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Do you use a barlow with your SCT?

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#1 Dadadee

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Posted 20 August 2014 - 10:42 AM

Hello guys,

 

I am a new SCT owner (Celestron Nexstar Evolution 6 inches).  Being also a Dob owner, I already have a functionnal collection of eyepieces.  With my Dob, I was used to make a massive usage of my Barlow 2x.  But I find it hard to use a Barlow with my SCT.  I can not put the whole tube of the Barlow in the diagonal.  Then I have to put the eyepiece on top...  It is not very convenient.  And I am afraid everything could fall on the ground!

 

So do you use a Barlow with your SCT?

 

My SCT is operating at around 1650mm of focal length.  My shortest eyepiece is a 8.8mm giving me 188x.  If I can not use my Barlow, I would probably need an eyepiece in the 7-8mm range for a magnification of around 206-235x.  Since I need 20mm of eye relief, I would probably go for either a Delos 8mm, a Pentax XW 7mm or a Hyperion 8mm.

 

Thanks

 

Ben



#2 rguasto

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Posted 20 August 2014 - 10:56 AM

Hi Ben

This is the reason for shorty barlows. If you inserted your barlow any further it would hit the mirror in the diagonal. I use a celestron ultima 3 element 2x barlow which is actually around 2.2x in reality)

-Rob



#3 mrowlands

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Posted 20 August 2014 - 11:05 AM

Hi Ben,

 

A Tele Vue Powermate will also work.  Assuming you're using 1.25 inch, that size Powermate will work in a 1.25 inch diagonal without hitting the mirror.

 

Mike R.



#4 Ed Whitney

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Posted 20 August 2014 - 12:10 PM

Ben,

 

If you can afford regular eyepieces, then forget the Barlow. I don't even own one. They're just to much added weight and trouble.

 

As an aside, Barlows were popular many years ago because there weren't many eyepiece types to choose from. So, you -had- to rely heavily on the "Barlow". But, you know, things do change.

 

Clear Skies! :)


Edited by Ed Whitney, 20 August 2014 - 12:19 PM.


#5 evan9162

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Posted 20 August 2014 - 01:18 PM

I only use a barlow with my SCT for star testing (checking collimation) or planetary imaging.  



#6 WebFoot

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Posted 20 August 2014 - 02:06 PM

I have a very fine Televue 2x Powermate.  And I don't remember the last time I used it.

 

Barlows have their uses (principally, IMO, the combination of having to own fewer eyepieces and being able to use an eyepiece with better eye relief for a given "magnification"), but I don't like dealing with them.

 

So I don't.

 

Mark



#7 RAKing

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Posted 20 August 2014 - 02:23 PM

Hello guys,

 

I am a new SCT owner (Celestron Nexstar Evolution 6 inches).  Being also a Dob owner, I already have a functionnal collection of eyepieces.  With my Dob, I was used to make a massive usage of my Barlow 2x.  But I find it hard to use a Barlow with my SCT.  I can not put the whole tube of the Barlow in the diagonal.  Then I have to put the eyepiece on top...  It is not very convenient.  And I am afraid everything could fall on the ground!

 

So do you use a Barlow with your SCT?

 

My SCT is operating at around 1650mm of focal length.  My shortest eyepiece is a 8.8mm giving me 188x.  If I can not use my Barlow, I would probably need an eyepiece in the 7-8mm range for a magnification of around 206-235x.  Since I need 20mm of eye relief, I would probably go for either a Delos 8mm, a Pentax XW 7mm or a Hyperion 8mm.

 

Thanks

 

Ben

 

 

I wouldn't worry about it sticking up. As long as you tighten the screws enough, everything will be fine. Plus, isn't the Evolution an Alt-az mount? Nothing will be flopping around on one of those anyway.

 

I use a Televue 2x Powermate a lot with my SCT and it really works great. It allows me to walk outside with only three eyepieces (Pentax XW 40, 30, and 10mm) and gives me plenty of magnification choices with my C925. Yes, the combination of Barlow/eyepiece sticks up a little, but I don't care -- it's the views through the eyepiece that count. :)  

 

Cheers,

 

Ron



#8 VooDooBlade

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Posted 20 August 2014 - 09:32 PM

If you get a barlow that the lower lens part unscrews, you can screw that on your eyepieces like a filter. Way shorter.

 

May not work with every eyepiece. But it seems to work with all of mine.........



