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shanmac

Eyepiece for 10” f/5 Dobsonian

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Hey Guys, I’ve recently purchased a 10” Bresser Messier Dobsonian f/5, I need some advice on eyepieces. It would seem these type of scopes are quite picky in reguards to eyepieces. It is mostly going to be used for observing DSO’s. The Scope can accommodate both 1.25” and 2” eyepieces. I am a total newbie to the world of Dob’s and 2” eyepieces so all help will be appreciated. Budget is not set in concrete but value for money is a must.

I also have a 5” Mak for which I use - Revelation Astro 32mm plossl - Baader Hyperion 13mm - VixenNPL 10mm and 20mm.

 

Edited by shanmac

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Hi Shanmac, the BST StarGuiders are pretty good all-rounders and excellent value for money, good sized eye lens and good eye-relief with twist-up eyeguard found here:

https://www.ebay.co.uk/sch/i.html?_from=R40&_trksid=m570.l1313&_nkw=Bst+starguider&_sacat=0

For a wide field 2" ep I would go for the 28mm Explore Scientific 68° Series Eyepiece found here:

https://www.firstlightoptics.com/explore-scientific-eyepieces/explore-scientific-68-degree-series-eyepieces.html

If you can afford it the ES82 series 30mm is even better with its wider AFoV, but not good if you wear specticles.  

BTW, the 13mm Baader Hyperion does not work so well in a fast scope like yours

 

Edited by rwilkey
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35 minutes ago, rwilkey said:

Hi Shanmac, the BST StarGuiders are pretty good all-rounders and excellent value for money, good sized eye lens and good eye-relief with twist-up eyeguard found here:

https://www.ebay.co.uk/sch/i.html?_from=R40&_trksid=m570.l1313&_nkw=Bst+starguider&_sacat=0

For a wide field 2" ep I would go for the 28mm Explore Scientific 68° Series Eyepiece found here:

https://www.firstlightoptics.com/explore-scientific-eyepieces/explore-scientific-68-degree-series-eyepieces.html

If you can afford it the ES82 series 30mm is even better with its wider AFoV, but not good if you wear specticles.  

BTW, the 13mm Baader Hyperion does not work so well in a fast scope like yours

 

Thanks man. Yea the ES82 30mm seems great value alright. I’m wondering if I was to buy one EP for viewing DSO’s would a low power 30mm be the first one to invest in, and also would 3 in total, low, mid and high power be the way to go? 

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13 minutes ago, shanmac said:

Thanks man. Yea the ES82 30mm seems great value alright. I’m wondering if I was to buy one EP for viewing DSO’s would a low power 30mm be the first one to invest in, and also would 3 in total, low, mid and high power be the way to go?  

Hi Shanmac, your plan to invest in the 30mm ES82 would be great for DSO's which thrive at low power, the only thing is that it does not have the eye-relief specified on the ExSc website, it is slightly shorter so you have to get the eye a bit closer to see the whole view.  Your idea to get 3 eyepieces in total is the best way to go, I think.  I suggest something like the 18mm, 12mm or 8mm StarGuiders.  Good luck with your choices!

Edited by rwilkey

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52 minutes ago, rwilkey said:

Hi Shanmac, your plan to invest in the 30mm ES82 would be great for DSO's which thrive at low power, the only thing is that it does not have the eye-relief specified on the ExSc website, it is slightly shorter so you have to get the eye a bit closer to see the whole view.  Your idea to get 3 eyepieces in total is the best way to go, I think.  I suggest something like the 18mm, 12mm or 8mm StarGuiders.  Good luck with your choices!

The ES82 30mm has 22mm eye relief, so it’s in the lead at the mo ?

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I am more or less ready to pull the trigger on an ES82 30mm. One last hurdle, I’ve been doing some research and just come across (coma), which is something I know nothing about. Anyone know if my scope + ES 30mm will have the chance of suffering from (coma)?

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Slow down, please. You are already owner of a decent 32 mmf Plössl, and I'd try out first, if it works well with your 10" scope at your given location.The magnification with the 32 mmf will be almost the same- it's just the field of view that will be more extended with the 30 mmf/2". If you are suffering from light pollution, the brightness of the sky background might reduce the contrast of certain DSO's markedly (esp. galaxies, gaseous nebulae). In this case, your eyepieces from 20 down to 10 mmf would be more suitable; just try out.

