Author Topic: The 2" 2X Barlow Choice Dilemma  (Read 303 times)

stimtinpaso

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The 2" 2X Barlow Choice Dilemma
« on: December 29, 2017, 01:55:58 PM »
I have somewhat of a dilemma. I love my ES 82 30mm as its about the easiest eyepiece in terms of eye placement and comfort for my observing style. It seems to be a very well matched eyepiece to my C8. My other eyepieces are a 22mm Olivon (also super easy eye placement) and then I have a 14mm Baader Morpheus, ES11 82 and then a Long perng 9mm (Levenhuk ER20). The Morpheus is a little more time consuming on eye placement.

My only experience with barlow lenses has been an Orion Shorty 2X barlow so I don't have much to compare to.

I'd like to experiment with barlowing the ES30 82 as its eye placement is so much easier than the Morpheus. I'd also like to see how the ES11 82 does.

My main question is:
-If I get a good barlow would using the ES30 82 render the Morpheus obsolete or am I still going to get a "better" view from a 14mm without a barlow?

I've started the Astronomical League Globular Observing Program and really like the views in the ES30 82 but would like to get a little more magnification to see some more detail.

Also i'm searching a few barlows and wondering which you'd pick. Try and be objective as possible

Lowest cost:
GSO 2X Barlow with 1.25 Adapter $70-80 shipped depending on which re-label branding
http://agenaastro.co...arlow-lens.html
http://www.highpoint...2-by-high-point
https://www.astronom...ces_p19092.aspx

Middle of the Road
Explore Scientific 2X Focal Extender ~ $214.99
http://www.highpoint...tender-fe02-020

Highest Cost
Televue Powermate 2X 2" ~ $309.50
http://www.highpoint...ermate-pmt-2200

Regards,
Jon



hiswacoka

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Re: The 2" 2X Barlow Choice Dilemma
« Reply #1 on: January 01, 2018, 03:21:48 AM »
You can pick up a Televue Big Barlow for about $100 in the classifieds on a regular basis. I did that a while back and am happy with it. I've been using a GSO for a while and it worked fine, but if you're starting out just spend a few more bucks and know you've got good stuff.

It makes a lot of sense to use a barlow to "multiply" quality eyepieces, I use mine with my ES 100 eyepieces, for $100 I get the effect of an additional $1000 worth of eyepieces and can't tell the barlow is in use other than the increased magnification.

urinhatmo

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Re: The 2" 2X Barlow Choice Dilemma
« Reply #2 on: January 04, 2018, 04:46:11 PM »
Quote
....I get the effect of an additional $1000 worth of eyepieces and can't tell the barlow is in use other than the increased magnification.

I can say the same about my ES 2" 2X Extender. I have an ES 102CF triplet APO and five ES eyepieces, from 40mm to 4.7mm... and the Extender has no degradational effect on the views whatsoever. I also have the ES 1.25" 3X Extender, and the same applies.

Bobby Javier

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Re: The 2" 2X Barlow Choice Dilemma
« Reply #3 on: January 10, 2018, 01:45:52 PM »
Hi Jon,

Very timely that you should ask this as I am currently doing the exact same research!

You must read the product description for the ES Focal Extender at Agena Astro Products (the item is currently out-of-stock, but read the description) here:

https://agenaastro.c...w-fe02-020.html

If I understand this correctly, the ES focal extender is the only barlow on the list (your list is identical to mine) that can be inserted anywhere in the optical path and still achieve it's stated 2x magnification.

This is very interesting to me, as the ES Focal Extender is quite heavy by itself, and combined with a premium wide-field 2" eye piece, would make quite a heavy "chimney" stack on top of our 2" diagonals. I use an Explore Scientific AR152, the big 6" achromat. I'm really interested in trying the ES Focal extender placed first in-line from the focuser draw-tube, followed by the 2" diagonal, then a widefield 2" ocular.

I'm also fond of the Baader Fringe killer filter to somewhat correct CA in my achromat, and I usually just leave the fringe killer threaded to the front of the diagonal so it's on for every eyepiece. I'd probably move the fringe killer up front, attached to the focal extender, with this new set-up.

Further, I believe you can place the Televue, or really, any other barlow, ahead in the focal path as I've described, but the stated magnification will change... It would be less than 2x if placed before the diagonal and eyepiece in the case of the Televue.

What we both need, is somebody who has already laid out the money and tried this to tell us!

I'll follow your post. Sorry if I seem to have hi-jacked your question! I guess great minds think alike! Or, in my case, we just happen to be researching the same thing at the same time... My mind is far from "great"! Ha!

Thanks,
Mr. Joey

tidutamar

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Re: The 2" 2X Barlow Choice Dilemma
« Reply #4 on: January 12, 2018, 06:59:48 PM »
Quote
Hi Jon,

Very timely that you should ask this as I am currently doing the exact same research!

You must read the product description for the ES Focal Extender at Agena Astro Products (the item is currently out-of-stock, but read the description) here:

https://agenaastro.c...w-fe02-020.html

If I understand this correctly, the ES focal extender is the only barlow on the list (your list is identical to mine) that can be inserted anywhere in the optical path and still achieve it's stated 2x magnification.

