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  #781  
Old 19-05-2017, 08:00 PM
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wasyoungonce (Brendan)
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Ok PCB2 cheap canon 50mm lens, dirty sensor poor light bad focus, light leaks...hey it has all the hallmarks!

Sensor & PCB is a good'un.
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  #782  
Old 20-05-2017, 09:17 PM
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wasyoungonce (Brendan)
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Ok Garys PCB1 is done. Again I had left hand noise bars in the dark frames although this time they were hard to the left not across the image. Again removing C38/C46 and inserting a 220uf electro cap fixed the issue.

I'm going to leave this capacitor in as a fix as this has been successful for me. I think the noise is a combination of issues: the ceramic caps are poor at noise ripple removal; the caps are laid in the wrong place; the filter capacitance is possible low. Its normal to use a combination of ceramic caps and electros for power line filtering and I suspect this is why adding the electro works.

Of note is that many many others with different PCB layouts have had similar issues.

I'm making a "camera obsucera" (pin hole camera) to do a daytime light frame. Busy like a kindergarten kid with toilet roll tubes paper glue/mache etc! Anyway I've already done light frames so its really just a play time task!

Oh this PCB draw a little more current than PCB2 but not enough to worry no ICs are getting hotter than normal. Just monitoring it.
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  #783  
Old 21-05-2017, 02:04 PM
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wasyoungonce (Brendan)
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Ok pin hole camera was a bit of a fail. The image is too out of focused! Probably an issue with the actual pin hole size and sensor distance. The sensor is ~ 11cm from the sensor and the pin hole...just a pin hole!

Yet it was fun building it....for awhile!

Also found it difficult to get correct effective shutter speed with Cam86view. Yes I could have used another imaging program...

The Pin hole camera did show a good RGB response and over all it tells me the PCB/Sensor is working like advertised.

Anyway I won't pursue the pinhole much more as I've already run the PCB optically.
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  #784  
Old 22-05-2017, 09:23 AM
flolic (Filip)
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Brendan, you need MUCH smaller pinhole
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  #785  
Old 22-05-2017, 02:02 PM
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wasyoungonce (Brendan)
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Thanks Filip...I was thinking the focus is out because of the hole dia.

I tried a smaller hole....better focus now but image is either too dark or bright. I probably have stray reflections as I used some silver Alloy tape inside to seal it.

I won't pursue this it kinda self defeating. It ran fine with a lens jigged in front of it.

Oh from memory I think I failed Kindergarten ...looks like I haven't improved since! That's our humble abode in the image.
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  #786  
Old 31-05-2017, 01:08 AM
luka
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Cam86 quantum efficiency... what is it? How to measure it?

On one hand we have D70, D40 or D50 with the same sensor and they have QE of 21% according to sensorgen. But then QHY8 has the same sensor and has QE of 50-60%.
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  #787  
Old 01-06-2017, 01:12 AM
pat30
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Brendan, good progress .

Luka,

The Mono sensor has a lot of remanence, and it's very difficult to make flat like that, the option " sensor clr" works well but starts at 1 sec.
Can make sure to put it in forced mode for example with 0 in the box it always empty or when mono and active the "sensor clr" is all time ???

For the QE, it is very difficult to measure, you need a source of light whose exact spectrum and power is known. 21% seems small and 60% big, it seems to me that I had read somewhere 42%
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  #788  
Old 01-06-2017, 01:24 AM
luka
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Hi Pat,
I will look into the sensor CLR and try it with my mono sensor. I did not use it yet, although I had it debayered for several months... actually today I finally decided to glue the glass window on it.

It may take me a few days, things are quite busy at the moment.
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  #789  
Old 01-06-2017, 02:37 AM
pat30
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Quote:
Originally Posted by luka View Post
Hi Pat,
I will look into the sensor CLR and try it with my mono sensor. I did not use it yet, although I had it debayered for several months... actually today I finally decided to glue the glass window on it.

It may take me a few days, things are quite busy at the moment.
Thank you Luka.

What did you put on the glass?
It takes an antireflective otherwise the stars will be enormous.
I did a test with an antireflective but the quality must be bad because the stars were awful! I will do a test but without glass this time, when it is beautiful weather....
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  #790  
Old 01-06-2017, 11:44 AM
luka
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Hi Patrice,

remind me in few days if you don't hear from me about the ASCOM driver :-)

I just used the original glass but from a D40 sensor (the D70 sensor glass cracked). I filled a container with argon gas and under argon atmosphere glued the glass with neutral cure silicone. That should keep the space between the sensor and glass dry. I did not test the mono sensor yet, it will be cloudy for the next few days.

Filip, from memory you debayered a 450D before. What glass did you use in front of the sensor?
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  #791  
Old 01-06-2017, 04:46 PM
pat30
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Hi Luka and everyone,

No problem; it is a good choice argon.

I put 2 comparative images of my test, if you want to see:
1 color version and 1 B / W version with the glass, I would put another without the glass when the clouds are gone.

https://drive.google.com/drive/folde...00?usp=sharing

Last edited by pat30; 01-06-2017 at 08:47 PM.
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  #792  
Old 01-06-2017, 10:55 PM
luka
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Got some more info from another person who previously debayered their sensor. He made two excellent points:

1. We could use Astronomik MC-Klarglas as a high quality (and high cost) replacement glass. Multicoated, comes in various square sizes for different Canon DSLRs. I could not find the dimensions on the Astronomik website, it may need cutting to the right size.

