Andrews 2"/1.25" 70° super-wide

[mbo (Pat and Kirk)]

Does anyone have info / experience with these?
http://www.andrewscom.com.au/site-section-10.htm (third pic down)

I'm looking at getting their 8" GSO dob and swapping out some of the standard ep's in the deal for fewer but better ones.

Thinking of getting the 8 mm

[casstony]

Those eyepieces look the same as the Celestron Ultima LX series which I've read are decent eyepieces. You could ask Andrews if they are the same eyepiece and check the net for reviews. It's common for Asian manufacturers to repackage the same eyepiece for different retailers.

[AG Hybrid (Adrian)]

Check out the 100* AFOV eyepieces. I wonder how they perform, pretty pricy. They might be decent performers!The focal lengths are the exactly same as the TMB 100 Series Which was named a Sky & Telescope Hot Product for 2010!

[Suzy]

lI have the the Andrews 2" 30mm 80 deg - it performed poorly in my 6" dob (I imagine it would be even worse in my 10" -haven't tried my 10" with it yet- as the 6" dob is supposedly more forgiving on ep quality compared to 10"). Great for surfing the skies, but don't expect quality. Stars aren't pin point and hugely lacks in contrast (the sky was never black for me, compared to all my other eps). The glass itself has got a green tinge. I ended up using the cheap 25mm that came with the scope more, and even my Orion Expanse 15mm (66 deg i think) was a massive improvement. It is cheap for a 2", and if you're driven by price, what you pay for is what you get with this ep in my opinion. Here is a link to a review (tho on the 80 deg).

http:////www.iceinspace.com.au/42-134-0-0-1-0.html

The equivalent I think would be William Optics. A 2" William Optics 72deg SWA sells for around $185. Or a 1 1/2" for $104.95 from Ozscopes .http://www.ozscopes.com.au/william-o...eyepieces.html

I think W.Optics would be a step up, I've read good reviews on it, and Liz here has the SWA and she loves it. Personally, I prefer around 70deg, as I find it just too much work and loss of light with 80deg. Once you start talking 2", you start talking lots of dollars as no doubt you are finding out. But if you don't want to critique them too much and driven by budget, that's a different story.
Just my experience and opinion.

Regards,
Suzy.

[mbo (Pat and Kirk)]

I've managed to pick up a Japanese"Widescan Type III" 13mm pretty cheap, and a 9mm Nagler not so cheap (Ebay fever). Now I guess I'd better go and get a scope to poke them in! That's right, I haven't got that part yet
My Lady and I have been reading and head scratching on this for ages , so we're really looking forward to some real stargazing at last. I think I'll be in Sydney on Thursday, so I'll drop into Andrews and finally get something.
I'd like to grab a low power eyepiece while I'm there, and I'm leaning toward the 30 mm Superview (68deg.)
I'm still curious what those 70deg Super-wide ep's actually are so I'll ask while I'm there.
Thanks again all!

[mental4astro (Alexander)]

The GSO SuperViews are a great eyepiece for their price! I've got the 30mm & 15mm- These are the EPs I use the most.

I've used them in an 8" f/6 dob too. They perform better in a scope of this focal ratio or slower as a fast scope will begin to reveal the astigmatism they are prone to. In my f/5 & f/4.5 scopes, the image starts to degrade towards the edge of the field of view. Yet I'm very happy with their performance until I get a better quality EP. The distortion is very tolerable.

Mind you, as a comparison, I've also tried an Orion Q70 30mm in my 17.5" f/4.5. It is three times the price of the GSO. The image quality was appauling!

I've also had a Nagler 30mm EP with its 80deg FOV in the same scope- also appauling- way too wide and impossible to overcome the astigmatism the EP/stumpie light cone combination creates. I also needed to move my head to see the whole image this EP provides, not just my eyeball- our eyes can see well within a 68degree range, NO coincidence!

There is a balance that needs to be achieved with a scope's f/ratio and the FOV of a given EP. These giant FOV eyepieces are really best suited to long focal ratio scopes, like an f/10 SCT, where the cone of light it produces is very tight. But the need to move your head to see it all still applies, regardless of the focal length of the EP.

Suzy, I've had a go of an Andrews 30mm 80* EP in my 17.5" f/4.5. It performed surprisingly well. Actually much better than the Nagler!

Another thing about these high end long focal length EPs is that they can get really, REALLY big and heavy- try to balance a 1.5kg lump of glass on the end of your dob!