This is very interesting to me, as the ES Focal Extender is quite heavy by itself, and combined with a premium wide-field 2" eye piece, would make quite a heavy "chimney" stack on top of our 2" diagonals. I use an Explore Scientific AR152, the big 6" achromat. I'm really interested in trying the ES Focal extender placed first in-line from the focuser draw-tube, followed by the 2" diagonal, then a widefield 2" ocular.

I'm also fond of the Baader Fringe killer filter to somewhat correct CA in my achromat, and I usually just leave the fringe killer threaded to the front of the diagonal so it's on for every eyepiece. I'd probably move the fringe killer up front, attached to the focal extender, with this new set-up.

Further, I believe you can place the Televue, or really, any other barlow, ahead in the focal path as I've described, but the stated magnification will change... It would be less than 2x if placed before the diagonal and eyepiece in the case of the Televue.

What we both need, is somebody who has already laid out the money and tried this to tell us!

I'll follow your post. Sorry if I seem to have hi-jacked your question! I guess great minds think alike! Or, in my case, we just happen to be researching the same thing at the same time... My mind is far from "great"! Ha!

Thanks,
Mr. Joey

No problem Joey. Thats what Cloudy Nights is for.

nijambaci

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Re: The 2" 2X Barlow Choice Dilemma
« Reply #5 on: January 13, 2018, 07:27:34 AM »
PS - Also, focus "in-travel" becomes a concern. My understanding is the ES focal extender needs a bit more in-travel than the Televue.

This can become an issue. The focus draw tube on my AR152 must be, I dunno, probably 6 inches long. Some of my favorite low power, high mm, 2" widefield's reach focus with the drawtube only extended about an inch or so... Not much more room for "in travel", another reason I was considering placing the ES Focal Extender first in line...

Then again, I might be misunderstanding something here...

Clear Skies!
Mr. Joey

blufdestholreng

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Re: The 2" 2X Barlow Choice Dilemma
« Reply #6 on: January 13, 2018, 09:22:54 AM »
Olivon also makes a decent 2" ED barlow that can have its lens attached to the eyepiece or adapter as well as used with a 2" eyepiece.
The issue with nearly every barlow is that they will require additional in-travel of the focuser, which you may not have.
If used in a star diagonal, they often require a HUGE amount of in-travel of the focuser.
A 2" TeleVue PowerMate doesn't require the in-travel, doesn't vignette, doesn't affect eye relief, and has the same magnification no matter what distance it is from the lens.
Alas, it's expensive.

But, as a general rule, 2" barlows are not compatible with star diagonals.
The good news is that a 1.25" barlow will be, and, most likely, you'll be using mid-power 1.25" eyepieces with the barlow to yield high powers, so the 1.25" size is more likely to
be what you want and need.

Using the 2" barlow in front of the star diagonal doesn't help. It adds a lot of additional magnification, still requires in-travel, produces more vignetting of 2" eyepieces in that position,
and can have unpredictable effects on spherical aberration on-axis.

The Explore Scientific 2" Focal Extender is supposed to be telecentric, so shouldn't affect magnification by much in the forward position, but not all telecentric barlows
yield identical powers at all distances. Look at the 5x PowerMate in the graph, for example:http://www.televue.c...?id=53&Tab=_app
I don't know what the ES FE will yield in the forward position.

ifaclidis

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Re: The 2" 2X Barlow Choice Dilemma
« Reply #7 on: January 14, 2018, 01:17:48 AM »
Quote
But, as a general rule, 2" barlows are not compatible with star diagonals.
The good news is that a 1.25" barlow will be, and, most likely, you'll be using mid-power 1.25" eyepieces with the barlow to yield high powers, so the 1.25" size is more likely to
be what you want and need.
Don
When you refer to a "barlow" not being compatible with a star diagonal did you mean only true barlows or are you saying that statement applies to the TV Powermate as well as the ES Focal Extender?

Jon

Joe Maillet

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Re: The 2" 2X Barlow Choice Dilemma
« Reply #8 on: January 15, 2018, 03:40:30 PM »
Yes, any 2" accessory that has a barrel longer than the star diagonal's barrel into which the eyepiece fits will result in that 2" accessory
being lifted out of the star diagonal so the "shoulder" of the accessory does not sit on the lip of the star diagonal.
And most 2" barlows (maybe not all) will be lifted out of the star diagonal because of the length of their barrels.
Since the barlows typically require additional in-travel even if seated fully, then MORE in-travel will be needed to accommodate the
outward lifting of the barlow by the fact it doesn't seat fully in the diagonal.
This would apply to PowerMates as well, but since they are parfocal with the eyepieces (on a newtonian, no focus change takes place when one is inserted between the focuser and the eyepiece),
The additional in-travel needed would only be the amount it is lifted out of the diagonal.
Whether the scope would have sufficient in-travel would depend on the scope. Most SCTs are probably OK with anything. For refractors, it would vary a lot from scope to scope.

