Orion 2" Crayford Focuser

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Brand and Model:Orion 2" Crayford Focuser
Price ($USD):$69.95
Description:The Orion Crayford focuser appears well made. It has a black cast aluminum base and a dull colored aluminum drawtube. The over sized aluminum focus wheels are equiped with rubber grips on their edges. There is a focus lock thumbscrew on the underside of the focuser just below the focus wheel. A bit closer to the tube body is a focusing tension adjustment set screw. There are three pairs of socket head set screws and socket head cap screws for collimation.

Hex keys are included for the various screws. Also included is a 1.25" adapter.

Turning the focuser over reveals two small roller bearings. Unseen and further up the drawtube are two small roller bearings. On the oppisite side of the tube, midway up the shaft, there is a large roller bearing.

The focus height is 70MM without the 1.25" adapter and 80MM with the adapter. Focus travel is 40MM.

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Orion 2" Crayford Focuser
My review will consist of 2 parts: (1) Installation and (2) Performace.

Orion sells this focuser as a "drop in" replacement for their two DOB lines with an aperture of 8" or greater except for the 8" Classic DOB which Orion states is not compatable with the new Crayford.

Unitl 11/06 all Orion DOBs came standard with an good Rack and Pinion focuser. After 11/06 the Intelliscope DOB line with an aperture of 8" or greater now come standard with the Crayford focuser. If one had purchased a Intelliscope DOB from Orion prior to the before mentioned date one could order the upgraded focuser and install it yourself. Orion states the focuser can be used on other reflectors with small modifications needed.

I have an Orion xt8i purchased 10/03, so I ordered the Crayford.

Indeed installation seemed easy. The stock R & P focuser was removed without a problem. Intallation of the Crayford was just as smooth. (A note of caution, the instructions advise the use of a wrench for the removal and installation of the focusers. This requires the tool to be used close to the secondary mirror. For me, the use of a wrench was not necessary. I simply held the nuts with my fingers while removing and tightening the screws. With this technique, removal and installation was easily accomplished).

Afer installing the Crayford I decided to check collimation by using the Orion collimation cap. It seemed dead on. However I know that the cap cannot check the position of the focuser in realationthip to the secondary mirror. To accomplish this I had to use my Cheshire eyepiece. When doing so it was obvious the Crayford was off center and thus out of collimation.

The section of the base of the focuser closer to the primary mirror was too "low". I loosened the two bolts at that end of the Crayford and slowly lifted it up from the body of the OTA. I had to pick up that end of the focuser approximatley 1/16". I reinstalled the R & P focuser, it was fine. The only explanation was that the Crayford was a bit out of "plumb", not level across its base.

After a few conversations with Orion tech I decided to shimm up that section of the base. This was accomplished by the use of two rubber water faucet washers. I placed a washer under each screw just as one would a metal washer. I scrapped off a bit of one of the washers taking my time till, per the Cheshire, collimation was dead center.

Next I checked the mechanical motion of the focuser. I racked the focuser in and out. In doing so, I noticed a "bump" mid way through the drawtube. I could feel the bump. Also, I could hear a gritty sound when the tube was racked in. Neither produced any image shift through the Cheshire. Applying a small bit of WD 40 took care of both problems. Apparently there was a bit of dust or dirt on the drawtube.

With installation complete I moved the scope outside to test the focuser.

It was not a great night, but I had two objects that I felt I could use to check the collimtation and mechanical functions of the focuser. There was a "1/2" Moon out as was the Orion Nebulae.

On the Moon I pushed the magnification up to 300X till I noticed a breakdown of image. At the Orion Neb, I concentrated on the embedded stars. They were clear and sharp up to 200X and beyond. Next, I picked a bright star and performed a star test. The collimation was fine.

Per the focusing, the Crayford was great. At the before mentioned 300x I did not notice any image shift nor backlash that often accompanies high mag viewing. In fact, focusing was a pleasure. "Buttery Smooth" is a term that comes to mind when describing the function of this focuser.
I used an array of EP's at different mag and had no problem whatsoever with viewing.

I rated the performance at "9" only because I an not familer with higher end focusers. Perhaps they do a better job, but it is hard to believe the improvement would be worth the extra expenditure. The value is a "10". At the price given this is a great deal.

I would advise anyone with a reflector who wants to improve the focusing to give this Crayford a try. It truely is a top notch bargin.

Overall Rating: 9
Performance:9 Value:10
Weight: 5 (Veritable Vote)
By: nafa823
Link to this vote: http://www.excelsis.com/1.0/displayvote.php?voteid=545356

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