symmetal

Excellent Image. Well planned and executed to capture all those targets in one picture. On the scaled down preview image the Crescent Nebula looks like a 1950s UFO. 😀 Alan

Thanks David for spotting that. It's actually in the top right. 🙂. I kept enabling the catalogs in Stellarium and it was identified with the PK catalog of Planetary Nebula. It's PK 084+01.1, mag 16.5 😀 Alan

Hi KEJ, As Adam says your sensor is quite a bit smaller than my APS-C size 071 camera so the 2" filter size is not a necessity, neither is prioritizing M48 extensions. I should have mentioned this in your instance but at least your system is future proofed against a bigger camera if you get one. 🙂 As you've now done, it's best not to use the 1.25" eyepiece adapter in the imaging train but to screw everything together so that the camera is held in a fixed orientation to the flattener and reduces any chances of any tilt happening. Your first post asked if the FF was actually necessary. As you have it you may as well use it. The corner stars may be good enough without it, but using it should make them better. 🙂 Alan

Using the PCB calculator tools in KiCad you can work out the temperature rise for different current and track widths. The track around the regulator is about 1.25mm (half the width of the regulator pin spacing) and passing 10A the PCB track will rise to around 200 deg C above ambient. 😬 The calculations are only valid up to 100 C though, and a current of 7.7A gives a 100 C temperature rise. With Adam's original burnt track I think it's just the green solder resist layer which has burnt off and the track itself probably survived, though the bonding holding it to the board may have been weakened. Alan

What's the value of the fuse on the board Adam? As it's also supplying the power to the motor it's likely to be quite high like 10A or so, as the motor start up current will be high. To quickly blow a 10A fuse you need to pass far more than 10A through it. If the 7805 fails again, by the time the fuse blows, if it does at all, then along with the newly added zener, diode D3, the faulty 7805 and the PCB track connecting them will have possibly, burned away. The first component to burn to an open circuit will stop the current flow. Not necessarily the zener. To make the scenario work without causing a lot of smoke and charred remains, another fuse of a lot lower capacity, like 0.5A, needs to be fitted in series with diode D3, which involves cutting the PCB track and adding a fuse holder fixed to a blank area of board, wired to each side of the newly cut track. This fuse would likely blow before the zener got too hot so the zener would survive too. However, as the PIC is the only component which is difficult to replace on the board, and it seemed to survive with 12V, you could leave things as they are, just adding the heat sink as mentioned as a precaution to the regulator. The relay coils only draw 80mA and only 1 is ever switched at a time so I wouldn't have thought the regulator gets too hot. Passing say, 150mA, it dissipates 1 watt, fed from 12V, so would get quite hot eventually if the shutter was driven continuously, but that's not the norm. 🙂 Alan

Hi Jarek, I started off with around 68mm like the GT102 but had quite bad elongated corner stars pointing towards the centre so kept adding distance until the corner distortion was minimized. I also had to add a tilt adjuster, as the 6200 is a full frame sensor, and I couldn't get left and right stars in focus at the same time. The final total back focus distance is now 78.5mm, which seems quite a bit longer than for the scopes listed on the WO 68III flattener page, but seems to work. Your 1600 is a smaller sensor so the flattener spacing is not so critical for you but this may be helpful as a starting point. 🙂 Alan

Hi KEJ, I have a ZS61 + Flat 61A + ASI071MC. The back focus distance from the flattener rear to the camera sensor is 67.7mm as shown below for the ZS61 scope. This is with the adjustment ring set to zero on the flattener. A DSLR and T-adapter has a standard back focus distance of 55mm so to achieve 67.7mm you can set the adjustment ring on the flattener adjuster to add the difference of 12.7mm as shown below. This shows 12.9 instead of 12.7 but it's close enough. The flattener rear thread is M48 so I used an M48 extender followed by a M48 to M42 adapter to screw on to the camera. Using M48 for most of the distance reduced any possible vignetting that may occur. The 533 back focus is 6.5mm so you want a total spacing of 61.2mm. You have up to 15mm of adjustment on the flattener so the extension spacing needs to be between 61.2 and 46.2mm with any shortfall below 61.2 made up on the flattener adjustment. With the flattener adjustment ring fully removed you can insert a 2" filter in the rear of the flattener if you wish though the filter will reduce the adjustment range by the thickness of the filter. With a UV/IR cut filter in mine the adjustment range is from about 7mm to 15mm. Filters can be added as part of the M48 to M42 extension if preferred as indicated in the camera manual. There are a number of extensions and adapters with the camera which will work but as I preferred M48 for as far as possible I bought a separate 30mm M48 extender from FLO. Alan

