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Vox45

YAQAE (Yet another question about Eyepieces)

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So, I've read tons of threads and I still can't figure out what I need. I do have a vague idea but I need some reassurance (don't we all) when comes the time of spending 200£+ on pieces of glass ;)

I am looking for EP's that are reasonably good at a medium range price. I do like to have a good eye relief and good FOV. I will be observing planets, moon, sun and some DSO when I get the chance to go to dark sites.

I've read excellent reviews on BST and I also looked at the X-Cel Series from Celestron. I do have the 25mm Celestron E-Lux Series that came with the scope.

A couple of questions:

(1) Which combination of these would cover the basic needs ? My scope is a 150mm/1500mm (6" SCT)

18mm BST Explorer
15mm BST Explorer
12mm BST Explorer
 8mm BST Explorer
 5mm BST Explorer

(2) should I stick to the BST brand to keep things parfocal or should I go with the Celestron series since I already own the 25mm ? Is this even an issue ?

(3) I am struggling with the idea of buying a 2x barlow and I guess this would complicate my choice of EP's. Isn't a 8mm EP a waste if I get a 15mm with a 2x barlow ?

Thanks all, any comments and feedback will be appreciated !

I am aware that this will not be my last set of EP's, so go easy on me ;)

Edited by Vox45
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I'm so glad you have asked this question. I too have just got a 6" SCT and I hope to look at exactly the same things as you, so will be watching this thread intently!

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Glad this could help more than me ;) It can be quite confusing and the fact that it's my first purchase of EP's makes thing even harder. I have no point of comparison...

I see that Skysthelimit who sells the BST EP's lets you try them out. That maybe a way to go but I still need to know which power of mag I should get...

http://www.skysthelimit.org.uk

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Now we wait ...

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Hiya, 

There's a good thread comparing BSTs and Explore Scientific MaxVisions here , which I've been following for exactly the same reason as you. I'm favouring the MVs, myself, though the shortest focal length offered is 16mm. One thing I have learned, though, is that it seems that 5mm is often too much, in terms of magnification, and may get used only on the clearest of nights.

Kev. 

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I am reading this thread now. Thanks for pointing it out :)

I think my choice is made regarding the brand (BST) but I still need to figure out the other questions about which focal lenght and the barlow issue. Like you said, and from what I understand, 5mm is ok for the clearest night, so 8mm would be good for planetary and 5mm used when seeing is great.

but the gap between 5mm and 25mm is where I am not too sure ;) What about above 25mm ?

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I was going to say to take a look at the Maxvisions, but you're probably already there by now.

A 32mm plossl would be an option for over 25mm.

A low power EP is very handy to have in your collection.

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What about a Baader Zoom? Ive just picked up a mint s/h one for £100 so worked out cheaper than a host of individual eyepieces,

Cheers,

Rob.

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Hiya,

How about using Stellarium, and entering a variety of eyepiece configurations with your scope and compare some views on planets, nebulae, galaxies, etc. It's not perfect, but'll give you an idea of what you can expect to see.

Kev

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Hi again,
 
Because I've been researching EPs lately myself I knocked up a little thing in Filemaker to do some mag/fov calculations on the various combinations. I input your BST EPs, plus a couple of MVs for the hell of it, and took a couple of screenshots (hopefully attached here!). If you compare the various EPs' fields of view against magnification, at x300 the 5mm BST is probably way beyond what's useable (plus it'll have a tiny fov). The MVs win out on fov, with the 16mm MV also beating the BST 18 on mag as well ... Also, the MV 24 beats the 32mm Revelation polls on both counts. (hope that all makes sense :smiley:   )

 
Kev

post-30297-0-79596500-1413833540_thumb.p

post-30297-0-52574200-1413833565_thumb.p

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What about a Baader Zoom? Ive just picked up a mint s/h one for £100 so worked out cheaper than a host of individual eyepieces,

Cheers,

Rob.

Congratulations, you've got an excellent combination of EPs for DSO and planetary observing..

