Archive for January, 2017

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Unboxing the Bresser Messier AR102S Comet Edition

January 31, 2017

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I’ve been interested in this scope since late 2014. The Celestron TravelScope 70 turned me on to the joys of refractors back in 2012, which led to the C102, which led to the C80ED, which got me firmly hooked on low-power, widefield scanning, which led to this.

This is the Bresser Messier AR102S Comet Edition, which I believe is a record for the longest name of any telescope I’ve owned. And you actually do need all of it, because there is another Bresser Messier AR102S that is a completely different scope. That other AR102S is a standard f/6 achromat. The AR102S Comet Edition is an f/4.5 rich-field scope. And as you can see from the photo, it’s built funny. Instead of having the focuser at the back end of the tube, the focuser is mounted on the side of the tube, as in a reflector, and a reflector-style secondary mirror* bounces the light from the objective lens to the eyepiece. This makes for a very short, compact scope, and theoretically for easy collimation via that secondary mirror (I haven’t tried that yet). Scopes like this are sometimes called “reflactors” because they combine an objective lens with a secondary mirror. I’ve seen ATM builds using this design, but I’ve never seen another one marketed commercially.

* Existential telescope question: is it still a secondary mirror if there’s no primary?

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As far as I know, this scope has only ever been sold as part of a travel kit that includes the OTA, an eyepiece, an alt-az mount, 7×50 binoculars, and a backpack to carry it all. That package has a list price of $349, but the list price has been creeping downward. Explore Scientific’s online store and OpticalInstruments.com both carry the AR102S Comet Edition (man does this scope need a nickname) package for $299, but B&H Photo-Video has it for $249 with free shipping. Amazon used to have it for $249 as well, but I seem to have gotten the last of those – as of this writing, the price is hovering in the $340s.

I’ll have a first light report along soon, this one is mostly photos of the unboxing and the scope.

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Outer box…

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…contains the middle box…

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…contains the inner box. That’s right, three boxes before you get to anything other than packing material and the instructions.

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Inside box number three are the backpack and two more boxes.

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Inside the backpack is the OTA in a plastic bag, and on the right you can see the eyepiece peeking out of the side pocket.

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Oh, also in the backpack are the 7×50 binos. Everything bagged.

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And inside the bags, the telescope OTA with wrapping paper, the binocular case with the binos in yet another plastic bag inside that, and the eyepiece bolt case with the eyepiece in yet another plastic bag inside that. Oh, and a couple of hex wrenches inside the bag with the bolt case, for collimating the OTA.

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And here’s everything finally outside of the various bags, bolts, and cases.

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The OTA is 20″ long and 4″ in diameter, with a 4 1/4″ diameter dew shield. In the shots before this one, you can see the dovetail on the right side of the OTA, and here you can see the shoe for a finder (not included) on the left side of the OTA. Having the dovetail on one side and the finder shoe on the other is convenient, because it means the OTA can’t roll over and bang the focuser if you set it down on a flat surface.

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Here’s the lens cap. If you’re thinking it looks like a Meade, you’re not wrong.

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And way down inside the dewshield, 4 1/4″ in, is the objective lens, with its dark green anti-reflection coatings. The achromatic doublet is fully multicoated. The dewshield has an outside diameter of 4 1/4″, and an inside diameter of 4 1/8″. Past the objective lens you can also see the single baffle inside the OTA, which is otherwise just painted flat black inside.

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Remember those other two boxes? The long one has the tripod and the short one has the alt-az head.

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The alt-az head, which is metal, and the eyepiece tray, which is plastic.

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The mount assembled. The alt-az head looks like my SkyWatcher AZ-4/Orion VersaGo II, but it lacks the adjustable tension knobs.

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Here’s a feature that I really like: the eyepiece tray goes solidly onto the spreader bars with no tools. It threads over a central bolt, and then rotates to snap into position. This is super-handy at the end of the night, because I can unlock and rotate the eyepiece tray without taking it off, and fold the tripod legs in just enough to get through the door.

