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

43 minutes ago, ollypenrice said:

Many (or maybe all) of these issues have been extensively discussed on here and I think you are reiterating a number of mistakes in your video. The most obvious is 'The F ratio myth.' Your Hyperstar does not speed up capture by 25x.  It does not speed up capture at all.  Please bear with me. Exposure time does reduce as the square of the F ratio, as you say, when the F ratio is reduced by increasing the aperture. That's why 'F ratio' and 'aperture' are used as equivalents in daytime photography but note that, in this case, the focal length of the lens has remained the same and the iris has been opened to let in more light. You are not doing this. You are lowering the F ratio by reducing the focal length. 

If you point your scope at a small galaxy which will fit on the chip at F10 and F2, you are getting exactly the same number of photons from the object either way. What changes is the number of pixels you put them on. The Hyperstar puts them on fewer pixels so those pixels 'fill' faster. However, you would get exactly the same result from using larger pixels, or binned pixels. Professional telescopes often have slow F ratios but they have cameras with huge pixels and they are, therefore, incredibly fast. However you go about it, putting your object photons onto fewer pixels simply trades resolution for speed. In an over-sampled system this trade-off may come at no cost in terms of final, real, resolution.

You don't need to convince me that imaging at F2 is great. I love it and do so with two rigs. My point is that the 8 inch F2 RASA I use cannot be compared with with an 8 inch F10 SCT because it has a focal length of 400mm. I'm not going to compare it with an 8 inch SCT with a focal length of 2000 mm. They don't take the same pictures. I'll compare it with a Takahashi Baby Q, though, with a FL of 450mm because they do take comparable pictures - and the RASA is way faster.

I strongly object to Hyperstar hype because it suggests that you can take 'the same photo' 25x faster when, very obviously, you can't.  The manufacturer is perfectly well aware of this deception and may one day fall foul of European trading standards legislation.

Olly

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.

3 hours ago, Elp said:

It's a good video, covers a lot of points especially why it's so faster than the default f10 configuration.

You touched upon the cable routing, I found it can significantly affect the diffraction spikes around stars especially bright ones, having a standard usb cable sticking out the side of an uncooled camera is also noticeable as a chunk taken out of any star halo. I mitigated this by using a 90 degree usb connection so it doesn't stick out so much into the clear aperture, and then wrap the remaining cable around the camera and HS and onto a custom made ring bracket I made to run the cables to the OD.

Using cooled cameras for AP it also helps to cover up all around the USB and power connections with black tape so the lights from inside the camera do not radiate out.

For taking darks, using a filter drawer and having a black dark frame filter makes it easier to do, no need to cover the front or anything, just change to the black filter and take your dark frames, this obviously only applies when using an uncooled camera for DSO.

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

10 hours ago, AstroKeith said:

I believe a so called boost converter will allow you to get the stated capacity out a lot of the time.

Advertising gives a capacity which is either a) available from a lower regulated voltage output, ie 5V USB, or b) unregulated 12V output allowed to drop down to 10V (or even less). Neither of these is right for most astronomy set ups. So using a boost converter allows you to get a useable voltage right up to the point where the pack shuts down at say 10V. You will lose about 5% with a good converter, but in case a) that will already be factored in.

I've started to use USB C to 5.5/2.1MM converters that have a PD trigger circuit in them. See below. With a power pack with PD or equivalent outputs I'm getting the rated capacity at a perfect 12V. 

 

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.

18 hours ago, Carbon Brush said:

Do not try this test at -18C in your freezer. Lithium cells don't work this cold and you can cause damage.
Lithium is fine to freezing point-ish and perfrms almost as well as at room temperature.
 

You can see I have avoided having to know anything about cell chemistry, internal protection circuits, regulators, etc.

 

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

19 hours ago, EarthLife said:

The easy solution to this problem is to use a boost regulator on the 12V output, something like this will give a couple of amps capability .. https://www.ebay.co.uk/itm/374835259124

You can get higher current/power units from places like AliExpress etc if you want more output current capability.

You will get more than 12V output from the boost regulator/converter, you simply adjust/set it to say something like 13.5V or 14V, which is perfectly fine. Once set you will have a constant regulated DC supply for whatever you want. Just try not to drain the power banks battery too much as some battery types don't always recover too well from being over discharged.

 

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. 