To OP's questions, just as kev showed in the graphs above, 5mm will be waste of money for your scope. I'd recommend you to have a look at the discussions here before making decision:

http://stargazerslounge.com/topic/217907-first-eyepiece-upgrade-what-you-wish-you-had-done/page-3?hl=%2Bfirst+%2Bupgrade#entry2362198

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Hi there........I really get on well with the BST's  If you want to get a minimum set then the  8mm 12mm & 18mm would be just fine. remember, if you not satisfied with the EP's you can return them easy as chips and get a refund?

Their not exactly parfocal in my 200P Dob f/6 , I have to adjust slightly.

A Barlow is fine, as long as its a decent one. I was recommended the Skywatcher 2x, and have no regrets, even the lens cell can  be fitted alone to the eyepiece giving about 1.5X.

Edited by Charic
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Informative graph you got there Kev ! :) thank you!

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Congratulations, you've got an excellent combination of EPs for DSO and planetary observing..

To OP's questions, just as kev showed in the graphs above, 5mm will be waste of money for your scope. I'd recommend you to have a look at the discussions here before making decision:

http://stargazerslounge.com/topic/217907-first-eyepiece-upgrade-what-you-wish-you-had-done/page-3?hl=%2Bfirst+%2Bupgrade#entry2362198

Thanks for this link ! it's great to ba able to learn from other's mistakes hé hé :evil:

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Hi there........I really get on well with the BST's  If you want to get a minimum set then the  8mm 12mm & 18mm would be just fine. remember, if you not satisfied with the EP's you can return them easy as chips and get a refund?

Their not exactly parfocal in my 200P Dob f/6 , I have to adjust slightly.

A Barlow is fine, as long as its a decent one. I was recommended the Skywatcher 2x, and have no regrets, even the lens cell can  be fitted alone to the eyepiece giving about 1.5X.

Hemm let see: if I get 8mm/12mm/18mm and a 2x barlow then I get 5.3mm/8mm/12mm wich is redundant or am I doing the calculation wrong ?

12mm / 1.5 = 8mm 

18mm / 1.5 = 12

Correct ?

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Informative graph you got there Kev ! :) thank you!

Hiya, cheers! Like I said, I've been researching EPs for ages now myself, and thought I'd put something together in Filemaker to help illustrate various options (it's a work in progress!). I got the calculations from a similar website to this one: http://www.nexstarsite.com/_RAC/articles/formulas.htm (can't remember exactly which one it was ... Ten you just enter the various EP / barlow / scope details and plot it on a graph! :)

post-30297-0-14806400-1413882161_thumb.p

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Hiya, cheers! Like I said, I've been researching EPs for ages now myself, and thought I'd put something together in Filemaker to help illustrate various options (it's a work in progress!). I got the calculations from a similar website to this one: http://www.nexstarsite.com/_RAC/articles/formulas.htm (can't remember exactly which one it was ... Ten you just enter the various EP / barlow / scope details and plot it on a graph! :)

attachicon.gifEPs.png

Thanks for the link !

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What about a Baader Zoom? Ive just picked up a mint s/h one for £100 so worked out cheaper than a host of individual eyepieces,

Cheers,

Rob.

Thanks for the hint Rob ! I guess it's the way to go for me. I'll have everything in one go and if ever I need it, I'll build a better optical set over the years.

This Baader zoom  solves my immediate need and it's good quality as far as reviews go. The price for the zoom is 198€ so that's 198/5= 39€ for each focal lenght :)

Edited by Vox45
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Hiya, How about using Stellarium, and entering a variety of eyepiece configurations with your scope and compare some views on planets, nebulae, galaxies, etc. It's not perfect, but'll give you an idea of what you can expect to see. Kev

Great tip. I just did that and from what I see the Baader Zoom would cover my needs at 8mm/12mm/16mm/20mm/24mm..

Still not sure about the Barlow ;)

I was going to say to take a look at the Maxvisions, but you're probably already there by now.

A 32mm plossl would be an option for over 25mm.

A low power EP is very handy to have in your collection.

