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The NJP Temma 2 Goto Mount from Takahashi

Posted by Morgan Spangle   09/13/2005 12:00AM

After considering my budget and my options of available German equatorial mounts, I settled on a Takahashi NJP Temma 2. I had used other Takahashi equipment (a Mewlon 210; Takahsahi eyepieces, a great little .965 turret) and had a very favorable impression of Takahashi’s well-earned reputation for attention to overall quality, and solid, well-designed construction. With three nights of using the NJP under my belt, I thought I 'd share my first impressions, for those of us looking for a premium, large capacity mount for visual observing or astrophotography.

I have set up the mount with a Celestron 9.25 SCT, mounted with top and bottom Losmandy D plates, secured to the head with a Robin Casady saddle. I use a Telrad finder mounted on the tube to do initial sighting of alignment stars; then refiine that with a Celestron 9 x 50 straight through illuminated reticle finder that is perfectly aligned to my CCD chip. The 9.25 has a SBIG ST2000XM camera, for imaging double stars at the high resolution of .65"/pixel. Presently, for visual pleasure, I keep a little William Optics 66ED Petzval design scope mounted on the top plate - I view the star fields through this while waiting for the mount to settle after slewing. The total weight of my setup is around 45 lbs.

I use Software Bisque’s suite of software to control the mount and camera -theSky6 pro, CCDSoft v.5, and Orchestrate - to run the scope and slew to targets that I select, using a great astronomy plan-generating software, Astroplanner. The last 3 nights have been splendid in the Northeast, with cool temps and clear and steady skies, and I've collected about 180 images of doubles, for my program of measuring neglected doubles from the Washington Double Stars catalogue.

The NJP has made acquiring the CCD images easier than any of my previous mounts. Setup is quick. I have the mount attached to a wooden tripod that is mounted onto JMI’s large wheeley bars, with 5” wheels. I can wheel out into the driveway from my garage and be imaging in about 15 minutes. Once the scope is outside, I fire up the computer and the software and start up the camera to cool it down while I align the mount.

Polar alignment has been made easy by Takahashi. A unique feature of the NJP is the bubble level on the declination housing, which allows one to polar align the mount without having to level the legs of the tripod – always a pain in my sloping driveway. Once the bubble is between the lines in the level, done by adjusting the declination shaft, I run a little software routine which gives me the placement of Polaris in the polar scope – putting Polaris there requires little effort, and has taken only a minute or two each time I’ve tried it, including the first time.

After aligning Polaris, I loosen the axes and move the scope so that it is in the Western alignment position – that is, the counterweight shaft level horizontally and pointing East; and the telescope vertical, perpendicular to the counterweight shaft and pointing at the zenith. I check the axes with a small spirit level to get it just right. I then turn on the Temma power and computer connection switches on the Temma control box mounted on the head, and synchronize the mount to the computer. Using the nifty little hand controller that Takahashi provides with the mount, I slew to a bright star in the east, center it in the finder and then again, for best accuracy , on the CCD chip using the focus routine of CCDSoft. Once I get the star in the exact center crosshairs of the chip, I take a 20 second image and do an Image Link, synchronizing the mount again. With this routine, I find that I can slew all over the Eastern sky all night, with my targets ending up on the chip every time – usually between 3-5 arcseconds from the center of the chip! ( I measured using image link plate solutions on some of my images. I generally image in one area of the sky per night, so I haven’t attempted a meridian flip yet). I re-synch the mount to theSky periodically, perhaps every 6th target or so; but doing so is more from habit than necessity with the NJP Temma 2. This entire alignment and synching routine took 20 minutes the first night, and only 15 minutes last night, the third night out.

The NJP is a very beefy, solid mount. I wouldn’t characterize the mount as “portable”, though of course it can be moved and set up by a reasonably strong person.. But I highly recommend the wheeley bar setup , or a permanent location – hefting the 49 lb. head up onto a tripod at night isn’t my idea of relaxation.. The counterweight shaft is big, stainless, and a screw-on type – not so easy for quick changes of weights and positions. The NJP seems more useful for someone who uses the same equipment all the time – like I do. It carries the 9.25 and the rest of my setup with ease, using the three counterweights provided with the mount. Damping time is very minimal, virtually unnoticeable in this setup. The mount runs on 12 or 24volt DC power – I use a power supply that transforms AC to 24 DC, and the mount hums along nicely when doing slews. The NJP is a little noisier than mounts other goto mounts I’ve used – at full speed, the motors make a high-pitched sound that my son characterized as sounding like an “alien invader” (that’s a positive from him). But on the positive side, the motions are very smooth and easy to control, both for rough centering at full speed and for guiding corrections at the hand-controller’s slow speed.

What is truly impressive about the NJP is the way the mount tracks and meets my imaging requirements. I generally slew to between 40 to 75 targets per night, stopping long enough for the mount to settle, begin tracking, and image unguided for 20-30 seconds per target, before moving on to the next. With the NJP, I can image at a 2350mm focal length unguided for those short exposures, and have the stars come out round and sharp – perfect for astrometry. I had been using various focal reducers with my previous mounts to be able to image, but the NJP makes those obsolete for my imaging train. Even under last night’s moderately breezy conditions, the NJP was unfazed. The NJP doesn’t have a lot of the bells and whistles of some other premium mounts (it doesn’t have a PEC routine, for instance – though it tracks so well, mine doesn’t really seem to need one.) It needs a computer attached to do goto with the Temma – but if you’re imaging, you’ve got a computer at your side most likely anyway. If budget is a consideration, it is a lot less than some of the other premium mounts that have its capacity. In its favor, it IS readily available, and the stated visual and photographic capacity (80 lbs.) seems very realistic, given my experience so far. And, the build quality is so good, so solid that I anticipate many years to come of very satisfying imaging with the NJP at my side.

Click here for more about this subject. -Ed.