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Old 27-09-2016, 04:35 PM
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Since I have Hartridge spectrometer at hand, I measured (with help of red LED) the cut-off wavelength of my Rocolax UVIRCUT filter.. 656 nm is passing through without much attenuation.
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Old 27-09-2016, 06:19 PM
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Bojan, can you measure the transmission of the filter in the far IR? A clear light globe with a glowing filament will be a good source of IR.

The 450D sensor will happily detect photons at wavelengths over 1100nm and your filter seems to start transmitting again around that range. See for example here.
On the other hand the Canon filter in your unmodified 60D may be blocking this far IR.
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Old 27-09-2016, 06:48 PM
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Quote:
Originally Posted by luka View Post
Bojan, can you measure the transmission of the filter in the far IR? A clear light globe with a glowing filament will be a good source of IR.

The 450D sensor will happily detect photons at wavelengths over 1100nm and your filter seems to start transmitting again around that range. See for example here.
On the other hand the Canon filter in your unmodified 60D may be blocking this far IR.
I will try.. later.
The setup will be a bit more difficult than this one, because Hartridge spectrometer is visual instrument, and was holding the whole thing in hand.

Previously taken spectra of Eta Carinae (attached) doesn't show a lot above 945nm.. it depends of how much IR is in eta spectrum for th estart [NB: my 450D is modified (filter was removed), but not de-bayered (yet)]
Attached Thumbnails
Click for full-size image (eta.jpg)
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Last edited by bojan; 28-09-2016 at 08:01 AM.
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Old 27-09-2016, 09:15 PM
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Filip, congratulations, that is great news

Which Peltier did you use? Was it single or double-stacked?
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Old 28-09-2016, 12:41 AM
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Bojan, I did a bit more reading tonight and the maximum photon wavelength that will interact with the monocrystaline silicon is 1125nm (1.1eV photon energy). Photons with lower energy (higher wavelength) will go through it without any interaction. Now I am not sure what else Canon added to their sensors but this wavelength is probably the maximum wavelength you need to worry about.

Now, the transmission graph for the Rocolax filter stops at about 1090nm, i.e. short of our maximum of 1125nm. While not likely it is possible that the transmission goes up in this small but unknown range. For example, Baader BCF does exactly this, the transmission rises from 0% to 80% between 1100nm and 1140nm (it is about 40% at 1125nm).

Also to consider is that the sensor efficiency at this far IR end is quite low.

Just some food for thought
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Old 29-09-2016, 04:03 PM
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Thanks guys!
I really don't know what's wrong with my Rocolax filter (and I don't think it's image processing error either). Ha regions are just not there...

Could it be that I turned filter the wrong way around? The red reflective layer should point to the telescope side, maybe I installed it backwards. Does it really matters? Hmm...


Luka, Peltier is double stacked DIY type

https://dl.dropboxusercontent.com/u/...ge_peltier.jpg
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  #227  
Old 29-09-2016, 04:23 PM
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Hi Flip

I have a few UK admirers of your work asking questions. I said they should join and post. Excellent work!

bojan...thanks for your assistance and input...much valued indeed!
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Old 29-09-2016, 05:07 PM
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Than they really should join
I'm sorry that I can't participate more, I am stretched between my job and my family, with very little spare time dedicated to this project...
Progress on my cam86 board is exactly 0%
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  #229  
Old 29-09-2016, 06:14 PM
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Thanks guys!
I really don't know what's wrong with my Rocolax filter (and I don't think it's image processing error either). Ha regions are just not there...

Could it be that I turned filter the wrong way around? The red reflective layer should point to the telescope side, maybe I installed it backwards. Does it really matters? Hmm...
I will check spectrometer calibration with neon lamp....

Last edited by bojan; 29-09-2016 at 07:01 PM.
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Old 29-09-2016, 07:05 PM
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Calibration looks OK.
According to Christian Buil's webpage spectrum of domestic energy saving lamp (bright red line), my spectrometer is almost spot on (my reading of 6113A line is 6119A).
So, Rocolax filter does pass 6560A Halpha line.

For my measurement I used LED (which has a pretty broad spectrum around 656nm), and measured the wavelength of the (sharp) edge introduced by IR stop filter.
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Old 29-09-2016, 07:14 PM
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So, in the end, what is conclusion? My filter is somehow different or what?
I have Astronomik UVIR block but only in 1.25" size, on my next imaging session I will try with that.
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Old 29-09-2016, 07:25 PM
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So, in the end, what is conclusion? My filter is somehow different or what?
I have Astronomik UVIR block but only in 1.25" size, on my next imaging session I will try with that.
Hard to believe..
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Old 30-09-2016, 08:27 AM
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I just repeated the (visual) measurement with Energy saving lamp as reference.
The line I was monitoring (650.5nm) is marked with ellipse on the attached annotated spectrum of the lamp (it is quite faint).

