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Repairing Astro-Physics GTO Hand Pad Cable
The cable on my Astro-Physics GTO hand pad cable (AP part number E0190CABLE-E) had deteriorated over time. The rubber insulation had peeled and cracked, exposing the shielding and conductors...
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Takahashi EM-1S RA Drive Analysis
I had a look at the innards of the Takahashi EM-1S RA drive, because I wanted to see how hard it would be to convert it to center-positive. Quick answer: it's hard.Here is the outside of the EM-1S RA...
View ArticleBuilding and Using Astrometry.Net on MacOS
Why Astrometry.net on MacOS? because Macs are built to take bullets and have long battery life. Unfortunately building almost anything on MacOS is ten times as hard as doing it on Linux. There are some...
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Polar Alignment With A Bubble Level
In low-latitude locations such as Singapore (1.3521° N) or anywhere that Polaris is not visible, polar alignment can be difficult and time-consuming to achieve. One method for doing initial alignment...
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Canon EOS 6D + 35mm f/1.4L vs Fuji XE-2 + 23mm f/2
IntroductionI've been a Canon EOS user for almost twenty years, except for a brief foray with the earlier Pentax DSLR's (K10D and K20D) about ten years ago. My favorite camera for the past few years...
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Almost Full Frame: Fuji X Camera Lens Turbo Adapter (Ver II) from Mitakon
I very much like the form factor and UI of the Fuji X-mount cameras: they are very much the poor man's Leica.A challenge is that wide lenses are hard to find, due to the 1.5X crop factor, since the...
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Takahashi EM-1S Ersatz Polar Scope
I bought an old Takahashi EM-1S mount from Yahoo Japan, but it did not come with a polar scope. Since this mount is 25+ years old, I was not even sure if a polar scope could be bought for it. Also,...
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Right-Angle Finder Adapter for Takahashi Polar Scope
This is a Yashica/Contax right angle viewfinder, which can be obtained from ebay for under $20:I decided to 3D-print an adapter allowing this finder to be attached to a Takahashi polar scope, so when...
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Synta/GSO Finder Bracket for Astro-Physics AP130GTX
If you've ever had a hankering to attach a cheap and cheerful Synta or GSO finder scope (or red dot finder) to your spendy Astro-Physics AP130GTX triplet refractor, then this 3D printed design is for...
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3D Printer Use Case: Repairing a Dented Lens Filter Ring
I dropped this ancient Schneider-Kreuznach Retina lens on the floor, dinging the filter ring:To repair it, I 3D-printed two plastic pieces (in HIPS with 100% infill) one matching the inner diameter of...
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Lightweight Triplet Super-Apochromat Refractor
The Russian Lomo 80mm f/6 and f/7.5 OK4 triplet apochromats are considered by many to be among the finest 80mm refractors in the world. However, they are also known for being built like tanks. My APM...
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Viltrox EF-FX1 AF Adapter Brief Impressions
OverviewI have been using a Mitakon Zhongyi Lens Turbo II (Canon EF to Fuji X-mount) for almost a year and I'm pretty happy with it: you get "full frame" cropping, and the optical quality is...
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William-Optics New Adjustable Flattener P-FLAT6AII
William Optics has a new adjustable flattener with (they claim) 97% of full-frame (43mm image circle) coverage for a wide range of refractors from around 480mm focal length, up to 970mm. This is almost...
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Refractor Flattener/Reducer Comparison on Lomo 80mm f/6 Super-Apo Triplet
Some Hong Kong amateur astronomers have done their own testing of various flatteners with the Lomo 80mm f/6 Super-Apo. Their results can be summarized as such. Note that the Televue TRF2008 performs...
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William-Optics New Adjustable Flattener P-FLAT6AII on AP130GTX
I've attempted to create a general formula for spacing of the William-Optics New Adjustable Flattener P-FLAT6AII here. I've also done some rudimentary testing of this flattener on a Lomo 80mm f/6...
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Quick Test: Canon 300mm f/4 L (non-IS) for astrophotography
The Canon 300mm f/4 L (non-IS) from the 1990's is one of Canon's discontinued, older and slower telephoto lenses. It does have UD glass. Because I already had the artificial star set up, I decided to...
View ArticleViltrox EF-NEX IV AF Adapter on Sony A7 II Brief Impressions
I have written about the Viltrox EF-FX1 before.TL; DR - the EF-NEX IV performs pretty much the same way as the EF-FX1, is marginally better in some cases, and worse in other cases.AF performance is by...
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3D-Printed Finder Guider
This is a 3D-printed finder guider that I built from a 60mm achromatic objective in a metal cell from Sheldon Faworski, a length of 2" cardboard mailing tube, and some parts 3D-printed from ABS.The...
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50mm on Full Frame Test
This is a contrived test of center and corner sharpness of various 50mm lenses, SLR and rangefinder. I decided to compare the performance of my 1938 Leitz Summar before selling it. The test was fairly...
View ArticleProLink PIC3002WN Review
This is a discontinued IP camera from ProLink (https://prolink2u.com/product/pic-3002wn/). There is another review here but otherwise not much additional information.I bought four of these for home...
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3D-Printed Adapter for ZWO ASI120 to Lacerta OAG and Canon 650D
Lacerta makes a very low-profile off-axis guider with an M48 thread on one side, and a Canon EF bayonet on the other side. It is reasonably well-made, but the (used) one that I bought had some pretty...
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Getting Oracle Linux on Amazon EC2
Edit 08-Nov-2017:As per Oracle's instructions - https://linux.oracle.com/switch/centos/ adding the GPG key is no longer needed, the bad news is - the procedure documented by Oracle throws a "Broken...
View ArticleAWS Z1D, M5A (AMD EPYC) Performance Comparison
This is the time-honoured Linux kernel benchmark.In order to prepare a stock Amazon Linux 2 installation to compile the kernel, the following packages need to be installed:p.p1 {margin: 0.0px 0.0px...
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Intel and AMD Processor Micro-Benchmarking
There are a large number of synthetic CPU benchmarks available - for example, GeekBench, JetStream, SPEC. The utility of these benchmarks for whole-system performance is debatable. Then we have...
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Installing AWS CLI on Solaris 10
A (former) colleague needed to transfer an Oracle Data Pump file to Amazon S3 (in order to allow Amazon RDS Oracle to import said Data Pump file), but the origination server was running Oracle Solaris...
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