That's good news Adam. 😃 I didn't expect that. It may be because the PIC chips are actually CMOS based and not TTL as I first assumed, although they use a 5V supply. CMOS is more tolerant of voltage limits than TTL. The PIC power pins are labelled Vdd and Vss which should have been a clue. If it was TTL they would be labelled Vcc and Gnd. 😳 Alan

To save swapping the relays back you could make a slight modification to the PCB by cutting a track and adding a link which would power the relays from 12V instead of 5V. Or just monitor the PIC outputs on pins 6 and 7, that they change from 0 to 5V when the relays are meant to operate, which would indicate that the PIC somehow survived. Alan

Yes, Pics were the bee's knees 25 years ago or so, but are rather old-school nowadays. Alan

You also need the programming hardware with 3 power rails to program the EEPROM in the PIC. 😀 Datasheet. Alan

Glad to help Adam, I like a challenge. 😀 Yes, it's bound to be OP and CL signals coming into the board. I first read it as CP and didn't look at it closely again. 🤭 Your final analysis is correct Adam. 780x series regulators are pretty robust with thermal overload and short circuit protection so it's unlucky it failed. A replacement board is the best solution, I think, based on steppenwolf's design looks easiest, as the PIC solution is not on if you don't have the programming facilities. An arduino solution is a bit of overkill for what seems a fairly simple requirement. Once you and steppenwolf have worked out a working design, If you wish, I can do a board layout using KiCad which can then be sent off to have it professionally made. Or, for a one-off, I can do a less professional, home made one. 🙂 Alan

Here's the circuit layout Adam. Excuse the scribble. I can do a prettier one in KiCad but that'll take a while. 🙂 Note with the relay wiring, to run the motor in one direction you active only one relay, and to reverse direction you activate only the other relay, from PIC output pins 6 and 7 via the driver transistors. PIC pins 1, 2, 7, 18 are probably inputs connected to the CL and CP signals on connectors J1 and J2 via pull up resistors and noise filtering capacitors. Pin 8 drives the 'ER LEC' pin (I think that's how it's labelled) on J1 With the board unpowered connecting +12V directly to the motor would have shorted out the battery via the pcb track and relay contacts, hence the PCB track burning out and acting as a fuse. 😟 The resistance of the track was high enough not to drop the battery volts, so it still drove the motor. As the motor circuitry is isolated from the rest of the board, I can't see how that would have damaged the 7805 regulator, so that must have failed before for some reason, which most likely has killed the PIC, as it's TTL based, and can't cope with voltages above 5.5V 😬 D3 protects the board from inadvertant battery reversal. The PIC is effectively behaving as a set of logic gates with the outputs on pins 6, 7 and 8 dependant on the voltage states appearing on pins 1, 2, 17 and 18. An arduino nano could easily be programmed to replicate this if the function of the CL and CP signals were known. Alan

Adam, On the latest board picture you posted you've replaced the 5V relays with 12V ones. They are unlikely to operate from 5V. As you recently reported the 5V regulator appears short in to out I doubt the PIC survived as mentioned. Alan

Yes Adam, they look fine to work with. Can you read the markings on Q1 and Q2 just to check whether they're NPN or PNP, though looking at the finished circuit it should hopefully be obvious. 🙂 Alan

Hi Adam, If you could post 2 images looking straight down on both sides of the board, I'll work out the circuit diagram for you, which should help on determining what's gone wrong. 🙂 Alan

This issue was, I believe, resolved in Craig's follow-up thread here. 🙂 It seems the 533 by default has a significantly higher offset value in ADU compared to similar CMOS cameras. Alan

