Chickpea

Thanks very much for the advice. I watched yesterday this video with Robin Glover which covered the maths that you mentioned. It useful to know that I won't be able to get the read noise data from Canon. I had hoped to use the Sensor Analysis tool in SharpCap, but have not yet managed to get the DSLR driver working. I appreciate the advice regarding 1/3rd guidance and also the feedback on the image. With regards to the Histogram tool in APT, I suspect it is visualisation only, and does not affect the RAWs but for now I will leave it off when shooting. I took your advice on increasing the exposure and last night I captured for around 2 hours on M27, shooting 120s subs @ ISO 400 (plus 100 bias and 25 darks). This is the histogram in APT that was getting at the beginning By the end of the session, the peak had moved left, so that the left side of it was just overlapping the edge of the first segment. The is the one of the first subs in RT. And this is what I managed to get after stacking in DSS and fiddling around in StarTools (which I am still very new to). It is just a screengrab because I haven't bought a licence yet. Compared to the previous capture session, I was actually able to extract some colour, which was pleasing. I think that the exposure was probably much better, but I am still manually focusing and the guiding was bit hit and miss last night. Thanks again for all the advice, and if you have any further thoughts, they would be very much appreciated.

Hi, I am trying to better understand the use of histograms when deciding exposure lengths. I am using APT to capture with a Canon 400D (OTA is a Skywatcher 200P which is f/5). I took some 60s subs (@ ISO 400) of M27 a couple of nights ago and have been looking at them in Rawtherapee (which is completely new to me). Below is one of the images with the Linear histogram displayed, I have also included the Linear-Log and Log-Log histograms. My limited understanding is that I want the peak to be a third of the way across the histogram, so perhaps roughly in the orange box in the image below. Is that correct and is that when viewing in linear mode? I am hoping to shoot M27 again tonight and I shall be trying out the Histrograms feature in APT. My understanding is that I want the peaks to be in the 2nd or 3rd of the five regions in that tool I noticed that the APT histogram tool has an auto-stretch feature. As I intend to stack in DSS and then process in StarTools, should turn auto-stretch on in APT or leave it off (or does it not matter?) Any thoughts would be much appreciated. I have also included the raw file that I viewed in RT. L_M27_3_1962_ISO400_60s__NA.CR2

Thanks Wim and Michael. I managed to do a further run last night including two guiding assistants and ~90 mins of guiding. I did change the exposure to 1.5 secs before doing the first GA, and also set the RA and DEC aggression to 30 as previously recommended. I ran GA once, it recommended a recalibration, which I did, but did not refocus before running another GA. The DEC backlash was reported as ~8500 in both runs. The GAs and the calibration were run in this sky location The final results of the GA were Here are some snapshots of the guiding And here is the log PHD2_GuideLog_2023-06-15_235602.txt Michael - the analysis you did on the previous log file is very interesting and I really appreciate it. I note the RA PE error. Is that something that I would want to change physically (i.e. remove possible grit), or could that be trained out? I don't believe I have had PHD2 complain about the PA at any point. SharpCap reports a sub-arc-min error, but I am not sure how reliable it is. Is the HFD value based only upon the selected guide star, or all stars that are in view? I ask this because where guiding last night there was one very bright star in the view (please see screenshot below) and on the night that you analysed the log there were two bright stars in the few, fairly close to the guide star. When I use the focus assistant in SharpCap I get multi-star FWHM values in range of 3 to 4 (I don't think I have ever gotten below 3). Is there any possibility that the focus may be impacting the reported backlash values, by messing up PHD2's measurements? I'm disappointed that there we both approximately ~8500ms. Am I correct in thinking, that value means that when PHD2 sends a guide pulse, it believes that it is taking 8.5 seconds for the mount to respond? I took some 20 minute exposures, which to my untrained eye don't look too bad, but the stars in the centre of the image are definitely not perfectly round. I have also taken a video of the mount slewing, which includes the sound and also the current that the mount was drawing, which I hope to post later today. Thank you again for all the help and advice so far.

Thanks to both of you. I will drop the exposure and the aggression as you both suggest. I had clear enough sky last night that I was able to run GA again and also get an extended period of guiding, so I will post up the results of that, but I believe that the reported backlash was ~1500ms. I am running the mount from a bench supply which does show the current draw so I will certainly trying slewing to see what results I get (both in sound and current). I think there is certainly plenty that I can do to fine tune the guiding and will start with your suggestions. The backlash/stiction is the thing that potentially bothers me at the moment, as that is mechanical rather than guiding configuration, so I just want to make sure that it is within acceptable limits for the EQ6R. The numbers I have so far are 949ms, 4649ms and ~1500ms, so I have only gone under 1 sec once and only just under. I will post the results of last night plus the slewing noise/current as soon as I can.