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The whole rig set up. The tube looks not quite square here, but that’s just field distortion from the iPhone camera, which we’ve seen before here.

The OTA weighs 6.2 lbs, the mount weighs 6.8, so the whole rig clocks in at 13 lbs even. That’s pretty portable, although certainly at least flirting with being undermounted. More on that in the first light report.

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User end. The eyepiece is a Bresser 20mm 70-degree model, which is currently on sale for $40, down from $60, at OpticalInstruments.com. If you’re thinking that $60 seems like not much money for a new fully-multicoated 70-degree eyepiece, I agree, and I am likewise suspicious. I assume it’s some kind of Erfle, but I haven’t taken it apart to confirm. The size, form factor, and even barrel detailing are very similar to Orion Sirius Plossls, but the eye lens is just slightly too big for Sirius dust caps to fit (which is a shame, since it gets in the way of me stuffing this thing in my pocket while I swap Plossls and Expanses around). It gives 23x and a 3-degree true field of view.

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Here’s the left side of the back end, showing the finder shoe, the collimation bolts for the secondary, and another look at the focuser. The focuser is an all-metal rack-and-pinion job. Oddly enough, the focuser drawtube is 2″ in diameter but the 1.25″ adapter at the top is permanently mounted. So it’s a 2″ focuser that only accepts 1.25″ eyepieces. I think there’s a reason for this – the focal plane is 6-7 inches (150-175 mm) away from the center of the OTA, which means at least a third of the 459-mm light path occurs after the light hits the secondary. I think a 1.25″ drawtube would cut into the light path and stop down the scope.

The finder shoe is not one I’m familiar with. Almost all of my experience is with gear made by Synta (Orion/Celestron/SkyWatcher), which uses the same mostly-but-not-quite industry standard dovetail shoe for finders. This is a weird square rig that is outside my experience. I probably won’t use a magnifying finder – I can get by okay just dead-reckoning, and when I feel like cheating I can lay a laser pointer along the dovetail shoe or the square edge of the focuser and get on target very fast. But I might put a counterweight there, to get the balance point a little farther back so the eyepiece height would change less going from horizon to zenith. Or here’s an interesting thought: I bet I could gin up an eyepiece rack that would attach to the finder shoe. That would be cool, convenient, and a counterweight.
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Here’s the focuser again, with the axis drawn in blue. This is to make a point. I’ve seen one or two folks on Cloudy Nights alleging that this is a “leftover scope” – that Bresser/Explore Scientific had some leftover tubes, leftover secondaries, and leftover focusers, so they cobbled it all together into this Frankenscope. But that doesn’t hold up. The focuser is a single-piece aluminum casting with two features of note. First, it wraps tight to the 4″ diameter tube, which if it was leftover from a reflector would have housed a smaller-than-4″ mirror. There are 3″ reflectors out there, like Orion’s SpaceProbe 3, but no-one puts 2″ focusers on them. Second, and more importantly, the focuser knobs point across the tube on this scope – that’s what the blue line shows in the image above – as opposed to down the length of the tube as in all mass-produced reflectors. Again, the focuser is a single chunk of aluminum – the 2″ tube can’t be separated from the base, or rotated relative to it. So I’m confident that this focuser was purpose-built for this scope.

The “leftover scope” idea was pretty dumb anyway. The most expensive part of any refractor is the objective lens, which has to be figured to a tolerance of a millionth of an inch. The rest is just steel, aluminum, plastic, and fasteners, which cost peanuts by comparison. As far as I’ve been able to tell, neither Bresser/Explore Scientific nor their parent/partner Jinghua ever sold a 4″ f/4.5 scope before. It doesn’t make any sense to figure a bunch of bespoke objectives – the expensive part, especially after full multi-coating – just to sell the cheap hardware.

So, somebody decided that a fast, 4″ reflactor was a good idea. Were they right? Tune in next time and find out.

