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Old 16-02-2017, 01:27 AM
lynton
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Thumbs down f/4.7 dob eyepiece for planets

hi all, i am the proud new owner of a 10" skywalker dob that i found on gumtree for only $450. it had some extras too including some 2" eps at 15, 26, 42, 50 a 1.25" 2x barlow ( previous owner accidentally bought this as all his eps are 2" ) and a telrad target finder which i found really great to use especially locating saturn which was just a tiny spec in the sky.

I tried it out last night and as luck would have it got to see jupiter saturm and the moon, mostly through the 15mm knight owl uw80.

i now want to get an ep that will give higher magnification for planet viewing as , at least at this early stage, that is what i like the most.

from reading around it seems that with a f4.7 10" dob ,better quality eps and wide fov are desirable.

I like the look and price point of explorer scientific 82 deg 6.7mm.

i figure that this would give me 1200 / 6.7 = 180x and with the as yet unchristened barlow a whopping 360x.

the barlow is a super barlow 2x from seben.com and im wondering if i will be able to use this with an es82 or will need to get a better barlow ?

i am going along to meet with an astronomy club on saturday so im sure i will get some great advise and hopefully even get a look through some eps.

but i just thought id post this here in case someone has this ep with a 10" f4.7 dob and can tell me how well or not it works and whether an average barlow is ok with it.

any other suggestions are welcome too perhaps smaller / larger mag is better ? its a push to scope so l am a little worried about being able to keep up at high mag.

cheers

lynton
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  #2  
Old 16-02-2017, 08:08 AM
geolindon (Lindon)
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G day Lynton n

great first light! that's gotta have you hooked, n i reckon you are on the right track re Expl Scientific and larger fov for longer views between 'scope nudges

i find around 200x is the most used magnification at my usual sites, your site may permit higher - the best way is to 'suck n see' and getting with a group is the best way to do that. Try not to rush n waste $$, the planets n DSOs are hanging around for a while yet.

Enjoy, L
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Old 16-02-2017, 08:16 AM
Wavytone
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Linton there's a general rule - fewer glass elements are better than more. In this case a short eyepiece works better than a similar but longer one + barlow.

You'd do best with one around 4-5 mm.
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Old 16-02-2017, 08:22 AM
Wavytone
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Last edited by Wavytone; 16-02-2017 at 11:04 AM.
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Old 16-02-2017, 07:25 PM
lynton
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thanks for your comments guys, i will wait till after saturday and see if i can get to try out some different sizes.

i will have to keep my itchy fingers from jumping in a buying something before then was very tempted by the pentax xw 5mm and 10mm for sale on here at the moment but i guess others will come up.

i guess the barlow may be better used for lower magnification lenses and use the higher mags alone.
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Old 17-02-2017, 09:04 PM
bigjoe (JOSEPH)
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Quote:
Originally Posted by lynton View Post
thanks for your comments guys, i will wait till after saturday and see if i can get to try out some different sizes.

i will have to keep my itchy fingers from jumping in a buying something before then was very tempted by the pentax xw 5mm and 10mm for sale on here at the moment but i guess others will come up.

i guess the barlow may be better used for lower magnification lenses and use the higher mags alone.
The 10mm pentax or 10mm Delos are incredible eyepieces
They just dont come any better IMO! A lifetime EP.
bigjoe
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Old 18-02-2017, 02:50 AM
AEAJR (Ed)
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I have an F5.9 8" dob and I LOVE the Explore Scientific 82 degree eyepieces. I have the 8.8 and the 6.7. Will add the 11 at a future date. I have a 2" 2X barlow, 1.25" 2X and 3X barlows to extend my eyepiece collection.

Zoom - If you want to get a wide range of magnifications for a relatively modest investment, the Celestron 8-24 zoom is my most used eyepiece. Gives me 50-150 by itself. Drop it in the 2X barlow and I have 100 to 300. Not as wide as the ES 82s but I have everything with the zoom and the barlow. Over time I have added in single FL eyepieces as I have felt the need but this is still my most used eyepiece.

If you like the idea of the zoom and have a larger budget then go for the Baader Hyperion 8-24. 25% wider FOV than the Celestron and likely better overall optics but 4+X the price.
http://agenaastro.com/eyepieces/zoom-eyepieces.html

zoom eyepiece review
http://www.chuckhawks.com/comparison_zoom_eyepieces.htm

But even at the price of the Baader it is around the same price as 2 ES 82s and far more versatile. Some people say the Baader is now their only eyepiece.

BaaderHyperian III Clickstop zoom review
http://www.weasner.com/co/Reviews/20...ece/index.html



If you want to go single FL eyepieces then I would suggest the ES 82 8.8 mm first. A more practical jump from the 15 mm. That would give you 136X which can be useful on moon, planets and on DSOs. Slip it into the 2X barlow and you have 272X. A more versatile combination in my opinion than the 6.7 if you can only get one right now. If you can get both then the 8.8 and the 6.7 are a great combination.


I don't know what your sky conditions are like. I live just outside New York City so my light pollution is bad. I find that, between LP and seeing, I rarely get over 250X except on the moon. Most of my observing is done closer to 200X.

I use the 6.7 by itself a LOT at 179X but I also have a Meade HD60 4.5 to take me to 266X, that next level of magnification and typically, again, I only use this on the moon as the seeing often won't support this for other targets.

I have used my ES 82s in 2X and 3X barlows in my 80/400 refractor and they work just fine. You still get that wide view effect.

If you don't want to use the barlow then the 6.7 would be the way to go but don't expect to do a lot at 360X. But your smileage may vary a lot from mine.

Clear skies!