Your f/5 scope will, as any fast Newtonian, suffer from coma (a comet-like distortion at the field's edges; have a look at this: http://umich.edu/~lowbrows/reflections/2007/dscobel.27.html). A coma corrector can diminish this inherent optical fault; but the degree of "coma-tolerance" seems to vary considerably from observer to observer. I for myself have no problems with coma notion when observing with my f/4 to f/5 scopes; others claim, that anything faster than f/5 needs a coma corrector for them at any rate.

Hth.

Stephan

 

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1 hour ago, shanmac said:

I am more or less ready to pull the trigger on an ES82 30mm. One last hurdle, I’ve been doing some research and just come across (coma), which is something I know nothing about. Anyone know if my scope + ES 30mm will have the chance of suffering from (coma)?

Two things:

1) These may save you a few shillings. I believe they are the same, or very nearly the same as the ES82* range. If anything differs it might be something like coatings perhaps. But do have a look. http://www.opticstar.com/Run/Astronomy/Astro-Accessories-Telescopes-Opticstar.asp?p=0_10_5_1_8_322

2) You'll be on the cusp of where Coma might start to be noticeable to you (depending on how critical you are). I have a 4.7 Dob and a ES82* 30mm. Some nights I don't use the Coma Corrector and some I do. On the nights I do I can reduce the coma towards the edge of the FoV. On the nights I don't the views are still mighty fine with a little more coma visible, but it certainly doesn't spoil my enjoyment. @Littleguy80 raised the same question a while back and I'd tell you what I told him; buy the eyepiece, enjoy it, if the coma is an obvious intrusion, get a coma corrector. If it doesn't bother you, happy days... :thumbsup:

Edited by Stargazer McCabe
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13 minutes ago, Stargazer McCabe said:

 @Littleguy80 raised the same question a while back and I'd tell you what I told him; buy the eyepiece, enjoy it, if the coma is an obvious intrusion, get a coma corrector. If it doesn't bother you, happy days... :thumbsup:

Excellent advice. I’ve been happily using my ES82 30mm with my 10” F4.7 dob without a coma corrector. I find that personally I use the ES82 30mm primarily on Nebula, trying to get maximum TFOV and exit pupil with filters. Coma doesn’t even cross my mind on those targets. When you’ve got a beautifully framed Eastern Veil in the eyepiece, the last thing that gets your attention is coma!

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Excellent choice of telescope!  For finding your way round, an ES 82 30mm would be great, giving about 2 degrees of field.  Larger focal lengths would give a poorer view in terms of contrast/background brightness.  And Yes, coma will be noticeable at the edges, but it doesn't diminish the experience or detract from the enjoyment of nebulae and galaxies.  And with large clusters for example, you only focus on the central region anyway.  I personally prefer the less-than-sharp edge clarity to putting in more glass and weight.  (Not to mention more expense.)

Doug.

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1 hour ago, Nyctimene said:

Slow down, please. You are already owner of a decent 32 mmf Plössl, and I'd try out first, if it works well with your 10" scope at your given location.The magnification with the 32 mmf will be almost the same- it's just the field of view that will be more extended with the 30 mmf/2". If you are suffering from light pollution, the brightness of the sky background might reduce the contrast of certain DSO's markedly (esp. galaxies, gaseous nebulae). In this case, your eyepieces from 20 down to 10 mmf would be more suitable; just try out.

Your f/5 scope will, as any fast Newtonian, suffer from coma (a comet-like distortion at the field's edges; have a look at this: http://umich.edu/~lowbrows/reflections/2007/dscobel.27.html). A coma corrector can diminish this inherent optical fault; but the degree of "coma-tolerance" seems to vary considerably from observer to observer. I for myself have no problems with coma notion when observing with my f/4 to f/5 scopes; others claim, that anything faster than f/5 needs a coma corrector for them at any rate.

Hth.

Stephan

 

Yea, Im getting great results with the Revelation Astro 32mm on my 5" MAK. Its the ES's 82° FOV for the 10" Dob that prevents me from slowing down ?