Summa sumarum: Without Rocolax filter it is visible, with filter it is not.
Conclusions;
- I have made a mistake with first measurement reported earlier (it is not easy to pinpoint the cutoff wavelength visually)
- Rocolax filter is NOT good for Halpha (contrary to manufacturer's claim and supplied transmission curve) (I contacted them and asked for advice)
Attached Thumbnails
Click for full-size image (calibration.jpg)
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Last edited by bojan; 30-09-2016 at 03:19 PM.
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  #234  
Old 30-09-2016, 07:59 PM
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Getting lots of interest requests from CN on cam86, Mainly referred them here to join for access to our GD files etc. Makes it much easier. I think people are having a difficult time following the Ukrainian forum thread or finding info.

They discuss more than one camera type and its difficult with the language. That said...we wouldn't be here without their initiatives! Again much praise for Grim and Vakulenko.

So welcome to all new readers...join up and become active. The more mouths the better the tune!...well maybe!

Brendan
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Old 30-09-2016, 08:13 PM
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Old 30-09-2016, 08:21 PM
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About the Rocolax UVIR blocking filter, last night I again take few shots of M33 without it. And I can confirm Bojan's measurement, this filter is not good for astrophotography. Without filter Ha regions are clearly visible.

On the other side, I am totally surprised with the stuff I can pull out from my cam84 v3.1 camera. Cam86 should be even better, with lower noise.

M33 from the last night:
(8x900s, gain 63, offset 12, CCD temperature -10C)
https://dl.dropboxusercontent.com/u/...uced_stars.jpg
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  #237  
Old 30-09-2016, 08:33 PM
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Quote:
Originally Posted by flolic;/
.....On the other side, I am totally surprised with the stuff I can pull out from my cam84 v3.1 camera. Cam86 should be even better, with lower noise...
Damn you are getting good data. Damn that camera is performing well. Kinda like the Canon D20a of the modern era. Less mega pixels is more! Kinda hitting the sweet spot for many arc seconds per pixel wise!

Well done indeed.

Brendan
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  #238  
Old 01-10-2016, 02:26 AM
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Getting lots of interest requests from CN on cam86, Mainly referred them here to join for access to our GD files etc. Makes it much easier. I think people are having a difficult time following the Ukrainian forum thread or finding info.

They discuss more than one camera type and its difficult with the language. That said...we wouldn't be here without their initiatives! Again much praise for Grim and Vakulenko.

So welcome to all new readers...join up and become active. The more mouths the better the tune!...well maybe!

Brendan
yes, here i am
i'm Gilles, living in France. i completed Cam84, it took me 9 month
no picture under real sky, because my own challenge is to make it work with indlib under linux... No sucess for now .. No pictures

I'd like to try this Cam86, i thougt it could work easier with linux because of the Atmega, replacing FT2232 bitbang communication with a good old serial. But i might be wrong...
Doesn't matter, it'll be funny
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Old 01-10-2016, 03:02 AM
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Smile

Quote:
Originally Posted by wasyoungonce View Post
Getting lots of interest requests from CN on cam86, Mainly referred them here to join for access to our GD files etc. Makes it much easier. I think people are having a difficult time following the Ukrainian forum thread or finding info.

They discuss more than one camera type and its difficult with the language. That said...we wouldn't be here without their initiatives! Again much praise for Grim and Vakulenko.

So welcome to all new readers...join up and become active. The more mouths the better the tune!...well maybe!

Brendan
Thank you Brendan for the invite to Iceinspace. I'm Tom - a new arrival from the CN forum. I was about to begin construction of the CAM84 v4.1 when I saw the Ukrainians building CAM86. How do I go about gaining access your CAM86 pcb files on google drive? The gerbers from the Ukrainian AstroCCd site are difficult to use.

Thank You again.


Tom
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  #240  
Old 01-10-2016, 08:25 AM
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Good morning Tom and Gilles....welcome to downunder. Remember we are upside down here so hang on! Oh did I mention the time zone differences.....yeah this can produce disjointed conversations so please be patient, we are 10hrs faster than UK but 10 years behind!.

I think the ATMEGA328 does the "bit banging" timing in lieu of hardware and ASCOM driven timings in cam84/85m. This takes some communication load off the connection. Also the ATMEGA328 is capable of doing more...like on-board TEC cooling control, etc etc.

I've sent invites to our GD with "read" permissions at the moment. Please by all means use what you want but I need to discuss with the other IIS gents on accessing "write permissions" for you.

I think I've already sent the GD invite...please tell me if it does not show up.

Really good to see new members interested. Kinda.."new blood to spill"!

Brendan

Last edited by wasyoungonce; 01-10-2016 at 09:00 AM.
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