MBO, if you are after a good short focal length EP, have a look at the Williams Planetaries, or the TMB planetaries, the former have a 55* FOV, and the TMB's 60*. The are relatively inexpensive, but perform really well, with a very comfortable eye relief, meaning you don't need to rest your cornea on the eye lens of the EP to see into it. I have a TMB Planetary 6mm- I love it!

What I'm getting at, you don't need to spend big bucks to get good EPs. Understand how our eyes work and their limitations, the physical mechanics of scope optics, a little research and a little tolerance of aberrations, and you can get a really good set-up without spending big bucks.

[casstony]

Originally Posted by mental4astro

!
Suzy, I've had a go of an Andrews 30mm 80* EP in my 17.5" f/4.5. It performed surprisingly well. Actually much better than the Nagler!
.

In the 10" f/5 I had the Andrews 30mm was mainly used as a finder eyepiece - the outer half of the field was terrible. I wonder if there have been changes to the design of the eyepiece for it to perform well in your scope? The 17" would display less field curvature than a 10" but astigmatism should be diabolical at f/4.5.

You might find the Nagler is suddenly transformed with a paracorr in that fast scope.

[mental4astro (Alexander)]

Originally Posted by casstony

In the 10" f/5 I had the Andrews 30mm was mainly used as a finder eyepiece - the outer half of the field was terrible. I wonder if there have been changes to the design of the eyepiece for it to perform well in your scope? The 17" would display less field curvature than a 10" but astigmatism should be diabolical at f/4.5.

You might find the Nagler is suddenly transformed with a paracorr in that fast scope.

Yes, astigmatism is considerable, and no more or less than the Nagler. Shame I couldn't compare both at the same time, I'm really relying on my memory for the comparison, but I remember being really disappointed with the Nagler, and surprised with the Andrews.

The problem with adding a paracorr is the increase in weight at the top of the dob. It starts to get too top heavy. The Panoptic range of EPs is brilliant too, well corrected and 68*FOV. But we are again talking BIG bucks. Then when you add the cost of a paracorr, mate, when does it stop?

If your pockets do have a limited depth, there are still ok choices. That's the mission I've set myself on, .

[casstony]

Alex, imbalance is easily cured by adding weights/magnets to the other end and our exchange rate is good now. If the world economy implodes as it is threatening to do our dollar will drop precipitously.

Most of the top shelf gear I've owned was purchased used - makes it much more affordable - and a used Televue or Pentax is generally a better way to go (with fast scopes) than lower quality stuff that you're never quite satisfied with. 'Ausastronomer' has a lot of experience with which eyepieces really need a paracorr and which ones don't in big dobs if you wanted to find out more. Type 4 naglers and 14/20mm XW's benefited greatly in my 10", but the situation is slightly different in a bigger reflector due to reduced field curvature.

I'll stop my cheerleading now

[mental4astro (Alexander)]

Ta, Tony.

I'll drop Ausastronomer a line on the subject.

I guess I might be a bit precious about adding weights to my scopes. they are all DIY, so big magnets are not an option. Drilling into it to attach some counter weight mechanism doesn't thrill me, but it may well mean surgery.

[Paddy (Patrick)]

Originally Posted by mental4astro

Ta, Tony.

I'll drop Ausastronomer a line on the subject.

I guess I might be a bit precious about adding weights to my scopes. they are all DIY, so big magnets are not an option. Drilling into it to attach some counter weight mechanism doesn't thrill me, but it may well mean surgery.

I needed to add some weights to the base of my dob when I started using a parracor. I've strapped them on with self adhesive velcro. No holes, no worries.

[mbo (Pat and Kirk)]

Hey Alex, as I seem to have a case of early onset aperture fever, I'm considering an F5 12" GSO, so I'm curious if you have tried the 40mm superview? Would an increase in fov and a reduction in F value exacerbate the problems some people seem to have with these ep's?
Also, what celestial objects suit really wide FOV's (not AFOV's), in other words, are there things that wont fit inside the 1.4 degree field of the 30mm that would be better in the 1.8 field of a 40mm?
BTW, I'm going to buy a scope on Friday so I'll be free of the pain of procrastination soon :-)

[Steffen]

I'd prefer if eyepiece makers kept them at moderate viewing angles if that meant they'd be cheaper/more lightweight/more user-friendly and had good sharpness and contrast.

