
Cooled Nikon D5500a Chills the Sensor for Clearer Star Photos - uptown
http://petapixel.com/2016/10/11/cooled-nikon-d5500a-chills-sensor-clearer-star-photos/?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%25253A+PetaPixel+%252528PetaPixel%252529
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fest
There is a saying in electronics engineering world: "Every sensor is also a
temperature sensor."

What this means is: almost every electronic sensor is affected by it's
temperature- from expensive image sensors to cheap MEMS accelerometers and
gyroscopes.

That is why many of digital sensors also report their temperature, although
that is not their primary purpose- so that current temperature effects on the
measured result can be calibrated out either in sensor's logic, or by host
software.

~~~
gnipgnip
Erm, you can't calibrate out Boltzmann noise.

~~~
cperciva
You can calibrate out the _mean_ "light level" resulting from Boltzmann noise.
You can't calibrate out the _variance_ , but eliminating the mean noise is
better than nothing.

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anon1253
Not quite sure why this hits the front page. Most serious astrophotographers
have been using similar setups for a while now, or ideally peltier cooled CCDs
(like Starlite Express, Atik or QHY cameras). More recently cooled CMOS
sensors (like the ZWO1600MM-Cool) have also gained popularity. It's a bit of
niche market, but for long exposure photography having a cooled sensor greatly
reduces thermal noise. And since the signal is very faint you often do a lot
of "histogram stretching", bringing out the signal, but also the noise. In
addition to having a low noise camera you also often do things like bias, dark
and flat callibration, reducing impurities further. Dark subtraction is often
known as "long exposure noise reduction" in consumer cameras, but
astrophotographes like to do it manually. There are a lot of details to
consider when doing astrophotography, but I'm always happy I can set my CMOS
or CCD (own both the QHY10-OSC and ZWO1600MM-Cool) to a deltaT of -40ºC.

~~~
mustpax
The reason that this is on the front page is because not everyone is a serious
astrophotographer.

If you find yourself asking "I already know about this, why is this on the
front page?" Take a moment, you've just answered your own question.

~~~
joshumax
However it still isn't exactly that new or revolutionary... CentralDS has been
doing this with Canon cameras for a while now and it looks like P.L.L. has
just taken the cooler and retrofitted it to a Nikon this time. Still went with
the ASI 1600MM-Cool and MC-Cool based on their prices still being lower
_together_ than what they're charging.

~~~
echelon
I know little to nothing of astrophotography, so this article comes as news to
me. (I like the article, FWIW.) I wasn't even _aware_ cooling could be used to
account for sensor noise. Now my mind is actively aware of the problem and is
trying to enumerate other possible means of correction in this, and other,
imaging fields.

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foenix
Direct link to the product page which has the same images and description and
isn't blog spam: [http://www.primalucelab.com/astronomy/d5500a-cooled-
camera.h...](http://www.primalucelab.com/astronomy/d5500a-cooled-camera.html)

~~~
jplahn
Meta question: what do you consider spammy about this blog post? It seems like
a perfectly fine, digestible narrative of the product without requiring the
reader to sift through a product page.

On a more related note, I find it interesting that the product page says
there's a 4 year warranty on the camera body. I didn't see anything about the
warranty on the mod itself.

~~~
andrewguenther
I agree, the blog post is a much better quality post. Also, I would imagine a
direct link to a product page would turn a lot of people off.

~~~
foenix
Oh, looks like the OP link was updated since I posted that. The original link
was to Gizmodo: [https://gizmodo.com/this-upgraded-nikon-chills-the-sensor-
fo...](https://gizmodo.com/this-upgraded-nikon-chills-the-sensor-for-clearer-
shots-1787743794)

I should have linked to the original Petapixel post on the bottom of that
Gizmodo page. My bad.

~~~
jychang
Petapixel is half blogspam anyways, a tiny step up from Gizmodo. It was
actually banned from r/photography for spam reasons.

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Keyframe
_Sensor cooling can lead to moisture appearing in the camera, so the D5500a
Cooled uses a special anti-dewing system that uses targeted heat to avoid dew
drops appearing._

I'd like to hear more about this.

~~~
polyfractal
These are often called "dew heaters", and are really quite simple. It's
usually nichrome wire (e.g. what you see in a toaster), or sometimes a bunch
of resistors. The tiny amount of heat generated by these straps are enough to
raise the optical port a degree or two above the dew point.

My QHY8 (a dedicated astro CCD) for example has a poor/old design, where the
CCD compartment is not air-tight. This allows humid air to get inside, which
can then fog up the optical glass due to the peltier cooling the sensor down.

