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further recommendations needed for planet viewing, Barlow or not

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#1 rokuplayer

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Posted 18 September 2020 - 08:53 PM

D 114 f 910 f/8 meade reflector telescope. I know it's old and limited. I already have 9mm, 12mm, 25mm plossi (spelling?) Lenses. I was recommended those here for another scope awhile ago. I want to get the most out of what I have. I want to know if a 2x Barlow would be of use or perhaps a 6mm lense for planet viewing.



#2 sportsmed

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Posted 18 September 2020 - 09:11 PM

Well Barlow with the 9mm will be to much Magnification for that scope on most nights, you could use it on the 12mm and no point to use on the 25mm since you have a 12mm. So I would say forget the barlow right now and get a good eyepiece for viewing planets. If you are using a manual mount then you might want more FOV like 68o to 82o So since you have a 9mm I might look at a nice 7mm.


Edited by sportsmed, 18 September 2020 - 09:12 PM.

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#3 SeattleScott

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Posted 18 September 2020 - 09:19 PM

A barlow could be useful indeed. Or a Celestron Xcel LX 7mm (really 6.5). Realistically you will probably top out around 180-200x with that scope depending on coatings, collimation, etc. I would definitely want more than 101x that you get with the 9mm. The barlow would get you there, or the Xcel would get you close to 150x and it is better than your other eyepieces. So it would give you better mag for planets and give you a taste of a quality but still affordable eyepiece. If the view is still bright enough and sharp enough with the 6.5, you might look to add a 5mm for maximum power on good nights later.

Scott
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#4 Lazaroff

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Posted 18 September 2020 - 09:42 PM

If you like that 12mm plössl, then you'll like using it with a 2x barlow. The combination will be much better than a 6mm plössl alone, which would have an uncomfortably short eye relief. This is a reasonable and very economical way to go. You can buy a perfectly good barlow lens for less than $20.

 

The 9mm plössl + barlow combination would be more difficult to use because of the short eye relief and the small exit pupil, but you might very well enjoy trying it out for looking at planets on nights of exceptional seeing.

 

If you're thinking of spending more money, I'd suggest buying a set of "gold line" eyepieces--the so-called "expanse clones." They'd work very well with your telescope, and would give you enjoyably wide fields of view as well as comfortable exit eye relief at all four focal lengths--20mm, 15mm, 9mm, and 6mm. They are a very nice  and relatively inexpensive step up from plössls.

 

I own a similar telescope, so I speak from experience. I use the "expanse clones" almost exclusively with it. The 20mm eyepiece in the set has roughly the same true field of view as a 25mm plössl. The 6mm is just right for high power with that scope, but every once in a while I like to try pushing the magnification a little higher by using the 9mm with a 2x barlow.

 

The only drawback is glare in some of the "expanse clones" when observing the moon. I'd recommend saving your plössls for that purpose.


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#5 rokuplayer

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Posted 18 September 2020 - 09:58 PM

If you like that 12mm plössl, then you'll like using it with a 2x barlow. The combination will be much better than a 6mm plössl alone, which would have an uncomfortably short eye relief. This is a reasonable and very economical way to go. You can buy a perfectly good barlow lens for less than $20.

 

The 9mm plössl + barlow combination would be more difficult to use because of the short eye relief and the small exit pupil, but you might very well enjoy trying it out for looking at planets on nights of exceptional seeing.

 

If you're thinking of spending more money, I'd suggest buying a set of "gold line" eyepieces--the so-called "expanse clones." They'd work very well with your telescope, and would give you enjoyably wide fields of view as well as comfortable exit eye relief at all four focal lengths--20mm, 15mm, 9mm, and 6mm. They are a very nice  and relatively inexpensive step up from plössls.

 

I own a similar telescope, so I speak from experience. I use the "expanse clones" almost exclusively with it. The 20mm eyepiece in the set has roughly the same true field of view as a 25mm plössl. The 6mm is just right for high power with that scope, but every once in a while I like to try pushing the magnification a little higher by using the 9mm with a 2x barlow.

 

The only drawback is glare in some of the "expanse clones" when observing the moon. I'd recommend saving your plössls for that purpose.

Is there a specific Barlow I should look for.



#6 CeleNoptic

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Posted 18 September 2020 - 10:16 PM

IMO, the best solution for planetary would be a Zoom+Barlow.

 

E.g. this SVBONY 7 to 21mm or if you need it faster same Zoom rebranded as Orion E-Series 7-21mm . You can read more about it here.

 

As for the Barlow, it all depends on how much you'll be willing to spend on it. For example, this, GSO 1.25" 2.5x Apochromatic Barlow is highly regarded, inexpensive and it's actually 2.1x. it's out of stock on Agena, but I see it available as a rebranded Apertura 2.5x Barlow


Edited by CeleNoptic, 18 September 2020 - 10:38 PM.