I've never quite shared the obsession with super-wide, ultra-wide and even wider FOV eyepieces. I'd agree that a wider field of view is handy for finding things and keeping them in view when using non-tracking telescopes. However, the eye isn't able to take in big panoramic views. Our angle of sharp vision is tiny (probably 5º or less) so we're scanning our vistas all the time. I found scanning around some of the very wide FOV eyepieces to be hard work. I don't care how sharp stars are at the very edge that I can only see if I roll my eyeball all the way to the stop.

I'm more comfortable with 52 to 60 degree eyepieces. I recently picked up an Edmund RKE 28mm on astromart and despite its "measly" 45º FOV this thing is something else! No hint of barrel vision, on the contrary - the eyepiece seems to project a floating image right in front of your face. It's also cheap and hardly weighs anything. Why can't we have more eyepieces like this?

Cheers
Steffen.

[astro744]

Originally Posted by mental4astro

I've also had a Nagler 30mm EP with its 80deg FOV in the same scope- also appauling- way too wide and impossible to overcome the astigmatism the EP/stumpie light cone combination creates. I also needed to move my head to see the whole image this EP provides, not just my eyeball- our eyes can see well within a 68degree range, NO coincidence!

You'll find the Naglers are highly corrected and show no astigmatism. In fact they show beautiful coma that can be corrected by a Paracorr. I say beautiful coma since only a highly corretced eyepiece will show it properly as poorer corrected eyepieces have astigmatism added.

Any astigmatism you may see using the Nagler would be either the eye or mirrors (pri or sec). Often the eye when straining to see the edge of field will show considerable defects from the eye.

The Nagler has a much flatter field than cheaper 80deg clones also giving sharper stars at the edge.

[mental4astro (Alexander)]

Originally Posted by astro744

You'll find the Naglers are highly corrected and show no astigmatism. In fact they show beautiful coma that can be corrected by a Paracorr. I say beautiful coma since only a highly corretced eyepiece will show it properly as poorer corrected eyepieces have astigmatism added.

Any astigmatism you may see using the Nagler would be either the eye or mirrors (pri or sec). Often the eye when straining to see the edge of field will show considerable defects from the eye.

The Nagler has a much flatter field than cheaper 80deg clones also giving sharper stars at the edge.

I'm glad you mentioned coma & the paracorr in one breath, astro. You answered a question I've had about coma correctors and their part in correcting for astigmatism- they don't! I had suspected this when trying out a Baader MPCC, and the astigmatism was still there, but no coma .

Originally Posted by Steffen

I'd prefer if eyepiece makers kept them at moderate viewing angles if that meant they'd be cheaper/more lightweight/more user-friendly and had good sharpness and contrast.

I've never quite shared the obsession with super-wide, ultra-wide and even wider FOV eyepieces. I'd agree that a wider field of view is handy for finding things and keeping them in view when using non-tracking telescopes. However, the eye isn't able to take in big panoramic views. Our angle of sharp vision is tiny (probably 5º or less) so we're scanning our vistas all the time. I found scanning around some of the very wide FOV eyepieces to be hard work. I don't care how sharp stars are at the very edge that I can only see if I roll my eyeball all the way to the stop.

I'm more comfortable with 52 to 60 degree eyepieces. I recently picked up an Edmund RKE 28mm on astromart and despite its "measly" 45º FOV this thing is something else! No hint of barrel vision, on the contrary - the eyepiece seems to project a floating image right in front of your face. It's also cheap and hardly weighs anything. Why can't we have more eyepieces like this?

Cheers
Steffen.

I agree, Steffen!! I advocate the max. FOV as being 68º (how did you get your degree symbol? I copied and pasted yours here) for the reasons I've outlined. Only two of my EPs go to 68º, everything else is less, and I'm ok with that. However, it is good to have a 60º+ high power EP for a dob as the objects stay in the field of view for longer as they drift. Really good in a push-pull dob!

I LOVE my RKE 28mm . It is by far the best performer in my fast scopes. Its narrower field of view is really not an issue here as its actual field size is great for low power. I've wondered why there isn't a 2" version of it too! I guess that most manufacturers try to convince us that wider is better, and it is not seen as being sexy enough to only have three elements- its got to have seven, or more, be made of exotic glass and designs, and cost us a fortune, not $60. Steffen, next time we're up at Katoomba, try your RKE in my dobbie.

