#41  
Old 14-04-2008, 11:58 PM
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Vavles will produce a purer sound that transistors. If only our cameras were built like that.. A bit heavy, but still.
Miss those old radios.

Heres a little snippet about valve..
"Engineering techniques invariably involve making compromises, eg. presence of HUM against overall ease of manufacturing, so that at home one can take extra steps to maximize hum rejection in otherwise well-built amplifiers. By observing every possible "injection" mechanism and making efforts to minimize each one can the overall hum index of a tube amp be brought down to nil. What follows is a synopsis of the work I do to tube amps to eliminate the hum without resorting to costly DC filament supply blocks."

Full readings about these baby's here : http://www.lynx.bc.ca/~jc/hum.html
I think most hum comes from our own hears after a concert !.

Theo.

Last edited by Gama; 15-04-2008 at 12:09 AM.
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  #42  
Old 15-04-2008, 12:09 AM
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hehe, a valve CCD cam, id be into that, results sort of like film you think?
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  #43  
Old 15-04-2008, 12:11 AM
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Tell ya what, dont mismatch those cables.. Kaboom

theo
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  #44  
Old 15-04-2008, 12:11 AM
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hehe, a valve CCD cam, id be into that
So do we cool them or wait for them to heat up first?

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  #45  
Old 15-04-2008, 12:15 AM
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I work with Hi power Valves, and i mean HI POWER.
20Kw, 30 Kw, and 50Kw valves for the Broadcasting Stations.
They arent that big, and actually are prefered to Solid state. But they do have limited life, but they are smaller in total size.


A Valve cam, yeah, and you dont need to buy a power supply.
Just plug it straight in the wall socket !.
Gees, even park under high voltage power lines and toss over 2 cables.. Free power..

Theo
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  #46  
Old 15-04-2008, 12:18 AM
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well, hum can be eliminated from any amp (valve or SS) with DC only supplies and sufficient shielding. The only hum scource then is from external (pickups etc). Pro studio audio uses low impeadance balanced inputs (unlike domestic) so hum is minimised by default.
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  #47  
Old 15-04-2008, 12:20 AM
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sigh, a 50kw valve bass amp, Ill sleep on that one, sweet
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  #48  
Old 15-04-2008, 12:55 AM
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My thoughts

I'm very happy with the Q8. It's true for most instances you don't have to worry about darks. Flats are important, and if your picky then do what I do. Have a master dark and a defect map.
Peter, if they put a Q8 on the hubble next service mission I'll promise to calibrate the raws as best I can.
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  #49  
Old 15-04-2008, 01:04 AM
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Quote:
Originally Posted by Peter Ward View Post
O.K watched this thread with interest. Can anyone explain how a HAD sensor and differentiate a thermally liberated electron from one freed by a photon?

My understanding on this is: you can't.

A high QE sensor is rather like a high power amplifier. Crank it up and you'll hear a "hum". HAD sensors bleed charge all the time...O.K. low noise...but the signal is being bled as well.... in short they never really hum as the gain is being suppressed.

Yes, it does take some work to separate the signal from dark current in various sensors, but the results are worth it.
Im not sure what your trying to fault/compare, but hey lets add that NONE of the everyday Sony or Kodak sensors use Back illuminated technology. KAF sensors lose heaps of signal as do the Super Hads.

Every camera has its place and use, the KAF series have a place, the EV2 and the Sony sensors etc all have their place.

Theo.
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  #50  
Old 15-04-2008, 01:13 PM
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a list! But, my real question is what more will we have to spend on top of a QHY8 before we start imaging?
Do we need to purchase third party camera control and image capture software such as CCDSoft (USD349), AstroArt (USD185), MaximDL (USD399) or is there a simple and free image capture utility available? Perhaps I'm missing something obvious but I want to ask on this forum for the benefit of all. Bearing in mind that the 40d comes with great control/capture utilities included in the package.
Doesn't the latest version of Nebulosity support the QHY8 if you don't like the supplied software ?
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  #51  
Old 15-04-2008, 01:23 PM
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Doesn't the latest version of Nebulosity support the QHY8 if you don't like the supplied software ?
Yes it does, well on Windoze anyway. BUT it costs $45. Still cheaper than the listed alternatives.
Gary
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  #52  
Old 16-04-2008, 11:51 PM
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Info from the US

Hi all. I just wanted to chime in a little from a different perspective. I just bought a Q453-HR which is a US modified version of the QHY8. I too was a looking to step up my astro imaging and started looking for a new camera. I came across the QHY8 which led me to CCD-Labs (the US distributor/modifier)(www.CCD-Labs.com). At first I looked at the chip size and the price and thought this was one of the "too good to be true" cases. Most of the camera's I looked at were at least 3x more expensive. Even a camera that uses the exact same ccd chip. In my opinion the astrocamera market is over priced and the gravy train will be ending soon. The prices of the ccd/cmos chips keep fall and it is a matter of time before someone puts together a camera that is much cheaper than the competition. I think we are seeing the first of such offerings.

