Shimonu

I was out tonight trying to figure out what was wrong with my guiding. I would always have the Total RMS climb to around 2" and it could be stable for some time and fluctuate, sometimes as bad as going to 4". Most of the error would be in RA from what I could see so I was worried my mount had to much play in the RA axis and tried to tighten it and make sure I couldn't feel anything. This didn't seem to have any effect. After being out for an hour trying to run PHD2 guiding assistant among other things and failing I just started to look at what options i had in Ekos and eventually I just tried setting the binning to 2x2 thinking maybe some different stars would be chosen. Bam, suddenly my guiding is great! It'll be around 0.75" at the best and 1.5" at the absolute worst. I'm ecstatic, I feel like such a weight has been lifted and everything is falling into place!

But what about this makes a difference to guiding? What is changing by going to bin 2x2 to have the guiding improve so noticeably?

Finally had a clear night where I could get the new setup out on a real target. For the start of the season I've had my eye on M27 so I gave it a shot. Unfortunately I've found out my battery is far from adequate with the new setup, by the time I was photographing the battery was showing 11.4 V and I didn't dare to do more than just take a 60s sample each for the LRGB filters but I have to say the result is impressive considering.

Still a bit new to editing so some of the stars have odd colours and fringing. I'm just so excited to see how low the noise is compared to my previous Canon DSLR and how good the signal is.

This is going to be a fun season!

Or if I should perhaps have a more concrete question. Is it possible to see the RA backlash measured in the calibration? I've only seen it referenced as an output for the PHD2 guiding assistant.

One of the problems I was having before the summer was somewhat poor guiding and I haven't figured out if this is due to my mount, the guide scope or perhaps something I'm doing wrong with balancing, PA, etc.

I've found some guide logs that I've been looking at but I'm not quite sure what I'm looking at or where I should pay attention. I've got the PHD2 log viewer and one of my sessions from January looks pretty decent, I've got an average of 1.38" total RMS which for my image scale is more than fine. However, looking at a later log from April it shows an average of 1.79" and I remember around this time having pretty poor guiding, even after starting to use multi-star guiding.

My main suspect right now is my mount and I'm hoping the guide logs can help me confirm it. For one it's quite an old mount that I've bought second hand. On the controller board I've seen parts marked from -06 and -07 so likely at least 10 years old and I'm not sure if any maintenance has been done. If I try to move the RA axis by hand I can feel a bit of play, compared to the DEC axis which is rock solid.

I'll post some logs, hopefully they'll tell a good story.

guide_log-2021-04-03T21-48-41.txt guide_log-2021-07-21T23-49-10.txt guide_log-2021-01-26T19-05-16.txt

Someone care to explain the benefits of Astronomy Linux over running something like Ubuntu and kstars?

Mono certainly brings a lot of extra costs with filters and related equipment. I don't have a lot of experience with avoiding light pollution but from what I hear it's quite possible with OSC and correct filters.

I was also interested in the 533 but also had my eye on 294 as they're in the same price range. You'll have to consider how you feel about the sensor format and amp glow. I believe those are the big differences. I don't remember the pixel sizes.

Personally I made my choice about 3 weeks ago and went for mono. It's certainly put a strain on my wallet but I would really like to try playing the the narrow band filters and I feel that I'll be doing this for some time and I'm willing to put the time into it to learn and feel that I'm able to get as good results as possible.

15 hours ago, vlaiv said:

ImageJ will let you stack with minimum.

Just form a stack from your subs (which is just a "pile" or "collection" of images - in ImageJ lingo that is stack whether you stack it or not - you can simply do it by "File / import / image sequence") and select:

Image / Stack / Z Project and select minimum method:

If you shoot bias - which means minimum exposure time, temperature should not make much of a difference - but in principle - it is temperature dependent. As temperature causes dark current buildup and dark current will also raise signal level - it can skew results.

It will be gain dependent as well - that is why I mentioned that you should set your parameters the same way as when imaging - gain, temperature, etc ... and only vary offset to determine which value to use.

I'll see if I can do it with more consistent and realistic temperatures.

Thank you very much for the help!

On 24/07/2021 at 20:48, vlaiv said:

Here is methodology that I would suggest:

- Set other parameters as per your preference (gain, temperature, whatever) - and start with some offset.

- determine what is minimum value your camera outputs (probably 0 but it can sometimes happen that floor is not 0)

- take set of bias subs. Maybe couple dozen of them - stack using minimum method

- inspect resulting stack for minimum pixel value - if it is equal to floor value of your camera (again, probably 0 value) - increase offset and go to step 3, if minimum pixel ADU is larger than floor - you are done.

I figured this sounded easy enough but I hit a slight snag. Which tools allow you stack using minimum? I checked both AstroPixelProcessor and DeepSkyStacker but they don't have options for minimum. So is it something you do manually in an editor like Photoshop or GIMP?

EDIT: Even manually going through the bias frames in ImageJ I found an offset of 5 will give a minimum above 100. But from other comments I read that seems like a very low offset as people are saying even 8 which in some cases is default is very low. How temperature sensitive is this? I haven't exactly been running the cooling at max.

6 minutes ago, vlaiv said:

Here is methodology that I would suggest:

- Set other parameters as per your preference (gain, temperature, whatever) - and start with some offset.