If you're not doing so, it's worth binning 2x2 for auto-focus in SGP. With binning, I use 2s exposures for L, 5 seconds for RGB and 25 seconds for NB. Works every time. 😀 You also get faster downloads. Alan

Thanks Alan, tomato & MarkAR. 😀 I believe the Astronomik Deep-Sky RGB filter set and L3 Luminance helped with avoiding coloured halos on the medium brightness stars which I tended to get with the lower cost Baader filters. I thought after spending that amount on the camera, it's worth splashing out a bit more on the filters, and it's seemed to have paid off. Startools HDR module is very good at revealing DSO core details. 🙂 The galaxy is enclosed in a bright oval which is largely independent of the spiral arm structures. Some images seem to deliberately suppress this oval and make it similar to the background level. Doing a simple stretch on the data does show that the bright oval is real and not a processing artifact. I suppose it's just dust and debris left over from the galaxy formation. Increasing the sky background level would help reduce the effect of the oval 'glow' if that's what you want to achieve I suppose. 🙂 Alan

I have an AZ-EQ6 rig with a WO 50mm f4 guidescope and ASI120, and an HEQ5 rig with the ZWO 30mm f4 mini-guider and ASI120. Looking at the PHD2 graphs there is no difference between them. Both will guide within +/- 1 arcsec when conditions are good. I'd recommend the Zwo mini-guider, but if you can adapt your current guide scope I think it would work just as well. Your mount and setup will more likely be the limiting factor in guiding performance, rather than the guide scope. 🙂 Alan

Thanks Paul, 🙂 Very impressive result and useful to compare results between a OSC and my LRGB one I posted yesterday. I'm told my background is too dark. 😀 The Ha regions show up very similar between the two. I binned mine early on in processing, primarily to speed up processing as Startools was a bit slow with a 62 mega pixel camera. 😄 Also, like the bonus video end. 😀 Alan

I admit my monitor is not properly calibrated, just set so you can see the individual steps on a grey scale stepwedge. Thanks for the info on the ASI6200 gain setting. I was going to do some tests to see the difference as the Zwo claims on dynamic range retention may have been exaggerated. I thought I'd do luminance on 0 gain as the exposures are relatively short anyway, but if it's not really noticeable in the results, I'll use gain 100 for L too. 😀 Alan

Thanks kirkster501, 🙂 Binning helped a lot with cleaning up the stars and making them look better. 😀 I find Startools keeps the background fairly dark during processing to emphasise structures and when it comes to adding the colour the default saturation looks too much so I dial it back. I do the final background lift in Photoshop which does desaturate the image overall. Perhaps I should leave the default saturation in Startools and see how it looks after Photoshop. I tried adding the Ha as a 'lighten' layer to the red channel in photoshop and it just enlarged and brightened the already red patches and added some noise. I'll try again. I imagine you can denoise or blur the Ha layer quite a bit without it affecting the final result. Thanks Xplode, 🙂 I was going to scale down in Photoshop at the end, but the full resolution image was quite slow in processing in some of the Startools modules. I like to process the full image and then crop the result in Photoshop. Startools suggested workflow order, says to 'bin' early in the processing steps, which certainly helped with processing time. It also shows more how the final result will look during each step. You can 'bin' to any resolution in Startools so it uses downsampling algorithms. I lighten the image in Photoshop, as in Startools it's best to keep the background fairly low or it will tend to stretch the background noise. Olly and others suggest 23 as the background level and I tend to use around 20. I'll try it with a higher value. 🙂 Alan

Here's my first processed image using the ASI6200 with my FLT98. I've binned it 2x2 in software as little real resolution is lost. It's a centre crop to just show the galaxy. L = 3.9 Hrs total at gain 0, RG and B = 1.6 Hrs total each at gain 100 (3.2 x actual gain), and HCG mode. Sky brightness -21.34 using Unihedron. Processed in Startools. Small final adjustmests in Photoshop. I also tried blending in some Ha to Red but it just made the red patches brighter without really adding much so I left it out. Click for full size. 🙂 Alan

I'm wondering if I may have the S2 and Hb swapped over in the filter wheel as I got quite a bit on Hb position but nothing discernable on S2. 🤔 Hb doesn't seem to feature in many images I've seen so assume on many targets it gives nothing. Alan