Fred_76

Yes, I was used to work with Iris. Very powerfull for "small size" RAW images like the ones taken by a Canon 1000D. But the size of the 500D is too big and Iris is very very slow. Iris is compiled in 32 bits and does not take advantage of multicore processors. My computer is a Core i7 with 4x2 cores (with hyperthreading). As Iris can only use one core, it only uses 1/8th of the power of my computer ! And this is very slow... DSS is multicore-able, and can run all cores. That is why I now prefer to use DSS to Iris.

Yes Luis, this is it ! But still at 120 EUR+port, which is quite significant. The EOS Clip filter holder costs only a few EUR... this is a "solution for the poors ;)" I've got another question, but it should better be adressed in a separate topic : how do you set up Deep Sky Stacker to work with Black & White RAW files made from a CFA removed DSLR ? There are 4 options : and none of them is generating a pure B&W image. Tell me if a new topic should adress this subject. Fred

This is not really solved... The EOS-T2 short adapter is 1 mm thick. The T2-M42 filter holder is 10 mm thick. The M42-M48 adapter is 3.5 mm thick. Most coma correctors need 11 mm back focus...

Too bad the TS adaptor is threaded with M42... It doesn't fit the GPU coma corrector (and almost all other ones) which is M48.

Hi! Now I have a B&W EOS 500D, I can use OIII, Ha, SII filters. But the filters I have are 1"1/4 and I can't afford buying 2" filters. I called 3D-clever guys to design a 1"1/4 filter holder to be put inside a Canon DSLR like an EOS Clip filter. Below is the 3D Printer view of 4 stacked filters holders : They arrived to a design that works quite well, as shown : Now, I just have to wait for the weather to calm down and let the sky going on !

As Luis Campos and François Bernier noted, the original Canon glass cover is not good against reflexions of light when the sensor's bayer matrix has been removed. Therefore there is no need to keep it intact as it is better to replace it with a real A/R coated glass. Anyway, this is a good job !

I also calculated a flat field image. One can see that removing the CFA matrix is quite aggressive : However all these scratches can be removed by the flatfield as shown below : translation : - poussières = dust - rayures = scratches - restes de matrice de Bayer = remaining patches of CFA layer - avant/après application du flat = before/after flatfield correction Fred

Hi all! I restarted the calculation of the efficiency of the CFA removal on the light gathering of a Canon EOS 500D/T1i. This time, I took a photo of a white cloud in the sky, close to mid day. The results is quite impressive : - green chanel : +55% - red chanel : +80% - blue chanel : +95% The overall gain is therefore (2x55+80+95)/4 = ca. 70%. The older calculation was done from a photo shot using a tungsten light.

@D4N : I compared, for each chanel (red, green, blue) the level of the debayered photosites and the levels of the intact photosites. The average gain is shown below for each chanel : - red : approx +30% - green : approx +30% - blue : approx +75% There is therefore no loss, at least on the 500D, but a real gain, in particular in the former blue photosites.

Hi Stuart, There is no reason that the QE decreases with the temperature. In fact, the signal to noise ratio is increasing as the noise decreases. And this is exactly what we are looking for Merry Xmas to all ! Fred

Hi! More test report from my brand new monomodded 500D. First of all a reminder on the global characteristics of the sensor : EOS 500D/T1i Sensors characteristics Photosites: 4.7 µm (width x height: 4752 x 3168) ISO Gain e-/DN Gain DN/e- RON e- RON DN Dynamic (bits)100 2.13 0.47 15.9 7.5 11.0200 1.10 0.91 8.7 7.9 10.9400 0.53 1.89 5.0 9.5 10.7800 0.27 3.75 3.5 13.1 10.21600 0.13 7.52 2.8 20.8 9.53200 0.07 14.71 2.8 40.6 8.6These figures are unchanged by the monomod. Thermal noise An average thermal level is substracted from the value measured on the "darken photosites" around the sensor. This operation is performed before the RAWs are saved so that it is not possible to directly measure the dark current. However, only an average level - constant - is substracted from all the pixels. Each pixel has its own behaviour vs dark current and its specific respons to the temperature remains. We can therefore measure the remaining variations as a "thermal noise" (no more a dark current). The following graph shows the thermal noise in DN vs temperature before and after the monomod. The temperature here is the real sensor's temperature - even if read in the EXIF - as Astroghost changed the position of the internal 500D's thermal probe from it original location (close to the sensor's processor) to the sensor itself. On can see that it is better not to allow the sensor to heat above 10-15°C. This is why I asked Astroghost to insert a copper plate under the sensor with a fan to extract the heat. Test on cooling Freezer: I placed the 500D in the freezer at -24°C. After about 1 hour, to allow the sensor to cool down, I started shooting photos of 5 min with a delay of 5 s in between, at 800 ISO. The temperature of the sensor was always between -19 and -21°C, therefore about 5°C about ambient temperature. Fridge: I then placed the 500D in the fridge at +4°C. The temperature of the sensor rapidly increased and stabilised at +10°C, therefore about 6°C about ambient temperature. Ambient: And I placed the 500D outside in a box at +24°C. Again, the temperature increased rapidly and stabilised at +29°C, 5°C above ambient. Therefore I can conclude that the copper+fan allows the sensor to stabilise at 5°C above ambient temperature in about 30 minutes. Before the mod, the difference was about 12-15°C and the temperature was longer to stabilise (more than 1 hour). Test on daylight As the weather is horrible since a long time here in Normandy, I can't test my modded 500D on the night sky. I therefore tested it on daylight with an Astronomik Proplant 807 nm infrared pass filter. This is more an "artistic" photo as I wanted to obtain the look and feel of the old days photos with harsh grain. Canon EOS 500D + Canon EF 55-200mm f/4.5-5.6 II USM at 55 mm F/11. 1/100 s @ 3200 ISO. Darks I did a comparison of the darks for 3 temperatures for 300s at 800 ISO : Before CFA removal is above, after is below. Offset has been removed. Offset Again, before CFA removal is above, after is below. One can see that the offset has quite changed. This is mainly due to two things : - the CFA removal is quite brutal for the sensor, it has an effect of the structure and induces some defects - to insert the copper plate, François had to remove the rear sensors's shielding However the offset is easily removed in post processing. Merry Xmas to all ! Fred

Hi everybody ! I finally jumped on the dark side of the moon, and made my Canon 500D debayered (by Astroghost, in France). I asked him to do one additional thing : adding a copper blade under the sensor with a radiator and a fan to extract the heat out of the box. Astroghost found a way to move the internal thermal sensor of the 500D close to the imaging sensor so that I will now have the right temperature in the Exif. Don't ask me how he did !!! I am still waiting for the camera who is on its way back home, but Astroghost sent me some RAW images and I could start making some measurements. Noise and resolution The picture on the left shows an extract before the CFA matrix removal, and on the right, after removal. One can see that the noise drops significantly, and there is also a real gain in resolution. Sensitivity I analysed areas where the CFA pattern was not removed, in the corners or on the sensor's borders. Nine areas were big enough to be able to do some stats. I compared, for each chanel (red, green, blue) the level of the debayered photosites (area 2) and the levels of the intact photosites (area 1). The average gain is shown below for each chanel : - red : approx +30% - green : approx +30% - blue : approx +75% This explains why the signal to noise ratio increased : - each debayered photosite is receiving more light, so the signal increases - there is no more colour equilibration that multiplies at least the noise of the blue channel by a big number, so the noise decreases => therefore S/N increases. I will post more info when I receive my 500D. Fred