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By Matt Hayden
What with all this locking down business and home schooling my ten year old son, I have dusted off my TAL-1 and created a slightly less than ideal setup in his room. The westward facing window has been providing great views of the moon and venus over the past week. Obviously doing this indoors is not great (the floor is pretty solid, as is the TAL stand!) but it does mean we get to use the scope every evening, rather than going through the process of carrying the whole rig outside every day.
I have a T-mount converter for my old-ish Pentax k-M DSLR, but have quite disappointing results with the camera, when compared to the observed image using the eye. The eyeball view is nothing less than banging - crystal clear detail with a 25mm eyepiece, strong contrast - it's spectacular. I add the camera with an eyepiece inside a tube, and can't replicate the same result, or anything like it. It's OK, but not good enough.
I've cleaned the eyepiece today and collimated the scope. The primary mirror looks fine other than a couple of tiny dust particles, no scratches or weirdness on the coating. The camera is working pretty well as far as I can tell. Apart from a little clumsy-ness with the adjustments, the clarity in the eyepiece suggests it's all working fairly well. Photo attached of best result from last night.
My question is: is this a focusing issue or some sort of aberration? Should I expect focusing to be difficult in the camera eyepiece? What's going on?! Does anyone have any other tips I can try to get this working better?
I am wondering if anyone has a suggestion that might help me
My imaging set up is an RC reflector with an FLI proline 16803 camera and 50mm Astrodon filters (LRGB + 5nm narrow band)
I have had a string of issues...everything from my mount had mechanical problems to my telescope had issues with the mirror cell to some family distractions...but at long last I seem to have everything working with the exception of the Astrodon Ha filter.
Attached are representative 30minute subframes of the horse head and Pacman nebulae in Ha, SII, and OIII. I get similar results with different objects although for bright, broad spectrum targets like M42, I will get data from the Ha filter (much as the stars shine thru on the HH and Pacman) although even that data does not comport with other imager’s Ha images of those objects. The LRGB performance appears to be normal. My hypothesis is that this Ha filter is defective, perhaps not centered on 656.3nm
I have contacted Astrodon and exchanged a couple of emails with Cary Chleborad seeking some help. At first he claimed there was no issue because with enough manipulation some data could be extracted from the Ha. Later, when confronted with the other narrowband frames and the obvious difference to the Ha, at first he ghosted me, but when I said I would ask other imagers for help, he responded with a new position stating that because of the way the filters are made and their robust quality processes, it is impossible for the filter to be defective and therefore something else must be at issue. He does not offer a suggestion of what might be the problem, nor is he interested in having me send the filter back for evaluation. Frankly, I’m more than disappointed given the premium I paid for Astrodon filters
All that aside, and taking Cary’s position at face value, does anyone have an idea of what might cause this behavior other than the filter? In a perfect world, does anyone live in the Austin, Texas area who would be willing to try my filter one night and see what they get with their equipment?
The attached link is to the raw, uncalibrated files right off the camera. I think a simple blink process in PixInsight will show what I’m talking about.
I’m a little at my wits end, please help!
I made an acquisition and processing tutorial a while back (3 years ago? Yikes!) and it is fairly dated in terms of what I'm doing these days. I've been asked for a long time to make a new one showing what I'm doing these days. Specifically how I'm processing a single shot image for both the surface and prominences and how to process them together to show prominences and the surface at once. I've abandoned doing split images and composites and strictly work from one image using layers. Acquisition does not use gamma at all anymore. Nothing terribly fancy, but it's not exactly intuitive so hopefully this new video will illustrate most of the fundamentals to get you started. Instead of an hour, this time it's only 18 minutes. It's real time from start to finish. I'm sorry for the long "waiting periods" where I'm just waiting for the software to finish its routine, it lasts 1.5 minutes and 30 seconds tops typically at first. The first 4 minutes is literally just stacking & alignment in AS!3. I typically will go faster than this, but wanted to slow down enough to try to talk through what I'm doing as I do it. Hopefully you can see each action on the screen. I may have made a few mistakes or said a few incorrect things or terms, forgive me for that, this is not my day job. I really hope it helps folk get more into processing as its not difficult or intimidating when you see a simple process with only a few things that are used. The key is good data to begin with and a good exposure value. Today's data came from a 100mm F10 achromatic refractor and an ASI290MM camera with an HA filter. I used FireCapture to acquire the data with a defocused flat frame. No gamma is used. I target anywhere from 65% to 72% histogram fill. That's it! The processing is fast and simple. I have a few presets that I use, but they are all defaults in Photoshop. A lot of the numbers I use for parameters are based on image scale, so keep that in mind, experiment with your own values. The only preset I use that is not a default is my coloring scheme. I color with levels in Photoshop, and my values are Red: 1.6, Green 0.8, Blue 0.2 (these are mid-point values).
