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Post by vmetoile on Jan 15, 2012 12:15:43 GMT -5
hi everybody,
does any of you guys check there scope collimation with the diagonal on. what hare you finding out when you rotate the diagonal 360° let say by 45° increment. i have a antares diagonal and i found the collimation completely off and changing all the time when i rotate it. i put push screws underneth the diagonal mirror so i can compensate a little.
picture to come later.
clear sky
Vince
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Post by mikey cee on Jan 15, 2012 22:43:10 GMT -5
I've seen a diagonal that was not threaded square and wasn't even close to 90° honest to God! Mike
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Post by Ales - iStar Optical on Jan 16, 2012 5:02:27 GMT -5
Vince, scope is normally collimated without the diagonal attached, but if your diagonal is throwing collimation off, first rotate the focuser alone, if the laser beam dos not move around too much ("define too much" ..depends on FL of your scope..on 1500mm FL scope it should not move more than 3-4mm off center ) than its time to get rid of your diagonal. Look into ISTAR rock solid and truly great looking CNC machined 99 perc. reflectivity diagonals made of a solid block of alloy and laser engraved and mirror polished stainless steel back plate with a color coded metal plate below and a special dust gasket..newly re-designed in 2011, you will be more than happy with one of these, take my word for it. There are two models to choose from, the BK7 requres less time to accomodate for temperature changes. Optically they are equal. See more info under istar-optical.com/istar_061.htm but remember that we redesigned both diagonal models in 2011 and they belong to the top end category both optically and mechanically. Be well, talk to you soon, Ales ISTAR Optical
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Post by vmetoile on Jan 16, 2012 8:00:47 GMT -5
thank you,
yes i am definetly looking for a new diagonal, for my new home made istar scope. and i might take your word and get an istar diagonal as well.
Vincent
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Post by istarmullet on Jan 16, 2012 12:06:13 GMT -5
I want to purchase an ISTAR diagonal to go with my scope, how should one go about this, STARIZONA never has any.
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gord
Full Member
Posts: 82
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Post by gord on Jan 16, 2012 22:03:49 GMT -5
Vincent,
I've found it's something you have to do in stages. First with no diagonal to ensure the focuser is completely square. Then on to the diagonal. If you are using a diagonal, then it is important to check the collimation when it is in the train. Otherwise things could be off (as you are seeing).
If you are seeing things off that much, I would be checking to see what is out with that diagonal or look at replacing it.
I'll also add a comment about collimation at the other end too (lens cell). After things are all good at the focuser end, you can start tweaking the other end. It depends on the design, but some refractors seem to be more tollerant of mis-collimation than others. There is a myth that refractors have to only get close, and don't degrade much when off.
My experience has been otherwise. I especially notice this with the 150 F10. If the diffraction rings are not perfect, I find I lose sharpness and planetary detail. I'm wondering if it's because these ones (the early ones) are Steinheil's and not Fraunhofer's. At any rate, it's worth paying attention to.
Clear skies, -Gord
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Post by vmetoile on Jan 17, 2012 7:47:02 GMT -5
thank you gord,
first i did the check without the diagonal and the focuser not instaled on the tube, to see if the beam was center in the focuser draw tube;no problem ok. then with the focuser in place but no lens to see if the beam was center in the tube, i had to shim the focuser (0.5mm) then ok. after that i did the usual lens collimation using the push pull screws. everything was fine. then when i instal the diagonal the beam was off center on the lens and when rotating the diagonal the beam was describing a nice circle of about 50mm diameter.i dismentle the diagonal , drill and tap 10-32 then silicone the mirror and collimate the diagonal when in place with not perfect result let say it was still describing a small circle of about 10mm dia. note: i like this diagonal is part of my learning curv
clear sky
vince
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Post by Mike on Jan 18, 2012 0:25:42 GMT -5
Guys, I have plenty of diagonals in stock. Just email me at mike.harden@istar-optical.com
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