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Old 14-05-2015, 06:48 PM
Hans Tucker (Hans)
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Why the move towards KAF-11002

What is the more skilled Astrophotographers attraction towards the 11002 CCD Sensor. I have noted the increase number of for sale/trade ads for cameras with Kodak KAF-16803 where the seller is looking to move to cameras with the Kodak KAF-11002 sensor. I thought the Kodak KAF-16803 was the ducks guts and when first released there was the trend to move from Kodak KAF-11002 to the Kodak KAF-16803, now it seems to be going in reverse. Whilst the pixel size, @ 9 micron, is the same for both sensors it seems a backwards trend towards a sensor with a reduced number of pixels in a smaller array.
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Old 14-05-2015, 07:51 PM
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Hi Hans,

I am not aware of the trend you have mentioned, but perhaps someone else can shed some light on this mystery

To my limited knowledge, KAF 16003 has higher QE and well depth than KAI 11002 becuse the latter is interline sensor. There is a thread on this website discussing some differences between different CCDs - http://www.iceinspace.com.au/forum/s...ad.php?t=77479
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Old 14-05-2015, 08:13 PM
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I own and have used both and I'd much rather image with the KAF-16803. As Slawomir said, the KAF-16803 has all the specs on its side. The only disadvantage that I can think of is that the KAF-16803 can have a problem with RBI but I have found that quite manageable.

Now, if you could get a sensor with Sony ICX-694 QE and read noise and a 52mm diagonal then I've be an instant convert.

Cheers,
Rick.
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Old 14-05-2015, 10:12 PM
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I think the attraction is the AOX which can be used with the STXL11002.
The only other AO unit on the market is the Starlight Express one and I get the idea the AOX is in another league.

The 11002 still has the largest number of super images taken with it.
The 16803 is a lovely sensor though, higher QE, lower read noise, larger well depth. File sizes are larger though which makes processing slower and more tedious.

It also may be the way the 11002 renders an image which is different to a full frame sensor.

Greg.
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Old 17-05-2015, 02:44 PM
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Quote:
Originally Posted by RickS View Post
Now, if you could get a sensor with Sony ICX-694 QE and read noise and a 52mm diagonal then I've be an instant convert.
There are a few out there that are even better than the ICX-694, the deep depletion eXcelon (Princeton Instruments) being one of them. The Eagle V with the E2V chip being another. From memory, the diagonal on both of these cameras is 38mm.
The catch being the that the retail cost for the Eagle is ~$80K.

Not withstanding the extraordinary cost, I was curious to see if there was a case for cameras such as these amongst amateurs so I did some note pad calculations to that end. The results may surprise you...

First up, the quantum efficiency of three chips of interest:

Wavelength__ eXcelon QE__ ICX-694 QE__ 16803 QE___ (adjusted QE)
400nm_________82%________65%_______41%_________(36%)
450nm_________92%________72%_______45%_________(39%)
500nm_________90%________76%_______55%_________(48%)
550nm_________90%________76%_______60%_________(52%)
600nm_________90%________72%_______56%_________(49%)
650nm_________92%________66%_______46%_________(40%)
700nm_________93%________53%_______42%_________(37%)

I don't think too many people would argue that the CHART32 telescope represents a benchmark for amateur imaging instruments so I will use it for comparison. It is an 80cm cassegrain made by ASA with a camera using the 16803 chip.
Now, considering the relative QE of the choices we have above, what size telescope would you need to operate with these chips to achieve the same signal? fwiw) I added a fourth column (above) to reflect the slightly lower transmission of the Keller cassegrain as a function of its coatings. The assumption was enhanced coatings for the secondary (94%) and Al/SiO2 for the primary. The smaller theoretical telescopes with the eXcelon and Sony chips were assumed to have Max 'R'EAL from Spectrum Coatings, FL. (which wouldn't be an option for a 32" telescope)

Anyway here are the apertures derived for telescopes with equivalent signal as a function of wavelength and detector: The assumption is that the focal planes of each telescope are scaled to achieve the same angular resolution per pixel.


Wavelength____eXcelon____ICX-694_____16803
_____________RC or DK___Newtonian___CHART32
400nm_________21.2"______24.1"________32"
450nm_________20.8"______23.8"________32"
500nm_________23.4"______25.7"________32"
550nm_________24.3"______26.8"________32"
600nm_________23.6"______26.7"________32"
650nm_________21.1"______25.2"________32"
700nm_________20.2"______27.0"________32"

It is probably fair to say that An eXcelon chipped camera on a 22" cassegrain or an ICX-694 on a 26" Newtonian would be functionally equivalent to the CHART32 with the 16803. When you include the mounting, housing and logistics of each choice, the 16803/ASA cassegrain combination comes in dead last if the metric by which we evaluate these systems is a function of signal per dollar. It's only advantage being the number of its pixels. It is also probably fair to say that the QE advantage of the eXcelon alone isn't enough to make it a viable choice over the ICX-694 in the context of instruments even the most ambitious amateurs are likely to deploy, with the assumption being that all three systems are operated such that they are shot noise limited.