Processing Tutorial Video (18 minutes):
RAW (.TIF) files available here to practice on (the same images you will see below as RAW TIFs):
Video for Acquisition, Focus, Flat Calibration and Exposure (20 minutes):
(Please let me know if any links do not work)
Results from today using this work flow method.
SSM data (sampled during 1.5~2 arc-second seeing conditions):
Equipment for today:
100mm F10 Frac (Omni XLT 120mm F8.3 masked to 4")
Baader Red CCD-IR Block Filter (ERF)
PST etalon + BF10mm
SSM (for fun, no automation)
So I had a free day yesterday and decided to sort out my equipment and update my astro laptop software packages. I downloaded the latest Stellarium and managed to get it to sync with APT. I installed my Xmas present from my sweetheart (Optolong L-eNhance filter) how did she know it's what I wanted??? I recently installed the free trial version of Pixinsight on my main laptop so after watching a few YouTube videos decided to get some Dark and Bias frames to create some masters ready for my next session.
The weather was good yesterday and it stayed clear here as the sun started to set, so I set everything up outside hoping the apps were wrong and it wouldn't get cloudy. As it got darker I launched Sharpcap and completed a polar allingment, I used Stellarium and APT to slew to Vega and checked the focus was good. I then used Goto++ in APT to slew to NGC 7380 (Wizard Nebula), I set PHD2 off guiding and then I had my first issue; my laptop would not connect to my Lyn Astro dew controller so I manually set the temperature to quite low as it wasn't too damp at that time. So I started capturing 5 minute subs went inside and remoted into my astro laptop from my main laptop to check how it was going, all appeared good.
I recently set up a Rpi NAS at home so I'm able to transfer data to it and then to my other laptop on the go, so after I'd got a few subs I opened them in PI to check the quality, they looked ok to me. after about an hour PHD2 started binging a lost star warning so I went outside and the clouds were starting to cover the sky, I then took loads of flat frames using my main laptop, Notepad and 3 sheets of white paper and decided to take some more darks in case it cleared. I then set about trying to process the 9 subs I'd managed to capture with the 200 flat frames the master bias and dark frames I'd created earlier. Despite the lack of subs I'm quite pleased with the result, I have done a quick Histogram stretch, and the knowledge I have gained, I'm definately going to purchase PI when I can afford it.
So this morning I thought I'd sort out the issue with the connection to the Lynx Astro dew controller, you won't believe it, my Astro Laptop will not turn on, it's been playing up for a while I suspect the battery has died. So just when I thought I was getting on top of this frustrating hobby I get another spanner in the works. So do I gamble and order a new battery then discover it is the laptop that has failed, do I set up another old laptop I have and hope it will be ok, do I set up my Rpi3 with Indigo or do I buy a mini PC as I know my way around windows?
Anyway here's the calibrated stacked image as it is in PI with a quick stretch.
Skywatcher 80 ED DS-Pro outfit including matched flattener and motor focus. Now only £350
This kit gives you a great introduction to astronomy and imaging, which is why it's so popular. You can see details over at FLO but there is:
80 ED Ds-Pro OTA (Objective Lens Diameter: 80mm, Telescope Focal Length: 600mm, f/7.5)
SW Eyepiece (2"): 28mm
2”/50.8mm Di-Electric Star Diagonal
Dual-Speed 11:1 2” Crayford Focuser (Backlash-Free)
Supplied with Tube Rings & Mounting Plate - please note there is a longer black vixen type dovetail fitted, not the fancy new green short one you will see on the FLO site
SW motor focus and fitting kit - I've never used this, hence it's not fitted (more details over on FLO)
Dedicated SW 0.85x reducer/flattener (see FLO for more details)
Aluminium Carrying / Shipping Case
The RRP is over £720, so grab a bargain while you can.
Collection from Nottingham, or DHL for £20 (within UK)