Debayering a DSLR's Bayer matrix.

[tahoetomahawk]

Will it be possible to use a filter wheel with the DLSR that is debayered?

[Gina]

Will it be possible to use a filter wheel with the DLSR that is debayered?

I will be working on this. As it stands this would be feasible only on refractor telescopes where the extra optical path can be accommodated. On Newtonians there is generally insufficient back focus for this and I think this applies to other scope designs too. Even refractors that use focal reducers don't have enough back focus behind the reducer.

What I'm planning is to reduce the focal path within the DSLR by using a custom enclosure. This means that I will no longer be relying on the camera construction to align the sensor at right angles to the optical path. The new design will include Peltier cooling as in astro CCD cameras in addition to a debayered sensor and no colour correction or IR/UV filters. As this is beyond the subject of this thread, I have started a special thread which will report my progress on a debayered and cooled 1100D with built-in filter wheel. By combining the filter wheel with the camera, the optical path can be shortened considerably.

[JamesF]

I will be working on this. As it stands this would be feasible only on refractor telescopes where the extra optical path can be accommodated. On Newtonians there is generally insufficient back focus for this and I think this applies to other scope designs too. Even refractors that use focal reducers don't have enough back focus behind the reducer.

SCTs and Maks would probably be ok too, because focusing them involves moving the focal plane, not the eyepiece or camera.

James

[Luis Campos]

As to fixing the 1000D, I've taken the top apart to see what connects to where. The two pairs of wires from the power board connect to the flash unit and have nothing to do with the power on circuit. The ON/OFF switch, function dial and push buttons all connect through a ribbon cable that goes to the main board. I have visually checked the ribbon cable, contacts and connections and can see nothing wrong. Things are pointing to a main board fault or possibly the power board. The usual way of diagnosing the fault would be to swap major components with working ones but I can't do that until I get the working 1000D, of course.

Maybe it's a blown microfuse on the power board Gina?

Cheers,

Luís

[Gina]

Good thought Luis - thank you I'll see what I can find.

[flolic]

IIRC, there are few microfuses on power board. Also, check contacts on SD card door.

[Gina]

Thanks Filip

[Gina]

I'll probably leave any more fault diagnosis until the working 1000D arrives - I'm more interested in bebayering.

Talking of which, I wonder why I found the cover glass so difficult to remove when others found it easy.

[Gina]

The working 1000D has arrived I've checked it out on terrestrial subjucts and it's fine.

Next step will be to strip it down to the sensor and check that the one without cover glass works. Then I can see about removing the CFA. I'm planning to use the abrasive paste I used on the other sensors - I don't want to risk scratches with a sharp chisel ended implement, though I may need to just start it that way.

Edited August 29, 2013 by Gina

[Gina]

So far so good - the test sensor works fine I put the filter assembly back taking care not to let anything get near the fine wires then put it into the working camera and put enough of it back together to try terrestrial shots.

Two photos - first is with working 1000D untouched - second is with the sensor swapped for the one I removed the cover glass from.

Edited August 29, 2013 by Gina

[Gina]

Ready now to apply epoxy resin to the fine wires and sensor edge.

[Gina]

Epoxy resin applied - not perfect by any means but better than my last attempt. It's now put away to set overnight.

[StuartJPP]

Hi Gina, do you think it will be possible to save the CFA so that you can install it again later

Good luck with removing the CFA, I am quite intrigued by all this.

[pixueto]

Hi Luis, I'm obviously doing something wrong when stacking in IRIS. This is what I got with a stack of only two images (you can see they aren't properly aligned). used 9 offsets, 9 darks, and 9 flatframes. I think I did what I'm supposed to do but, obviously, the result isn't right.

I had a couple of doubts:

-when preprocessing it asks for an 'output generic name'. Where does this file go? What about the cosmetic file? What's that for?

-for 'add a sequence' what's the 'input generic name' ?

-for 'stellar registration', what should I choose for 'input generic name' and 'output generic name? Should I tick the box for 'select a zone'?

Thank you very much for your help. Inow know I'm close to successfully processing this in IRIS but I'm finding the different file options confusing.

[Gina]

Hi Gina, do you think it will be possible to save the CFA so that you can install it again later

Good luck with removing the CFA, I am quite intrigued by all this.

Thank you

In the event of you wanting a camera with the CFA replaced and returned to original condition, this I could provide when I have finished my experiments. A 1000D with all accessories and kit zoom lens I could do for... er... let me see... £180

HA HA HA !

Edited August 29, 2013 by Gina

[pixueto]

Gina, try to avoid scratching the sensor as those will come up in your subs. See attached a 4 min sub with the monochronme sensor. If you stretch it you'll see the scratches and defects. What I don't know is if the flat frames will correct them. I'm still trying to get IRIS to stack the control frames.

