Herra Kuulapaa

Ah, I have forgotten much data during the years. Anyway, here is one comparison done with both full spectrum RGB and mono. Cameras were D5100 and the light was white led through Ha filter. Identical exposure by all of the variables and true sensor raw extracted. And a quick n dirty histogram: Far right are RGB red pixels. Second form the right is mono. This is the amount of signal gained (~8,5%) by micro lenses with IMX071 - but don't extrapolate this into any other sensor or even mono mod type. It's only valid with the process I used and polishing deeper or shallower will most likely result something else. Anyway, far on the left are the blue pixels and second from the left are green pixels. Remember, there is signal in all of the three color pixels despite of the red Ha color and RGB pixels have absorption as well - removing them will slightly compensate lost micro lenses. Edit: Summary: Now I'm talking about IMX071 sensor (Nikon D5100). There will be increased spatial resolution because all of the mono pixels record the signal same way. This is seen with mono CCD vs RGB CCD comparisons as well. Mono mod will result a decrease in signal (lower QE), but the difference is not many fold like mentioned before and it's easily compensated with small increase of exposure time. Best option will still be a native mono CMOS astrocamera, but a DSLR monomod is a valid and possible path into narrow band imaging when the budget is tight and especially if a full frame sensor FOV is preferred.

Target is exactly the same, but I don't remember how the exposure was so it's better to take this only as an example of spatial resolution. In this sense it's hard for me to accept that the full monochrome signal would have a lower spatial resolution than RGB, especially with narrow band such Ha.

Unfortunately I've sold the mono and converted RGB to cooled so it's not possible to conduct more tests at this point. I must say that the demosaicing algorithm is very good to replicate almost same detail level. The true difference comes in narrow band where all the four matrix pixels will record signal same way. Here is a small comparison of the same full spectrum target in true raw: RGB: Mono:

Hmmm., there is something funny in your test. It might be the sensor too, because Exmors seem to behave very nice after mono conversion. They have much more narrower conductors than 1000D though, which may decrease the amount of photons hitting them. Here is some real world testing Here is a comparison of full spectrum RGB D5100 on left vs D5100am (astromono) on right. Both files are true raw (non debayered). click it large

Interesting, did you debayer a D750? How was the sensor cover glass?

Good job! The comparison however looks a bit soft. I wonder if the focus was spot on? Did you process the images without demosaicing? There is some sort of pattern in mono image, but it should be flat and uniform. Left image below is a true raw converted RGB image (not demosaiced and showing the RGB filters) and the right one is mono, also true raw converted. It doesn't show any pattern because there is no filtering anymore.

Hmmmm., It can be very difficult in real life due to the fact that the sensor response is quite low in UVA range compared to VIS. This results UVA signal being just a tiny fraction of total signal - UVA gets swamped heavily by VIS. Interesting idea though and UVA should be there, if one just can separate it

It's so bright here in north this time of year it makes no sense even trying astrophotography. So, more UV: D800 reference: And D600am (astromono) UVA:

Hi Ola, I've used my D600am as well and it's doing great with Ha. Can't recall which ISO it was, but propably 200 or so. And with that the full well capacity is nearly 40ke-, which means absolutely fantastic dynamic range! Your 6D should be very similar what comes to the saturation maximum. I however can get slightly larger magnification with D5100am smaller pixels (4.78um vs 6um) so I've mostly used it lately. I have also one monochrome D800 sensor, but haven't yet installed it to camera. It has practically same size pixels with D5100 (4.78um vs 4.88um) so it should really rock also in solar imaging.

I posted this on the Solar imaging thread, but I guess I won't get trown into jail linking it here as well Anyway, I had this idea, a crazy judged one, to image sun as a full sphere in Ha with DSLR. It came out rather good I think.. Taken yesterday, first of May.

Do you mean some sort of multispectral imaging? I've given some thought taking red channel from H-alpha, green from O-III and blue from UVA - should be rather interesting

Yes, it has been taken with a UG1 UV pass filter and IR block. It's quite interesting how flowers look different in UVA light than in VIS. Visually transparent SPF 20 sun screen in UV:

So quiet.. Astrophotography isn't the only use for monochrome cameras. NIR and UVA can be imaged quite easily with mono camera. In fact removal of UVA absorbing RGB filters makes the total short wavelength response better.

I dont think it's the "missing" grounding. There should be a connection from the sensor metal frame to camera body without it as well. Error sounds to me somekind of connector issue. Is the sensor main connection cable intact?

Yes. you need a IR/UV cut, but not when you're using already a narrow NB.