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By Padraic M
I spent the full night out last night and got 6 hours of Ha lights on the Bubble and the Horsehead. Reasonably pleased with the results, but even though I followed my usual process and got good focus statistics in APT, I am slightly out of focus with roundy stars and some are even slightly donutty. Samples are attached below.
- After getting close to spot-on focus, the APT Bahtinov Aid showed a focus distance oscillating from -0.02 to +0.02. Seeing seemed good to the inexpert eye. Not so sure about transparency as there was some thin, wispy cloud throughout the night. So, I started the night's imaging with focus 'Close' rather than 'On' focus.
- Different subs show different quality stars, ranging from small donuts to circles.
- HEQ5 Pro Rowan; SW Esprit 80 with field flattener, SW stock manual Crayford focuser; ZWO EFW Mini; Baader 1.25" 3.5nm Ha filter; ZWO ASI1600MM Pro binned 1x1 @ -20c.
- AA Starwave 50mm guidescope with ZWO ASI290mm Mini guidecam binned 2x2.
- All subs are 300s, gain 139, offset 10.
- Polar alignment with Sharpcap to 17 arcsec ("Excellent"); capture with APT; guiding with Phd2. Focus with Bahtinov mask and APT Bahtinov Aid. Stacked in DSS with Darks, Flats and Dark Flats.
- Mount is well balanced in RA, but is very camera-heavy in Dec.
- PHD2 guiding was around 2"/px. Imaging pixel scale is 1.9"/px.
- Do I put the round stars down to seeing, given that the Bahtinov Aid focus distance was bouncing equally above and below zero?
- Can poor seeing cause the donut stars?
- Would an electronic auto-focuser do any better in this situation?
- Would the Seeing Monitor in Sharpcap give useful information? I didn't think to use it last night.
- Could my guiding performance, and possibly the Dec balance, have affected the image quality in this way?
- What are my options in future - abandon imaging for the night? Bin all images in software 2x2 or 4x4 to sharpen the stars at the expense of lower resolution?
- Other suggestions?
Sample 1: Detail from a single 5-min sub of Bubble nebula at 100% showing round stars, and a blurred bubble.
Sample 2: Detail from a different sub of the Bubble nebula at 400% showing donuts
Sample 3: Detail from a 5-min sub of the Horsehead nebula at 100%, showing both round and donut stars
Finally, both images stacked, calibrated and stretched, scaled to 4x4 in Gimp. 28x300s Ha on bubble, 22*300s Ha on horsehead.
As I am ready to invest in this new CMOS camera from ZWO the Asi2600mc pro , I am trying to understand why this camera will be better than a DSLR with a filter Infront....
How this camera will give me better images ?
I have used DSLR camera some years ago , when I was starting this hobby but after that I have been through mono ccd's , since the time I realized that unfortunately due to lack of time I can not continue with mono imaging and filters....
So I am thinking to give it a try with a brand new, let's say technology of Color CMOS and see what I can get out of it....
I see some really nice examples on the net but am I going to achieve them ?
The Zwo Asi294mc pro widely used around the world is also very promising...Discontinued already as I hear...Amp glow issues....is it really so annoying ?cheaper than the new asi2600 MC pro by half price....
So can someone persuade me that the Zwo Asi2600mc pro is better than the others ? 🤔
Can I please ask, is there anyone out there with the following or a similar setup to this:
William Optics Z61 Scope + WO 61A Flattener + ZWO ASI533MC Pro (or other ZWO Camera) ?
Currently, I have been using the following setup:
William Optics Z61 Scope + WO 61A Flattener + Nikon DSLR
However, by the end of the week I am hoping to have this new setup:
William Optics Z61 Scope + WO 61A Flattener + ZWO ASI533MC Pro
I was really just wondering how the more experienced out there had configured/connected their equipment together?
How people connect their ZWO cameras to the flatteners?
Are the flatteners still required with the smaller sensor cameras ?
I was just wondering if anyone has any pictures of similar setups to above please (equipment trains)?
Thanks in advance for any comments or advice.
Question, is my pier out of level if I'm trying to PA (with asiair pro) and both directions are moving when I adjust the alt bolts? I can't get the mount polar aligned.
Mount neq6 pro
Pier mounted on a concrete slab
OTA c8 with .63 reducer
Camera asi294mc pro
Thanks in advance