Astrams in love w/ CCDs' Big Pixels do fear BSI CMOS full of tiny pixels ! ;) Clic Image, Ctrl+ to Enlarge
Despite tiny sensor 1/3 of area of APSc, the 1" BSI has equal SNR, better CS, Better DR than Kings of Astro Golden-New-Age : Canon Eos 30d, Nikon D80. Last Big Pixels 12bit APSc, first w/ all Dxo Measurements 100% acceptables from ISO 100 to 3200. Eos 30d w/ 20d(A)'s CMos, the D80 got D200's CCD. The Pentax K200d, then the KM also had D200's CCD in early and late 2008.
Huge Progress from 2006 Big Pixels FSI CCD to 2013 tiny pixels BSI CMos (Sony Rx100 II) Clic Image, Ctrl+ to Enlarge
As usual Canon is the Conversion Noise champion, even w/ the 1" Exmor R.
I tried to show what would be the Full Well Capa. of the olders if they had the
performance of the 1" BSI CMos. The area of each Eos 30d's pixel is 7.11x
Larger than the NX-mini's one ! Note the Huge Gaps in Quantum Efficiency
levels from FSI to BSI tech, moving Wiring, Addressing under Photo Diodes.
+ 4 min. Exposure at F/5 => NoiseLess ISO 400 ! + a Top Resolution of 20.50 Mega-Pixel ! + a Peak Quantum Efficiency of 84% + a Price of $100 €, or even less + IRcut filter Easy Removal . More Advantages to the Samsung NX-mini over other 1" BSI cameras – the NX-mini is the unique 1" BSI cam. to support Interchangeable Lenses. – MA4NXM optional Adapter opens the NXmini to the whole NX Lens system. – NX-mini has Huge 2330 mAh Battery, lasts a whole night in worse conditions (As nights become warmer, could be very easy to cool this camera from inside) – Bulb Mode holds 240(256)sec. Long Exposure, the Top for AstroPhotography. – So, one can lower the ISO setting down to a NoiseLess ISO 400 at F/5 – the NX-mini is a Costless camera : I bought mine for €183 in spring 2015. – the IR-Cut Filter inside the Samsung NX-mini is very Easy to Remove : TheSamsungNXminiIsTopIR.html
– IR-Cut removed, the Auto-Focus is still Reliable with 9 + 9-27 mm lenses, the NX-mini could be the Best for Landscape-IR : nor High-ISO, neither Tripod, get ten times, 10x the Light, for twice, 2x the Price of 1 R72 IR-Filter : Search.for/?q=landscape-IR-photography&tbm=isch . Clic Image, Ctrl+ to Enlarge
I superimposed the curves of Relative QE from 3 Zwo BSI mono Astro-Cams : the Asi178mm is very sensitive toward the Blue, the Asi290mm which sensor is advertised as Near-IR by Sony, and the Asi183mm which seems the very best compromise between the 2 others ! At 656 nm, their Relative QE is : ~60% for the 178, ~80% for the 183 and ~93% for the 290 ! If I could achieve the same "easily readable graph" for their Color Version with a Bayer Filter, I'll do it. But, there is no reason things will change dramatically. What we can see here is their Silicon response to different wavelengths and the effect of deeper photodiodes : the deeper, the more IR sensitive. Asi183mC & Samsung NX-mini could reach an Absolute Peak QE of ~84% in both Green channels, an excellent sensitivity !
Asi533MC vs Asi183MM-Cool vs Samsung NX-mini : Altair, Qhy, Zwo - Clic Image, Ctrl+ to Enlarge
The Drawbacks of the Samsung NX-mini with its 1" imx183 BSI sensor – ISO 1600 shows Amp-Glow localised in the Bottom Corners of the frame, but the 240 sec. Bulb Exposure was enough. I just once had to set to ISO 800 : wind and Turbulence were so strong that Guiding over 30 sec was very difficult ! U do need ISO1600, it's not so bad to reduce the format ratio from 1.5 to 1.4 or even to 1.33. That means from 8.8 x 13.2 to x 12.44, even to x 11.74 mm wide. . DSS-336, Levels upped to Highlight the ISO 800 Amp-Glow at bottom corners Clic Image, Ctrl+ to Enlarge
I Never subtracted nor Bias-Maps (Offsets) neither Dark-Frames from my subs. Even during last Summer 2019, where nights Temperatures climbed over 25°C But you do need a Set of 3-4 ISO-100 Flat-Fields from your well-lit clear ceiling
Add a M48 x0.75 Mount Thread to your NX-mini
How to Add a M48 x 0.75 Mount Thread on your Samsung NX-mini Please, don't begin doing it if you don't feel able to achieve it... It's Your Own Full Responsibility to do it... Or not to... You have to find a M48 x0.75 T2 Mount Adapter of any brand, with the thicker 8mm M48 threaded Inner-Ring + a M48 to M42 Adapter – 0) remove Battery & Lens + Protect the Sensor from Glue, Scratches – 1) unscrew the 3 screws that hold the Inner-Ring in the T2 Adapter... – 2) remove this Inner-Ring : « 48mm conon » off the T2 Adapter... – 3) Remove the Latch, Button, Spring off the Samsung NXm Mount... ( 3+4 need to remove the Front Panel : SamsungNXminiTopIR.html ) – 4) Cut the Aestetic-Ring off the Front Panel at diameter of Inner-Ring – 5) Verify the Inner-Ring slips around the NXm Mount of the NX mini... /!\ Crucial : the Inner-Ring to be firmly glued around the NXm Mount /!\ – 6) Screw the M48 to M42 Adapter in the Inner-Ring from its marked ... side, letting 4mm free M48 Female Thread at the Non marked side... – 7) Cut a 48mm Paper diameter, put it at bottom of the 4mm free M48... – 8) Prepare some Araldite glue, apply it on the 4mm free M48 Female : ... the Paper at bottom prevents the M48 to M42 Adapter to be glued too – 9) Slip the 4mm free M48 Female Thread around the NXm Mount... ... keep parts quiet ~24 hours at ~22°C... unscrew M48 to M42 Adapter put the Front Panel w/ enlarged hole back : SamsyNXminiTopIR.html
/!\ No Glue, No Scratch on Sensor /!\
Any brand M48 x0.75 T2 Mount Adapter w/ its 48mm conon Inner-Ring : this Inner-Ring must be at least 8mm thick Clic Image, Ctrl+ to Enlarge . If your Reflector, Refractor is an Up to Date instrument with a M48 thread... ... go to Adjusting the Focusing Distance... at the bottom of page . If your Reflector, Refractor is a Classic instrument with a M42 thread... ... you'll have to screw in the M48 to M42 Adapter M48 male to M42 female Adapter : Clic Image, Ctrl+ to Enlarge
Adjusting the Focusing Distance with Extensions : – 1) The distance from the Sensor to the NXm Mount is ~ 7.5 mm ~ – 2) Backfocus Distance of your instrument minus 7.5 = ~ the length to add... – 3) With the Moon / a Bright Star, verify the Right Focusing on the Sensor... Backfocus Distance of a T2 instrument or lens = 55mm