#9 A6Q6

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Posted 21 August 2014 - 12:17 AM

Hi Ben

This is the reason for shorty barlows. If you inserted your barlow any further it would hit the mirror in the diagonal. I use a celestron ultima 3 element 2x barlow which is actually around 2.2x in reality)

-Rob

+2 on the shorty barlow, I use it with my C5 and old TV plossls and Konigs. They are small eyepieces.

Attached Files


Edited by A6Q6, 21 August 2014 - 12:23 AM.


#10 Mariner@sg

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Posted 21 August 2014 - 12:22 AM

I used to do so when I have lesser number of EPs and need to get a better view of the planets. Now I mainly use it for planetary AP.



#11 Hesiod

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Posted 21 August 2014 - 05:16 AM

Some Barlow can not be screwed to eyepieces like filters, like the TV ones.

Usually the Celestron small cats have a prism diagonal and little to none harm is done even if the the lens body "touch"  the prism upper face (better diagonals have a small rim to avoid the direct contact); the ensemble looks frail and prone to drop, but in fact it is quite strong and safe.

The most common "disaster" is when the diagonal turns upside down after a contact, but even so usually the pieces stay all toghether.

However  I do not advice to put an heavy eyepiece (like a Delos, LVW or other big glass) on a long Barlow in the standard Celestron diagonal.

If you want to use the Barlow, maybe a stronger diagonal could be a good idea (maybe one of the "SCT-diagonal" which screws directly on the SC thread lying under the visual back).

 

My personal preference would incline towards the additional eyepiece, but it is just a preference



#12 Sarkikos

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Posted 21 August 2014 - 06:12 AM

 

So do you use a Barlow with your SCT?

 

 

No, I almost never use Barlows.  I handle most everything with zoom eyepieces plus some fixed focal length eyepieces for special purposes.

 

Mike



#13 Jon_Doh

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Posted 21 August 2014 - 09:01 AM

I use a Meade Shorty 2x.  Works great.



#14 Dwight J

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Posted 21 August 2014 - 11:08 AM

I always put the Barlow in first and the diagonal into the Barlow.  A little less magnification but it never falls out.  They are useful to provide more eye relief as you can use longer focal length eyepieces for higher magnification.  I would rather look thru a 20mm than a 10mm eyepiece.  


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#15 cray2mpx

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Posted 21 August 2014 - 11:40 AM

I only use a 2.5x Barlow for planetary imaging to step up the fl to 5000 mm (if the seeing permits, of course).

For visual I prefer an EP only.

 

cs,

 

Cray



#16 gunfighter48

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Posted 21 August 2014 - 06:21 PM

I use a 1.25" and 2" ES focal exterder. I've never had a problem with them tipping over or falling out with my visual backs, Crayford focusers, or diagonals.  I just make sure everything is tight and have no problems. I put them into the top of the diagonals, have always done it this way. :)



#17 Geo.

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Posted 22 August 2014 - 11:16 AM

Ben,

 

If you can afford regular eyepieces, then forget the Barlow. I don't even own one. They're just to much added weight and trouble.

 

As an aside, Barlows were popular many years ago because there weren't many eyepiece types to choose from. So, you -had- to rely heavily on the "Barlow". But, you know, things do change.

 

Clear Skies! :)

 

Not so fast Ed. If you have to wear eyeglases as I do, you will appreciate that a Barlow or telextender will increase magnification while preserving the eyepiece's eye relief. This is the secret of the TV Radians' eye relief. Each essentailly has a built in Barlow element.



#18 DeSoto Kid

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Posted 23 August 2014 - 01:27 AM

I always put the Barlow in first and the diagonal into the Barlow.  A little less magnification but it never falls out.  They are useful to provide more eye relief as you can use longer focal length eyepieces for higher magnification.  I would rather look thru a 20mm than a 10mm eyepiece.

 

 

Dwight,  that should give you more magnification. If you put a 2X barlow ahead of your diagonal it will render 3X magnification. 

 

 

 

Wayne R.


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#19 james7ca

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Posted 23 August 2014 - 04:09 AM

Barlows are a necessity for high-magnification astrophotography. Otherwise, it's pretty much a personal preference when working visually.



#20 Eddgie

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Posted 23 August 2014 - 08:29 AM

Ben,

 

If you can afford regular eyepieces, then forget the Barlow. I don't even own one. They're just to much added weight and trouble.

 

As an aside, Barlows were popular many years ago because there weren't many eyepiece types to choose from. So, you -had- to rely heavily on the "Barlow". But, you know, things do change.

 

Clear Skies! :)

 

Yes, I agree.   Fussing with Barlows just isn't all that productive, and with used Hyperions going for $80,  it may simply be easier just to add one and not have to worry about changing barlow in and out of the light path.