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My article in the March 2017 Sky & Telescope

January 27, 2017

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This is one was an easy write-up, because it had been in my head and in my notebook for a long time. Way back when I first got tapped to write for S&T, I pitched a tour of the winter Milky Way from Puppis to Gemini. I’d never written for a magazine before and I had no idea how much sky it would take to fill 1600 words. Turns out, all I got through on the first attempt was Canis Major, Puppis, and a couple of odds and ends like M48. That was my article in the December 2015 issue.

Right after that came out, I pitched the unfinished second half, and now it’s out. Like that first article, it’s a tour of the winter Milky Way pitched at binocular users, but hopefully useful for telescopic observers, too. This piece runs from Monoceros through northeastern Orion to southern Gemini. The March issue of Sky & Tel is probably hitting newsstands this week. If you get a copy, I hope you enjoy the article.

If you’re thinking that Gemini is a pretty arbitrary place to stop cruising the Milky Way, you’re not wrong. I can say no more for now, but stay tuned…

Update: whoops, I originally put January in the post title instead of March! This is, of course, the March issue, it just came out in January. Sheesh.

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Impromptu binocular digiscoping

January 18, 2017

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I grew up in Oklahoma, on the Great Plains. The plains have a wild, forlorn beauty, but I have always craved seeing mountains. When I was a kid, that meant waiting for a family vacation to the Rockies or the Black Hills of South Dakota. I have been very fortunate that since moving to California in 2001, I have essentially always lived within view of mountains. In Santa Cruz and Berkeley it was the coast ranges, which are really more like ambitious hills. In Merced it was the Sierra Nevadas, which are legit, but not particularly close to Merced. The mountains were only visible as a low line on the eastern horizon, and only when the air quality was good, which was not often. Fortunately that was just one year.

Since 2008, I’ve had the privilege of living at the feet of the San Gabriels and especially Mount Baldy (formally Mount San Antonio, but universally ‘Baldy’ to locals), which looms directly north of Claremont like a slumbering god. So I get to see proper mountains – the San Gabriels are still rising fast so they are impressively steep, and Baldy tops out at 10,064 feet (3068 m) – pretty much every day that it’s not raining and there are no nearby wildfires. In the winter the mountains are often snowcapped, although never continuously so, it’s just too warm here.

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A couple of days ago I was out running errands and the mountains looked so good that I had to drive up to the top of the First Street parking garage downtown to get some unobstructed photos. Off to the northwest, 22 miles distant, I could just make out the gleaming white domes on Mount Wilson. Then I remembered that I had my 10×50 binos in the car, so I got them out and spent a few pleasant minutes scanning the whole northern skyline, from Mount Wilson in the west to mount San Gorgonio, above Big Bear, 51 miles due east.

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Then I got to wondering – if I held my iPhone up to the binos, would I be able to get a recognizable photo of Mount Wilson? It was worth a try. I had to prop the binos on my sunglasses to get the angle right, and the raw shot is vignetted because getting the camera-to-eyepiece distance correct is a little hairy, but hey, there are the domes.

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Here’s a cropped, tweaked, and labeled shot. Except for the CHARA Array, an optical interferometer using six 1-meter telescopes in small domes that started work in 2002, all of the historically important installations are visible from 22 miles out.

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I also got some shots of the nearby peaks, especially the higher foothills of Mount Baldy. This shot is a pretty good match for the last photo in this post, which was taken through a different instrument at a different time of day in a different season, but focused on the same peak. This peak is 10.5 miles from my house, as the crow flies, so about 10.25 miles from the Claremont parking garage where the photos in this post were taken.

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Cropped and tweaked. Not too bad for 10×50 binos that cost less than $30.

