Way better! Yeah given your exposure time this is a squaring issue. Your CCD plane is tilted. Should be very easy to fix.
I think it is actually the drawtube. The cheap GSO ring clamp pushes the
2" barrel off axis a bit.
Just by eye it looks at least 0.2mm, more like even a whole millimetre.
The qhy-forum post I mentioned below says this is unacceptable for
a fast optics Newt like this. This might be a great part of the problem
right there.
Also, Marc, how exactly do you do a RGGB debayer. Are the settings
correct that I have entered here in the manual text box in Neb?
This is what I get when I select CIM debayer and 7.8 sq pixels 1x1:
Its drawtube/fociser flop.
If the CCD was out slightly, you will find only one side out a little. The whole image is off, meaning focuser/drawtube flop. You need to stregthen it somehow.
The later model QHY-8 cameras have tilt adjustments (3 plastic spirniged screws).
I think it is actually the drawtube. The cheap GSO ring clamp pushes the
2" barrel off axis a bit.
Just by eye it looks at least 0.2mm, more like even a whole millimetre.
The qhy-forum post I mentioned below says this is unacceptable for
a fast optics Newt like this. This might be a great part of the problem
right there.
Also, Marc, how exactly do you do a RGGB debayer. Are the settings
correct that I have entered here in the manual text box in Neb?
This is what I get when I select CIM debayer and 7.8 sq pixels 1x1:
Steve
Sounds about right. Tilt is a killer on a field. Sometime I get it right. I found to use extension tubes and keep the focuser barrel in as much as possible helps. I also use GSO 10:1 focusers.
Sorry I use CCDStack not Neb for processing but from your colors you're using the right pattern.
RG
GB
two greens, one red and one blue in that order. Two Gs are recombined in one pixel.
I think I've removed most of the off axis tilt tonight because the
focus seems a lot crisper.
The only misalignment now might only be collimation, seen here
with this crop of NGC2822 and Miaplacidus.
Edit: Eta Carina from tonight added too.
Mia was almost centre to the FOV so the ghost shows the extent of the
collimation.
I'm glad that blooming type artifact is gone too.
This camera is a bloody beauty. The dynamic range is lovely under a
big light bucket. This is just a 10s shot series and stars have saturated.
G'Day Steve, These settings are correct for nebulosity. I also found just doing a RGB manipulation is all you should need for OSC imaging. I didn't see any real advantage in splitting the image into 3 colours, manipulating the recombining.
Looking better Steve.
I didn't see any real advantage in splitting the image into 3 colours, manipulating the recombining.
I got into the habit of splitting channels because the very first times I used CCDStack I used to get color ringing around my stars. That was due to undersampling and doing the data rejection on color subs. After a chat with Stan Moore he advised me to process and stack every channel independently and in my case it did smooth out star edges. The problem was gone. I never had the problem with the C11 though because my image scale is 0.4 asp. Overtime I 've also found that processing separate channels allowed me to be more selective with noise reduction because I always seemed to attract more noise in green and blue pixels when the reds have always been relatively clean.
Tonight I'm going to try binning for the first time on the QHY-8,
weather permitting. I have never owned a camera capable of
binning so I'm flying blind tonight....as I do most nights
If any QHY-8 gurus could help me...
I plan to:
Do a deep set of something like M83...by deep I mean maybe over
30 sec! WOW...unusual territory for Steve
For the lum/raw frame set.
Then do a binned 2x2 set for RGB data.
I assume the 2x2 set are done at 30sec exposures also? or
am I way off here?
Also, so far I have used Gain=zero and offset at 126 (for 5-10sec sets)
Is this around the mark for a good offset or logic tells me that the offset
will be exposure length dependent......go longer and the histo creeps up
to the right therefore offset can be less?
The offset is a set and leave setting, same for gain.
You could take the color set at a shorter exposure time with 2*2 binning.
When i do 600 Sec L exposures at 1*1 binning then i take the RGB's at 2*2 binning and 300 Sec.
In the end, the RGB is only there to get the colors in the picture and just have to be noise free.
This is with the QHY9, so in your case it might be different and someone owning a QHY8 might say something different.
The offset is a set and leave setting, same for gain.
You could take the color set at a shorter exposure time with 2*2 binning.
When i do 600 Sec L exposures at 1*1 binning then i take the RGB's at 2*2 binning and 300 Sec.
In the end, the RGB is only there to get the colors in the picture and just have to be noise free.
This is with the QHY9, so in your case it might be different and someone owning a QHY8 might say something different.
From tonight.
NGC3324 was the target.
Inspired by Danielsun's great result in the Deep Sky section
here is a quick 17 frames at 15sec.
No Darks, flats or bias frames.....some hot pixel artifacts
showing in processing.
As for your comments earlier regarding taking lum at 1x1 and RGB at 2x2 with the QHY8... If you bin the QHY8 2x2, the resulting image is monochromatic, not RGB... It is unfortunate, as it would make a good camera fantastic... 2x2 colour binning is supported by some of the newer sony sensors, but not the ICX-453 in the QHY8. Your best bet is to capture as much data 1x1 as possible.. capturing a lot of 2x2 data might work for brightening the image, but it will not be a true luminance layer in that you would be getting your best resolution and detail from the 1x1 colour image, and the 2x2 monochrome lum would just be used to brighten up the image...
I'm not quite sure which lobe of the NGC3372 complex
this one from tonight is. I looked at Mill's great widefield
shot in DS to try and pinpoint it but I'm about to give it away
for the night...work tomorrow
Interesting little string of stars highlighted in the neg version.
Grabbed a few favourites again tonight....
Apologies for tacking these on to the 'first light' thread but
it's a better way for me at least to check my progression.
This one is similar curves but different noise reduction.
More frames needed. A different curve to show Trap detail.
I discovered last night I have a drive PEC index error and
the PEC was engaging at a different point on the curve
to where it should. This means all of my recent results have
had PEC actually working against me rather than correcting
or zeroing most of it out.
This is not all bad news. It means the pics can only get better
once it's fixed. The culprit is the toothed belt gear on the end
of the worm. It has somehow slipped and turned approx 2hrs
on my 'clockface' index wheel. Loose grubscrew!
Tonight I grabbed another set of the 3372 complex
and it stitched together quite OK with my 18/19Feb set.
This is a good sign that the MPCC is keeping things
under control as far as coma and field flatness goes I suppose.
You can see the join, not a lot of effort done here
to hide it.
These cameras are such a pleasure to use.
Yeah given your exposure time this is a squaring issue. Your CCD plane is tilted. Should be very easy to fix.
