,30mm is not really the most used EP also it does weight a ton regardless will it be ES or meade.24mm will be used more often ,only picked it up because i got it for half price ,and for the price of 159 USD or 160quid delivered to UK for the 24mm EP and they best diagonal in bundle thats no brainer.

[Stargazer_00 749]

I Would state optically the 24mm meade is comparable but it is not waterproof like the es and ergonomically out is not as good as the same focal length es. It's An amazing price currently though. If they were equal price to the es I would take the es for comfort.

[Dan Watts 13]

Thank you all so much for your input in this thread.

It's been really informative to hear of the different EP's that are simliar to the ES°82 as well, I had not considered Meade EP's before now! Dude_with_the_tube thank you for your input in regards to the the sizes to look for etc.

Spaceball - Thank you so much for your informative thread you posted above, duly read and noted all the points you have put down there...I'm going to chop in my Baader Zoom and then start with a high power 8.8mm ES°82 and prob a med power 14mm as you mention then save up for the 24mm I think

Again, thank you all that have given advice on this as i was really stumped originally but i'm much more up to speed

Dan.

[Stargazer_00 749]

You're welcome. I hope you get on well with them. For me the 8.8mm and the 14mm are the pick of the litter with the range of ES eyepieces I have at the moment. The 14mm being my current favorite, it's an absolute DSO killer in a 1200mm focal length scope.

[Dude_with_the_tube 542]

I Would state optically the 24mm meade is comparable but it is not waterproof like the es and ergonomically out is not as good as the same focal length es. It's An amazing price currently though. If they were equal price to the es I would take the es for comfort.

I agree on the statement that the Meades are not waterproof,however,I have now been using them for a while in cold (up to -3) and in nights with quite high dew and never had any issues whatsoever with the Ep`s.I even leave them on the observation table sometimes when i am observing on object and again no issues.Also you are not planning to put the Ep`s for a bath or observe in rain

As for ergonomics,well, that's purely individual thing.Some like porches or mercs,where others like bmw or vauxall I personally love the twist up body with integrated eye piece and found them very comfortable through out the whole range,yes there is the point of added additional weight for this,but i never found that being an issue and you can always put the Ep`s on the diet by taking the whole shabang off what will leave you with a very slim EP.

Dan, you can try and get to some star party or alternatively if you have astro shop near by who does sell both Ep`s and ask them to show them to you and then you can decide what is the best for you.Both ES and Meade`s are great ep`s and optically there will be no difference at all,just the ergonomics and if you are not prepared to shell out large amounts of money for top premium Ep`s like Televue Naglers(82 deg) or Ethos(100 deg), then ES or Meade`s is the way to go.

P.S.there is of course the other route of 100deg POV and 120..... but thats a very dangerous road.

[Dan Watts 13]

With my current obsession with DSO's, this will be a very welcome addition! I also noticed the 8.8mm is only available in the USA at the moment, I may take a chance with the import as they are only $99 at the moment, unless you get stung by the customs, prob still worth the risk though...maybe!

[Stargazer_00 749]

I imported a bunch of eyepieces and the import duty and tax charged was half what I calculated it to be. Obviously I didn't question it.

I was expecting £70 and it was closer to £35 on a $450 import.

[Dan Watts 13]

That's interesting to know! I will save a little more cash up i think and do it in 1 go.

[Dude_with_the_tube 542]

i had something between 30-35 quid tax and duties for 400 usd worth of EP`s,not bad .

[cs1cjc 158]

You're welcome. I hope you get on well with them. For me the 8.8mm and the 14mm are the pick of the litter with the range of ES eyepieces I have at the moment. The 14mm being my current favorite, it's an absolute DSO killer in a 1200mm focal length scope.

The 14mm is the only one I could not get on with, being very short of usable eye relief and having excessive field curvature.

[Damo636 452]

Dan

If you intend going for the 24mm ES 82° as your lowest power widefield, I would skip the 14mm and go with the 11mm. The 11mm is not only the pick of the line (apparantly), but its a better jump in magnification, as well producing an almost perfect 2mm exit pupil for medium power observing with your 1200mm fl f6 scope. I would then choose the 6.7mm as the highest power fixed focal length. The 11mm + 2.25x barlow would get you to 4.8x (250x) if conditions allowed. :-)

[Stargazer_00 749]

The 14mm is the only one I could not get on with, being very short of usable eye relief and having excessive field curvature.

I find them all short eye relief. I dont use any of the range with the eye cups rolled up except the 8.8 and even then on occasion I feel as if im not seeing the whole field without pushing against the eyecup to get a mm or so closer. I quite like the right eyerelief though. I would say none of the eyepieces I have are usuable to a spectacle wearer they are all far too tight.

I must say I hadn't noticed field curvature in the 14mm, nor really much in the 18mm. I only start to see it as obvious in a 24mm. Did you have the current 14mm or the previous fatty one?

[cs1cjc 158]

I had the 14mm nitrogen purged, so almost current.

I find that the 24mm and 16mm 68* and the 11mm and 8.8mm 82* are usable with spectacles but I am very shortsighted so my spectacles extend the eye relief. The 6.7mm is tight and the 4.7mm even tighter, but I do not need spectacles for small exit pupils. Of these only the 24mm and perhaps the 11mm are comfortable for daylight viewing.

[Stargazer_00 749]

Interesting. I'll look more closely next time I'm out to see if i can detect it

[cs1cjc 158]

I should perhaps add that not only am I short sighted but that at 61 I have significant Presbyopia, so limited ability to focus my eye which is likely to make field curvature more of an issue.

Strangely though my iris still opens to about 7mm contrary to what I am told is typical for my age. It is good that something works...

[Dan Watts 13]

Dan

If you intend going for the 24mm ES 82° as your lowest power widefield, I would skip the 14mm and go with the 11mm. The 11mm is not only the pick of the line (apparantly), but its a better jump in magnification, as well producing an almost perfect 2mm exit pupil for medium power observing with your 1200mm fl f6 scope. I would then choose the 6.7mm as the highest power fixed focal length. The 11mm + 2.25x barlow would get you to 4.8x (250x) if conditions allowed. :-)

That's interesting to hear! I will prob make the dive in the near future - prob from the USA, so much cheaper than the £157+ over here...It's almost worth the customs charges!

Dan.

[Dunkster 258]

My guesstimate is that if they draw attention to themselves, sent individually, expect to pay just over £100 including shipping/duty/vat/fees. For about an extra £20 you could get them from Germany (explorescientific.de) a little more quickly. I've had decent odds with them not drawing attention to themselves

Btw, I use the 11 and 8.8 with and without a Baader 2.25x barlow with my f/5.9 Zenithstar to much delight given that they're supposed to be waterproof, I don't feel so bad travelling with them and exposing them to sandy environments, etc. I'd probably not feel so easy with this if I had a pocket full of Naglers

[Damo636 452]

Here's another source from Europe.....

http://www.optical-systems.com/explore-scientific-m-343.html

Edited April 10, 2013 by Damo636

[Stargazer_00 749]

I Use them and they are good. Marginally More expensive but closer and alot faster