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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...
View ArticleAWS M5A (AMD EPYC) Performance Comparison
This is the time-honoured Linux kernel benchmark.Preparation was simply unzipping the 4.20-rc3 tarball from kernel.org, running "make menuconfig" and immediately saving the config (no changes) and then...
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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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Intel and AMD Processor Micro-Benchmarking
2018009There are a large number of synthetic CPU benchmarks available out there - for example, GeekBench, JetStream, SPEC. The utility of these benchmarks for whole-system performance is debatable....
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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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Canon 28-105mm f/3.5-4.5 USM II
TL; DR - use it at f/8 and it has (almost) L-class sharpness.Back in 2001 or 2002 this was one of the lenses I wanted. It was too steep for me and I ended up with a Sigma 28-105mm f/2.8-4 (the...
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Takahashi Mewlon 210 Maintenance
I've been looking for a Takahashi Mewlon 210 Dall-Kirkham Cassegrain since about 2010, but the new prices are pretty high and I didn't want to pay list price. I was able to find a used one (I am...
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Takahashi Mewlon 210 Vignetting on Full Frame
The Takahashi Mewlon 210Dall-Kirkham Cassegrain only has an 18mm image circle at prime focus, and 39mm with the dedicated reducer.Here are some images of daytime scenes taken with a Canon 6D full-frame...
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