Hi, I've recently purchased an EQ6R, having previously used an EQ5. I am using a Skywatcher 200P, imaging with a Canon 400D and guiding with a ASI224 on the 9x50 finderscope. After a few teething problems, I finally managed to get the mount polar aligned using SharpCap on Tuesday night and then ran the Guiding Assistant in PHD2. My initial objective is simply to check that there are no fundamental problems with the mount and then I am happy to take the time to fine tune everything. I will describe what I did, and I would really just appreciate and observations and advice you folks might have. I initially polar aligned with SharpCap, ending up with the following configuration. I then ran an initial calibration in PHD2 and then ran the Guiding Assistant for 25 mins, and got the following output (I applied all of the recommendations). As PHD2 was reporting a 4 minute PA error, I tried to fine tune the focus and then ran another PA in SharpCap. SharpCap showed this as the error before I ran the second PA, and this error once it was run. I then ran Guiding Assistant again for another 25 minutes, and got the following output. As you can see it reported a much more significant backlash error. I applied the recommendations. I then decided to get some actual data while imaging, so I pointed at the Tulip Nebula and ran about an hours imaging. The link below is a 4 minute video, showing APT and PHD2 during 40 mins of imaging, sped up 10 times. https://youtu.be/kT1Ou_w6_CY And finally here is the PHD2 log which covers the whole evening, including the calibration, guiding assistant runs and then the guided imaging run. PHD2_GuideLog_2023-06-13_235005.txt The RA rate and DEC rate were both set to x0.5 in the ASCOM PulseGuide settings (a bit difficult to make out in this screenshot which was taking just before the PHD2 calibration). As I mentioned above, I just really want to check that there are no major problems and would appreciate any advice or observations. I would be especially keen to know if any of the numbers might suggest a problem with the mount and what steps I should take to further analyse and/or calibrate. Thanks.

Thanks Alan. I suspected that there might be a valid reason that there would be a larger current draw for a short time at start up, but didn't know enough to have any idea what the cause might be. Your explanation of the cause is very clear and very much appreciated. I have the supply sent to constant voltage which I think it the appropriate setting, but I am now less clear about the current setting. As I understand it, with it set to 4A, the supply will provide up to that amount (at a constant 13.7V) but will not provide more (so a maximum of 13.7 x 4 = 54.8W). I wonder if you could please advise on the following: In terms of protecting the mount's electronics, is there any value in engaging the OCP rather than simply limiting the current? (the new cable I bought also has a 10A fuse installed). If I only use current limiting, rather than OCP, is there still a need to provide the higher current (8A - 10A) for start up? Would the capacitors still charge if only 4A is provided? In terms of protecting the mount, is it possible to determine what a maximum current that it could safely be exposed to for an extended time is? Thanks again for all the advice.

The cable arrived yesterday so, despite a starless sky, I managed to get the mount powered up and EQMOD configured so that I could command the mount with Stellarium. Although I had no stars to confirm tracking accuracy, there were no obvious slewing issues and I left it tracking for a few hours, without issue. I did have an issue when powering up. I had set the bench supply to 13.7V and 4A (the same as the official skywatcher supply) and had engaged the over current protection feature on the supply. However, when I turned the mount on the OCP tripped immediately. I tried again and got the same result. I then raised the current limit to 4.5A and tried again, but it tripped again. I then raised the current limit to 5A and switched the output back on. I hadn't remembered to switch the mount off, and I then realised that it was powered on and working, and drawing 0.25A. I'm not sure whether the mount did actually temporarily try to draw over 4.5A at start up, with the OCP tripping correctly, or whether the OCP tripped incorrectly. I'm also not sure whether it worked the last time because the current was raised to 5A or because the mount switch was set to ON before the bench supply output was switched on. The good news is that the OCP did trip, but I'd be more comfortable if I knew exactly what had happened. Any thoughts would be much appreciated.

Thanks to both of you. I will go ahead and use the bench supply for now (the cable is arriving on Monday, and the forecast for Monday and Tuesday is OK). Until then, I am back to using the EQ5.