 

But even better might be to dump the 12mm, 10mm, and 8.8mm (which are all rather to close together in my opinion) and replace them all with a Baader Hyperion Zoom.

 

I sold off a bunch of Hyperoin eyepices in focal lenghts from 17mm to 8mm and replaced them all with Hyperion zooms in my binoviewer.

 

In my Mark V and my EdgeHD 8", I now use only the ED 24/68s and a pair of Hyperion Zooms. 

 

I don't even carry out an eyepeice case anymore.

 

I used to be distracted by all the eyepice changing, and adding barlows was even worse.

 

Just offering an alternative.  Maybe not the right thing for the OP, but if he has not considered it, he might find that he can meet 100% of his observing requirements for his SCT with just these two eyepeices.

 

I agree though that I would pass on the Barlos.   Used Hyperions are just so inexpensive.


Edited by Eddgie, 23 August 2014 - 08:30 AM.

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#21 Eddgie

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Posted 23 August 2014 - 08:38 AM

Another option has occurred to me. With his close eyepiece spacing, he could also use a Baader 14mm tuning ring to bring up the existing 10mm to about 7.9mm.

 

This would give him 12mm, 8.8mm, and 7.9mm.    I just think that he is to close in spacing with 12mm, 10mm, and 8.8mm and 8m would be to granular I think.

 

But that is me.   As I said, I would zoom this problem, but I don't think a Barlow is the right thing to do, and using the 10mm with a tuning ring would give him (in my own opinion) less granular and more even magnification steps.

 

Zoom still looks far more attractive to me personally though.  I have a box of eyepeices that I don't use anymore since starting to use zooms.


Edited by Eddgie, 23 August 2014 - 08:42 AM.

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#22 JerseyBoy

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Posted 23 August 2014 - 08:58 AM

I have just placed my order for a Celestron NexStar Evolution 9.25" (my first Telescope!) and with it I am buying the Baader Hyperion Mk III 8-24 zoom plus the Baader 2.25x Barlow. These two are offered together, the Barlow is made especially for the zoom eyepiece. The reason I am buying the Barlow is that I wear glasses and want as much eye relief as I can get. Using the Barlow for high magnification will give me 2x-2.25x the amount of eye relief that I will get from the zoom without the Barlow.

 

"The Baader Hyperion Zoom Barlow quickly attaches to any Hyperion 8-24mmm Clickstop zoom eyepiece, instantly converting it into a 3.5-10.5mm Zoom. The matched optical design results in a virtually transparent 2.25X multiplication, without any optical compromises, essentially giving a 7X zoom range with outstanding optical performance throughout the 3.5-24mm range."

 

"Baader Hyperion Zoom Barlow 2.25x, specially designed for the Baader Hyperion Clickstop Zoom Eyepiece Mark III with triplet lens design for non-astigmatic flat field suitable to complement the high image quality of the Hyperion Zoom Eyepiece."

 

http://www.365astron...ow-p-3335.html 


Edited by JerseyBoy, 23 August 2014 - 09:01 AM.


#23 Sorny

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Posted 23 August 2014 - 07:45 PM

An f/10 SCT of 9.25" won't have any real use of a barlow on the zoom. 8mm is about the practical limit for magnification unless you've got exceptional seeing conditions.



#24 JerseyBoy

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Posted 24 August 2014 - 02:49 AM

Hi Sorny,

 

The Evolution 9.25 has a maximum 'useful' magnification of 555x which equals a 4.25 eyepiece, therefore I can use the Barlow with the Zoom and get 2.25x the eye relief than I would get without it for anything less than or equal to a 10 eyepiece . I am more interested in the eye relief at higher magnification than the higher magnification that I might get with the Barlow.

 

I am hoping for good seeing as Jersey is an island and I am on the edge of it, a fair distance from any build up of lights. Once I have negated the nearby light pollution from two street  lights with a filter there should not be much to worry about.



#25 JerseyBoy

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Posted 24 August 2014 - 03:40 AM

Hi Sorny, 

 

As you can see from this article, the area where I live should have very good seeing, probably not quite as clear as Sark, an island not far from Jersey, but still very good. If I have any issues from home I can always head 10 minutes to the west coast where there are no street lights and get even better seeing, or I could jump on a boat and go to Sark for perfect skies  :cool:

 

http://www.theguardi...ark-sky-island 

 

Where it shows La Ville Roussel, that is Sark

Attached File  channelmap.jpg   30.49KB   0 downloads


Edited by JerseyBoy, 24 August 2014 - 03:54 AM.







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