Hello!! It's Joseph

 From SAO in russia, IFP is used for study of seyfert galaxies data are in 3 dimensions or more:

 located in resolute bay and in boulder, managed by NCAR Canada   on top of roof  

 ebay   ranges from basic $95 to $8xx or more  construction guidelines on upenn seems from the same Sam ( Sam Goldwasser) repairfaq   for sky-scanning    cloudynights   Instructables , around 500 GBP

 by Kathy Geise application:  solar chromosphere imaging ERF: Schott RG610 or RG630 red dyed glass cloudynight RIT u phys 230 class .   Indiamart SLSoptics

  VTT (Finland) claim this is Integrated circuit chip size,, mass-manufacturable, light weight, low cost application: miniaturized hand-held hyperspectral imager for VNIR range of λ = 600 – 900 nm 

T mount: Tamron introduced the T mount back in the late 1950’s as a potential “Universal” lens mount. The T mount is a threaded screw mount, has a 42mm diameter 0.75mm pitch (M42x0.75).  Similar to the Pentax M42 screw mount, but with finer pitched threads. The Pentax screw mount is a 42mm diameter screw with a 1mm pitch (M42x1), T-2 mount: which is simply the name that Soligor used for its version of the T-adapter.  A T-adapter consists of an inner ring with T-mount thread and an external ring with corresponding lens mount. The T-ring and the T-2 ring are identical to each other. Both of them have the inner and outer ring. The two rings (inner and outer) are held together by 3 peripheral screws on the external ring. Loosening these screws allows rotation between the lens and the camera body. This is especially useful when the camera body is attached to telescopes or microscopes. Registration (flange distance) on a T-2 mount is 55mm, to allow room for the adapter, and still match up wi

  Simple answer: There was a war.   After the WWII, many patents owned by German companies were taken by the allies as war reparations. In an interesting turn, the US decided to play God again and gave significant funding and technology to Japanese companies (even though they were the ones who originally attacked the US). That's why a Nikon I had a Leica shutter but a basically Carl Zeiss lens mount and body shape. The biggest companies in Germany managed to bounce back slightly but almost all collapsed before by the 1970s, while the smaller ones were wiped off the face of the Earth (usually by Bomber Command or the 8th Air Force). Many firms had their plants (some their entire operations) in cities like Dresden or Leipzig, which pretty much ceased to exist as something other than a burning cinder (again, thank the Mighty 8th). Add to that the country being split in half by bickering Allies and the combined loss of, oh, 10 percent of every man, woman and child in the country, and y

      Scientist, film director, teacher, initiator of the creation of the Planetarium children's and youth center in Novosibirsk. Born July 23, 1937. In the 1970s, he directed and filmed at the NovosibirskTelefilm film studio a series of television programs called Physics for Kids. Head of the children's television studio "Staraya Mill", professor at NSTU. He raised the issue of creating an observatory in Novosibirsk back in 1969 at the House of Entertaining Science (which was never built), then at the House of Pioneers. As a result, he himself built an amateur observatory in a village in the Bolotninsky district, where he worked with children from the "Club of Astronomy and Telescope Construction". In 2006, he again raised the issue of creating an observatory in a letter to the mayor of Novosibirsk, Vladimir Gorodetsky. The idea was accepted. The building concept and project was developed by Leonid Sikoruk and architect Igor Popovsky. After Leonid Sikoruk a

 from NPZOptics .  exotic design, but actually quite practical.  aperture: 250mm  focal length: 1500mm   Ritchie-Chretien telescope, built by AB Balluesam, 1500mm  focal length light is reflected to eyepiece via nasmyth focus (eyepiece is aligned to declination axis) according to the scheme of the Novosibirsk designer Yu.A. Klevtsov. Since 2002, there have appeared: TAL-200K, TAL-150K and the most powerful TAL-250K to date. Another new direction - the production of apochromatic refractors with improved image quality, started in 2009 with the TAL-125-5 APO telescope. Thus, the production line of TAL telescopes covers all major areas of telescopic construction and offers quality tools for beginners,and for the trained amateurs of astronomy. but how does it compare with truss tube construction?