Yes. I will look into a low power EP as you recommend. Thanks !

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Thanks for the hint Rob ! I guess it's the way to go for me. I'll have everything in one go and if ever I need it, I'll build a better optical set over the years.

This Baader zoom  solves my immediate need and it's good quality as far as reviews go. The price for the zoom is 198€ so that's 198/5= 39€ for each focal lenght :)

There is one on Ebay at the moment, I dont think its a MK111 but Im sure they are all good.

VCheers,

Rob.

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Not sure how all this will be working out....

[scope] > [focal reducer] > [Diagonal] > [Zoom EP] > [barlow]

focal reducer for f/6.3 therefore bigger FOV (I guess) but then I need to barlow ... not sure this makes sens ...

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So, I've read tons of threads and I still can't figure out what I need. I do have a vague idea but I need some reassurance (don't we all) when comes the time of spending 200£+ on pieces of glass ;)

I am looking for EP's that are reasonably good at a medium range price. I do like to have a good eye relief and good FOV. I will be observing planets, moon, sun and some DSO when I get the chance to go to dark sites.

I've read excellent reviews on BST and I also looked at the X-Cel Series from Celestron. I do have the 25mm Celestron E-Lux Series that came with the scope.

A couple of questions:

(1) Which combination of these would cover the basic needs ? My scope is a 150mm/1500mm (6" SCT)

18mm BST Explorer

15mm BST Explorer

12mm BST Explorer

 8mm BST Explorer

 5mm BST Explorer

(2) should I stick to the BST brand to keep things parfocal or should I go with the Celestron series since I already own the 25mm ? Is this even an issue ?

(3) I am struggling with the idea of buying a 2x barlow and I guess this would complicate my choice of EP's. Isn't a 8mm EP a waste if I get a 15mm with a 2x barlow ?

Thanks all, any comments and feedback will be appreciated !

I am aware that this will not be my last set of EP's, so go easy on me ;)

5mm is unlikely to be useful in this scope, giving too much magnification.  Even the 8mm will be pushing it so could be a later purchase inf you find you like the BSTs and that the 12mm does not give you enough magnification.  I would also skip the 15mm which I think gives too small a gap for a basic eyepiece collection. Instead I would go for an an eyepiece nearer the maximum for a 1.25" barrel, like the 24mm BST (or perhaps a 30mm plossl).  This would then give the following ratio steps between eyepieces

8 * 1.5 (later)

12 * 1.5

18  * 1.3

24

I hope this helps.

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Hemm let see: if I get 8mm/12mm/18mm and a 2x barlow then I get 5.3mm/8mm/12mm wich is redundant or am I doing the calculation wrong ?

12mm / 1.5 = 8mm 

18mm / 1.5 = 12

Correct ?

Hi  Vox45.........from your statement,  your calculations ARE wrong? ............With a 2xBarlow you will get  4mm, 6mm, 9mm.

Yes, the Skywatcher 2x Barlow, can be used separately from its barrel and screwed directly onto the base of an eyepiece, giving effectively 1.5x Factor.

Your calculations are correct   for using just the  1.5x  cell, and from this calculation you have already  noted  the downfall  by using just  the 1.5x Barlow. I did not point this out!

Why Barlow the 18 at 1.5x when you can just use the 12mm?  The eye relief may be better on the 18mm/Barlowed, thats all. You should try and cater for either just using EP's only, therefore less glass in the optical train, or Barlow a specific set, whereby the focal lengths don't replicate after the conversion factor.

A 5mm BST would be near the limits of your telescope giving 300 x power and 0.5mm exit pupil, causing a dimmer image. This might be  fine for the Moon, but anything further ( just about everything else) you may struggle at this magnification. Use your aperture as a guide to your practical limits, and exceed them cautiously!

I have the 5mm as it just completes the set. It was the last BST I purchased replacing my  6mm TMB/PII. I feel the 5mm  BST is more comfortable to use than the TMB, however, I now have the 6mm WO SPL, which is good, but due to the weather I've been having, I need to compare some more.

Edited by Charic
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