That does look a bit noisy but NGC6357 is quite faint. Maybe you've got your gain set too high? I used gain 12% and offset 110 in the ascom QHY9 setup box. Pedestal 88.
What have I forgotten after so long away? Were you getting this Marc?
This is not normal. Make sure your power cable between the controller and camera is plugged in the right way. The EMC ring should be on the DC102 side not the camera side. If reversed you will get lots of noise.
This is not normal. Make sure your power cable between the controller and camera is plugged in the right way. The EMC ring should be on the DC102 side not the camera side. If reversed you will get lots of noise.
Cheers
Mark
That's interesting. Will keep this in mind. I always had it the right way but it's pure luck. Never thought much about it.
So I assume it acts like a ferrite block on USB lines? Having said that on USB lines would you have the blocks closer to the cam or hub or doesn't matter?
I've only got as far as bolting it to the scope, I calibrated it , though my settings are way different than yours I got 20 gain and 80 offset, I'm happy that that is correct so once I get some decent skies. It's clear here but blowing a gale. Rain due in a couple of hours so it will be days before I get a chance.
This is not normal. Make sure your power cable between the controller and camera is plugged in the right way. The EMC ring should be on the DC102 side not the camera side. If reversed you will get lots of noise.
That's interesting. Will keep this in mind. I always had it the right way but it's pure luck. Never thought much about it.
So I assume it acts like a ferrite block on USB lines? Having said that on USB lines would you have the blocks closer to the cam or hub or doesn't matter?
Those EMC suppression lumps are ferrite beads. It's a few coils of wire over a ferrite core and acts as a low pass filter, removing high frequency noise. You normally position them at the end where the nasty stuff is coming from to prevent it radiating as well as to clean whatever is coming over the cable. In the case of USB cameras I'm not sure if the concern is radiated EMC, noise going in or noise coming out (the camera will probably contain a DC to DC converter which could generate noise).
As a software guy who works with electrical engineers my tongue in cheek view is that ferrite beads are a kludge to get around poor hardware design
Those EMC suppression lumps are ferrite beads. It's a few coils of wire over a ferrite core and acts as a low pass filter, removing high frequency noise. You normally position them at the end where the nasty stuff is coming from to prevent it radiating as well as to clean whatever is coming over the cable. In the case of USB cameras I'm not sure if the concern is radiated EMC, noise going in or noise coming out (the camera will probably contain a DC to DC converter which could generate noise).
As a software guy who works with electrical engineers my tongue in cheek view is that ferrite beads are a kludge to get around poor hardware design
Cheers,
Rick.
Thanks for the info Rick. I have always used ferrite blocks on my USB lines. It helped during camera readout with the QHY8. I used to get little wide dots in the picture immediately followed by a dark line.
With the QHY9 I still get this kind of artefact but only on very bright objects. Last night I framed the HH and Orion on 5min exposures with a 200mm lens. Just fits the whole thing nicely. Obviously I did burn the core as I wanted to get some of the neb in between the HH and M42. The core values are well over saturation. I had the clamping off but it still came out with a dark shade in the direction of the read out left of the neb. See attached. I don't know if it's a driver issue at this stage.
My SX H-18 was producing dark lines on one side (readout side?) of bright stars when binned x2. The fix was to turn down the gain. Unlike the QHY cameras this is a physical trim pot on the H-18.
My SX H-18 was producing dark lines on one side (readout side?) of bright stars when binned x2. The fix was to turn down the gain. Unlike the QHY cameras this is a physical trim pot on the H-18.
Cheers,
Rick.
Good stuff Rick. I'll play with the gain settings again and report back.
If you look at the S video cable that comes with the QHY CCD camera's it has a lump (for want of a better word) towards one end. It must be plugged into the DC102 not the camera end. When I got it wrong there was a lot of noise in the subs (similar to Chris's pic).
Marc try taking a short 1 - 2 sec exposure before the long exposure. I have had that line happen a couple of times on bright objects and short exposure between long exposures seems to get rid of it for me.
Testing has begun, gain 20 and offset 80
According to the calibration proceedure this was the setting BUT having just tried a 10 min exposure on ngc253, all the dim details are missing .... Which suggests offset too low perhaps.
Trying with offset at 100
Back soon
Ok back with the 100 offset and much more faint detail has emerged. Will try 90, 110 and 120 to see what happens.... Yep very technical ..... But I tried the proper way and it's wrong.
Interesting point, I stacked a single frame in deep sky stacker, settings in fits needed to be unpicked, it saves as a gray file, I imported to Photoshop and immediately converted to adobe rgb profile.... Photoshop couldn't cope with working in gray.
Love the resolution this thing has wow.
Last edited by Alchemy; 23-09-2011 at 10:28 PM.
Reason: Next exposure
I have mine set at Gain = 15, Offset = 115 if that helps. Below is a 5 min Ha test shot of M8 through a 98mm refractor in heavy LP. No processing just a dark subtraction and autoscale in CCDstack.
Ok done shots now at 80 100 and 110
Very interesting to pull the fits file into deepskystacker, use the sliders to set the histogram BEFORE stacking , flick between exposures and effects of offset is obvious . 110 is waaaay too much .
I have mine set at Gain = 15, Offset = 115 if that helps. Below is a 5 min Ha test shot of M8 through a 98mm refractor in heavy LP. No processing just a dark subtraction and autoscale in CCDstack.
Thanks marki, I tried the u beaut method for calibrating, I got full wells at 17 gain, but they suggested to allow a few % more to allow for non linear responses so 20 it was, I think qui suggests 20 as a good place for beginners anyway.
I'm narrowing it down to somewhere between 80 and 100 will see how it goes. I guess with varying gains the offsets will be different.
Oh thanks for the explanation of the lump on the cable.
To those struggling with the offset pulling it into DSS is working a treat.
Actually pulling the fits files into maxim is helping too, star centers peaking at about 62300 so I reckon I can up gain by one notch.
Whew glad we've got clear skies, could be a while tinkering. The hiatogram in maxim also shows a min value of 900 for all pixels so offset must be about right....... Errr maybee.
I used to set mine at gain = 3 and offset = 120 on the old power board. When this was replaced (my fault) and the camera returned it calibrated best to the levels I use now 15 and 115 respectively. So there is going to be lots of differences between individual cameras if the same camera can vary so much. On my current settings min = 450ADU and max = 65480 ADU which is about as good a dynamic range as I am going to get. Interesting that you were told to lift the gain above saturation, I have always been told to stay just below it so you have the max dynamic range with the min noise.
, will watch your progress with interest.
I have always used ferrite blocks on my USB lines. It helped during camera readout with the QHY8. I used to get little wide dots in the picture immediately followed by a dark line.
