Risingcam IMX571 not a gamble?

[ONIKKINEN]

4 hours ago, Stuart1971 said:

768 wow that is a large offset…😮

It honestly doesnt matter with 65k ADUs to spend. I tested mine and found that 500 (equivalent to offset 50 with ZWO) would also work to bring the noise floor above 0 but just used the stock because its not that relevant.

[Stuart1971]

13 minutes ago, ONIKKINEN said:

It honestly doesnt matter with 65k ADUs to spend. I tested mine and found that 500 (equivalent to offset 50 with ZWO) would also work to bring the noise floor above 0 but just used the stock because its not that relevant.

Hmmm, not sure about that, I think the offset is very relevant from what I have read….🤔

[ONIKKINEN]

6 minutes ago, Stuart1971 said:

Hmmm, not sure about that, I think the offset is very relevant from what I have read….🤔

The important part is that 0 pixels have a value of 0 with the shortest exposure time (bias frame, just containing read noise). Increasing the offset high enough to push the lowest pixel values above 0 is the key thing. Whether its a lot more or just a bit more is far less important with such a high fullwell and dynamic range camera.

But yes, you lose 268 ADUs of range with 768 compared to 500 offset which i find is not relevant.

[Stuart1971]

5 minutes ago, ONIKKINEN said:

The important part is that 0 pixels have a value of 0 with the shortest exposure time (bias frame, just containing read noise). Increasing the offset high enough to push the lowest pixel values above 0 is the key thing. Whether its a lot more or just a bit more is far less important with such a high fullwell and dynamic range camera.

But yes, you lose 268 ADUs of range with 768 compared to 500 offset which i find is not relevant.

Ok, I am coming from years of using a CCD, so this  CMOS lark is all new to me, trying to get my head round it, but everyone I talk to gives varying options on starting gain and offset settings for the QHY268c especially as it had four Modes to choose from too, where as the ASI has only one….🤯🤯

[ONIKKINEN]

1 minute ago, Stuart1971 said:

Ok, I am coming from years of using a CCD, so this  CMOS lark is all new to me, trying to get my head round it, but everyone I talk to gives varying options on starting gain and offset settings for the QHY268c especially as it had four Modes to choose from too, where as the ASI has only one….🤯🤯

Gain is very important, true. RisingCam/Touptek cameras also have 2 readout modes and the gain values are not relatable between these.

The ideal gain (IMO) is gain 100 in the HCG mode (high conversion gain or high gain mode, depending on software used to capture). This is the best gain for a low readnoise of 0.86 electrons, while still retaining a fullwell of 16k and a dynamic range of over 14 stops. The lower gain readout mode is realy only useful if you need a fullwell of 51k for some reason, but with it readnoise also triples so the dynamic range remains the same.

To further complicate things there is a "low noise" setting for both readout modes that does something. Or does it? I dont know, its just on for me. Havent actually tried measuring sensor stats without it so could be magic and tricks for all i know.

[Stuart1971]

8 minutes ago, ONIKKINEN said:

Gain is very important, true. RisingCam/Touptek cameras also have 2 readout modes and the gain values are not relatable between these.

The ideal gain (IMO) is gain 100 in the HCG mode (high conversion gain or high gain mode, depending on software used to capture). This is the best gain for a low readnoise of 0.86 electrons, while still retaining a fullwell of 16k and a dynamic range of over 14 stops. The lower gain readout mode is realy only useful if you need a fullwell of 51k for some reason, but with it readnoise also triples so the dynamic range remains the same.

To further complicate things there is a "low noise" setting for both readout modes that does something. Or does it? I dont know, its just on for me. Havent actually tried measuring sensor stats without it so could be magic and tricks for all i know.

Yes this is the issue, the QHY seems a bit different with its ideal settings compared to the RisingCam and ASI version, so I need to learn…👍🏼

[tomato]

I use the 268c in DSO Photographic mode and don’t touch it, the Risingcam will be alongside it, same scope, same sky, same time etc, so I will try to dial it on the actual image quality.

[ONIKKINEN]

2 hours ago, Stuart1971 said:

Yes this is the issue, the QHY seems a bit different with its ideal settings compared to the RisingCam and ASI version, so I need to learn…👍🏼

If you have Sharpcap pro, you can run a sensor analysis on the camera that will clear out most of the confusion on the different settings.  You will get a result like in the attached pic, measured stats on the sensor. If you want to get the data from all the readout modes you need to run the analysis on all the modes separately. Will take a while, so dont run it if you need the camera (or need to do anything else) for a while.