Edited by shanmac
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1 hour ago, Stargazer McCabe said:

Two things:

1) These may save you a few shillings. I believe they are the same, or very nearly the same as the ES82* range. If anything differs it might be something like coatings perhaps. But do have a look. http://www.opticstar.com/Run/Astronomy/Astro-Accessories-Telescopes-Opticstar.asp?p=0_10_5_1_8_322

2) You'll be on the cusp of where Coma might start to be noticeable to you (depending on how critical you are). I have a 4.7 Dob and a ES82* 30mm. Some nights I don't use the Coma Corrector and some I do. On the nights I do I can reduce the coma towards the edge of the FoV. On the nights I don't the views are still mighty fine with a little more coma visible, but it certainly doesn't spoil my enjoyment. @Littleguy80 raised the same question a while back and I'd tell you what I told him; buy the eyepiece, enjoy it, if the coma is an obvious intrusion, get a coma corrector. If it doesn't bother you, happy days... :thumbsup:

Thanks for that. I will take a look at those Opticstars for sure, though I would be a bit cautious on having faith in a clone but yea, worth a look.

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1 minute ago, shanmac said:

Thanks for that. I will take a look at those Opticstars for sure, though I would be a bit cautious on having faith in a clone but yea, worth a look.

I have some of the other opticstar eyepieces (Orthos) and they are exceptional... Opticstar can be trusted. They aren’t substandard “clones”...

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57 minutes ago, cloudsweeper said:

Excellent choice of telescope!  For finding your way round, an ES 82 30mm would be great, giving about 2 degrees of field.  Larger focal lengths would give a poorer view in terms of contrast/background brightness.  And Yes, coma will be noticeable at the edges, but it doesn't diminish the experience or detract from the enjoyment of nebulae and galaxies.  And with large clusters for example, you only focus on the central region anyway.  I personally prefer the less-than-sharp edge clarity to putting in more glass and weight.  (Not to mention more expense.)

Doug.

Cool, cheers Doug.

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+1 for the ES range of eyepieces.  FWIW I have 3 of the BST eyepiece and find them very easy to get on with in my mac, so although they lack the fov of the es eyepieces, they are very cheap and offer great value for money.

 

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1 hour ago, Stargazer McCabe said:

I have some of the other opticstar eyepieces (Orthos) and they are exceptional... Opticstar can be trusted. They aren’t substandard “clones”...

Ok, thanks, I'll have a look ?

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41 minutes ago, bomberbaz said:

+1 for the ES range of eyepieces.  FWIW I have 3 of the BST eyepiece and find them very easy to get on with in my mac, so although they lack the fov of the es eyepieces, they are very cheap and offer great value for money.

 

Yea, I do though want to get the best out of my 10" Dob, i'm not sure if i could accomplish that with the BST. But i am no expert so I may be wrong.

Edited by shanmac

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Could I possibly throw a 2" Revelation 30mm 70° into the mix before my head explodes?

Edited by shanmac

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I had a 2" rev, but used it in a F10 scope. Result brill but your F5, doubt results would be as quite as pleasing although you should be ok but over the outer part it will get comma. 

Suggestion though, if you want to get going and are happy to accept some issues, which if on a budget and lets be honest, you have to.

Plus why spend a lot of cash to find out your chosen targets/scope/eyepieces or whatever are not what you actually wanted/needed/or dont work for you. 

IDEA if you must spend as I feel as though your wallets on fire ??

Get the rev 30mm. Aint got the quality of the ES but the width of field will keep you going until you settle on what you really want.  Will give lovely wide field views and will also be a great spotter.

Next a Skywatcher 22mm SWA 70fov eyepiece. I have Had this too and is a fantastic piece of glass for the price. It was my stalwart for 2 years at least until I upgraded. Even now I miss it, it really was that good.

Also use the 13mm Hyperion, read on.

A good 2" barlow with the above eyepieces gives the following options. A low power eyepeice from the rev (x42 by 2 degrees)  3 med (57, 83 and 114)  thats from the sw 22, rev 30mm plus barlow and sw 22mm plus barlow and finally you have a high mag eyepiece (13mm hyp plus barlow) with that combo for probably around the same as a single bit of glass such as the ES  30/82. 