2. The effect of glass on the optical path. If a glass is inserted in the optical path the distance to the sensor has to be lengthened.

"Typically this is referred to the Rule of 3rds, where for each 1mm of glass added to a optical path you will need to allow 1/3mm of extra path spacing. This can be critical with CCD and mono cmos cameras. So typically colour or narrowband filters will be say 2mm thick, and sensor windows that cover the sensor chamber are usually 1mm thick, so that is a combined 3mm of glass, therefore using the rule an extra 1mm of spacing is needed to ensure precise backfocus distance is maintained."

This is not a problem for everybody but, for example, if a field flattener is used, usually they require exact spacing to the sensor and extra glass can affect this. My flattener needs spacing to be within 0.5mm. The above example shows that the flattener will not work correctly unless 1mm is added to the optical path.


Also, when I was removing the glass with heat to do the debayering, at some stage it looked like something was "burning" on the glass. Perhaps this was the reflection coating?


I will check my mono camera in 2-3 days, once the clouds go away.
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  #793  
Old 02-06-2017, 06:04 AM
gehelem (Gilles)
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Hi

Luka, i've noticed a little thing on the driver :
when your cooling is already on, and you've already reached some low temperature, if you set another (lower) temperature, cooling is restarting at "Startpower", not taking care of what your actual power is.
This is not a big deal, just a little annoying when playing with cooler...
I'll try to workaround on my linux driver, but i think i'd be better to do that at firmware level.

Gilles.
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  #794  
Old 02-06-2017, 08:22 AM
glend (Glen)
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Luka the burning you notice during removal of the cover glass is likely the epoxy glue used to seal the coverglass to the sensor body. Typically it starts to turn white in the area where heat is applied which indicates it has broken its bond. The application of heat to that glass, to break the glass loose, is a risky step but there is no other way to do it that i am aware of. A hot air workstation is sometimes sighted as the 'safe' way to do this, but many of us use small butane torches that can supply a pencil type flame. As some of the online videos show, its how you apply the heat that is critical; movement of the torch in 'passes' to get the initial white edge under the glass is important to avoid hot spotting that can damage the sensor fine wires which are soldered in place. Also the glass can break through uneven heat application to cold glass, so don't try to get under the glass with a tool or blade to lever it off. A cracked cover glass is much more problematic to remove without damaging the sensor surface or the wires. It only takes a small chip falling into the sensor surface area to cause damage.
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  #795  
Old 02-06-2017, 09:56 PM
luka
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Glen, I don't think it was epoxy. It looked like a small amount of black-ish smoke came off from the glass itself. I remember repeating the heating on a different side and again the smoke came off in a similar fashion. After those initial "smokes", there was nothing further. I could be wrong and I may have not seen it correctly but I remember it being unusual.
Also I noticed this only on one of the sensors I did an not on the other one. Don't know. I could be very wrong about this.


Gilles, I will see what I can do. I have been working on a new driver version, with some minor bug fixes, but I stuffed up something and it does not work any more. Can't figure out what. Will need to go a version back and do all the changes one by one. Not much time at the moment unfortunately.
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  #796  
Old 03-06-2017, 12:57 AM
luka
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Patrice, a question regarding the mono sensor and sensor clearing before exposure... I can set the sensorCLR to zero here. Then if the duration of the flats is greater than zero (0.01s for example) it will clear the sensor before exposure. Are you using APT?

Can you describe which options you were using?
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  #797  
Old 03-06-2017, 01:11 AM
luka
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Quote:
Originally Posted by gehelem View Post
Hi

Luka, i've noticed a little thing on the driver :
when your cooling is already on, and you've already reached some low temperature, if you set another (lower) temperature, cooling is restarting at "Startpower", not taking care of what your actual power is.
This is not a big deal, just a little annoying when playing with cooler...
I'll try to workaround on my linux driver, but i think i'd be better to do that at firmware level.

Gilles.

Gilles, do you stop the cooler to change the target temperature or do you just set the new target temperature while the cooler is running? The starting power percentage is set only when the cooler is switched on.
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  #798  
Old 03-06-2017, 01:15 AM
luka
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New driver in the usual place, v0.7.1L.
Only minor bug fixes.
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  #799  
Old 06-06-2017, 12:37 AM
luka
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Tested the mono camera with the original glass. Patrice, just as you said the star bloating is visible.

My cameras are not finished yet but I will use the Astronomik MC-clear glass at the front of the mono camera to seal it. MC-clear has excellent anti-reflection coatings. So, I will leave the sensor without a cover glass and try this first. It may be few more weeks before everything is ready though.

One issue I can foresee is that my colour camera will have 1mm thick glass in front of the sensor while my mono camera won't have it. So, the colour camera will have about 1/3 mm longer optical path to the sensor. This is very close to the tolerance of my flattener which is +/- 0.5mm.
Possible solutions are to remove the cover glass from the colour camera or to use anti-reflective MC-clear glass at the front of the sensor. Hmmm... will probably need to test it before making any decisions.
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  #800  
Old 07-06-2017, 12:08 AM
rsevs3 (Ryan)
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I just wanted to share the first image from my camera.

Still a few issues to sort out as well as a case, but some progress is better than none.
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