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Les Tilly

CCD Camera

19 posts in this topic

Looking to upgrade from the DSLR to CCD any thought on a camera was looking at Starlight Express 25MC also Sbig 4000XCM but not sure if I should go for a mono camera

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Hi Les,

You'll find it less of a jump going to an M25C, however, I am very much biased towards mono myself.

I switched from DSLR to SXV-H9 mono, and am enjoying myself immensely with it. If I could afford it, I would upgrade to an SXVF-H36 :)

Reasoning-wise - because its more sensitive, supports narrowband filters, and gives alot more options.

The downside is the additional cost of filters, filter-wheel, etc.

Cheers,

Richie

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Would that be the same DSLR that produced one of the best HHN widefields I have seen....

Tut tut...

Peter,,,,

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I am in the same boat at the moment, and have been thinking about this for months.

Its gonna be a mono for me. Something with a 285 chip, partly due to cost, but mainly due to sensitivity. The larger mono chips are not as sensitive (well in that type of price range).

Being in a LP area, I will be mainly going for narrowband, and want as much sensitivity as possible. Plus I like to spend hours and hours on a target, so using filters wont be a problem, as I am not after quick results!

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How about the Apogee 8300 anyone heard about this camera ?

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Gota agree with Pete on this one. I think you have been getting some absolutely stunning results with your DSLR, which surpass many CCD images I have seen. It's going to have to be one heck of a CCD to get an improvement on your HH image. :)

Regards

Kevin

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I know the HA in the HH image made it what it is and now the summer is coming with temps reaching at times 100F the cooling of a ccd will help big time I need to move forward too the next level I am very happy with what I have done with the DSLR I just need to have ago with a CCD I will go to my local observatory tonight and see if I can use there Sbig 8 before I move into CCD land :)

Thanks Les

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as richie says, the mono will be more sensitive than a colour chip of the same kind.

in terms of type of sensors, kodak interline sensors have a lower QE. The reason being half the pixel is covered by the vertical shift register. They also have anti blooming. The sensors have the designation KAI, such as KAI4021, a 4MP sensor found in a variety of manufacturers.

I have analyzed this CCD in detail in the SXVf H16.

This chip can be found in other formats such as ATIK. I measured the peak QE of this chip at 56% at 460nm. Ha was about 0.3

The more sensitive chips are the Kodak Full frame, KAF series. These sensors do not have antiblooming and have 100%fill factor. The QE of these FI sensors is quite good. Unfortunately they bloom. And all show RBI (residual bulk image). But their sensitivity is impressive, especially the KAF3200ME which has a 85% peak. Which is astonoshing for a front side sensor. Believe it or not an non AR coated back thinned sensor will have a lower QE than this. These sensors also have a higher well depth than their interline cousins, and are generally parametrically better, especially with regards to linearity.

The sony chips have lower dark current, higher QE than an interline sensor, but poor well depth and dynamic range. Also the larger sony chips are OSC, so that hits the QE and limits the Narrowband use (not impossible though).

So if Kodak interline.....lower QE, lower full Well, antiblooming, cheaper

if Kodak Full Frame...higher QE, higher well depth, better linearity, but RBI no antiblooming and dearer

if sony.....good QE, lower dark current, lower well depth, smaller size sensors if mono

i like the look of the KAF 3200ME, not huge, but not bad, excellent QE. or if you feel a bit rich, then the KAF6303E, again a very common sensor, with great QE too.

thats most of the obvious options.

That may just confuse things though.

Any questions, fire away

Paul

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I have a question lets say I grab the Starlight express M25C could I get better results with this camera than my DSLR ?

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yes, for a start the M25 is cooled, secondly it is a sony sensor so it is quite sensitive, but not as much compared to a mono version, which i dont think exists.

however the sonys feature low well depth and dynamic range

but yes, I would stongly believe you would get better results than with an SLR.

i believe steppenwolf has one, so he can give you the practical results.

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Agree with Paul.

The reason the M25 is less sensitive (in fact, all OSC cameras are less sensitive) is that there is no such thing as a colour camera. The way you get colour out of an OSC camera is micro-filters in front of each pixel. Read this wikipedia article on the Bayer Filter for more explanations of how it works.

The upshot of all of this is that a theoretical OSC camera compared to a mono camera with the same chipset would approx 1/4 of the sensitivity in red and blue, and 1/2 as sensitive in green.

It also means that narrowband filters such as Ha will only be triggering 1/4 of the available pixels when used with a OSC camera. I haven't tried it, but every now and then someone posts some good results on the forum.

The main argument I've heard for/against OSC vs Mono is usually the weather - with our skies, a OSC makes life a bit easier, and gets everything in one shot.