Originally Posted by mbo

Hey Alex, as I seem to have a case of early onset aperture fever, I'm considering an F5 12" GSO, so I'm curious if you have tried the 40mm superview? Would an increase in fov and a reduction in F value exacerbate the problems some people seem to have with these ep's?
Also, what celestial objects suit really wide FOV's (not AFOV's), in other words, are there things that wont fit inside the 1.4 degree field of the 30mm that would be better in the 1.8 field of a 40mm?
BTW, I'm going to buy a scope on Friday so I'll be free of the pain of procrastination soon :-)

MBO, you need to be aware that reflectors have a limiting factor to the maximum focal length eyepiece that can be used with them. Exceed this limit, and you will begin to see the shadow of the secondary mirror through the eyepiece, and there is no way around it.

Wavytone gave me this formula to find out this upper limit:

max focal length = f/ratio of scope X 6

So, for the 12" scope you are looking at, with its f/5 ratio, the longest focal length EP you can use on it is 30mm. Some say you can push this to 7 X the f/ratio, making it 35mm. The thing is, the 30mm limit is safe, the 35mm is the max limit.

As an example, my 17.5" f/4.5 scope's safe limit is 28mm. Its theoretical limit is 32mm. When I look for a low power EP, its focal length needs to sit between 28 & 32mm. I've got an expensive 35mm EP, I just can't use it with this beastie! The 30mm SuperView I have sits within this upper limit range for this scope, so it works.

The 40mm superview may just be too long for the 12" f/5 scope. I'd suggest getting the 30mm first. You know it is safe for your scope, but 40 pushes things a little far if you don't have another low power EP. Once you are up and running, you can borrow someone's 40mm EP and see how it goes in your scope.

Object wise, there are only few DOS's that exceed the 1.4º AFOV. It is something I wouldn't worry about. You'll soon learn how to nudge the scope to see any areas that fall outside this. Your eyes can only see so much at once too. Eta Carina nebula is one, the Andromeda galaxy is another. Maybe the Orion Nebula, and a few other open clusters would fall into this category. Oh, and the Large and Small Magellanic Clouds too. I wouldn't concern yourself about it though.

Whilst you are at it, look at getting a pair of binos if you don't have a pair already. These are fantastic as rich field telescopes! 7X50's are the classic astro size, and double up nicely for daytime viewing too. They don't need to be expensive too, that they are aligned properly is more important.

[Suzy]

Originally Posted by Paddy

I needed to add some weights to the base of my dob when I started using a parracor. I've strapped them on with self adhesive velcro. No holes, no worries.

This is what I do as well. I use a camera case that has the strap on the back (hand grip- short and flat- if that makes sense?!). I then pass the velcro thru it. Get your kitchen scales out and weigh the weights inside the bag to make sure the weights will be reasonable all rounders to match ep weights. I find attaching the weight off centre of the tube, in line with the focuser, balances my scope better than when I have it in the middle. You'll soon find this out when you experiment with its position.

[casstony]

Originally Posted by mental4astro

I'm glad you mentioned coma & the paracorr in one breath, astro. You answered a question I've had about coma correctors and their part in correcting for astigmatism- they don't! I had suspected this when trying out a Baader MPCC, and the astigmatism was still there, but no coma .

The Televue Paracorr does give some astigmatism improvement by virtue of slowing the light cone a little - your f/4.5 effectively becomes an f/5.2 (magnification, focal length are increased by 15%).
Field curvature is also reduced; I don't know if thats purely a result of the increased focal length (and therefore longer effective radius of curvature) or if the Paracorr was designed to reduce field curvature. In any case, reduced field curvature is glaringly obvious in some eyepieces.

[mbo (Pat and Kirk)]

Ahh, thanks Alex. I realise now that I blundered the calculation of eyepiece focal length, your version:
max focal length = f/ratio of scope X 6
is nice and straight forward.
By the way, for those that don't already know, the value of 6 (or 7) is for the Exit Pupil.
As for the super wide apparent fields, I suppose I wont know until I try. There doesn't seem to be an astronomy club in Dubbo so I haven't been able to sample anyones gear (If any one on the forum is from around here, please say G'day)
I'm going to Sydney tomorrow to pick up a scope, so at last theory will yield to practical... when this rain clears up anyway!

[mental4astro (Alexander)]

mbo, I've sent you a PM. When do you go home from Friday's scope reclaim?

[mbo (Pat and Kirk)]

Hi Alexander, I just replied, but my sent items is empty?, did you get the message?