Tested the Orion 80mm ED

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VinSnr
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Postby VinSnr » Thu Mar 25, 2004 12:41 am

harlequin2902 wrote:
On Jupiter, there was no "softness" in the image and still tack sharp even at 210X. Surface details were easily seen. There was no bothering purple halo that normally plagued short achromats at high power. I figure that even 250X should not trouble this scope at all. And honestly, i rather use this scope to see Jupiter than using the 8" SCT. The contrast made a lot of difference.


How pure was the image (i.e whiteness) ? Even without the purple halo from chromatic aberration, was the image as white like in TV and Tak APOs ? Or did it still have a yellowish tinge like on normal achromats ?


no..it's not exactly as white as the expensive APOs but it wasn't really yellowish like the achromats either. I would say somewhere in between.

I wasn't using exactly the best diagonal too......was testing it using the Meade 1.25" prism diagonal.

dew
 
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Postby dew » Wed Apr 14, 2004 10:59 pm

ok, last night i was finally able to take my own orion 80mmED for a real tryout on my new sphinx. the night was pretty far from perfect but i managed to take some interesting pictures throught the 80mmED.
if you go to this link:

http://www.singastro.org/album_personal.php?user_id=27

i took a picture of a out of focus star (i cant remember which star but i think it was procryon) so you can see the diffraction rings. i dont have enough experiece with star testing optics so i dont know what defect the picture implies of the optics.. is it pinched? does anyone know how i can (if i can) fix the problem?
i also took 2 pictures of a just slightly off focus star. you can see that on one side the star is green and the other its purple (honestly it is actually hardly visible through the eyepiece and is only apparent at high magnification on camera) the picture of the focused star looks a little greenish too so either i didnt get it to focus tightly enough or my scope just has got some colour in it.. i will try out again on another night to confirm..
anyway i also put a picture of ju[iter that i took through the orion last night, i dont see any false colour and it actually looks more pleasing (to my eye at least) than my other pics of jupiter that i have taken through my ETX125.
i would rather not make comments as of yet on my opinions of the 80mmED. ill have a couple more nights of observations under better skies and then will write an update here.


eu-wen

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Postby harlequin2902 » Thu Apr 15, 2004 2:48 am

i took a picture of a out of focus star (i cant remember which star but i think it was procryon) so you can see the diffraction rings. i dont have enough experiece with star testing optics so i dont know what defect the picture implies of the optics.. is it pinched? does anyone know how i can (if i can) fix the problem?


Hi Eu-wen,

The Jupiter image looks OK - I see that you managed to catch one of the moons in transit too. Lucky you :D

But your out-of-focus star images seem to show some astigmatism (note the different orientations of the oval shaped out-of-focus star image on either side of the focus). Did you do the test with or without a diagonal ?
Samuel Ng

dew
 
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Postby dew » Thu Apr 15, 2004 10:23 am

But your out-of-focus star images seem to show some astigmatism (note the different orientations of the oval shaped out-of-focus star image on either side of the focus). Did you do the test with or without a diagonal ?


it was taken without a diagonal.. i did not see any error through the eyepiece though. then again is was paying more attention to my mount and photos rather than the view through the eyepiece..


eu-wen

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VinSnr
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Postby VinSnr » Thu Apr 15, 2004 1:07 pm

dew wrote:
But your out-of-focus star images seem to show some astigmatism (note the different orientations of the oval shaped out-of-focus star image on either side of the focus). Did you do the test with or without a diagonal ?


it was taken without a diagonal.. i did not see any error through the eyepiece though. then again is was paying more attention to my mount and photos rather than the view through the eyepiece..


eu-wen


Did you check for collimation?

On my Orion ED, the out of focus star pattern is round.

If your focuser is totally misaligned, you can get that kind of star pattern.

Use a collimation eyepiece, the kind with a crosshair at its end. Put it into the focuser end and look though the peep hole. Did you see the crosshair centred onto the lens?

Better check this first.

dew
 
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Postby dew » Thu Apr 15, 2004 2:17 pm

Did you check for collimation?

On my Orion ED, the out of focus star pattern is round.

If your focuser is totally misaligned, you can get that kind of star pattern.

Use a collimation eyepiece, the kind with a crosshair at its end. Put it into the focuser end and look though the peep hole. Did you see the crosshair centred onto the lens?

Better check this first.


umm, well like i said, i really dont have much experience with star testing and i dont really know how to collimate or how to check collimation. i dont have a collimation eyepiece either.. is there another way for me to check collimation without such an eyepiece?


eu-wen

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Postby VinSnr » Thu Apr 15, 2004 3:15 pm

dew wrote:
Did you check for collimation?

On my Orion ED, the out of focus star pattern is round.

If your focuser is totally misaligned, you can get that kind of star pattern.

Use a collimation eyepiece, the kind with a crosshair at its end. Put it into the focuser end and look though the peep hole. Did you see the crosshair centred onto the lens?

Better check this first.


umm, well like i said, i really dont have much experience with star testing and i dont really know how to collimate or how to check collimation. i dont have a collimation eyepiece either.. is there another way for me to check collimation without such an eyepiece?


eu-wen


you will need at least some tools. If you dun have a collimation eyepiece, then get a laser collimator. Put the collimator into the focuser end then switch on the laser. Look at the exit of the laser, is it somewhere at the middle of the lens? (please dun look direct....)

If not, you can come to my place at Sembawang and I see if I can check this for you.

dew
 
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Postby dew » Thu Apr 15, 2004 9:27 pm

you will need at least some tools. If you dun have a collimation eyepiece, then get a laser collimator. Put the collimator into the focuser end then switch on the laser. Look at the exit of the laser, is it somewhere at the middle of the lens? (please dun look direct....)

If not, you can come to my place at Sembawang and I see if I can check this for you.


wow thanks for the offer! cause i dont have a laser collimator or anything like that.. but ill take the orion out again and do more star tests just in case.. wouldnt want to waste both our times for nothing.
thanks!


eu-wen

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