The fix is a small ring that screws into the port, and raises the temperature
just enough to combat dew. You could also wrap a dew heater strap around the
part of the optical train at that point for a similar effect.

Dew (and frost) are the astrophotographer's great, persistent enemy and not
just on the CCD. You'll also have dew problems on the telescope itself. For
example, my newtonian sometimes has dew problems on the secondary mirror,
occasionally on the main mirror, and always on my guide scope.

Most people just create some DIY dew heater straps with nichrome wire... it's
super simple and effective.

~~~
Keyframe
Interesting. So it's a heating element (wire) which serves as a controlled
heater to keep the close environment above dew point. If it's controlled, that
is. Maybe it works as a dumb heater also?

OTOH, I've never considered somewhat more performant (not to say extreme)
cooling of CMOS in order to eliminate noise. I'm surrounded by CMOS and CCDs
every day, in film cameras and telecines (both array and linear chips). I
knew, and saw, that temperature can influence noise, but apart from staying
within 'normal' operating range, I never considered it would eliminate more
noise if significantly cooled down. Probably because I knew noise was inherent
to the way those things work and not much could be done to eliminate it
altogether. Interesting. I'll try to experiment with a bit more extreme
cooling on my equipment to see what yield would come out of it. I'm not that
concerned about dew, because equipment is in controlled environment (dry and
+-2C deg. stable environment), but nice to know.

~~~
polyfractal
They are usually "dumb" heaters... literally just some voltage applied to wire
(you can read more about them here, along with calculation according to wire
AWG and length: [http://www.blackwaterskies.co.uk/2013/05/making-your-own-
nic...](http://www.blackwaterskies.co.uk/2013/05/making-your-own-nichrome-dew-
heater.html))

A major pain point of dew-heaters is if they are too strong, they induce "tube
currents". E.g. the heat from the dew-heater causes the air around the heater
to start convecting, which causes ripples in the final image. It's not really
visible as ripples, but a general blurring of the image. It's essentially
recreating astronomical seeing conditions inside the telescope itself, which
is obviously not ideal :)

I think some fancier setups will be "active" and regulate themselves based on
ambient temperature, but it's a lot more common for people to over-build their
heaters and then use a dimmer switch. So you make your dew-heater for the
worst winter night you expect, then dim it down for the rest of the year
manually.

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Hasz
They're essentially using Peltier elements to cool the elements
electronically. They're also using two elements stacked in series for a lower
total temp.

Thank god the CCD is small -- a Peltier unit, as a heat pump, is pretty
inefficient, topping out a ~15%, at a low t delta. When you stack two on top
of each other, the efficiency is now 2.25%, and this only gets worse as the
delta increases or more units are added.

~~~
Retr0spectrum
The CCD also doesn't generate that much heat, so the peltier cells don't need
to do that much work.

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thebakeshow
Question to those astrophotographers out there. I notice the cooler has a fan
on it, is the fan vibration damped somehow?

I shoot a lot of long distance photos (300mm F/2.8 and 600mm F/4 are my main
lenses). Any vibration is greatly amplified when I shoot, and this is a much
longer range than that.

~~~
aortega
Good question. I have a peltier cooled ccd (atik 460) and the fan stays on
during the entire exposure, but it doesn't affect the final picture at all,
touching the camera I can't feel any vibration, but can hear the fan. Quality
is much better than in my fanless Canon 400D.

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matt_wulfeck
There's simply no way that the fans don't cause considerable vibration
artifacts for such long exposures. Am I missing something?

~~~
subnaught
Peltier cooling does not require a fan, which is why it is often used in
precision optics.

[https://en.wikipedia.org/wiki/Thermoelectric_cooling](https://en.wikipedia.org/wiki/Thermoelectric_cooling)

~~~
aortega
Peltier cooling or heating does require a fan. The peltier cell only moves
heat from on side to the other side. Then, you still have to remove the heat
somehow (heat doesn't simply dissapear) that's why most peltier setups have
fans.

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raverbashing
If you can't tell the difference between the chilled and regular frame I have
to suggest taking the dust out of your monitor, as in certain conditions the
difference might not be visible

(I just did that)

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dom0
> “It’s the first ever cooled Nikon camera ever for astrophotography,”

* first ever commercial

The technique isn't at all new, even in DSLR space.

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mutagen
I recently ran across this homemade camera mod [1] to reduce astrophotography
noise. There's some brief notes on creating it somewhere in the creator's
(James Tobin) profile [2] but G+ isn't the happiest place to search.