Thanks Alan and Jim. I did consider just using the bench supply rather than order the Nevada (which I haven't ordered yet). I only use the bench supply for the occasional odd job, so it is available most of the time. My only concern was all the talk of the power from the Nevada being a particularly clean signal and I am not sure how the bench supply I have would compare. As I understand it, linear supplies deliver a cleaner signal that a switched supply, which is what I currently have. Could that be a problem?

Hi, I have just realised that my EQ6R doesn't come with a power supply, just a male cigarette to female 2 pin aviation cable. It looks like I will go for a Nevada supply as the solution, but it won't arrive for a few days, and I would like to get up and running faster and am wondering if there is any reason that I can't use this bench supply, which I have to hand https://www.amazon.co.uk/gp/product/B09C8LWV9W with this cable https://www.amazon.co.uk/gp/product/B01N2O153Z I don't see any reason that I can't, but given the cost of any mistakes, I would appreciate any thoughts you folks might have.

Thanks again for all of the support here. There have not been a huge number of clear nights over the last few weeks, but there have been enough that I have managed to go from "spending all night trying to get a target in view, while PHD2 refuses to calibrate and APT refuses to plate solve, with intermittent equipment disconnects and tracking stops and dead DSLR batteries every half hour" to a point where, for the past couple of nights, I can now setup quickly, usually recalibrate PHD2 on the first attempt and use Goto++ in APT with few failures. I am using my ZWO ASI 224MC attached to the SW 9x50 Finderscope for guiding and an unmodded Canon 400d for imaging, with an Explorer 200P on an EQ5 goto. Following advice here I have decided to take the plunge and upgrade the mount. I decided on an EQ6R rather than an HEQ5 because it was only a couple of hundred extra and I suspect that I would have regretted not going that little bit further. I do still want to look at some form of autofocusing, but the focusing tools in APT and SharpCap have really helped to increase the speed and accuracy of my manual focusing. I am also looking to understand more about the DSLR modding options that are available. I also really have no idea what I am doing in DSS, and am currently just randomly picking options and sliding sliders until the image look better, so I have a lot of learning to do there. Below is the best I have managed so far (15 x 5 minute lights + 3 darks). I'm looking forward to learning a lot more and am very appreciative of all the advice,

I just wanted to post a further update on this, in case it is useful for others. The USB Serial Relay has been working well in APT, and I spoke with members on the NINA discord channel, who confirmed that the USB Relay options is definitely not supported in NINA for Canon cameras (it is supported for Nikon).

Quick update on this. I made up the cable today and, as expected, it is detected and works fine in APT. Unfortunately it does not work in NINA. I am going to move forward with creating the second type of cable, but I am also going to see if I can make the USB Relay a virtual COM port in the hope that NINA can then detect and use it. I understand there is also the ability to create scripts in NINA, which may enable me to tie in firing via the USB relay. Will update here as I learn more.

Thanks Philip. I had a look on Lindy, but couldn't see a suitable cable and also couldn't find any mention of bespoke cables, but I probably looking in the wrong place. I found some information about linking the camera to APT and also linking a Nikon to NINA. https://www.astrophotography.app/usersguide/canon_nikon_shutter_cables.htm I had a look at NINA with the Canon plugged in and it has the options shown in the picture below. I am going to try this DIY "USB relay" cable, and have bought the parts today https://www.astrophotography.app/usersguide/kmtronic_or_sdr_05v_cable.htm I am not sure if NINA will be able to us that via the Serial Relay option, or whether it would need a serial cable design instead (which I would connect with a USB-Serial connector as my PC has no serial port). Something like this http://www.beskeen.com/projects/dslr_serial/dslr_serial.shtml So, if the "USB Cable Relay" works for NINA, then great. If not I wil move to the second design (which doesn't seem much more complicated), or perhaps I will have a look at using APT instead.

Hi, I am just getting back into imaging, after a brief introduction a few years ago. I have had some great advice so far, especially from Malcolm and I am still making plans to get some guiding in place. I have an ASI224, but last night I tried using an old Canon 400D with NINA, and managed to get the basic setup working (shot some sequences and stacked in DSS), but encountered the 30 second maximum exposure issue (i.e. that the USB cannot be used to get an exposure of more than 30 seconds). Setup is SW Explorer 200P on an EQ5 (which I will probably look to upgrade, once I get a bit more familiarised with imaging). Having read up on I can see that there are some designs out there for a DIY serial cable, and it looks like currently there are no sources to buy one (at least in the UK). I would be OK building a cable, but just wondered if anybody knows any current suppliers in the UK and/or whether there is a cable design that is most recommended. Any thoughts would be much appreciated