DMK21 sensitivity mod for the brave

[kinetic (Steve)]

I recently read about a CCD swap modification on these great
cameras, that are based around the ICX-098 mono chip.

These guys are real pioneers. Understandably, they don't get a lot
of co-operation from the manufacturers regarding reverse engineering
one of their products and so make a calculated and brave choice to
do a modification such as this.

It involves swapping it for an ICX-618ALA-E CCD which also has
5.6u pixels but is much more sensitive, both overall and in the red.

Of course, any such mod would void your warranty quick smart
I cannot verify the claims but thought it interesting enough to
pass on this link to fellow webcam modders / electronic dabblers.

http://www.astrokraai.nl:80/wiki/ind...D_on_the_DMK21.

Emil is a very well respected long term member of the QCUIAG forum
where I read this post.

Steve

[Quark (Trevor)]

Hi Steve,

I have been following this on Cloudy Nights, Emil has posted some pretty amazing images with the modded DMK. He also has encounted a few problems that he has documented quite extensively. A Saturn image that he recently made from 3 different wavelength IR filters caught my attention. I think he is only using a 10" aperture and it amazed me how bright the final image was in IR with such a small scope, this mod definitely has possibilities and I would hope that Emil's efforts don't go unnoticed by "The Imaging Source" the makers of the DMK, maybe they might put out a camera with this more sensitive chip.

Regards
Trevor

[kinetic (Steve)]

Trev,

It sure is promising. I hope it works out for Emil and others who have
gone down that path.
I re-iterate the point about TIS not wanting to help out though.
Myself and a few dozen others have tried for nearly a decade to get
info regarding driver protocols and signal processing details from the
manufacturers of the most popular and successfully modified webcams.
Their main market is obviously the usual market for webcams, not a
minority like amateur astronomers. Even though a very large fraction of
the purchases of Toucams and Phillips SPC900s would have been people
like us.
For a manufacturer like TIS I would hazard a guess to say they wouldn't
want to go down the path of retro-fits to existing customers, more likely
bring out a whole new line at twice the price.
I have done a pin for pin CCD changeover of a few webcams myself
but only the ICX-098 and it's nearest equivalent the Sharp LZ.
Most CCDs will not have pin for pin footprints so it involves an IC socket
with the right pin spacing and some appropriate jumpers.
I have pulled apart several compact digital cameras and even got a
3.0 megapixel colur CCD doing long exposure.
It is all done with a wing and a prayer though because I have to
resign myself to knowing I could kill the camera or processing circuitry
with a wrong move.
That's why I have so much respect for these guys like Emil.
They openly share their results so that we, as a group, can get a benefit
from their generosity to share.
We all gain something. Do you really think cameras like the TIS range
and the dedicated astro range cameras would be the price they are today
without some of these annoying little dabblers in a back shed proving it
can be done at a fraction of the cost?

Steve

[citivolus (Ric)]

I have not looked at any pictures of results of this swap, but would suspect that with non-cooled cameras such as these, increasing sensitivity is going to come with a noise trade-off. I guess I need to go dig up more information.

[citivolus (Ric)]

After a quick look at their web site, I would suggest that they would get better noise and durability results by using a secondary PCB and socket for routing signals than by using wires. The design would no longer be parfocal with a non-modified camera, but that would be a mostly moot point.

For a practical comparison of the output, I'd also like to see the raw data stretched to the same level as the modified camera, to compare noise levels.

Edit: socket like this, from here

[Troy]

That’s a nice image of Saturn and very brave move to mod the camera. To desolder a ccd and then to solder another ccd sensor to the circuit board would be very hard. I wonder how he overcome some of these problems static electricity, heat and then to get the ccd sensor parallel. He must be highly skilled at soldering that is if it was done by hand?

[Emil (Emil)]

Hey,
I'm not highly skilled at soldering, but a friend of mine is, and he also has the proper equipment available at his work.

"I have not looked at any pictures of results of this swap, but would suspect that with non-cooled cameras such as these, increasing sensitivity is going to come with a noise trade-off"

From my experience, the noise levels are the same as before. I often used the highest gain settings before, and have not noticed an increase in noise. I pretty much dare to say that at least 95% of the increase in sensitivity is increase in signal to noise.

"After a quick look at their web site, I would suggest that they would get better noise and durability results by using a secondary PCB and socket for routing signals than by using wires."

I have not done any extensive testing on this (testing sounds easy, but it is actually quite difficult and time consuming to get more or less reliable results... so for now you'll have to do with my 'experience' ). We do have some sockets for this purpose, but I first want to do some testing to see if the wires actually cause extra noise (by my gut feeling says that if it makes a difference, it will only be a very minimal amount, and probably not worth the risk of messing up a resoldering job)

I'm actually thinking of getting the Basler Ace camera within the next few months. Higher FPS, more output bits, same sensitivity, price comparable to the DMK21. But I don't want to be the first to test that camera extensively I would if I had the funds though

btw; to prove that the DMK21 is still working nicely for planetary images:
http://www.astrokraai.nl/viewimages.php?id=150
http://www.youtube.com/watch?v=TiQHzvxW6Ng

I could probably get some raw data stretched to the same levels to give a better noise comparison. But that will be somewhere next week.

[citivolus (Ric)]

Thanks for the response Emil. I'll be very interested as well to see the cameras purpose built with these sensors.

Regards,
Eric

[Troy]

Hi Emil,
Nice picture of late with the modded camera well done
Is your friend interested in doing mods on other peoples cameras
I have a neximage here not doing very much at all.
It's just a thought
Looking forward to your future developments with this camera.