Edit: Found one of them [3]

[1]
[https://get.google.com/u/0/albumarchive/11010321236096143315...](https://get.google.com/u/0/albumarchive/110103212360961433158/album/AF1QipNHCy7jXdvjcNpJonAk2aRuyBxEEiIOq329Mloq)

[2][https://plus.google.com/110103212360961433158](https://plus.google.com/110103212360961433158)

[3][https://plus.google.com/110103212360961433158/posts/58k5AgTx...](https://plus.google.com/110103212360961433158/posts/58k5AgTxwku)

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abetusk
I was experimenting with visual calibration of my desktop CNC by hooking up
one of those cheap USB 1000x cameras. I had done some back of the envelope
calculations to figure out that it was about 5 pixels per thousandth of an
inch.

After a few hours of getting weird inconsistent results, I finally figured out
to my shock and horror that the image was drifting and warping by upwards of
20 pixels after the camera had been one for a while (I think it was 640x480
resolution). My friend and I thought this was due to the CCD heating up and
warping.

It looks like they're using the cooling for noise suppression but I bet the
CCD also has the same effect I noticed of 'pixel drift/warp'.

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anovikov
No way this will beat a dedicated astronomy CCD camera. And price point is
already not so attractive, ST-8300C costs $1995 and while has 30% less sensor
area, is light years away in thermal current at given temperature, and quantum
efficiency. For me, if a wanted a color camera (bad idea most of the time),
picking between ST-8300C and this would be a no brainer in favor of ST-8300C.

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DigitalJack
That's really interesting. Better watch out for condensation on the
electronics.

~~~
blincoln
The actual product page that foenix linked to
([http://www.primalucelab.com/astronomy/d5500a-cooled-
camera.h...](http://www.primalucelab.com/astronomy/d5500a-cooled-camera.html))
mentions that there is an anti-dew system for at least some of the internal
bits.

------
wyager
Given the fact that (correct me if I'm wrong) camera sensors use the same
sensor elements for red, green, and blue, but with a different filter in
front, it seems strange to me that blue and green are almost eliminated by the
cooling but red remains to a large degree. I would expect this distribution if
the camera used different photodiode types sensitive to their respective color
range.

~~~
planteen
What makes you say that blue and green are eliminated? The stars are still
white. The California nebula itself is mostly red.

[https://en.wikipedia.org/wiki/California_Nebula](https://en.wikipedia.org/wiki/California_Nebula)

~~~
wyager
I mean in the noise image.

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andy_ppp
Would combining Peltier coolers with CMOS/CCDs on high ISO photos work? How
much of the noise at higher ISO is heat, little I'm guessing?

~~~
Sanddancer
Quite a bit, actually. It's why high end telescope CCDs do similar things. A
high ISO means you're ramping up the gain, so the bits of random noise get
amplified too. Cooling it means you're getting rid of one of the more
significant sources.

------
GregBuchholz
Anyone using liquid nitrogen to cool their CCDs on a hobby / amateur level?

~~~
tomkinstinch
Hobby use would be a pain: LN2 could be used, but it boils off so a dewar
would need to be constantly refilled. For sensor applications where cold
matters but a Peltier TEC is insufficient, a Stirling/Joule-Thomson/turbo-
Brayton/Gifford–McMahon cryocooler can be used to remove heat, but they're
expensive (this is how the Hubble Space Telescope does sensor cooling). They
often have high-pressure LN2, neon, or helium as the working fluid, with a
cold head attached to the sensor and a remote compressor. Cryocoolers are also
used to chill superconducting RF filters (of the sort that may be used in cell
phone towers). They're also used to cool MWIR sensors, and thus are often
ITAR-controlled. Sometimes higher-temp cryocoolers pop up on eBay...

~~~
CamperBob2
_Sometimes higher-temp cryocoolers pop up on eBay..._

One of Ben Krasnow's videos comes to mind:
[https://www.youtube.com/watch?v=7PWESWqhD8s](https://www.youtube.com/watch?v=7PWESWqhD8s)

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Apreche
Is this more effective than dark frame subtraction?

~~~
raverbashing
No because dark frame removes the systemic differences between sensors, not
noise

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toomanybeersies
I'm amazed at the difference only 20 C makes.

Does this mean I'd get much better photos in winter than summer?

~~~
raihansaputra
it's not that much of a difference if you're shooting less than 15seconds
exposure.

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maxxxxx
I wonder why they didn't pick a full frame camera like the D750. This would
make more sense to me.

~~~
amdavidson
APS-C sensor cameras get you an effective 1.5x multiplier on your focal
length, handy for astrophotography.

You could always crop down a full frame photo to get the same effect, but then
you're just wasting pixels.

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peignoir
Used to do that with an ST6 back in the 90s :)

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gohrt
Admins/Mods, can we ban titles that use clickbaity "This"?

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sctb
We almost always edit that out of titles and it's fine if submitters do the
same.

