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Dakin 1.25x barlow

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#1 GeezerGazer

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Posted 26 February 2015 - 03:40 AM

This barlow arrived about 2 weeks ago but last night was my first opportunity to use it.  I purchased it specifically to use with my 5mm Pentax XO, which then becomes a 4mm.  But I also wanted to test it on a 10mm, which becomes an 8mm.  It arrived in a nice little red box with two soft plastic caps.

 

It is nicely made and compact at 1" (26mm) long and has standard filter threads to screw into the barrel of an eyepiece.  Vernonscope makes two models, a 1.5x and the 1.25x, and each of them is produced with either Brandon specific filter threads or standard filter threads... I chose standard threads for use on more of my eyepieces.  Ironically, I cannot use it on my Chester Brandons which are very old and have no threads at all.  The attached photo includes a UO HD 6mm for size comparison.

 

Using a TEC 140 and a Zeiss Prism Baader diagonal with the 5mm Pentax and Dakin 1.25x seemed quite satisfactory.  Targets were Luna, Jupiter, the F-star in the Trapezium and double stars Zeta (2.5" sep), 32 (1.1"), and 52 (1.2") in Orion.  Seeing was not the best and atmospheric moisture was obvious, but the image through the Pentax with the Dakin attached held up quite well and appeared to be at least equal to a  UO 4mm Ortho.  I'll have to wait for steadier seeing to give it a fair test though.  

 

Attaching the Dakin to a 7mm RG ortho, UO 9mm ortho, and a UO 18mm ortho, provided satisfactory results. The field appeared very sharp on axis with little softening at the very edge.  

 

Wide field eyepiece performance was good on axis, but dropped as the EOF approached.  With a 20mm RG (Erfle), stars in focus on axis soften at about 70-75% from center, and the edge was obviously distorted.  No seagulls... but bloated stars

 

I then attached it to a 10mm Ethos (making it an 8mm) and found that on axis was fine, sharp and clear, but softening started about 50% out from center and increased significantly to the edge.  I don't think the Dakin was really made for a wide field eyepiece, since it is a barlow... light rays exiting it's lens are divergent.  BUT on axis it was fine.  So next time there is a clear, steady sky, I'll attach it to a 4.7 Ethos making it 3.7mm and look for a good target to put in the center of field.  

 

I'll keep this little barlow for now, specifically for the Pentax XO, making the eyepiece serve double duty at 5mm and 4mm.  I'd be interested to hear results from anyone else who has used one of these compact Dakin Barlows.  

 

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#2 catboat

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Posted 26 February 2015 - 08:59 AM

Thanks for this report.  I’ve been interested in these. 



#3 Sunspot

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Posted 26 February 2015 - 09:30 AM

I use this exact barlow for my planetary imaging and I am very pleased! I use a 3/4" extension tube and screw it directly into the nose piece of the camera. With the C14 it ginve me F/18.5. I even prefer it over the Baader barlow I have. Check my website with Jupiter images to see my results.

 

Paul M.



#4 george tatsis

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Posted 27 September 2015 - 01:22 PM

Anybody else ever tried this one ? I would be really interested in mating one with my Meade 5.5mm to turn it into a 4.4 eyepiece!

 

George



#5 george tatsis

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Posted 07 October 2016 - 01:46 PM

Nothing yet and it's been over a year now :hmm: .

 

George


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#6 Mike Allen

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Posted 07 October 2016 - 04:13 PM

There is another thread in this forum on the Magic Dakin barlow.  I use a 1.5X MDB, mostly with 16, 12 and 8mm Brandons and University orthos.  I have the version with the Brandon threads, so I use an adaptor ring for non-Brandon eyepieces.  Very sharp views to the very edge in my f/8 apo refractor with no vignetting.  Found out that if I use a 1-inch extension on my MDB it will boost the magification up to 2X.  Nice, versatile accessory.


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#7 Jeff Morgan

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Posted 07 October 2016 - 11:52 PM

The MDB sounds like just the ticket for the both my 10mm Supermono and my night vision eyepiece.



#8 ron scarboro

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Posted 16 October 2016 - 10:08 AM

I have both the 1.5X and 1.25X barlows.  I've used them across a wide group of formats (in front of binoviewers, with Takahashi LE's and Orthos, and even with the Docter, Pentax and Delos eyepieces from 12.5mm - 4.5mm) with success.  

 

 

My only problem is their really small and black and in the dark are a bit hard to find when I lay them down.

 

Best,

 

Ron


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#9 george tatsis

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Posted 10 December 2016 - 02:41 AM

I have both the 1.5X and 1.25X barlows.  I've used them across a wide group of formats (in front of binoviewers, with Takahashi LE's and Orthos, and even with the Docter, Pentax and Delos eyepieces from 12.5mm - 4.5mm) with success.  

 

 

My only problem is their really small and black and in the dark are a bit hard to find when I lay them down.

 

Best,

 

Ron

The question is how much better can it be than the GSO barlow element :hmm: . It would be great if could turn my Meade 5.5mm into a 3.5mm eyepiece. I guess nobody has tried both to chime in with some info.

 

George



#10 Steve Cox

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Posted 06 February 2017 - 02:51 PM

Sorry if I'm digging up an old thread here, but I just had to repeat what others are saying.  I got the 1.25X sometime last year and have to say it's a wonderful, transparent little barlow, and an absolute perfect match for my Tak Abbe lineup, filling in perfectly between the focal lengths between each eyepiece.  I personally haven't been able yet to tell any difference in image quality with the barlow in or out.


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#11 Marcsabb

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Posted 07 February 2017 - 04:01 AM

Is this Barlow telecentric? I'm looking for a 1.5x extender whose ratio stay constant regardless of the distance to the eyepiece



#12 Steve Cox

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Posted 07 February 2017 - 08:50 AM

It's a screw in element Barlow so there is no variability.



#13 ron scarboro

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Posted 09 February 2017 - 02:45 PM

Is this Barlow telecentric? I'm looking for a 1.5x extender whose ratio stay constant regardless of the distance to the eyepiece

It is not telecentric.



#14 BGazing

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Posted 03 May 2017 - 01:57 PM

How heavy is it? Looks very light, just perfect for refractor and balance...


Edited by BGazing, 03 May 2017 - 01:58 PM.


#15 Steve Cox

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Posted 03 May 2017 - 03:48 PM

I just weighed mine on my digital kitchen scale and it came it at 1.1 ounces or 31 grams.


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#16 starcam

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Posted 03 May 2017 - 10:00 PM

I love them, my 6 zao becomes a 5mm and 4mm, my 8mm clave becomes 6.4mm and and a 5.3mm.

Tho xo 5mm becomes a 4mm and 3.33mm, haven't used them on wide fields. Mainly use on planetaries.


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#17 MartinPond

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Posted 04 May 2017 - 06:41 PM

I use the cell/nose of my Tri-Mag as a 1.3x often.

The power boost is nice, but mainly it's for the field edge improvments

of the Konigs and Plossls and aspherics with the F5 scope.

A little F-push means a lot at the point.



#18 turtle86

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Posted 04 May 2017 - 06:50 PM

I love them, my 6 zao becomes a 5mm and 4mm, my 8mm clave becomes 6.4mm and and a 5.3mm.

Tho xo 5mm becomes a 4mm and 3.33mm, haven't used them on wide fields. Mainly use on planetaries.

 

Good to know.  I'll have to get at least the 1.25 for my 6mm ZAO II and 5mm Pentax XO.

Jupiter is looking good right now and Saturn is on the way.


Edited by turtle86, 04 May 2017 - 06:50 PM.



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