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ISTAR 8" F8.8 With Chromacorr II

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#51 James Ling

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Posted 14 August 2013 - 01:36 AM

Hi Gord....

I would not want to say or comment on the result of the chromacorr II at this moment....but we know the CA is well controlled at the central of the view....
And I still can see CA starts appearing, but not that much against without the chromacorr II, when you move the target object away in both directions (greenish-yellow in one direction, and violet in the other direction)

And I am still waiting for the opportunity for the next setup of this ISTAR during the night time, which I hope I can do so on this coming weekend...., and make the adjustment for the trial and error on the spacer distance...

The photo shows a cnetral attachment or spacer I have my machinist machined for me to thread between the diagonal forcuser end, and the chromacorr II end...
The thread that goes into the diagonal end, is able to extend out for at least 10mm....for my trial and error....testing...

REgards

James Ling

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#52 James Ling

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Posted 14 August 2013 - 01:41 AM

Hi Gord...

And the machined attachment is tested with a laser collimator , after assembled onto my other diagonal and the chromacorr II...
The the assembly is again , mounted onto my Istar forcuser, and the laser beam is projected from the lens front to a wall 3M away, and final adjustment is on the Istar countercell 5 holding screws....

This will ensure my tested object is at the centre of the view....and that is easier for my adjustment on the spacer distance....

Regards

James Ling

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#53 James Ling

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Posted 17 August 2013 - 07:04 PM

Hi All...

This are two photos I shot from the 8" ISTAR with the chromacorr II, using my canon 550D with 2X barlow...., at the 11 days old moon, during the end of the side walk session at our army club house....

Regards

James Ling

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#54 beanerds

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Posted 17 August 2013 - 10:04 PM

Woaw! that's very good James , the chromocor looks to be working very well .
Brian.

#55 James Ling

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Posted 18 August 2013 - 08:04 AM

Hi ALL...

Last night testing done at the 11 days old moon confirmed the following :-

1. Using my TV55mm eye-piece at 33X,there is a thin stripe of greenish yellow CA visible on the edges of the moon.
The amount is very much reduced, more than 50% to 80%,very close to my APM 152 ED APO...

2. When I used my baader zoom eye piece, to power up , and move the edges of the moon closer to the centre of the FOV, the CA completely disappear....IS COLOUR FREE AT CENTRE OF FOV.

3. When I further moved down the edges of the moon away from the centre of the FOV, the slight trace of violet or purple CA appears....

4. When I shoot the moon with my 550D , now the edges are colour free, with the chromacorr II, whereas previously my photo shot, will show the purple or violet at the edges.

Last night beside the moon, having a good visual view, the giant gas planet, is not able to make a good comparison....

It is sighted quite low, less than 30 deg, and with plenty of " atmospheric disturbance ".
I can even power up my Istar to 450X with my 4mm eye-piece..
and still see the view of Saturn and its 2 moons with good contrast, except is not able to show the cassini division very clearly (razor sharp), as well as the cloud bands...

Regards

James Ling

#56 James Ling

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Posted 24 August 2013 - 01:58 AM

Hi ALL....

This is a better photo comparison of the moon photos shot through the 8" ISTAR, using the same Canon 550D.
Although they are taken almost 3 years apart by me, but when using the moonlite focuser, the focusing is precise, from the 3" viewer, before the photo shot is taken...

In both occasions, no UV/IR cut or contrast booster are taken...
So the Chromacorr II is able to eliminate the purple or violet CA, when a photo shot is taken.

Regards

James Ling

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#57 Psion

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Posted 24 August 2013 - 10:57 AM

Nice report thanks.

#58 jrbarnett

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Posted 24 August 2013 - 08:18 PM

The Chromacorr really works!

Brilliant design. Sheer genius on the designer's part.

Very nice images, too, James.

Regards,

Jim

#59 mitsos68

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Posted 07 November 2013 - 09:55 AM

Hi,
I am old user of Chr II. I have a 152mm f/8 scope with a fine objective from RR Holland (original strehl 0.95). My focuser catch the diagonal / chromacor complex with a self centering adapter, and the focuser itself is push pull squared adjusted to the OTA. You can magnify the lower part of the scope to sse. Results as perfect you can imagine.
Regards
Dimitris
Athens-Greece

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#60 mitsos68

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Posted 07 November 2013 - 10:06 AM

The focuser complex

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#61 mitsos68

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Posted 07 November 2013 - 10:07 AM

test with the Chr II

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#62 mitsos68

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Posted 07 November 2013 - 10:07 AM

Test 1. CHr II on

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