Stacking barlow lenses (1 Viewer)

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Paul Corfield

Well-known member

• Feb 16, 2009

• #1

Made a possible breakthrough in the quest for more power today and that was achieved by inserting an old 2X barlow element into the rear of the Celestron Ultima 1.25" chrome barrel as per 1st photo. To make it a tight fit I just wound some tape around the glass element. If anyone copies this make sure you don't push it all the way in otherwise it's hard to get back out. Once that's done I mounted the chrome tube inside the T-mount/scope adapter section.

The other images below range from 10m to 100m and all are uncropped to give an idea of how much the bird fills the frame at each range. Last image shows a 600mm comparison with the stacked barlows.

Only problem I have found so far is because the second element is coming from a really cheap 2X barlow the contrast wasn't all that good but it wasn't too bad either and a tweak of the levels was an easy fix. I'll try the same experiment when I get the 2X Televue next month and things should improve a lot. Nothing else to fault with the set up. Close focus was around 11m which is enough at this much power.

Paul.

 

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Fritzz

Member

• Feb 16, 2009

• #2

These images look really great to me, especially the last two. The first two show a little chromatic aberration, but not that bad.
I can't wait to see your experiments with the 2x TeleVue barlows.

Thank a lot for your answer!

 

ostling41

registered user

• Feb 16, 2009

• #3

A search for "Celestron Ultima" shows that this could be a spotting scope, a Schmidt-Cassegrain telescope, or even binoculars. Can you describe the set-up you used for these photos?

 

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Paul Corfield

Well-known member

• Feb 16, 2009

• #4

Sorry, should have explained in more detail. It's the Celestron Ultima 2X apochromatic barlow, also known as the Orion Shorty Plus apo barlow and as far as I know the same as the Antares 2X apo barlow. The glass I put in the back of the Ultima barlow came from a basic 2X barlow. The rest of the set up is Canon 450D and 600mm Skywatcher Evostar Pro 80ED.

Paul.

 

ostling41

registered user

• Feb 17, 2009

• #5

Paul Corfield said:

\It's the Celestron Ultima 2X apochromatic barlow, also known as the Orion Shorty Plus apo barlow ..
Paul.

Click to expand...

Paul,

I have the Orion Shorty Plus (arrived in the mail last week), so it's now clear what you are referring to. At first I thought it looked nothing like your photo, but then I discovered that the chrome lens barrel unscrews from the black socket.

I'm guessing you have changed your "Shorty" into a 4X Barlow. Orion makes a 5X Barlow but it is quite long. You seem to have achieved almost as much magnification without increasing the length.

 

JGobeil

Nature Photographer

• Feb 17, 2009

• #6

Interesting Paul. Why would this be better than a 4X or 5X barlow or a TC/Barlow stack ?

 

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Paul Corfield

Well-known member

• Feb 17, 2009

• #7

Can't really comment on the higher power barlows like 4X or 5x until I get hold of one.

Been looking through reviews on astro sites such as Cloudy Nights and the Antares 3x gets very good reviews. I'm torn between getting either the Antares 3X or the Televue 2X. People who own the Antares 3X say it lets through more light than my Celestron Ultima 2X so it could be the sensible one to get.

Stacking a teleconverter with a barlow works well up to a point, as in stacking a barlow with a 1.4X teleconverter which works very well. To get the really high power from the barlow/TC set up though it involves messing around with macro tubes which all takes time to set up in the field. Stacking with a 2X teleconverter I find the loss of light to be too much and the detail isn't as good as what I've been getting with the barlows. A 2X TC with 7 elements is just a few glass element too far.

Inside my T-mount/scope adapter I have inserted a length of tube that is the right internal diameter for the 1.25" chrome barrels that house the barlow elements. This allows me to slide the barlow forwards or backwards to alter the power. Plus I can slide in more than one chrome barrel to allow easy stacking.

It's early days yet but I'm getting photos at 100m of small birds that are as good as what I used to get at 40m with a TC so I think barlows are the way forward. It's just a question of testing and finding the right ones.

Paul.

 

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bluedubius

Rick

• Feb 17, 2009

• #8

Gonna be fun, Paul. From what I read on the Agena Astro site, the Antares 3x barlow is an achromat and not apo. Wonder if this will make much difference? Looking forward to more results.

Rick

 

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Paul Corfield

Well-known member

• Feb 17, 2009

• #9

bluedubius said:

Gonna be fun, Paul. From what I read on the Agena Astro site, the Antares 3x barlow is an achromat and not apo. Wonder if this will make much difference? Looking forward to more results.

Rick

Click to expand...

Shouldn't be a problem at all as most of the best barlows tend to be two element designs. From what I read the Antares 3X has a high standard of color correction and I shall be able to tell you soon because I ordered one today. :t:

Paul.

 

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Paul Corfield

Well-known member

• Jan 15, 2010

• #10

Nice one from today, a pair of stacked barlows from 9m range. Image is mostly uncropped.

Paul.

 

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cango

Well-known member

• Jan 15, 2010

• #11

love the big reflection in the eye

 

Musoman

PETE - Nikon/Sony Shooter

• Jan 15, 2010

• #12

Some great customisation here and cant wait too see what the Antares can do and then later, the tele-vue

Great pics. I think they're more than acceptable, and thats with an old Barlow, so IQ can really only get better, hopefully

 

Last edited: Jan 16, 2010

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Paul Corfield

Well-known member

• Jan 16, 2010

• #13

I never got the Antares 3X in the end. I had ordered it but after a month of waiting and being told it would still be a few weeks I cancelled the order.

The next one I get at the end of arch (birthday) will very likely be the Televue 2X as it's one of the few available in 1.25" that have ED glass. Plus there's not much better than the quality of a Televue.

Paul.

 

Musoman

PETE - Nikon/Sony Shooter

• Jan 16, 2010

• #14

Do you need 1.25" ?

I thought your gear was 2"

 

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Paul Corfield

Well-known member

• Jan 16, 2010

• #15

Whatever I use needs to go in behind my 2" GSO so it's easier for me to do that with a 1.25" than with another 2". Plus a 2" Televue is twice the price. A 2" Televue barlow sold on ebay yesterday for £97 so even that was a bit out of my range. The 1.25" version is around £60.

Paul.