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#7 rokuplayer

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Posted 18 September 2020 - 10:40 PM

Perhaps I'll start with the cheaper one you mentioned and graduate to that one later on. Im looking on Amazon. A normal barlow or a shorty? Is there a major difference?

#8 SeattleScott

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Posted 19 September 2020 - 12:37 AM

Probably a regular one since you have a reflector. Shorty is for using in a diagonal mirror, although it should work fine in a reflector too.

I would suggest a 2x barlow if using with your existing eyepieces to get the best spread. I would plan on paying at least $40 if you want to get something that won’t negatively impact the view. Barlow is something you don’t want to cheap out on or it is just a waste of money.

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#9 Lazaroff

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Posted 19 September 2020 - 11:23 AM

You asked: Is there a specific Barlow I should look for?

 

I'd recommend getting one of the short-style barlows. It will work fine and be more versatile than a long one, because you'll be able to use it in the diagonal of a refractor if you ever get one of those.

 

I've found this barlow to be excellent:

 

https://www.cloudyni...ns-review-r3077

 

https://www.cloudyni...39#entry9195371

 

Notice that the black part at the bottom, which contains the lens, is a little smaller in diameter than the chromed barrel. That's important to distinguish it from other, similar barlows.

 

In fact, though, just about any decent barlow will be fine. I just can't personally vouch for any others now on the market. In my experience there's no need to buy a more expensive model. I own one and it's no better.

 

Incidentally, right now you can buy the barlow I'm recommending, with a few filters to experiment with, from a company called Frys:

 

https://www.frys.com/product/9602203

 

Unfortunately, the price of shipping will raise the total cost to around $20. Still a good deal.


Edited by Lazaroff, 19 September 2020 - 11:29 AM.


#10 Lazaroff

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Posted 19 September 2020 - 12:26 PM

IMO, the best solution for planetary would be a Zoom+Barlow.

 

E.g. this SVBONY 7 to 21mm or if you need it faster same Zoom rebranded as Orion E-Series 7-21mm . You can read more about it here.

Since the question of a zoom lens has come up, I'll say a little about that.

 

First, please realize that whether you use your 12mm plössl with a 2x barlow, a zoom with a barlow, or a fixed lens like the 6mm "expanse clone" you'll get similarly good planetary views. The differences lie in comfort of use (eye relief) and in the size of the field of view.

 

So, if you like your 12mm plössl you can do just fine by adding an inexpensive 2x barlow. (But notice that the barlow mentioned in post #6, above, is 2.5x. That's too strong for the 12mm and your scope.)

 

The Svbony 7-21 zoom works well with a telescope like yours. I have one. Yes, you'll have to use it with a barlow to get the equivalent of a 6mm eyepiece. If you do, you can create a virtual 6mm lens with a noticeably wider field of view than the 12mm plössl + eyepiece combination, and with much better eye relief. But remember: you'll be paying for both the zoom eyepiece and the barlow, and the total cost will be well over $50. That may be hard to justify, considering a third alternative.

 

Consider buying a 6mm "expanse clone" (alone, not the full set) for planetary observing. You'll get good eye relief and an even wider field of view than the zoom + barlow combination. It would be an excellent high-power eyepiece for your scope, without the small nuisance of using a barlow, and for not much more money than an inexpensive barlow.

 

For what it's worth, here's my experience with that Svbony 7-21 zoom. I bought one recently out of curiosity, because it has gotten such good reviews. It works very well with my scope (the one that's similar to yours). But I found it to be no match for a set of "expanse clones." At the long end (21mm) it's not long enough for the best low-power views and the field is narrow. It's quite inferior to a 25mm plössl. At the short end (7mm) it's not short enough to get the most out of a scope like yours, so you need to add a barlow to get the best planetary views. If you look at it that way it fails at both ends. In the middle the fields are narrow, so it's not great there, either.

 

However, I found it has a very specific use with a scope like yours. I mentioned earlier that some of the "expanse clones" work poorly with the moon, because of glare from internal reflections. (The 9mm and 6mm also suffer from blacking out at the edge of the field if you don't hold your eye at exactly the right place while looking at the moon.) The 7-21 zoom works great with the moon, though. It doesn't matter that the field is small at lower powers; you're only looking at the moon in the center. And it's pretty much glare free, with very good eye relief.

 

So, in my experience, a great set of eyepieces for a scope like yours is (1) a Svbony 7-21 zoom for the moon, and (2) a full set of four "expanse clones"--20, 15, 9, and 6--for everything else. That's what I'm using right now. But remember: you could see just about as much, though less comfortably, simply by adding an inexpensive barlow to your nice collection of plössls.