I contacted about 15 people that used the camera around the world and asked them about performance and the darks thing. Some of these people produce absolutely incredible images. All of them LOVED the camera. Most (if not all) had stopped taking darks or went the master dark and defect map route. My personal opinion is that the dark thing is a big deal considering that you should take at least five dark frames at each exposure length the get a good average noise. If you take a five minute exposure thats 25 minutes on darks alone. For those of us with limited time that is a big amount of time. Heaven forbid you take a 20 minute shot!

The Q453-HR version is modified slightly from the original. They seal the CCD in an argon purged cell to keep moisture out. They also sell the camera with the upgraded cooling power supply that lets you control the current to the camera. They do this not because of cooling control (it is not close loop controlled) but to be able to step back on the power consumption. They also include Nebulosity in the deal. The down side is delivery time is 3 to 4 weeks.

I started a Yahoo group http://tech.groups.yahoo.com/group/QHYCCD/join Feel free to join the group and share. We are small right now but we will get bigger!

Ed
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  #53  
Old 17-04-2008, 06:41 AM
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Excellent information, Ed! Thanks and to IceInSpace.
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  #54  
Old 17-04-2008, 07:48 AM
Alchemy (Clive)
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Originally Posted by StardaddyEd View Post
. In my opinion the astrocamera market is over priced and the gravy train will be ending soon. Ed
and about time. competition will make them all rethink their strategy, if this qhy8 takes off with the Ice In Space crowd like i think it will, it will corner the intermediate market for a little while- there will still be a part of the market that will pay premium for cutting edge technology.
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  #55  
Old 17-04-2008, 08:38 AM
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and about time. competition will make them all rethink their strategy, if this qhy8 takes off with the Ice In Space crowd like i think it will, it will corner the intermediate market for a little while- there will still be a part of the market that will pay premium for cutting edge technology.
I am still very happy with my second hand SBIG2000 XCM for 2100 AUD landed.

includes
Pelican case, 200 AUD value
The Sky, 200 AUD value
CCDSoft, 300 AUD value
EOS adaptor, 50 AUD value

Built in self guiding, saves having to buy a guide camera and guide scope, 500 AUD value and no flexure.



Paul
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  #56  
Old 17-04-2008, 08:51 AM
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What's the resolution of the XCM?
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  #57  
Old 17-04-2008, 03:39 PM
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I think the XCM is lower resolution but it makes up for it with bigger pixels. At 2100 landed thats a real bargain.
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  #58  
Old 17-04-2008, 04:03 PM
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I think the XCM is lower resolution but it makes up for it with bigger pixels. At 2100 landed thats a real bargain.
Almost 2MP..
From Optcorp:
  • CCD: Kodak KAI-2020CM + TI TC-237H
  • Pixel Array: 1600 x 1200 pixels, 11.8 x 8.9 mm
  • Total Pixels: 1.92 million
  • Pixel Size: 7.4 x 7.4 microns
  • Full Well Capacity (Unbinned): ~45,000 e-
  • Full Well Capacity (Binned): ~90,000 e-
  • Dark Current: 0.1e-/pixel/sec at 0 C
  • Antiblooming: Standard
AUD2100, even 2nd hand, is still a bargain.
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  #59  
Old 17-04-2008, 06:40 PM
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im looking at getting a QHY8 soon too and was wondering how a baader mpcc would go with it?
im guessing id need a spacer to keep the proper distance from the chip
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  #60  
Old 18-04-2008, 01:08 AM
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Originally Posted by monoxide View Post
im looking at getting a QHY8 soon too and was wondering how a baader mpcc would go with it?
im guessing id need a spacer to keep the proper distance from the chip

The MPCC is fine, i use a spacer and the MPCC with the QHY-8, 20D, and the Nikon D200 on my 22" f4.5 and it does an excellent job to "Round up them there stars partners !".

Theo.
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