But what about when camera noise defines the system S/N ratio?
Let's now compare the above chips in terms of exposure required at common emission line wavelengths to achieve an equivalent S/N assuming system noise is defined by manufactures spec for readout noise alone.

Relative exposure to achieve same S/N
CCD chip_______R.O. Noise____Hbeta_____Oiii_____Halpha_____Sii
16803 Proline_____10e-1_______57_______50_______81_______86
ICX-694 QHY______5e-1________7________7_______10_______11
ICX-694 Microline__ 3e-1_______2.5_______2.4______3.5_______4
eXcelon__________2.3e-1_______1________1________1_______ 1

Conclusion:
Assuming that you employ a filter with enough finesse to achieve the condition where the readout noise of the camera is dominant (A fabry perot interferometer [etalon] with appropriate blocking filter would be such an example) then the eXcelon chipped cameras (can) become the most cost effective option, depending on the size of the telescope.

Last edited by clive milne; 17-05-2015 at 03:07 PM.
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Old 17-05-2015, 05:34 PM
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I'll see if the component procurement guys in our US office can get me a trade price on the eXcelon, Clive

Interesting analysis, thanks. Perhaps I'll be able to save on aperture and spend up on silicon for my retirement AP system.

Cheers,
Rick.
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Old 17-05-2015, 06:10 PM
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~$80K...I shall hope then that future generations of mass produced CMOS sensors will be suitable for DSO imaging...

Nevertheless I would be extremely happy to compliment my QSI 690 with the STXL11002 plus AOX
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Old 17-05-2015, 07:11 PM
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Quote:
Originally Posted by clive milne View Post

It is probably fair to say that An eXcelon chipped camera on a 22" cassegrain or an ICX-694 on a 26" Newtonian would be functionally equivalent to the CHART32 with the 16803. When you include the mounting, housing and logistics of each choice, the 16803/ASA cassegrain combination comes in dead last if the metric by which we evaluate these systems is a function of signal per dollar. It's only advantage being the number of its pixels. It is also probably fair to say that the QE advantage of the eXcelon alone isn't enough to make it a viable choice over the ICX-694 in the context of instruments even the most ambitious amateurs are likely to deploy, with the assumption being that all three systems are operated such that they are shot noise limited.
As far as saying "its only advantage is its number of pixels", I would not so easily right off this as being trivial. Mosaic work on galaxys isnt going to be fun, the field of view for a ICX-694 is 15' by 12' on a scope of 2800mm FL, which matches the sampling of the CHART32. There is one other overlooked parameter too well depth.
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Old 17-05-2015, 08:12 PM
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It is quite amusing and also interesting to watch, and also to actively help various threads deviate from original topics. One would be deceived by thinking that astrophotographers are very precise...
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Old 20-05-2015, 08:45 AM
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I use both cameras and I understand the strengths and weaknesses of each.

Nothing beats the widefield power of the 16803 sensor and its over 100,000 electron well depth. It can take a wide dynamic range and stars never bloat or go weird on you. Its quite sensitive and fairly low noise.

The 694 is very sensitive and definitely takes less time to get there. Low noise means its picks up faint details. Small wells can be a pain and overexposure on brighter stars is something to keep in mind when using it.

The 11002 being Interline does not suffer from RBI (residual bulk image - ghost images). The 16803 does but not badly. Although I would keep it in mind. I would not take a focus image of a super bright star then slew to my imaging object and image away. You may end up with a bright star residue in your ensuing images that gradually fades away over 10 exposures.

The KAI11002 has good dynamic range, reasonable QE and reasonable noise.

At the end of the day its a full frame sensor so like in DSLRS full frame rocks.

The 16803 is between full frame and medium format.

The KAI16070 seems to be an updated and possibly improved 11002. It seems to have the same imaging characteristics but 50% more pixels which could mean better resolution. But its only available from a few manufacturers none of which sell an AO unit.


Greg.
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Old 21-05-2015, 11:43 AM
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An interesting discussion and I am not sure how much more I can add to it. However, since I have a KAI11002 sensor I guess I ought to give my reasons for buying this product.

Firstly, I like the traditional 35mm format. Being a 35mm photographer since the early 1980's it has stuck with me, so I like the format. It is limiting to landscape but I have a rotator to get around this problem.

The guiding solution was another reason for choosing this camera and sensor. The STXL has an integrated guiding in the filter wheel. That meant I could fit a rotator, atlas, and eventually AOX into my back focus. I could have chosen the 6303E but it did not suit my field of view ideas and I am not keen on a sensor without ABG.

Whilst the specs all suit the larger sensor, the 11002 sensor is still a good sensor and produces good results. The addition of the AOX with the integrated guide solution in the filter wheel sealed the deal for me.

So for me it was all about a lot of factors and not just the sensor.
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Old 22-05-2015, 12:33 PM
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That's how I see it too Paul. The overall package is very appealling.

Greg.
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