curtisca17

I have always been a big fan of Robin's Sharpcap and that is the live stacking SW that I always recommend. However, since I have The Sky X Pro (TSX) which I use all the time to control my mount, etc., I recently decided to see how their live stacking SW feature works. This feature can be found in the Camera control tab and is called, what else, "Live Stack". I must say, it is the simplest of all of the live stacking SWs that I have used (Sharpcap, ASILIVE, Starlight Live, etc.). Just set the exposure and Bayer Matrix and hit start and you are off. Adjust the slider for stretching and you are looking at some great DSO images with a minimum of effort. Some beginners have trouble with the steep learning curve of Sharpcap and can be turned away from EEVA because of it. ASILIVE and the others are much simpler but still require more intervention than TSX's "Live Stack". Now I don't recommend that anyone pay $395 (US) just to use TSX for EEVA, but if you already have the TSX or want it for its primary features (equipment control, planetarium) and want to try your hand at EEVA, give their "Live Stack" feature a try. In time you may want to move on to Sharpcap or something else, but at least you won't be frustrated from the outset and can get going in under 5 minutes. To show how simple "Live Stack" is I made a demonstration video which can be found here. https://www.youtube.com/watch?v=0BSTEZx7txY Even if you don't have TSX you might want to take a look. Best Regards, Curtis

A field flattener is certainly useful for traditional astrophotography which I also do and is why I paid the additional $199 to get it with the OTA. That is because astrophotography is all about getting the best looking images one can get all the way to the edge of the field of view. EAA is a different animal. Primarily the objective is to be able to see much more than we can with an eyepiece but not have to go through all the work required to get a astro-photograph. 10 years ago it was common to use video cameras for EAA which had very large pixels ( 8 - 9 microns) which produced blocky looking stars with much less resolution than we get with today's CMOS cameras using 4 micron and smaller pixels. It was also very common to buy very inexpensive 5X reducers, essentially binocular objectives, use a back focus distance longer than the reducer was designed for to get a higher reduction factor or combine multiple focal reducers to get greater reduction. All of these things meant that we did not have great looking images across the entire field of view. But we were excited and happy to the advantages in speed that these gave us so we could see more in real time. EAA has evolved. I think most folks have put their video cameras on the shelf and are using the latest CMOS cameras. We do dark frame subtraction on the fly. And some do flat field correction on the fly. Both essential techniques for traditional astrophotography. Others pay extra for cooled cameras to beat back underlying noise even more. So too do many use field flatteners and coma correctors to improve the views. EAA has almost become astrophotography light where we not only expect to see many DSOs in real time throughout a night of viewing, but we expect them to have much of the image quality of astro-photos. So, is a field flattener an essential tool for EAA? In my opinion it is not any more than a cooled camera and other extras are. It comes down to personal preferences and personal budgets. If you want the best looking image possible then you will add these extras if you can afford them. If you do not have them you will likely still enjoy EAA views many times better than what we were excited to see 10 or more years ago with the equipment available to us. As far as the spacing for the reducer for your SD81, typically the spacing on focal reducers for refractors is 55mm but you should confirm that with the manufacturer of the focal reducer. 55mm is common because it works universally for DSLRs with adapter rings. 55mm is not the typical spacing for focal reducers for SCT like the Celestron 6.3X and 7X reducers where the spacing is 105mm for both. Regards, Curtis

Thanks. You should have fun with that setup.

I want to share a video tutorial I just posted on EEVA with a wide field scope. I made this at a recent star party using a Sharpstar 61 EDPH III wide field refractor I just bought on a Skywatcher AZ GTi mount I borrowed from a friend. I also bought an ASI858 color camera to go with this setup. In the video I explain my choice of equipment and point out some alternative scopes and cameras that will also work well. I also walk through the setup step by step and finish with a short live stacking demonstration of M31, M33, the Eagle nebula and others using Sharpcap. The objective is to show what can be done with a simple, light weight, moderately priced setup using a refractor and camera with a FOV of roughly 1 x 2 degrees. https://www.youtube.com/watch?v=h8cXY4mUBng Hopefully folks find this useful. As always I appreciate feedback so I can do better next time. Regards, Curtis

I think you haven't watched the video because we are saying similar things but coming to different conclusions. I clearly state in the video that the same number of photons from the DSO are entering the camera with or without hyperstar. And I go on to point out that it is the fact that the FOV has changed which means that those photons are concentrated on fewer pixels which is what increases the optical speed of the scope. In a nutshell, I believe that I said exactly what you are saying here. So, indeed, you get a 25X increase in optical speed. But, as you say and I point out in the video, since the FOV is much larger with hyperstar than without, the two images are not the same. Now, as I also say in the video, with the larger sensors typical on cameras these days, one can blow up the image a fair amount without significant impact to resolution since we are very likely oversampling to begin with. You seem to get this later point but apparently did not hear me say it in the video. As I point out hyperstar also allows one to fit much larger DSOs into the FOV of the frame which is a major advantage as well. If one wants a dedicated fast SCT type scope the RASA is a great choice, I agree. But an SCT is valued for its versatility in going from f/10 to f/7 (or f/6.3) and f/2. Hyperstar is the tool that gets it to f/2 and I don't consider what I say in the video to be "hype". But you are welcome to disagree with me.

