... 5.0 out of 5 stars Great value in a 16-inch Go-To Dobsonian … The Sky-Watcher 16 Inch Dobsonian Telescope was built to near perfection as the structural and mechanical components of the OTA display carefully crafted construction and excellent stability. That, my friend, is how it is done. So, if I take a blurry and somewhat ugly picture of M1, I have just delved into the world of AP. But most importantly, develop your own! Try this one day. A friend of mine with an 11-inch Schmidt-Cassegrain (SC) has told me there is no comparison between the two scopes. Field rotation also results in a loss of image data near the edges of the field. I don’t want to shoot too low because I am now competing with the Earth’s atmosphere…but too high of an elevation, I find the azimuth drive doesn’t track as well. An easy way to visualize field rotation is to think about the following: when Orion rises in the east, Orion’s trusty hunting dog, Canis Major is below Orion and has yet to rise. The Orion SkyQuest XT10 Classic Dobsonian Telescope is a big aperture reflector that stretches both specifications and the imagination in its power and design. The Orion SkyQuest XT6 Classic Dobsonian … Field rotation is rarely noticeable during normal viewing but is certainly an issue for AP. Many stacking software programs will calculate final pixel values using “additive” or “additive with scaling” algorithms. The ground board is quite bulky, and slightly larger and heavier than perhaps it could have been. Putting it together is a straightforward process, although the manual shows the differently designed cell for the smaller XX12g. More short exposures or fewer long exposures – Which is better? Alt/az mounts, however, track in both axes at the same time hence the probability of a bad frame due to a tracking error just about doubles. I then use PixInsight for debayering, dark/flat/bias calibration, image registration, image integration (stacking), and image post processing. The scope can be completely … Setting up the Go-To requires a two-star alignment process. The scope comes with a true parabolic mirror (versus a spherical mirror). I own an Orion 16-inch GoTo Dobsonian and as the name implies, it is a standard GoTo scope with the type of hand controller most of us are familiar with. During exposures, the field rotation effects are being captured by the sensor! My first “telescope” was a small spotting scope given to me by my grandfather. Next, when shooting lots of subs with an alt/az mount, stop imaging for a few minutes and do the following. Disassembling it into manageable parts to take outside or load into a car takes 5-10 minutes, while reassembly takes 20-25 minutes. Some field rotation effects can be removed during the stacking process however it still leads to poor image quality for longer exposures. We found the whole Go-To system to be well-behaved and relatively simple to use. Orion SkyQuest XT10 Classic Dobsonian Review. Photos showed exactly what is packed in each box and give comprehensive step-by-step assembly and operating instructions. If you want all of those things, then Orion’s new SkyQuest XX16g could be for you. The XX16g’s innovative design features enhance the appeal of owning a large Dobsonian. Second, let’s not tell people what their limitations are. I distinctly remember setting it up on the hood of my grandmother’s car and pointing it at the moon. Note their reaction. Don’t let its massive size fool … When John Dobson invented the Dobsonian he wanted the general public to have access to an inexpensive, lightweight, and yet at the same time a large aperture scope. I completely disagree on several levels. Some of these rotate the camera and some actually rotate the entire OTA. Star testing showed some minor differences either side of focus – possibly arising from uneven cooling of the mirror, which is substantially thicker at the centre than at the edges. With excellent light grasp, point-and-view ease of use, convenient portability, and a low price, the XT6 Classic Dobsonian reflector should be on the top of any beginner’s telescope wish-list. The Go-To made viewing the centre of the Virgo Cluster a pleasure rather than a chore and then drove us on a short distance to view the faint but wonderful razor of edge-on galaxy NGC 4762. Hopefully some of the mentioned tricks and techniques will help you along the journey. However, your guide star needs to be as close to your target as possible. You can do this by visually aligning stars within the field of view. Many faint galaxies can be viewed through my Dob whereas they remain invisible in his SCT. Many folks out there (I call these folks the “naysayers”), including formal and professional sites, will tell you Dobsonian scopes cannot do astrophotography. Astrophotography with a Dobsonian brings its own set of unique challenges. First, what is AP? And being a Dob, the OTA sits on a standard Alt/Az mount. Total weight of the basic scope is about 195 pounds. A lightweight extendable dew shield would help here. Especially for a target like the Horsehead Nebula. Or some will use the term “not ideal for astrophotography (AP) other than planetary”. Happy hunting! Astrophotography of brighter deep-sky objects may even be possible by stacking short exposures. Another challenge to Dobsonian AP with is tracking. On most days it is spot on and on rare occasion, a few resets are required to get it to behave. The 16-inch primary mirror is made from BK-7 glass and has a focal length of 1,826mm, giving a focal ratio of f/4.5 –a short focal length for its size. You can actually see how the “frames” rotate about one another. That, my friend, is how it is done. A lighter, less overly robust head would have eliminated this task and saved further weight. Explore Scientific 16-inch truss tube Dobsonian So, what makes a Dob a Dob? I often times stop imaging, recenter the target, and start imaging again. Field rotation is the apparent rotation of objects in the scope’s field of view, either through the eyepiece or on your camera’s sensor. If, out of 100 subs, 10 frames have noise at coordinate x,y but the other 90 do not, your stacking software will average the values of all the pixels at location x,y. Suppose you want to shoot 200, 30 second subs of the Horsehead Nebula. Now, rotate your camera such that the live preview (or a test sub) closely matches the first sub taken. Being Orion's biggest unit, it is as big as can be dealt with practically. The scope can be completely disassembled and transported. This equates to 15 degrees per hour or .125 degrees every 30 seconds. Happy hunting! Jupiter’s red spot and Saturn’s Cassini gap are both easily discernable. That’s a lot. It is the second largest Dobsonian … Auto guiding will not eliminate field rotation. Minor collimation adjustment of the main mirror is always needed before observing – it’s a relatively painless procedure and fully explained in the manual. The optional elasticated shroud helps keep thermal currents from an observer’s body out of the light path and noticeably improved images, but didn’t stop the secondary from dewing up after about two and a half hours. A Dobsonian telescope, simply put, is a Newtonian OTA (optical tube assembly) mounted on an alt/az mount. A fair amount of the assembly time was spent attaching the nine 1kg counterweights, which help balance the head unit that houses the secondary mirror. Experiment, take notes, try different techniques and combinations of techniques and tools. I almost always do some bit of post processing in Photoshop. My typical video processing: convert to AVI (if needed), process video in AutoStakkert (stack video frames), and pull out details using wavelet layers in RegiStax. The scope can be completely disassembled and transported. Where field rotation is a problem is during exposures.

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