My RisingCam IMX571C in high conversion gain mode and low noise on:

[Stuart1971]

1 hour ago, tomato said:

I use the 268c in DSO Photographic mode and don’t touch it, the Risingcam will be alongside it, same scope, same sky, same time etc, so I will try to dial it on the actual image quality.

On what settings gain and offset….??

[tomato]

For the 268c, Gain 30, Offset 30, 180 s exposures, IR/UV cut filter in place, Bortle 5 sky.

[Stuart1971]

4 minutes ago, tomato said:

For the 268c, Gain 30, Offset 30, 180 s exposures, IR/UV cut filter in place, Bortle 5 sky.

Do you ever use the next gain mode up, the high gain mode, I have heard that is good on Gain 0 and offset 30….?

[tomato]

I confess I haven’t explored the other modes, I was sufficiently impressed with the initial results I obtained on both BB and NB imaging, that I’ve not strayed from them. 
Another unfortunate side effect of very limited imaging time, I guess.

[tomato]

18 hours ago, tooth_dr said:

Congrats on the purchase.  I am also very keen to see how the camera works out.   I agree it does look a bit less robust and there also doesnt seem to be any way to adjust the faceplate of the camera to correct tilt.  Whats the back focus camera, looks to be less that 17.5mm?

Sorry, just seen your question, the back focus is quoted as 17.5 mm, that’s what I will work to when mounting the camera. I’m just working out how to put the UV/IR cut filter into the optical train.

[Stuart1971]

Well just been playing with my new QHY268c and thought I would try a few darks, so normally I would just put the lens cap on the scope, in the obsy, which is pretty dark even in the day, and Snap away, but with this camera I was getting some light in,  through the filter drawer or somewhere, never had this issue with my old CCD, so this one seems that sensitive that I can’t do it this way, I really though it would be dark enough in there, even in the day with lens cap on, so had to wait till it was dark outside before I could do them….

Does this sound normal….it’s fine now it’s dark….

 

[ONIKKINEN]

1 minute ago, Stuart1971 said:

Well just been playing with my new QHY268c and thought I would try a few darks, so normally I would just put the lens cap on the scope, in the obsy, which is pretty dark even in the day, and Snap away, but with this camera I was getting some light in,  through the filter drawer or somewhere, never had this issue with my old CCD, so this one seems that sensitive that I can’t do it this way, I really though it would be dark enough in there, even in the day with lens cap on, so had to wait till it was dark outside before I could do them….

Does this sound normal….it’s fine now it’s dark….

 

I cant take darks with the camera in the scope with mine. I have to take it out and properly plug the camera to get no extra signal. Also note that some plastic caps are partially transparent in infrared, in which the camera is still quite sensitive so extra signal could find its way through the aperture of the scope.

[Stuart1971]

47 minutes ago, ONIKKINEN said:

I cant take darks with the camera in the scope with mine. I have to take it out and properly plug the camera to get no extra signal. Also note that some plastic caps are partially transparent in infrared, in which the camera is still quite sensitive so extra signal could find its way through the aperture of the scope.

What about at night after a session, with lens cap on, does that not work either for darks…? My Tak lens cap is metal…

Edited December 10, 2021 by Stuart1971

[ONIKKINEN]

3 minutes ago, Stuart1971 said:

What about at night after a session, with lens cap on, does that not work either for darks…?

Focusers must have a gap between the body and the focuser tube to be able to move and this will let a couple of photons through. Also, the lens cap and mirror cap (newtonian) are really not airtight and could let light trough in some micron gap somewhere. Most of the time i am imaging from Bortle 6 or worse so there is no chance that i am getting decent darks with the camera in the scope. At my gain of 100 in the HCG mode i will get 4 ADUs of signal for every single photon, so just a couple of them on a long exposure and the dark is not a good representation of a pure dark anymore.

[Stuart1971]

13 minutes ago, ONIKKINEN said:

Focusers must have a gap between the body and the focuser tube to be able to move and this will let a couple of photons through. Also, the lens cap and mirror cap (newtonian) are really not airtight and could let light trough in some micron gap somewhere. Most of the time i am imaging from Bortle 6 or worse so there is no chance that i am getting decent darks with the camera in the scope. At my gain of 100 in the HCG mode i will get 4 ADUs of signal for every single photon, so just a couple of them on a long exposure and the dark is not a good representation of a pure dark anymore.

