david_taurus83

Just now, newbie alert said:

What range does  your camera have in terms of ADU 

14 bit so 16k

Sounds like it was set to output jpeg 8 bit. Let us know how you get on with this camera as they are a hell of a lot cheaper than the rest!

20 minutes ago, newbie alert said:

20 sec flat sub??

Surely it's going to massively overexpose that it wont show dust bunnies 

With my DSLR I used the av setting 

I aim for 2 to 3 second flats and 8K ADU. They calibrate out the dust bunnies but over correcting the edge.

The 20s subs above were just lights taken against the flat panel in an experiment to try and calibrate.

I've had somewhat of a result with this. Its more of a solution to the problem than finding out the cause and prevention! I had tried taking flat darks, full length darks, CR2 files from NINA, FITS files from Ekos, all the same. I found a method described by Adam Block on his Youtube page where he shows that the flat frame can be manipulated slightly to try and fix over correcting. In his method he applies a value of 0.2 and 0.3 to all the pixels in his master flat (in Pixinsight 1.0 is completely white) and shows how it can affect the calibration. I tried this but I had to use a much smaller value of 0.02. Link to his video below. The best improvement I had though is by unticking a box in the calibration tool in Pixinsight "Separate CFA flat scaling factors". This combined with the Adam Block method gives a much better result. Left image is using standard settings in PI. Right image is with scaling box unticked and master flat with 0.02 value added. I could probably experiment more with the values and try and get a better result but this is a big improvement.

The TalentCell has only 3 hours of power while drawing 12v /1 amp. I have a couple of USB dew bands and they draw just under an amp each on the low setting. The AIRPro needs 12v as well so I don't think it would last very long.

I use a couple of 20amp Anker power banks for my mobile setup but they are only 5 volt outputs. Fine for my dew bands and RPI4. I'm using a DSLR still but if I can also find a reliable, portable 12v powerbank I'd seriously consider selling the DSLR and getting one of the latest OSC astro cameras. Very interested to see what others are using.

+1 for a standard ethernet cable!

Outstanding!

It's the current weather. Make sure the screen is flipped out and switched off as well while your shooting. Try to avoid using LiveView to focus as this really ramps up the sensor temperature.

With regards to sensor temps and having a 10s gap between subs, this won't make any difference. I made a peltier coolbox for my 600D a few years ago purely to make temperature controlled darks. I noticed that the sensor temperature was more dependent on ambient temperature than an exposure length. So a 300s sub didn't have much of a temperature increase over a 60s sub. Maybe a degree or 2. At cooler ambient temps (winter) the sensor used to level out at around 5 or 6 degrees above ambient. At warmer ambient temps (summer) it would get to 8 or 10+ degrees warmer.

I accidentally left the flip out screen closed and lit up one night and I seen temps of over 40°C!

Live View is supposed to be like the live view on a DSLR but it's not great in NINA. You better off to set an exposure time, 10s for example, and make sure the loop tab is selected.

2.5 hours of integration isn't enough imo. My Atik 460, which is more sensitive, doesn't yield acceptable noise reduction until I get around 6 hours or so of data. Even when I had my ASI1600 I was never impressed with anything less than 4 or 5 hours per channel. The reason the dark areas look noisy is because their low signal. That's the reason we keep going for more data, to smooth out those faint areas.

What scope are you using? Whatever the focal length is, try measuring from the optics down the tube to where your sensor is. It should be roughly the same as the focal length.

If you want perfectly illuminated flats every time then splash the cash on an Artesky flats panel...

Or, just get one of those tracing pads as mentioned above. I got an A4 one for less than a tenner on ebay this week for my Redcat. Its too bright though even on its lowest setting so I've found 3 sheets of paper folded is needed to get flats of a couple of seconds for good even illumination. 

Can you see Jupiter? Brightest object in the sky at the moment.

Focused?

Post up your guide log. There will be a PHD folder in your documents. It automatically saves a guide log each session. You can post the log up here and we can have a look.

10s exposures is very short. You don't even need to guide. Are you sure the exposures are not overlapping the recovery time?

https://stargazerslounge.com/topic/380015-red-alert-zwo-camera-sale/

The ASI1600 is still a great camera. Thr only real negative is the microlensing on really bright stars. Even then it depends on the optics your using. This was a stack of 15 minutes subs and its barely visible on Alnitak. 

9 hours ago, tooth_dr said:

Comparison from last night - wasnt totally clear so not ideal (patchy cloud) and i've a bit of fettling to do with the spacing and tilt but interested to hear what you all think?  Going to try Oiii this evening as that would be a good test of haloes.

 

Huge improvement in contrast there Adam! Or is it passing clouds?! Either way, it's nice to see the halo around Sadr is gone.

21 hours ago, tooth_dr said:

Not long home from a long day at work. Clear skies 👍🏼👍🏼
Mounting the filters and noticed a small coating defect on the Sii filter.  Doubt it will have much impact on the image but didn’t expect it 

 

 

I really wouldn't be happy with that on a new filter. I have an OAG and somehow there's a small chip off the edge of the prism. Didn't think much of it as its only for guiding but I set it to close to the horizontal plane of the imaging sensor one night and the subs all had a terrible reflection artifact. What I'm trying to say is you really want everything in the light path to be as perfect as possible.

There's also the APT DC app which tells you how much imaging time you have for any given night.

Is it really that noisy? I know my old 600D used to make a bit of a clatter when the mirror flipped but I don't think it was that bad. 

31 minutes ago, vlaiv said:

I still wonder why is calibration failing.

How do you perform calibration in terms of math? Do you use 32bit numbers, do you create master with any sort of optimization - or simple average without rejection?

I'd have to look at the settings in Pixinsight but I'm sure average is the default setting. Just stack of 50 bias files to create master bias. Then calibrate flats with this and then lights with master bias and master flat. No optimisation used at the lights stage. I've not had this issue when I use NINA but that works with native CR2 files. I think I'll have to give it a go with NINA on a test subject, lights and flats and then follow up with Stellarmate with its FITS files. Compare the 2.

I'm currently using it for my mobile setup (OS on an RPi4) and I can't figure out how to use the app. I only use the app to connect to the device on startup so it updates the time and location, then it's VNC for everything after that.

1 hour ago, ollypenrice said:

It's best to measure the vignetting rather than eyeball a very posterized stretch. Just take the linear master flat and open it in software which lets you measure individual pixel values. I use my stacking/calibrating software, AstroArt, for this but lots of pre-processing packages let you do it. I get considerable vignetting in my Tak 106/2inch mounted filter/full frame CCD setup. The corners will give around 19,000 ADU when the centre is at around 23,500. That's a big difference but it calibrates out fine.

Olly

Hi Olly. The corners of the master flat are around 4600 ADU and the centre is 6300 ADU but camera is 14 bit so only goes up to 16k.

9 hours ago, vlaiv said:

That is rather interesting. Stddev (avgdev) value shows significant distinction.

Stddev is mix of bias (read noise + read signal) and dark current noise. It shows 8.6ADU in first case and 10.7ADU in second case.

That would make dark current expressed in ADU around 6.366.

Can you read off FITS header information? It should show black level automatically removed from raw file when converted into fits - at least FitsWork creates that Fits header - here is example of one raw file converted to FITS:

No, FITS header doesn't show anything like that.