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  #1  
Old 18-04-2018, 02:36 PM
JA
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GIANT Monochrome Sensor - 75 Ám Pixels, 9inch x 11inch, 12 MegaPixels

For your interest, just what you can't use, unless you have your own national observatory ????

A GIANT Monochrome sensor (camera actually, but you could hack it or maybe it's available as a digital back) , by LARGESENSE. It has 75Ám sized pixels, is 12 megapixels and 9 inches x 11 inches. Forget the view camera attached up front and hack it. Easy to do as it's only US$106K . And you can all handle that sort of size image circle right?

Here are some details.....
http://largesense.com/products/8x10-...al-back-ls911/

also....
https://www.dpreview.com/news/984647...ra-for-106-000


There is also a much smaller 4x5 in the works.

Best
JA

Last edited by JA; 18-04-2018 at 03:02 PM.
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  #2  
Old 18-04-2018, 02:41 PM
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Only $100k. Do they throw in the filters?
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  #3  
Old 18-04-2018, 02:57 PM
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Gonna need a very looong focal length to avoid single pixel stars
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  #4  
Old 19-04-2018, 10:21 AM
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Hmmm !
Out of curiosity I wonder what the real CCD specs are - Well depth, Dark noise, Read noise ?
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  #5  
Old 19-04-2018, 11:48 AM
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Only $100k. Do they throw in the filters?

Look, let's be serious, if filters are not included, I'm not buying...
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  #6  
Old 19-04-2018, 12:08 PM
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Surely you could use 1.25" filters....
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  #7  
Old 19-04-2018, 02:00 PM
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Actually not bad value! But the precise parts quotation would be a killer
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  #8  
Old 19-04-2018, 03:09 PM
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precise parts quotation would be a killer
When isn't it...
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  #9  
Old 19-04-2018, 06:49 PM
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Gonna need a very looong focal length to avoid single pixel stars
One could always drizzle the data...

Another use would be to put this sensor in an autoguider and a short FL finder scope - a perfectly flat guiding graph every night even with a $500 mount!
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  #10  
Old 19-04-2018, 07:39 PM
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I got the following information from the developer for interest.

Oh, and you get an IR filter !

==============

Thanks for asking.
Someone asked about astro use before. You need a 380 mm image circle for the LS911. I really assume the LS911 won't be too good for astro as the noise increases quickly over time till about 10 seconds max.

Your 100 mm image circle telescope will only partially cover the LS45, so you can calculate the pixels you will have with 50 micron pixels. The lens I'd think about using for stars would be the Kodak Aero Extar 7 inch f/2.5 as it is sharp and bright and should cover the sensor. That leaves you with just a standard lens. There are some longer aero lenses though.

The LS45 sensor is a newer generation sensor and that I assume would be better for astro than the LS911, but I would expect it would be bad a exposures more than a few seconds. I don't have all of the details yet. The FWC is around 1.6 Me- (or up to 2 Me-) with noise around 300 electrons, which gives about 12 stops of DR. But when gain is applied, the FWC and noise are reduced. Once I get the sensor I'll play around with gain and see how it works out. I am assuming the base ISO is over 2,000. It could be possible to have clean ISO 16,000 with low DR, I'll have to see.

The sensor is 16 bit but once you start applying gain your effect bit rate goes down.

You can publish it as tentative info. I actually don't have the full info yet but I have an engineering sample on order. Production won't happen till the end of the year.

The LS45 will have a swappable IR blocking filter.

I'm open to adding extra cooling for a special LS45, it could be the LS45a. I'm planning 5mm of aluminum heat sink behind the sensor, but that could be thicker and other stuff added. I was looking into some cooling options such as a Peltier cooler, though those take a lot of power.

============
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  #11  
Old 19-04-2018, 10:14 PM
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9" x 11" ... heck you may as well load a sheet of Ilford Multigrade IV paper directly. Bung it through a desktop scanner afterwards to obtain a digital version at rather higher DPI.

$100k buys an awful lot of paper.
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  #12  
Old 23-04-2018, 09:21 AM
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One piece of interesting information I was provided by the developer is : "the LS45 sensor has a non destructive readout function . . . . So you can read the sensor data as fast as 1/30s while it still builds up signal."

I wonder how you could integrate this novel ability (compared to our standard sensors) with a process that can do automatic calibration during the image acquisition process
It also means that you no longer need to take a whole series of different length subs to get your HDR, you just read out at whatever intervals you want during each long exposure.
It might also mean that you could identify (temporally) when a cosmic ray or satellite trail went through and potentially eliminate that part of the subexposure by simple addition and subtraction of the series of readouts !
It might be a stretch, but if some bad seeing/poor tracking went through you might also be able to subtract that out too !

We're so used to a particular paradigm in our image processing due to inherent design issues that you dont even think about the alternatives.

What do you think Ray ?
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  #13  
Old 15-05-2018, 10:02 PM
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Was informed today
FWC is 1Me-
Wow !
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  #14  
Old 15-05-2018, 10:26 PM
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This really deserves a MOTS (Minitrack Optical Tracking System) Camera in front of it - 8" F/5 with monochromatic filters and designed to cover an 8x10" plate.

These were made by Perkin Elmer in the 50's.

There was one in amateur hands in Canberra in the 1980's... picture of one at Honeysuckle Creek at the bottom of this page https://www.honeysucklecreek.net/oth...ck_photos.html

... it's probably the same scope I knew of. Not particularly sharp from a visual perspective, and 12MP x 75 micron pixels is probably overkill.

But... to be honest a modern full-frame sensor with a modern 200mm f/2.8 lens would beat what the MOTS could do, very easily.

A Riccardi-Honders, even a Celstron Fastar setup with similar field would do a LOT better.

Last edited by Wavytone; 16-05-2018 at 08:59 AM.
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  #15  
Old 16-05-2018, 02:10 PM
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So all we need now is a scope with 15m focal length to get 1" per pixel. However you'd probably want to use it in Chile somewhere where the seeing is good, 0.5". Let's go for a 30m focal length at, say, f/4. Only 7.5m aperture--about 300"
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  #16  
Old 16-05-2018, 05:58 PM
rally
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Geoff,

Yere image scale is tough !
And image circle is a bit of a problem for a mere amateur, but I can't help thinking that 1,000,000 e- well depth might be useful - I assume the read noise and dark noise are probably pretty standard for a typical CMOS designed chip. Thats a huge dynamic range

Ignoring the cost - you dont have to use all the photosites/pixels !!

Rally
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