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By Mikey wrighty
I am a complete nooby. And I’m trying to get going (on a budget) with what I have available. I am trying to use my dslr canon 2000d with Nina and sharpcap. Unfortunately after downloading the drivers etc it’s still not connecting to either. Please help!
many thanks, Mike.
I've run into a bit of a strange instance when calibrating my OSC subs using my master flat generated from a white tablet screen, especially with my L-eXtreme filter. One corner seems to overcorrect using these flats, however, when I use skyflats I don't see this overcorrection and the end result looks pretty good. Whilst the answer is clearly "take skyflats", I'm not always fortunate enough to take flats first thing in the morning (weather wise, it is the UK!) so it would be great to understand what's going on with my tablet and how to avoid this issue. Details are below, but my questions are:
How can I prevent over-correction with tablet flats? Am I over-exposing them? If I change my light source, will I see this same issue if using an EL panel (e.g. like this one )or a bespoke flat field generator (like those provided by Geoptik, Pegasus Astro etc.) Is there anything in the PI WBPP 2.0 script which can help identify overcorrection and adjust the amount of correction applied?
For the tablet method, I capture my flats using the auto-exposure tool in my ASI Air Pro (it calculates the optimum exposure time based on the light source presented). The light source is my tablet display at 100% brightness, no blue-light/night time filter, and displaying this blank, white page provided by Covington on the screen. The display is large enough to cover the entirey of my Redcat 51. I attach 2 layers of t-shirt to the front of the telescope and the camera used is an ASI533. It's a small sensor, so I wouldn't expect to see a significant amount of vignetting compared to a full frame camera. For the skyflats, I used the same approach but used 4 layers of t-shirt isntead of 2 to ensure I don't end up with too short of an exposure time.
The exposure time has been adjusted to ensure the average value of the individual frame is ~30,000 ADU for a 14-bit image. For the tablet flats, this results in a 7 second exposure using 2 layers of t-shirt. For sky flats (overcast day), this results in 180ms flats using 4 layers of t-shirt to ensure the exposure time wasn't too low. The optical train had not been disturbed in this time, and both approximate exposures were determined by the ASI Air Pro auto-expose feature (I rounded them up when shooting). There were 30 x flats for each case. The tablet flats were taken at midnight, the skyflats were taken in the morning. Other than this, there was no difference in imaging conditions.
All stacking is performed in PixInsight using the WBPP 2.0 script. All settings under flat are left at default settings. The script was executed twice: the first was using tablet flats, the second was using skyflats. No other changes were made in the stacking process.
Flat Images and MasterLights
Below are four screenshot images. The top row shows debayered master flats (purely for illlustration purposes), the bottom row shows the final stack. The left side shows the tablet flats, the right side shows the skyflats. The statistics are from the master flat, pre-debayered, and show there there is a small sifference in mean values. However, the images show much brighter corners for the tablet flats, especially in the lower left where I see over-correction. You can see this clearly in the master light images. Looking at the master light which was calibrated using tablet flats, you can see a red cast over the lower left corner which I suspect is overcorrection from the flat. However, you do not see this on the master light which was calibrated using skyflats, the background looks fairly uniform.
No questions but thought my experience with PA using Sharpcap and a Canon 800D might be of help to some.
Although I thought I was nailing Polar Alignment with a polar scope on my Fornax Lightrack, I could not get longer subs than 150secs. I considered buying a Polemaster but I thought was a bit pricey, so looked at a small guide scope and a webcam solution with Sharpcap which was a good bit cheaper.
Researching Sharpcap and DSLRs, I read that PA might be possible with my WO ZS73 (430mm) main scope. I needed to install the ASCOM platform and then the DSLR Camera Setup for Ascom and, of course, Sharpcap. Sharpcap recognised my 800D camera and I completed an "Excellent" PA within minutes. On the first night I managed 180sec subs and experimented with 240sec - all nice round stars. How far can I go? I had done a manual PA first which was a fair bit off from the Sharpcap PA, so not as nailed on as I thought!
I'd rather not be using a laptop but I can't argue against the results.
I hope that might be useful for some.
Hello everyone! 🙂
I'm into astrophotography for some time and I want to take another step ahead - guiding.
I'm new to this topic, but I read many threads on many forums and I chose to use an OAG.
I have SW150/750 on NEQ6 and my main camera is Canon 450D.
I have two questions:
1) I'm planning to use ASI120MM mini as guiding camera. Would it be enough for OAG?
2) I heard that I may came across some problems with focusing both cameras at the same time. What adapters would I need to get the right backfocus?
PS. Or maybe it's better to use separate guiding scope in my case?