[Gina]

Gina, try to avoid scratching the sensor as those will come up in your subs. See attached a 4 min sub with the monochronme sensor. If you stretch it you'll see the scratches and defects. What I don't know is if the flat frames will correct them. I'm still trying to get IRIS to stack the control frames.

Yes, I fully intend to avoid scratches if I can. Whether I succeed remains to be seen If, like the 1100D, the CFA won't come off with just the abrasive, I'll make a small surface scratch near a corner (but not too near) where it won't be too much of a problem.

It will be interesting to see if flat frames help with scratches. If they are actual dead pixels then they won't but you could try dithering. That should work if the scratch is just one pixel wide.

[Luis Campos]

Hi Luis, I'm obviously doing something wrong when stacking in IRIS. This is what I got with a stack of only two images (you can see they aren't properly aligned). used 9 offsets, 9 darks, and 9 flatframes. I think I did what I'm supposed to do but, obviously, the result isn't right.

I had a couple of doubts:

-when preprocessing it asks for an 'output generic name'. Where does this file go? What about the cosmetic file? What's that for?

-for 'add a sequence' what's the 'input generic name' ?

-for 'stellar registration', what should I choose for 'input generic name' and 'output generic name? Should I tick the box for 'select a zone'?

Thank you very much for your help. Inow know I'm close to successfully processing this in IRIS but I'm finding the different file options confusing.

Hi,

No probs mate, glad to help out

On preprocessing, first you have to draw a box (a zone free of stars will work the best) say with aprox. 500 x 500 pix., next input a generic name, this is what I do, I put "A" on input and "B" on output generic name and so on, so the previous output generic name will be the input generic name on next step, go for a, b, c, d ,etc...

The cosmentic file will clean you image of hot7cold pixels, works beautifully, Iris works with command lines, so go to the command box (litle icon on the left of the camera icon) and write the following: LOAD_DARK and then FIND_HOT COSME 150, if 150 doesn´t work you'll get a message with (too many hot pixels) so you must increase this number until Iris gives you a "hot pixel nr....." in the same command box. When this is done Iris saves automatically a "cosmetic file" with the name "COSME" so just write this word (COSME) under the preprocessing box in the cosmetic file.

So, lets recap, choose your CR2 raws and drag them into the box "Digital photo / decode raw files" and name these raw files with "IMG" for example, next press "CFA" and when done press "DONE". Next draw a box on a star free image and press "digital photo / preprocessing" and put on "input generic name" the name you gave to your raws, in this case "IMG" and put on "output generic name" the letter "A" so you can take from here, then when preprocessing is done, go to "processing / stellar registration" and choose "global matching" this method will take much longer but will compensate even for field rotation with perfect star match, when finished go to "processing / add a sequence" and choose "sigma median" with sigma coefficient of 3.00 and 3 iterations, don't forget that the "input generic name" is the "output " from previous step.

Sorry for the lenghty explanation, but Iris can be very confusing indeed

See the attached print screens:

Cheers,

Luís

Edited August 29, 2013 by Luis Campos

[pixueto]

Thanks Luis. Could you elaborate on this?

'next input a generic name, this is what I do, I put "A" on input and "B" on output generic name and so on, so the previous output generic name will be the input generic name on next step, go for a, b, c, d ,etc...'

Can you explain those steps? Not sure what I'm supposed to do with input the previous output?

I have now the ED80 out with the 1000D debayered and a 7nm H-alpha 2" filter. I'm taking 20 minutes subs. We'll see what comes out.

[Gina]

That'll be very interesting

[Gina]

After a nice long time for the epoxy resin to settle and set and time for most of the tiny air bubbles to surface and break, it's looking a lot better. I think I'm gradually getting the technique for delivering this strange stuff into where I want it and in the right quantity.

[Gina]

Hmmm... All reassembled - no errors - but no picture either No I didn't leave the lens cap on Image fine in viewfinder. I'm getting a totally black image both on the camera screen and saved to SD card I'll take it all apart again and check all connections etc. I'll put the other sensor back in too to check that everything else is working.

[Gina]

Well... As I suspected, everything appeared correctly connected. I put the working/untouched sensor in and everything back together and the camera works fine.

SO - I have succeeded in destroying yet another sensor

[pixueto]

That epoxy is the prime suspect now that heat is out of the equation particularly considering how badly I've treated my 1000D sensor and it's still working.

Edited August 30, 2013 by pixueto

[Kbramley]

I guess the epoxy could be damaging the wires as it sets perhaps (contracting slightly) or alternatively is it adding some capacitive effect between the wires and thus upsetting what i can only imagine being a very sensitive arrangement between the components and the chip?.