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Compnent quality for Planetary imaging: Barlows

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#1 APshooter

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Posted 01 August 2020 - 03:23 PM

Hey guys.  As the title states, I've got a question about my imaging train, specifically my barlow collection.  About 20 years ago I bought the bulk of my eyepiece collection as well as 3 individual barlow lenses.  I currently own an old style Televue 2.5x Powermate (single barrel) a 5x Televue Powermate (single barrel) and a Celestron 2x barlow. 

 

Most years I've been imaging with the celestron barlow.  My imaging train on my last outing was SCT>IR filter>ZWO ADC>Celestron barlow>ZWO224MC.  I just saw a post today where an imager put the ADC right in front of the camera.  When I tried doing that with my Powermates, the magnification got so large for the seeing (mushy images) that I felt I should step back to a 2x barlow rather than 2.5x.  Not being able to unscrew the Powermate 2.5 means I can't put the adapter on it I currently own.  I guess you can unscrew the new models and make it a shorter barrel.

 

With Mars approaching I'm willing to upgrade a few pieces of my system if it will help improve my mechanical setup.  I can't do much about my local seeing, but I'd like to see if there's something I may be over looking to better my system.  If what I have is sufficient but requires just reorienting individual pieces I'm fine with that too.  Thanks in advance for your help. 


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#2 RedLionNJ

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Posted 01 August 2020 - 03:42 PM

I've had my ADC directly in front of the camera (or at least, after the amplifier) for several years.

 

Some of the Powermates don't increase (in fact, they slightly decrease) the amplification with increased distance. There are also some barlows where you can remove part of the barrel and drop the amplification (via decreased spacing distance) to 1.7x or 1.8x

 

Antares (and likely others) make a 1.6x barlow which comes out to around 1.9x at sufficient spacing.

 

And finally, there's always a custom option where you get somebody to manufacture exactly what you want. I've used Siebert for this.

 

There are plenty options. Even undersampling on Mars isn't that big a deal - it's mighty bright.


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#3 APshooter

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Posted 01 August 2020 - 05:20 PM

Gotcha. My Powermate doesn't split. I could try staying with the Celestron 2x or experiment again with the Powermate.


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