Thanks. Actually, if you look at Dave's HH Nebula image you can definitely see diffraction spikes on the bright stars, so point well taken. Nice idea on the uncooled camera dark frames.

I had my first encounter with hyperstar back in 2014 with my Celestron 14" SCT and was blown away with what it could do for me during live viewing with a camera (EAA, EEVA, Video Astronomy, etc.). I had to let my 14" go as it was getting to heavy for me and replaced it with an 11" SCT with hyperstar an essential part of the package. These days I spend more time with traditional astrophotography and have found hyperstar to be just as amazing a tool as it was for EAA. If you have an SCT and haven't yet tried it I can highly recommend it as it provides a 25X increase in optical speed over the native f/10 (12.5X over f/7) and provides an equally larger FOV. With the increased speed it takes a lot less time to capture the subframes I need for my final image since I need less subs. There is a double payback with less image acquisition time and less post processing time with fewer subs needed Also, the image scale with hyperstar is usually much smaller than the seeing warrants so 2x2 binning is an option to further speed up the system. While most think that hyperstar is just for the larger DSOs and not the smaller ones like M27 that is not the case if you have a large sensor camera, say 20mm or larger diameter. Even with 2x2 binning images are most often still over sampled so it is possible to zoom into the final image and get a reasonable size image of these smaller DSOs without impacting resolution. I put together a video which gives examples of what hyperstar can do and shows everything one needs to get started with hyperstar (at least I think I covered everything). If you have an SCT and do not already have hyperstar or are considering an SCT you might want to take a look at this. Even if you already use hyperstar all the time I would appreciate any feedback on your experiences and inputs. You can find the video here https://www.youtube.com/watch?v=EA2TWvnIIbU Regards, Curtis

One cannot defy the laws of physics. If the power bank is not designed to output 12V then, while a boost converter can raise the voltage to 12V, it cannot fill in the lost capacity due to the need to boost the voltage. I am not talking about the efficiency of the boost converter which, as you say, is typically 95%. I am talking about the total energy (this is what we really use) in the power bank. It may have 72Wh at a lower voltage but that means it will not have 72Wh at 12V. That is precisely what the voltage versus capacity curves I measured and included in the video show. Otherwise we have invented a limitless energy source. The boost converter raises the voltage but at the cost of some of that 72Wh, not just the efficiency loss. So, yes a boost converter will get you 12V but the output will shut down before you have gotten the rated capacity.

Nothing wrong with your suggestion for testing with simple equipment. Good input. But avoiding knowing about Lithium chemistry, or at least Lithium battery specs has led to incorrect information about Lithium battery operating temperatures. Lithium batteries are rated to supply current down to -20C so a -18C test would be ok. Of course, all battery chemistries become sluggish at lower temps, but the nice thing about Lithium is it performs much better than lead acid at cold temps. Now, do not charge below 0C as that is a completely different situation which will lead, at first, to loss in battery capacity as the Li ions plate as Li metal on the cathode, and eventually in the worst case form dendrites which short through the separator leading to catastrophic failure. I like simple tests like you proposed, but I also like understanding things more than not. But maybe that's just the physicist in me. Best Regards, Curtis

Yes, one can put a band aid on a bad design to get it working, but there is no free lunch. A boost converter will give the voltage needed but will not be able to do it for the rated capacity. So, for instance, you are paying for 72Wh at 12V but only getting, say 55Wh. I don't consider that fair advertising.

That is the model I bought back in 2017. It has the same design problem, trying to get away with 3 LiNiMnCoO2 cells in series, as most of the other designs. The voltage drops below 12V as soon as a load is applied. It works with my Celestron 6Se and iOptron Cube Pro even down to 10.3V but others have reported problems with these power banks on the ZWO AM5. Amp draw will certainly drop the voltage faster.

That is a completely different design from the 12V power banks. It is sold as a 24V down to 12V DC but I suspect it has the same design flaw for supplying 24V that the Talent Cell has for supplying 12V. Talent Cell also has some of these 24/12V models as well. I am quite certain that the 12V output works well supplying 12V for almost all of the capacity, but will most likely drop well below 24V once any load is applied. It all has to do with cutting corners on the number of cells in series using LiNiMnCoO2 cells. Since I haven't tested one of these I may be wrong about the 24V output and would be curious to hear from any one who has actually checked that voltage with a load.

I stand corrected.

Good to know. I am not familiar with that brand.

Well, not exactly. Talent Cell does offer one version of a power bank with LiFePO4 which does not have a voltage regulator which works perfectly fine. As does any LiFePO4 battery as the voltage remains above 12V for at least 90% of its capacity. Voltage regulation is required for any power supply using LiNiMnCoO2 like a Jackery because the cell voltage will not add up to the voltage of a 12V battery with an even number of cells. 4 cells in series give 14.4 - 14.8V so a voltage regulator is needed. 3 cells fall too short of 12V and, hence, don't provide 12V.