The hyperion 13mm at near x200 will give a great view, you will not notice much difference from that to a nagler imho.

If you look at my signature I am a advocate of barlows.  Saves me having more glass than I need and in the case of my dob, 250mm as yours covers everything with 3 eyepieces and equivalent barlow. 

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In my experience on an UNDRIVEN F/5-Dob a good gradation of focal lenght(single eyepieces or combination with barlow) would be:

30mm, 2", 68-82°(ExitPupil 6mm) - for searching DSO's

20mm, 2", 68-82°(ExitPupil 4mm) - for galaxies, nebulars, star cluster

[~14mm, 2", 82°(ExitPupil 3mm] - the real workhorse for DSO's

10mm, 1.25", 82°(ExitPupil 2mm) - for star globulars, small galaxies or nebulars

-notice that under 10mm focal lenght the object you're looking at will rush quite fast trough the FOV-

[~7mm, 1.25", 82°(ExitPupil 1.4mm)] - see 10mm

5mm, 82°-110°(ExitPupil 1mm) - for planets and double stars

[4mm, 82°-110°(ExitPupil 0.8mm)] - see 5mm

- an alternative for 5 and 7mm could be the Antares Speers Waler Zoom 5-8mm(out of production)

- all focal lenghts in [..] can be added later(starting with ~14mm)

- watch out for eye eyereliefs bigger than 17mm if you wear spectacles

 

just 2cents from another newbie, open for other opinions(eyepieces will ever be a very personal decision)

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I love these threads. Everyone has their favourites. 

I enjoyed the ES30mm 82° a lot in my 10” f4.7, but it was the ES24mm 82° that really made if fly! Not everyone’s eyes can quite get to the required 6mm pupil aperture. Dark sky helps too?.

The optical challenges that are inherent to wide field eyepieces are harder to control at the longer focal lengths. At 24mm 82° they seem well controlled, but by 30mm they are noticeable. Weather these are acceptable is a matter of personal taste.

For shorter eyepieces, you will be happy at the less eye watering expense of 68°.

Paul

 

 

 

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Ok Guys, my ES82° 24mm arrived today :-). Unfortunately also have the clouds and the rain. Will update this thread after I get a chance to try my new toy out ☁️?☁️?☁️

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24 minutes ago, shanmac said:

Ok Guys, my ES82° 24mm arrived today :-). Unfortunately also have the clouds and the rain. Will update this thread after I get a chance to try my new toy out ☁️?☁️?☁️

Great news!  I recently acquired a Meade 5000 UWA 24/82 for my Bresser - it gives a decent field of view, without excessive exit pupil.  I'm sure you'll enjoy your new toy.  Going back a bit, you mentioned a 30mm EP.  That would be a good idea for finding your way round.  A Revelation 30 would not give much more than your new 24mm, but since you're into the ES 82 series, the ES 30/82 would give a handy 2 deg.  A lower cost/weight alternative is the Baader Aspheric 36/72.

Have fun!

Doug.

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46 minutes ago, cloudsweeper said:

Great news!  I recently acquired a Meade 5000 UWA 24/82 for my Bresser - it gives a decent field of view, without excessive exit pupil.  I'm sure you'll enjoy your new toy.  Going back a bit, you mentioned a 30mm EP.  That would be a good idea for finding your way round.  A Revelation 30 would not give much more than your new 24mm, but since you're into the ES 82 series, the ES 30/82 would give a handy 2 deg.  A lower cost/weight alternative is the Baader Aspheric 36/72.

Have fun!

Doug.

I actually opted to invest (in the near future) in decent Binos instead of the 30mm. After using an app for AFOV vs DSO's, I decided I would probably get better use from the 24mm. If the 24mm is not low powered enough for finding my way around I'll have too look at maybe the ES30. I'm gonna wait for clear sky before my next move, which may also include the 14mm Morpheus ? 

Edited by shanmac

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Consider a 5mm Skywatcher UWA Planetary eyepiece for planets, small DSOs and lunar closeups. Lot of bang per buck.

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