26 minutes ago, Elp said:

Time will tell. I bought a 72W 100WH one and it's the only one which powers my whole AP rig as one power source, feeding the asiair then using the 12v outs in the asiair to power my mounts including my gem28 and my cameras. I mention this as my gem28 is sensitive to voltage drop, it refuses to work in the same configuration with my "regulated" Celestron Lithium LTs designed for 12v out usage "with minimal voltage drop". 

Amp draw has more of an impact I believe because if I have dew heaters plugged in something else turns off so they need to be powered separately. It's also happened when I used a usb WiFi extender.

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.   

41 minutes ago, 900SL said:

I checked mine with a voltmeter under load at 50% reserve, was running 12.4V and no issues with any gear. I only use it for a lightweight travel rig, so a cooled camera, ASI Air Pro and tracker, no dew heaters.

I think the max draw was 1A on the 12V 5.5 x 2.1 socket. I don't plan on using it in cold weather. 

This does have a dedicated 12V/24V outlet, 12V USB-C PD  and possibly onboard regulation. So far I'm pretty happy with it

 

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.

1 hour ago, ONIKKINEN said:

Well, that might be a California thing, but here where the average imaging temperature is well below 0 an unregulated power supply (of any type) will simply be trouble waiting to happen.

I stand corrected.  

1 hour ago, Richard N said:

Some do use LiPo batteries. My Tracker power bank does. But as you say, it’s all about the design. 

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

53 minutes ago, ONIKKINEN said:

Yep, you should never use a "dumb" unregulated 12V power supply as a primary power source for astro kit. I have had 2 small ones like this, (a Celestron 84wh one and a car jump pack) and both become unusable after just a few minutes of load.

For travelling astrophotographers a proper power station like a jackery or similar is a must have in my opinion.

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.

Richard -  these power banks do not use Lithium Polymer cells, which I assume is what you mean by LiPo.  They use LiNiMnCoO2 which is not a problem if designed correctly like a Jackery which uses the same cells.

I bought a Talent Cell 8.3Ah power bank to take with me on an airplane to image the total solar eclipse in 2017 and have used it occasionally since for public outreach and for some simple power needs.  I never really used it for a demanding power application and never paid much attention to its design and ultimate performance.  But now that I have a detailed understanding of lithium battery technology I decided to buy several additional capacity versions of these to test when I read about folks having problems using them powering their ZWO AM5 mounts or their ASIAIRs.  I was surprised to learn that these are not designed to be 12V power supplies like the portable power stations from Jackery, Bluetti, etc. nor like a stand alone 12V LiFePO4 batteries.  In fact, they don't even output 12V when a load is supplied.  Now, as I mentioned, they do work with much of our astronomy equipment since many 12V devices can handle some level of voltage below 12V.   But there are limits.  And, even in those cases that work, we will not get the advertised capacity of the power bank since the voltage drops rapidly below 11V.   I made a video of my tests which show that the output voltage is not what you should expect from a 12V battery and explain how they scrimped on the design to minimize cost and reduce the size and weight of these power banks.  I do show one model of the Talent Cell power banks which is a "true" 12V battery.  So if you are thinking of purchasing a power bank from Talent Cell or anyone else, or if you have one you might want to view the video.   You can find it here https://www.youtube.com/watch?v=2Zm-tGT40No

Best Regards,

Curtis

Thank you, Peter.  Yes, EAA or EEVA surprises folks as to what it can do compared to visual with a telescope an EP.   As for the scope I had to downsize from my C14 as it was too heavy for travel and I had to sell  it to purchase the C11.  Almost half the weight but a lot less aperture.  I do some astrophotography which justified the mount.

Best Regards,

Curtis

I am at it again as I posted the 3rd installment of the video tutorial series I call "6 Essential Tools for EAA (or EEVA if you like)".  This one covers Live Stacking SW and Computers.  You can find it on my channel here https://www.youtube.com/watch?v=TRk2wsrOnNM    If you have not seen the previous two installments in this series there are links to them in this video.  I always appreciate feedback so that I can improve upon these things as I go.  I encourage anyone wanting to get into EEVA to take a look at the entire series.  Often we already have most of the equipment we need and where we are missing something we don't have to spend a fortune to get going.

Best Regards,

Curtis

Maybe I wasn't perfectly clear.  The discussion is solely about DSOs.  While many of us used the 224 for DSOs back in the day, there are much better choices today with bigger chips and at not that much more money.  I don't have any opinion about its use for planetary as I haven't tried it.  If you check the ZWO site you will see that they list it under planetary cameras.  I have used it as a guide camera with some success.