 

Long post, but here's one more thing. You described your scope as a "D 114 f 910 f/8 meade reflector telescope. I know it's old and limited." If it's anything like as good as mine (an Orion XT4.5), you have an excellent, highly versatile scope. You're lucky to have it. I love mine.


Edited by Lazaroff, 19 September 2020 - 02:05 PM.


#11 BillP

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Posted 19 September 2020 - 01:35 PM

Perhaps I'll start with the cheaper one you mentioned and graduate to that one later on. Im looking on Amazon. A normal barlow or a shorty? Is there a major difference?

Shorty Barlows need stronger lens curves or more than 2 elements to achieve that short length.  This can cause some vignetting with some eyepieces.  The longer ones usually come with less issues and more straight forward design.  I would go with a longer one vs a shorty for those reasons.  Tele Vue  2x is superb and well worth the extra price with solid no compromising build and excellent optics.  The older Japan Meade 2x Model 140s I have is an outstanding performer as well. 

 

If you use a 2x to Barlow your 12mm and 9mm eyepieces, both of those will provide useful planetary magnifications and exit pupil appropriate for the aperture of your scope.  The Barlowed 12mm will show optimum contrast on the planets (0.75mm exit pupil) and the Barlowed 9mm (0.56mm exit pupil) will be good when seeing is nice and steady or anytime for close up lunar observing.

 

The other advantage of using the Barlow over a 6mm Plossl is that the viewing will be more comfortable from your longer focal length eyepieces.  Eye relief on a 6mm Plossl is rather tight.


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#12 CeleNoptic

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Posted 19 September 2020 - 01:36 PM


 A normal barlow or a shorty? Is there a major difference?

 

IMO, the difference would be mostly convenience, some like lighter and shorter Barlows when others prefer long ones. Assuming that under normal barlow you mean long telenegative Barlow vs Shorty... it's considered that it's easier to achieve good quality of views in longer versions than in shortys.  Shorty Barlow creates steeper light cone so required extra lens to compensate that. But  as usual the devil is in the details, there are poor quality 'traditional' Barlows and good Shortys and vice versa. IMO, most important here, especially for planetary observations are 1) sharpness; 2) light scatter control achieved by good baffling. BTW, major benefit of the SVbony/Orion Zoom I referred to is pretty good light scatter control. I'd recommend to look into e.g. 2x Celestron X-Cel LX 3-element Shorty Barlow. I have a 3x version and it has perfect baffling and very sharp. IIRC, the same things about the 2x X-Cel LX has said a CN fellow Peter Besenbruch who has it, you can google his reviews in this forum.

 

You may want to read more about Barlows from older threads in this forum like

 

https://www.cloudyni...s-best-barlows/

https://www.cloudyni...e-3x-tv-barlow/

https://www.cloudyni...for-your-money/

https://www.cloudyni...-advice-needed/

https://www.cloudyni...s/#entry9150978



#13 CeleNoptic

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Posted 19 September 2020 - 03:10 PM

Since the question of a zoom lens has come up, I'll say a little about that.
 
First, please realize that whether you use your 12mm plössl with a 2x barlow, a zoom with a barlow, or a fixed lens like the 6mm "expanse clone" you'll get similarly good planetary views. The differences lie in comfort of use (eye relief) and in the size of the field of view.

Since this post addressed to me (?)... let me disagree with you. I have a 9mm Agena “expanse clone” and it is 1) not very sharp; 2) has poor scatter control (and you admit that for your 6mm); 3) shows pretty strong spherical aberration (“blackouts” – you also admit that) so it’s hard to find optimal eye position/uncomfortable. So I believe the 6mm is unlikely a good planetary eyepiece and just can’t be compared to a Plossl under good/above average seeing conditions. YMMV. Under highly varying seeing conditions (usually) a Zoom(+Barlow) has advantage over a Plossl and any premium eyepiece since allows fast matching magnification to specific seeing at that moment. Seeing is king and Plossl+Barlow good only for one specific magnification useful only in steady atmosphere which is rare.
 
 

So, if you like your 12mm plössl you can do just fine by adding an inexpensive 2x barlow. (But notice that the barlow mentioned in post #6, above, is 2.5x. That's too strong for the 12mm and your scope.)

 
If you read post #6 carefully you would notice that I said it’s actually 2.1x. For reference, see posts ## 14 and 15 here.
 

 

The Svbony 7-21 zoom works well with a telescope like yours. I have one. Yes, you'll have to use it with a barlow to get the equivalent of a 6mm eyepiece. If you do, you can create a virtual 6mm lens with a noticeably wider field of view than the 12mm plössl + eyepiece combination, and with much better eye relief.