 760mm dobsonian also from Mr. Sloboda, deltagraph 465mm f/3.2 ( zimmerald widefield ?)   with ASA 0.95x wynn corrector   reference books: written by  Leonid Sikoruk and Navashin Mikhail Sergeevich М.С.Навашин , “Телескоп Астронома Любителя,” Астрономическая Библиотека amateur telescope makers in Russia astronet  astroclub ua

 in mirror lens rework from CN fungus or delamination

From skyandtelescope.     German equatorial mount, with autoguiding, all-in-one Meade guiding starlock enables 1 arcsec guiding accuracy All in one.  Usd7250 for mount only

 there is discussion from Cloudynights For lunar/planet viewing, I would choose the C11. In most locations, the usual mediocre or poor seeing compromises scopes above 6-inches or so. Combine the seeing with objects that are not always positioned perfectly high in the sky and both of these scopes will be affected. The Mak might produce a very slightly sharper image compared to the C11. The C11 will produce a brighter image and will have more resolving power when the conditions are good. The C11 will be better for deep-sky viewing and imaging. There is a comparison here on CN between a high-end, 9-inch Mak and a C11. The C11 came close in most observations so it should deliver better performance against a commercially produced 7-inch Mak. (meaning C8 is inferior to a Mak7?)  Things to consider for best performance: Collimation, Thermal Management, Dew/light shield (some of the best nights are moisture heavy), A good aftermarket focuser, a good aftermarket high-end diagonal, good eyepiece

 The grinder, dis-assembled the coarse setting dial, 100um per click. total 30 clicks per revolution.   The micro setting dial itself, on 0.5mm thread. stepless. 5 micron per subdivision. The bottom side of coarse dial: youtube   From left to right: LIDO 3, Lide OG, Fixie The coarse dial is on 3mm thread, , the micro dial is on 0.5mm thread The coarse dial is 30 clicks per rev, ie 100 um per click micro dial is stepless,  5 um per sub division mark it's1.038kg in weight it's 27 cm tall, the hopper is same as LIDO 3, 70g The quick tasting by hand drip is overall blanced and smooth, rich in body, and no bitterness due to fine grounds. setting is 1400, 1: 15 ground to water ratio.   personally, I prefer the taste profile of this Lido OG grinder to 1Zpresso JX or K pro ( the latter has weaker body, and slightly more harshness from fine grinds) price: USD 285  easier to dial in than 1Zpresso JE Plus Lido OG will be more uniform grind than Timemore chestnut X, and in fierce compet

 another way I use to design, is by considerin surface load first. I take for heater fan application, the surface load is 15 to 20. i choose 19 for trial. next i consider using 0Cr22Al6 wires. from datasheet, cm2 per ohm , top right hand corner.  Then Calculate a table of various wire diameter, the length, power and applied voltage. As in this case, the applied voltage is 220V ac, you  can see, how the diameter of wire is affecting the length and power. As I want to achieve 1200W to 1800W, with length of ~5 m or less, the most suitable wire us 0.45 (less common) to 0.6mm

  The optical design is based on gregory-maksutov or spot maksutov telescope, and often called as CAT ( catadioptric) lens which is a combination of mirrors and refractive lens most of these lens are manual focus. The aperture is fixed. It is virtually free ( marketing bluff beware) of chromatic aberration, coma, and off-axis aberrations. However, due to central obstruction of secondary mirror, contrast is normally lower. However, lateral color aberration ( different image size for different colors) still exist, except on the Zeiss mirotar, which use dual corrector plates The overall image quality depends mainly on the secondary mirror aberrations. So in lower priced models, if the secondary mirror is a separate element, it has more room for improvement. Exposure: The secondary mirror blocks about 1/3 of the area of the lens aperture. This in itself would result in the loss of about 2/3 stop in effective lens speed (i.e. a T-stop that was 2/3 stop slower than the f-stop). The actual T

  manual jigs: leevalley   aliexpress and here and here       craftmanspace   ideas and tips instructable

excellent data table from Kanthal handbook Kanthal A ( 0Cr25Al5 or equivalent) from TB:   Nichrome wire Ni80Cr20 ( Nikrothal 80) in metric. list of other common alloy spec from TB:  from alloywire , there is a very handy spreadsheet 1. first of all, determine the type of heater wire to use ( Nichrome or 0Cr25Al5) 2. from datasheet, determine resistivity online resistivity convertor 3. from your design, determine resultant power to achieve and applied voltage  the spreadsheet will recommend the surface load ( depending on your application)