Last edited by AEAJR; 18-02-2017 at 03:06 AM.
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Old 18-02-2017, 08:05 AM
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Benjamin (Ben)
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Perhaps another thing to consider when looking for a planetary eyepiece would be exit pupil. Something good would be around an exit pupil of 1mm, which translates on the 10" Dob to around a 5mm eyepiece. Not great for DSOs which benefit from exit pupils above 2mm.

Given eyepieces are quite a personal thing it's best to try before you buy as everyone suggests. For me I find eye relief more satisfying than a super large field of view (for me 70° is just great) and this isn't because I wear glasses. The first time I looked through a Pentax XW 7mm at Jupiter I was completely gob-smacked and I owned and was very familiar with the comparable 6.7mm ES82°. I don't think the view was necessarily that much better but something about the large un-recessed glass surface area of the Pentax appealed instantly. So I guess in trying eyepieces as much as you consider magnification and field of view also see if extra eye relief appeals :-)
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Old 21-02-2017, 04:24 PM
lynton
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Originally Posted by AEAJR View Post
If you want to go single FL eyepieces then I would suggest the ES 82 8.8 mm first. A more practical jump from the 15 mm. That would give you 136X which can be useful on moon, planets and on DSOs. Slip it into the 2X barlow and you have 272X. A more versatile combination in my opinion than the 6.7 if you can only get one right now. If you can get both then the 8.8 and the 6.7 are a great combination.
thanks this is great detailed info to work on, I am liking the ES 82 8.8 mm now.

Mostly I will be viewing from home which is polluted by street lights somewhat and once a month at the astronomy club, so the 8.8 136x seems a good first choice to me that I should still be able to use in less than ideal conditions at home.

I went to the tas astronomical society meet up last saturday and although it was not a great night for it, we still were able to find the jewel box , trapesium and some double stars to look at.

People were great and it was very educational, I was able to get a look through a pentax 14mm in my scope and compare it to my 15mm nightowl.

Whilst it looked great and was able to better split a double star in cloudly conditions (at least to my untrained eye) it wasn't all that better than my one, so I think Ill stick to the less costly EPs for now.

thanks again for all the suggestions, I will try and get a look through a zoom piece at the next meetup. They sound good in that you can pick the "right" magnification for the conditions and also save changing EPs all the time.

It would be nice to compare a zoom to a fixed EP of the same make.
If I get a chance to do this I'll post my thoughts.


Now off to see if that 8.8 ES is still there
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Old 21-02-2017, 06:56 PM
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Hi Lynton,

You couldnt go wrong with the 8.8mm or something around that size. Ive got a 10" skywatcher dob with 25,18,12.5,9 and 6mm ortho eps and on most nights my 9mm is about as far as you can go due to seeing conditions. My 6mm does get used however only about 50% of the time. With your smallest at 15mm the 8.8 would be a good step to see more detail plus on nights of really good seeing then barlowing the 8.8 to 4.4 is doable.
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Old 23-02-2017, 11:20 AM
SkyWatch (Dean)
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Hi Lynton,

I notice that there is an ES 8.8 eyepiece on sale in the IIS Classies at the moment: just checking that you have seen it...

- Dean
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Old 02-03-2017, 08:49 PM
lynton
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Hi Lynton,

I notice that there is an ES 8.8 eyepiece on sale in the IIS Classies at the moment: just checking that you have seen it...

- Dean
thanks dean, i saw this but then noticed it was an older N2 purged one, instead of the newer Ar2 which probably doesn't matter in terms of performance but may be an indicator of age of the ep.

anyway the price of a new one is not that much more $189 vs $150 so will probably go for the new one unless there is a price drop or another one turns up.
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Old 03-03-2017, 12:47 PM
lynton
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Hi Lynton,

You couldnt go wrong with the 8.8mm or something around that size. Ive got a 10" skywatcher dob with 25,18,12.5,9 and 6mm ortho eps and on most nights my 9mm is about as far as you can go due to seeing conditions. My 6mm does get used however only about 50% of the time. With your smallest at 15mm the 8.8 would be a good step to see more detail plus on nights of really good seeing then barlowing the 8.8 to 4.4 is doable.
thanks simmo, good to hear from someone with the same telescope and what they use. Can I ask why you went for ortho eps on a DOB ? I was going down the line of something with a wider fov to make push to easier, are the ortho eps better for DOBs ?
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Old 03-03-2017, 09:45 PM
lynton
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Originally Posted by AEAJR View Post
If you like the idea of the zoom and have a larger budget then go for the Baader Hyperion 8-24. 25% wider FOV than the Celestron and likely better overall optics but 4+X the price.
http://agenaastro.com/eyepieces/zoom-eyepieces.html

zoom eyepiece review
http://www.chuckhawks.com/comparison_zoom_eyepieces.htm

But even at the price of the Baader it is around the same price as 2 ES 82s and far more versatile. Some people say the Baader is now their only eyepiece.

BaaderHyperian III Clickstop zoom review
http://www.weasner.com/co/Reviews/20...ece/index.html
thanks for all this detailed info Ed.
This made me look into the baader , reviews seem great so after some research i ordered one, there is a newer model now mark IV and i got a package with a hyperion 2.25x barlow. this was from 365astronomy.com and with shipping to aus only 217.53 GBP. about 350 aud, although with paypals exchange rate this jumped to 370 aud. oh well still much cheaper than the older mark III available here without the added barlow...

link here http://www.365astronomy.com/baader-h....6-10.7mm.html

i like the idea of one eyepiece you dont have to change and can quickly zoom with , and with the barlow hopefully this will do the job for all mags.

thanks for your advise, ill post when it arrives with my thoughts on how good it is.

cheers

lynton
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