I am in the process of putting together a series of videos which I call "The 6 Essential Tools for EAA" (forgive me for not using EEVA in the title).  I posted here last month when I released the first video which discusses the key things to look for when choosing an optical tube assembly and a mount for EEVA.  I received a lot of positive feedback on that video.  If you have not already seen it you can find it here https://www.youtube.com/watch?v=2OVjamLK72g   I just finished the next video in this series which focuses on what to look for when choosing a camera.  Many beginners have lots of questions including whether to get a cooled or uncooled , a color or mono camera.  There are so many camera features which can be confusing to sort through including the importance of read noise, chip size and how to match the pixel size to the focal length of the OTA.  And what do we do if we have a focal reducer or a hyperstar.  I tried to address all of these issues and more in this video.  If you are a beginner I think this will really help.  And even if you are very experienced you might learn something new as well.  Please take a look at this latest video and let me know what you think.  You can find it here https://www.youtube.com/watch?v=oFueKEuELOc

Best Regards,

Curtis

I appreciate the positive feedback and am happy to hear that the video is helpful.   Working on the next installment which will cover what to look for when picking a camera for EAA.

A couple of months ago I started putting together a series of videos which I call "The 6 Essential Tools for EAA".  I just finished installment number 1 and posted it this morning.  This covers everything I think a beginner should look for in Optical Tube Assemblys (OTAs) and mounts when first starting EAA.  I try to be very detailed and not assume the viewer already has much expertise in astronomy equipment.  If they do, they can skip ahead to more relevant parts of the video.  In subsequent installments I will cover details about choosing cameras, computers, software, and dc power supplies all with EAA in mind.  You can find the first video here  https://www.youtube.com/watch?v=2OVjamLK72g&t=1s                                                    

I hope beginners find these helpful.  They do take a lot of time to plan and execute, but I thoroughly enjoy doing them and like to hear back from folks who view them.

Best Regards,

Curtis

One year ago my friend Dave decided he wanted to improve the performance of his Celestron 11" Edge SCT for astrophotography.  His main motivation was to see if he could reduce mirror flop which is a well known problem with SCTs.  He had read on CN that someone installed nylon screws between the outer and inner baffle tubes to reduce the play between the tubes and minimize mirror flop.  This was his primary objective of the modification, but he decided that he should perform other modifications while he had everything apart.  In total, Dave made the the following modifications:

1.  Added nylon screws to the baffle tubes to try and minimize mirror flop

2.  Added internal fans and deflectors to direct the air flow over the front of the primary mirror to break up the air

3.  Added a temperature sensor on the back of the mirror

4.  Replaced the stock grease with a much better Krytox lubricant

5.  Flocked the inside of the tube

I jumped at the chance to help him since I also own an 11" Edge (and 6" and 9.25" SCTs) and decided to video the entire process including disassembly as well as the mods.  I previously posted a separate video showing the entire tear down process step by step.  A link to that video is shown below for anyone wanting to see how easy it is to disassemble an SCT.

In the process of tearing the scope down Dave noticed that the hardware included with his Celestron motorized focuser did not fit correctly allowing for excess play in the mirror assembly leading to additional opportunity for mirror flop.  I found the same issue on my Celestron motorized focuser as well.  In my case I experienced binding of the focus motor on several occasions which is a problem that has been reported by many others.  So we came up with two options to fix the problem and I made that into its own video as well.  Again, the link is below.  It appears that Celestron finally figured this out and corrected the problem recently, but if you own an older SCT and use the Celestron motorized focuser you might want to take a look and see if you are subject to the same issue.

Now a year has passed and Dave has had an opportunity to see how his improvements performed.  So we just shot some additional video as a follow up to the modifications where Dave tells which mods he would do over again and which we would not and does his best to quantify the improvements.  I put that together with the footage from last year showing each mod and posted this 3rd video in the series last night.

Here are the videos

Celestron Tear Down Video    https://www.youtube.com/watch?v=kTJs4r5Oj58                     

Celestron Motorized Focuser Issue and Fix   https://www.youtube.com/watch?v=kTJs4r5Oj58

Celestron Mods for Improved Performance   https://www.youtube.com/watch?v=2E3pnjDp56E

Hopefully this will help other owners of SCTs.  I would appreciate feedback from others who have made similar and different modifications and, especially anyone with the motorized focuser who has had issues with it as well.

Best Regards and Merry Christmas

Curtis