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What’s in my eyepiece case

January 9, 2017

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In the 9.3 years I’ve been stargazing, I’ve had three eyepiece cases. The first was a Plano tackle organizer with a thin layer of bubble wrap taped into the lid, which held half a dozen 1.25″ eyepieces. After that I got one of the cool foam-lined purpose-built eyepiece cases that Orion and everyone else carry, but that one didn’t last long – probably less than a year. The problem was that although it did a fine job of holding the eyepieces, it didn’t have room for all the other stuff I wanted to cram inside.

Then in 2012 or so I got the eyepiece case that I’m currently using, and the one that I’ll probably be using for a long time to come. It’s not bespoke – it’s a $20 Craftsman toolbox I picked up at Orchard Supply and Hardware. I think this particular model has been discontinued, but there is something almost identical on the shelves today, and there probably will be from now until the end of time (or at least civilization). This one is probably the current incarnation, and hey, it’s only 10 bucks and has a better latch.

The exterior doesn’t deserve much comment. I put my name on it, and its contents, mostly to make it clear to anyone who might find it among my stuff if they’re going through the garage looking for tools of the terrestrial variety. I don’t fully trust the single latch so I keep a zip tie run through the hole where the lock would go. The zip tie goes in the top shelf when the case is open.

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The top shelf, which is removable, holds my red flashlight, Astro-Tech dielectric diagonal (previously discussed in this post), eyepatch, Barlow, and quick-look and outreach eyepieces – various Plossls, the 6mm Expanse, and the dreadful 4mm VITE that I haven’t yet thrown away. Not shown in the photo are a spare pen and a little Sharpie, both buried under the bag containing the diagonal. You can see that all of the eyepieces are still living in the boxes or cases they came in, and they’re held in place against rocking or tipping by a thick layer of bubble wrap taped into the lid of the tool box.

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Another sheet of bubble wrap sits below the top shelf and cushions the gear in the bottom of the toolbox.

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The bottom of the toolbox holds my ‘top shelf’ eyepieces and a lot of spare gear besides. The three Explore Scientific eyepieces came clamshelled in foam, and each one rests in the bottom half of its original clamshell. One of the top halves forms a bed for the 5mm Meade MWA. The two slots in the middle used to hold my Stratus eyepieces before I let them go – the ES models are smaller, easier to handle, and do a significantly better job. Now those slots hold the 32mm Astro-Tech Titan, my only 2″ eyepiece, the GoSky iPhone adapter I blogged about here, and a cord to hang my eyeglasses when I’m observing.

Around the edges I have all kinds of stuff crammed into the spare spaces. Clockwise from the top:

  • Contact info, just in case the case ever gets lost and found by someone decent. Has my name, address, email, and cell number.
  • Lens cloth, just in case.
  • Spare AAA batteries for the green laser, the red flashlight, and the laser collimator.
  • A ziploc. Never know when you’ll want a small waterproof bag. Sometimes holds spent batteries if I have to do a field swap.
  • Laser collimator. Reminds me, I need to blog sometime about how to collimate a laser collimator.
  • A set of hex wrenches for collimation.
  • Small pliers for the same purpose – I’ve swapped the hex bolts on a lot of scopes for standard hex-head bolts that I can tweak with pliers. Much better than farting around with hex wrenches.
  • Green laser. Super-useful when stargazing with newbies and old hands alike.
  • Tiny atlas – so I’m never without one. This is the Collins Gem Guide to Stars, which has little charts of the constellations and a short list of the most impressive DSOs for each one. Unlike Sky & Tel’s Pocket Sky Atlas, this thing truly is pocket-sized, and small enough to take up essentially no space or weight in the case. It has saved my butt a couple of times when I forgot all other atlases.

There is one other thing. In the third photo you can see a light blue bag through the intermediate layer of bubble wrap. I think that’s the bag the eyeglasses cord came in. Now I use it to hold a set of iPhone earbuds, which serve as a remote trigger when I’m taking pictures with the iPhone adapter, as shown and explained here.

That’s it – an inexpensive, sturdy, and above all roomy case for my eyepieces, with nooks and crannies for a whole lot more.

What’s in your eyepiece case?