Home made Barlow.

Astroman (Andrew Wall) · #1 20-05-2006, 05:20 PM

Hi all, Made myself a barlow today, getting a little impatient waiting for mine to come through the post LOL, very rough and quick but it seems to work on a distant tree, it looked rather good. I will post results of it when I use it on Jupiter tonight.

Lester · #2 20-05-2006, 05:22 PM

Wow Andrew.

Barlow today, time machine tomorrow.

Astroman (Andrew Wall) · #3 20-05-2006, 05:57 PM

HAHA Lester, Not quite yet, pleanty of time for that

The barlow was made up of several different bits, the main tube where the EP or camera goes into is actually from an old barlow I had which I dropped and smashed the lens assembly. The bottom bit where the lens is is from an old 25mm Eyepiece that came with my TAL-1, (same with the barlow). The Lens assembly came from a stripped down 210mm zoom lens for a camera. All held together with good old electrical tape.

asimov (John) · #4 20-05-2006, 07:07 PM

Good one Andrew. I like seeing the inventive side of people, well done

Astroman (Andrew Wall) · #5 20-05-2006, 08:27 PM

OKay here is a comparison of image size, the jupiter on the left is unbarlowed, toucam straight in the hole taken using 640x480 res. The one on the Right is the barlowed one, no extension tube, also 640x480 res. If you can work out the magnification of the barlow using that I would be muchly appreciative. I think its around the 3x mark.

OKay Visually its a little lacking in contrast and there are some imperfections in the lens, but using my selection of plossls it really gave me a good idea on what the barlows can achieve. And Jupiter through it witha 4mm eyepiece WOW! it was HUGE!.

I must make mention I was using my TAL-1 which is a 4.5" F7.3

asimov (John) · #6 20-05-2006, 09:13 PM

Thats great Andrew! Certainly bigger scale than a standard 2X...Lester & I just did the scientific calculations...(tape measure up against the screen

) & we consider you have a 4X barlow there

Astroman (Andrew Wall) · #7 20-05-2006, 09:19 PM

WOW never thought of that method LOL. Great idea.

Astroman (Andrew Wall) · #8 20-05-2006, 09:45 PM

OKay just finished processing one of the AVI's I got, seeing was crap, and the image was jumping around and cloud was trying to pass over and my arm was aching turning the slow motion control on the mount and......... Anyway found a flaw in my design it has CA... When I processed the image it had bad yellowing around the edge, mainly on one side, so I am guessing that CA was the cause. Still I am happy with this attempt. 1.5x B-sline was used to increase image scale. 239 frames out of 301, 10fps. Dont know other settings yet lol.