That being said though, would shooting LRGB with say L x 2 minute binned at 1x1 and RGB x 1 minute binned at 2x2 totalling 5 minutes equate to the same exposure from a OSC camera?? Experimentation is required here I believe :)

Also - narrowband will reduce the time needed as well - I only have 2 filters at the moment - Ha and OIII - therefore I shoot the same length exposures, which would equate to a Ha x 2 minute and OIII x 2 minute, totalling 4 minutes - a potential saving of a minute......

I think I've rambled on enough now though :)

Cheers,

Richie

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Colour or mono? Some say that, since clear nights are relatively few in the UK, you should speed things up with one shot colour. My counter would be to say that, since clear nights are few and some will be moolit, why not make the most of them with narrowband - for which mono is far better.

I agree that your horsey is a real thoroughbred but again my thoughts are, Hell, what could this man do with a CCD? Galaxies begging for fine detail show CCD to advantage more than nebulae where a certain softness is a positive asset. Long luminance runs permit phenomenal sharpening.

Finally I'd say that you already have a good OSC setup so why not have fun with a new technique?

Olly.

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I'd agree with Olly.

I had an Atik OSC 16HRC for a while, but found that, in practice, the advantages in time from grabbing all the colour in one go were mostly offset by the lack of sensitivity meaning that many more subs were needed.

Also, you can't bin a colour camera for greater sensitivity, as you can a mono cam. Binning gives you the choice of either shortening your colour subs, thus saving time, or keeping them the same length as your luminance and going very deep with your colour data.

OSC cameras have lower resolution compared to mono due to the bayer matrix as described earlier, but this is often not a factor to be worried about as the seeing, certainly from the UK, doesn't allow really good resolution most of the time anyway.

Atik cameras are great BTW. They can do no wrong in my book :)

Cheers

Rob

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I would take a look at Greg Parker/Noel Carboni's images taken with a M25C as a good testament at what can be done with a OSC camera.

Regards

Kevin

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I would take a look at Greg Parker/Noel Carboni's images taken with a M25C as a good testament at what can be done with a OSC camera.

Regards

Kevin

And yours too Kevin :)

Plus the excellent work by SteveL and Steppenwolf.

Greg Parker goes for about 100 subs he reckons, which confirms what I found with my OSC and the 14 inch....when I got up to 45 or 50 subs, it was fine, and I am actively considering going for an MX25C, or QHY Pro, as they both have the sensitive Sony chip.

Cheers

Rob

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Hi All,

Well for my 2 cents worth, the new QHY9 CCD is worth looking at.

Yes it has a few drawbacks, one of them being it's sensativity due to it small pixel size, ans small well depth due to it's pixel size, but on the plus side it's a very high resolution ccd with a a large mono sensor.

Becuase it has small pixels it's perfect for shorter focal lengths, but it's also versatile enought to be used with long focal lengths with binning and still have a good FOV.

In general usage, because of the ccd real-estate, it means you can use the binning to get the higher sensativity and still have a wide Fov and a high resolution image.

Whilst the Kaf line of sensors dont have great dark current like the Sony's, this is compensated by the extreme cooling down to a possible -50 which and with temprature set point control, in theory you should only really need to create a single set of master darks.

All in all it's not the most sensative ccd, but this is made up by the fact that you'd be hard pushed to find another ccd on the market with this level of performance / ccd Sensor size anywhere else for the price £1999

Here's a pic of the rosetta nebula in universe today taken with the QHY9. it's only a small image but you can see the overall result.

http://www.universetoday.com/wp-content/uploads/2009/01/naturalroseparallel.jpg

QHY9 8.6mega pixel mono camera (CCD Info Page)

Main Features

  • Total pixel : 3448*2574 (8.9mega pixel)
  • Active pixels: 3358*2536 (8.6mega pixel)
  • Pixel Size: 5.4um*5.4um
  • FullWell: 25.5Ke-
  • Imager Size : 19.7*15.04mm 4/3inch
  • Readout noise: 8e-(Typic @1Mpixel/s)
  • Preview Speed: 3Mpixel/s (3sec download time)
  • Download Speed: 1Mpixel/s (9sec download time)
  • Peak QE: 56% @540nm 48%@Ha
  • Microlensing on chip
  • ABG: 1000X
  • 16bit ADC with CDS and Preamp
  • USB2.0 High Speed interface
  • Build in 32MBytes SDRAM buffer
  • Support Binning: No Bin, 2*2,3*3,4*4
  • Communication port to QHY color wheel
  • Improved 2-Stage TEC cooling -50 from ambinet
  • Improved Heat Sink For KODAK CCD
  • Build in Temp sensor and 16bit high presion ADC
  • DC201 DC adapter & TEC Controller, Regulated
  • Build in Mechanical shutter for Full Frame CCD
  • Fully Airproof with Two 4.0mm Air Socket
  • Weight: 510g

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