soecolerfe

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Re: The 2" 2X Barlow Choice Dilemma
« Reply #9 on: January 18, 2018, 03:06:05 AM »
I don't have the ES82 30mm, but I have the ES68 34mm and the 2X TeleEx. The total weight is huge, and in your case will be morer: about 2kg of moment to balance between OTA and click-lock system in case of lateral position. FYI, I quickly did substitute the 34/2 = 17 with an ES82 18mm just for the weight's concern; so if you have the 14 Morpheus, get the ES 2X TeleEx. only whether you want barlowizeing different FL than the 30mm, IMHO. IME, The ES68 28mm and the ES82 11mm barlows well; not so well the ES68 34mm and the ES82 18mm, but these weren't systematical comparisons within the same session in the same day, so do take it cum grano salis. BTW, I found the ES82 18mm better for PNs than for GCs; for these latters the ES64 28mm is still my favorite overall porthole.

Tyler Cox

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Re: The 2" 2X Barlow Choice Dilemma
« Reply #10 on: January 18, 2018, 10:04:58 AM »
A Barlow add much aberrations in the outer edge of field. It is better used in central planetary field.
I think common barlow (especially short barlow) for wide field is not a wise idea. You should try a high end one that garanty a decent field (the photo's barlow are better)

bardeperdi

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Re: The 2" 2X Barlow Choice Dilemma
« Reply #11 on: January 21, 2018, 07:45:15 AM »
HI, The question asked was this:"My main question is:
-If I get a good barlow would using the ES30 82 render the Morpheus obsolete or am I still going to get a "better" view from a 14mm without a barlow?"

The previous answer was a pretty emphatic no. I suspect that there is also the problem of the added weight and the difficulties that creates. I think that since you already have a 14mm eyepiece that the Barlow is redundant. What you are asking is can you get the benefits of the ES30 by Barlowing it to 15mm so that it will be more comfortable than your existing 14mm. I don't think we can answer that one, but the discussion was certainly interesting.

Basically from what I read here, there is not a clear understanding of the difference between a Barlow or telenegative lens and the Tele extender or Power Mate type lens. However, when I read the explanation at the Televue website the difference is clearly described. I wonder if everyone understands the difference as Don has tried to explain it.

As I understand your dilemma, it is should I buy a cheap Barlow and see if I like it or not? If I don't like it then should I blame the negative result on the fact that it was a cheap Barlow? So you are asking if the more expensive Tele Extender option will work and is it worth the extra money. I don't think we can answer that one.

scolposnimbworr

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Re: The 2" 2X Barlow Choice Dilemma
« Reply #12 on: January 21, 2018, 08:23:53 AM »
The 2.5x 2" Celestron Luminos Barlow sits properly in a star diagonal, is light weight, and a good performer.

Did you try upgrading the eyecup on the 14mm Morpheus to the eyecup offered at AgenaAstro?

Cory Bass

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Re: The 2" 2X Barlow Choice Dilemma
« Reply #13 on: January 23, 2018, 02:39:20 AM »
Quote
The 2.5x 2" Celestron Luminos Barlow sits properly in a star diagonal, is light weight, and a good performer.

Did you try upgrading the eyecup on the 14mm Morpheus to the eyecup offered at AgenaAstro?

I haven't got a chance to upgrade the eyecup...in the middle of everything this year i've trained my eyes to observe with glasses so i've been folding the eyecup down on the Morpheus.

Thanks for the idea about the Celestron Luminos Barlow. Now that you mention this my friend who I observe with quite a bit has that barlow so I may borrow it from him and try before I buy

I'm tempted to try a less expensive option as in looking at the others I mentioned I could get a nice planetary eyepiece or that Baader Clicklock diagonal i've had my eyes on for some time!

Jon

therpomercu

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Re: The 2" 2X Barlow Choice Dilemma
« Reply #14 on: January 31, 2018, 04:15:17 AM »
Quote
Quote

The 2.5x 2" Celestron Luminos Barlow sits properly in a star diagonal, is light weight, and a good performer.

Did you try upgrading the eyecup on the 14mm Morpheus to the eyecup offered at AgenaAstro?

I haven't got a chance to upgrade the eyecup...in the middle of everything this year i've trained my eyes to observe with glasses so i've been folding the eyecup down on the Morpheus.

Thanks for the idea about the Celestron Luminos Barlow. Now that you mention this my friend who I observe with quite a bit has that barlow so I may borrow it from him and try before I buy

I'm tempted to try a less expensive option as in looking at the others I mentioned I could get a nice planetary eyepiece or that Baader Clicklock diagonal i've had my eyes on for some time!

Jon
I would say give the Morpheus more time before you write it off. I've been observing with glasses for over 30 years. But if you are new to observing with glasses it might take you a while to get used to observing without blackouts. And some eyepieces take a little more adapting to than others. I've never had an issue with blackouts and the Morpheus - with or without glasses but I know a lot of people unhappy with the eyecup have had some issues.