Yes, well I took the camera off, put it inside upside down on my desk, so no chance of any light getting in, and took a 10 minute dark for the hell of it, and it was perfect….so it’s deffo light creeping in from somewhere….so wow this sensor is super super sensitive….my olde SX M25c CCD camera would never have picked up that….

[tomato]

It’s not possible to take darks on the RASA, so I took my 268 darks with the camera off. I will try to take the Risingcam darks with it connected to the Esprit which has a soft lined metal close fitting lens cap, and a solid optical train, (no filter drawer or wheel), otherwise I have to realign the camera again with it’s twin if I have to take it off.

Got the first subs on the Risingcam last night, on the first look they seem better than the QHY subs but that’s for another post…

[Stuart1971]

40 minutes ago, tomato said:

It’s not possible to take darks on the RASA, so I took my 268 darks with the camera off. I will try to take the Risingcam darks with it connected to the Esprit which has a soft lined metal close fitting lens cap, and a solid optical train, (no filter drawer or wheel), otherwise I have to realign the camera again with it’s twin if I have to take it off.

Got the first subs on the Risingcam last night, on the first look they seem better than the QHY subs but that’s for another post…

Interested to know how you get in with the esprit and darks, my Tak lens cap is metal and soft lined too, and was hoping to be able to,take the darks at night after a session, but I do have a Baader UFC filter housing in the optical train….🤔

[gorann]

This is a bit off topic but I was looking through the Risingcam web store (through Ali Express) and found that they are selling a camera with the IMX410 colour sensor. This is the same 24 Mp (6 µm pixel) full frame sensor as in ASI2400MC or QHY410 but at 75% of the price (about 2600 Euro without VAT if I calculated it right). An excellent sensor as far as I can tell with big pixels (104 ke- well depth) suited for longer FL scopes. I guess no one here has pulled the trigger on it yet.

https://www.aliexpress.com/item/1005002530783852.html?spm=a2g0o.store_pc_groupList.8148356.32.4b1a243fqbSqjY

[Stuart1971]

A quick question for you experienced IMX571c sensors users….when taking darks does the offset matter, by that I mean does it have to match the light frames, I know the gain does….??

[ONIKKINEN]

1 minute ago, Stuart1971 said:

A quick question for you experienced IMX571c sensors users….when taking darks does the offset matter, by that I mean does it have to match the light frames, I know the gain does….??

Yes, same offset for everything all the time. Otherwise none of your calibration frames will do what they are supposed to. You can change offset later if you want to for some reason, but then you will need a new set of calibration frames.

[tomato]

4 hours ago, gorann said:

This is a bit off topic but I was looking through the Risingcam web store (through Ali Express) and found that they are selling a camera with the IMX410 colour sensor. This is the same 24 Mp (6 µm pixel) full frame sensor as in ASI2400MC or QHY410 but at 75% of the price (about 2600 Euro without VAT if I calculated it right). An excellent sensor as far as I can tell with big pixels (104 ke- well depth) suited for longer FL scopes. I guess no one here has pulled the trigger on it yet.

https://www.aliexpress.com/item/1005002530783852.html?spm=a2g0o.store_pc_groupList.8148356.32.4b1a243fqbSqjY

Yeah, since purchasing the 571, Risingcam send me a daily email tempting me with all kinds of astro gear at discounted prices, but I will need another dual band filter at some point so I'm not tempted.

[nfotis]

9 hours ago, gorann said:

This is a bit off topic but I was looking through the Risingcam web store (through Ali Express) and found that they are selling a camera with the IMX410 colour sensor. This is the same 24 Mp (6 µm pixel) full frame sensor as in ASI2400MC or QHY410 but at 75% of the price (about 2600 Euro without VAT if I calculated it right). An excellent sensor as far as I can tell with big pixels (104 ke- well depth) suited for longer FL scopes. I guess no one here has pulled the trigger on it yet.

https://www.aliexpress.com/item/1005002530783852.html?spm=a2g0o.store_pc_groupList.8148356.32.4b1a243fqbSqjY

 

They are also offering the equivalent of the ASI 6200, I think (IMX455?).

In reality, I suspect that not many people have a need for a full frame sensor (and its costs regarding filters, tilt, etc)

 

N.F.