FWIW, you’re not right about noticeably wider field of view. The 12mm setting in this Zoom supposed to provide 51°AFOV, that is pretty much the same as a Plossl. For reference, see my post #111 here.
 
 

For what it's worth, here's my experience with that Svbony 7-21 zoom. I bought one recently out of curiosity, because it has gotten such good reviews. It works very well with my scope (the one that's similar to yours). But I found it to be no match for a set of "expanse clones." At the long end (21mm) it's not long enough for the best low-power views and the field is narrow. It's quite inferior to a 25mm plössl. At the short end (7mm) it's not short enough to get the most out of a scope like yours, so you need to add a barlow to get the best planetary views. If you look at it that way it fails at both ends. In the middle the fields are narrow, so it's not great there, either.

IMO, for planetary the expanse clones are definitely no match to this 7-12mm SVbony zoom since it has pretty good light scatter control. I recommended this Zoom above meaning reasonable use for planetary observations only within the range of 7-12mm (with Barlow). Nothing else. For that purpose it should have the expected AFOV of 57-51°.



#14 Lazaroff

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Posted 19 September 2020 - 04:31 PM

Wow.



#15 Thomas_M44

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Posted 19 September 2020 - 11:48 PM

Is there a specific Barlow I should look for.

Yes.

 

People are making answers to your question that are far too complex.

 

If you are planning to stay with standard 1.25-inch eyepieces for now, and you want a very high-quality 2X or 3X Barlow to help magnify for planetary and lunar viewing, I strongly suggest getting a TeleVue  Barlow.

 

There are many cheaper options, and a few more expensive options,  but the TeleVue Barlows are of excellent optical and mechanical quality, and hold value well.

 

If you can afford it, you should be quite happy with a TeleVue Barlow.


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#16 rokuplayer

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Posted 20 September 2020 - 07:27 PM

Ok. I’m attempting  to absorb the information here but this is new to me. Is it plausible to start out with a 20 to 30 dollar Barlow or is it a waste of time. And if so what company should I look for?



#17 scrufy

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Posted 20 September 2020 - 08:18 PM

I agree, the answers have been a little more complex than you probably are looking for.

I don’t believe you can find one for under $30 that will not make things worse, but I haven’t read any reviews on the stuff by the likes of Svbony, Omegon, GSO, etc... Some of the Chinese stuff does get ok reviews.

Consider that the Barlow is something that you will be able to use with every eyepiece you have or ever get(except of course if you go up to 2” EPs and limits due to seeing).

I’d save a little longer and get a good one.

I have a Luminous for 2” only because it was given to me or I would have bought a the TV 2” 4x. Probably still will eventually.

I have a Televue 1 1/4”. You can’t beat TV. Read any review. Barlow or powermate,  they are nice.

edit- Just noticed an active thread on shorty vs long Barlows, might want to read it..

https://www.cloudyni.../#entry10514334


Edited by scrufy, 20 September 2020 - 08:38 PM.


#18 rokuplayer

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Posted 20 September 2020 - 08:23 PM

Lol I just bought one off amazon. I’ll let you guys know how my cheap date goes. They always take things back if it ends up being complete trash


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#19 SteveG

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Posted 21 September 2020 - 05:41 PM

Lol I just bought one off amazon. I’ll let you guys know how my cheap date goes. They always take things back if it ends up being complete trash

It will probably be just fine. Which one did you order?



#20 rokuplayer

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Posted 22 September 2020 - 09:09 PM

A meoptex 2x barlow. Only one actual review so I took a gamble. I tried it out tonight, but I'm very tired so my eyes weren't cooperating much. it worked good with the 12mm plossl. Looked a Jupiter for a short time. When I could get my left eye to focus it was a decent view. Detail would come into view when my eye would allow. Of course I then relieved saturn was behind me after I moved the scope back in. I'll gander at that another night. Should be interesting. Is a filter worth the trouble for planets? To tone down the light a bit?

#21 Echolight

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Posted 22 September 2020 - 09:31 PM

I only have one planetary eyepiece. But TWO(or three) barlows.

Of course it's a zoom, so covers a bit of ground...err, sky.

 

I like using the barlows, and the zoom. Two oft criticized accessories. And run a lot of power on the moon with crisp clear views. 60x per inch. I don't know the names, but two large craters with volcanos in the center on the lower right half of the crescent moon the other night showed every detail and black shadow pushing up near 375x in what apparently is a mostly color-free fast achro(another four letter word). 

 

I use the same barlowed zoom setup on planets. Just dialed down a little.

 

I say don't sell your scope short. Barlow and push up all the power you got. You can always back off some if the views are too fuzzy. But you'll never know until you try. 

 

And every night is different. Some nights you might can max it out. And other nights you might have to lay low.


Edited by Echolight, 22 September 2020 - 09:49 PM.



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