- determine what is minimum value your camera outputs (probably 0 but it can sometimes happen that floor is not 0)

- take set of bias subs. Maybe couple dozen of them - stack using minimum method

- inspect resulting stack for minimum pixel value - if it is equal to floor value of your camera (again, probably 0 value) - increase offset and go to step 3, if minimum pixel ADU is larger than floor - you are done.

Thanks! Just a couple of questions. How do I find the minimum my camera outputs, is this some publicly available info or something I need to find by testing? What do I use to inspect the output values? I'm guessing there is some tool that can give something like a min pixel value?

Is there a methodology to determining what offset should be used with a camera? I understand it's somewhat individual but what kind of analysis can I do to find a good value or know that I have the wrong value?

2 hours ago, symmetal said:

The FF back focus distance is 56.8mm. A DSLR has a front plate to sensor distance of 44mm, The DSLR T-ring adapter has a thickness of 11mm so the 1.8mm added on the FF adjustment totals 56.8mm.

The 1600 has a front plate to sensor distance of 6.5mm (this distance is also called back-focus hence the confusion that arises.) The filter wheel is most likely 20mm so your total distance at the moment is 6.5 + 20 + 9 = 35.5mm. To reach 56.8mm you need to add an extra 21.3mm. The FF adjustment may only go up to 15mm, so a 10 or 15mm extension T-ring needs to be added and the remainder of the 19.3 set on the FF adjustment.

Alan

Are you saying the FF might need to be set differently depending on if you have  DSLR or astro camera? I've just got a mono camera and wondering if I should set my Flat73 differently. The WO instructions feel a bit unclear.

2 hours ago, alacant said:

To simplify things for now, run kstars on the Nuc and connect to it via vnc. It is then is then always local.

Make sure that you have specified a folder which exists on your Nuc of course;)

 

 

If possible I'd really like to stick with the existing solution, I like the way it currently works and it feels like a good method as long as I can get this little thing figured out. But it's certainly an alternative if this doesn't work out.

Appreciate the help!

1 hour ago, alacant said:

Hi

Set the values you want -2x2, local or WHY- then in the INDI camera control panel hit:

options -> save

Cheers

Not having much luck I'm afraid. I think this is because I'm running a remote computer physically on the rig which I connect to with my laptop and the settings aren't getting saved there. I tried playing around with the Upload settings in the INDI control panel but it doesn't seem to have much effect. The terminology is also getting me a little confused, "locally", "client", "remote" with respect to which computer are we talking?

Is there a way to set some default values for the camera in Ekos? Right now I seem to have an issue where if I forget to set the camera to bin 2x2 then the capture will fail without any helpful error message. It's very frustrating as well as the gain and offset never having a default value, just "--". The download location is also always locally while I want it remotely.

This camera is new to me so I'll probably learn with time but I also want to save time and not have to set this up each session.

What are valid but extreme orientations of the mount you can try to verify that no cables are too short or at risk of snagging? I'd like to do somewhat tidy cable management but I'm worried I'll tie up some cable that for certain targets or some time of year might just try to stretch it too far. So I want to manually and slowly try some extremes.

Is it just RA fixed and DEC 180 and vice versa and then both or am I overlooking something? Or should I set a slow speed and ask the mount to slew to something directly south?

I've just upgraded my camera from a DSLR to a mono and I'm looking what my second scope should be to complement my Z73. Newtons have always seemed like a good bargain but I've been a bit scared of the collimation, sometimes it seems trivial and other times I hear people never being able to manage it. From what I gather an f/5 shouldn't be too bad and I've gotten pretty interested in something like a 150/750 which would really let me photograph some of the smaller nebulae and make more galaxies available. Although a 200/800 would be sweet too if it's manageable collimating a faster scope.

What makes me hesitant is I feel like people are often modifying and replacing things to get a decent experience or having trouble with accessories and balancing. So let's say I want to buy something like the TS Optics or Skywatcher 150/750 and use my mono equipment, including an electronic focuser, how carefree would my experience be out of the box? Even with my Z73 I experienced the included dovetail was all but worthless once the imaging equipment was attached. Is guiding typically done successfully from the finder shoe? Should I attach a dovetail on the top and try to balance out the camera with equipment on the primary mirror end? A coma corrector is implied, I don't feel a corrector of some sort differs from other scopes.

I really like the included bahtinov mask on my Z73 which is also neatly built in to the cap. Otherwise I felt the dovetail wasn't very useful as soon as you start putting camera and other stuff on it, you're really pushing it when it comes to balancing DEC.

Well I'm a little embarrassed/confused. I was about to start measuring voltage after I went buying a PCB holder and other stuff for soldering. I plugged in the cable and noticed the LED came on. Connected the controller board and plugged in the handset which seems to work just fine, slewing no problem. But I don't get why powering on the mount yesterday caused the serial communication with the PPB to fail, even though nothing but the power cable was connected to the mount. I haven't tried running the whole rig, so maybe it'll show the issue again. Perhaps the second cable I used wasn't good enough, I just opened it too and there's no fuse in it. But that's the cable I got with the mount. I feel like if it can handle the mounts requirements it should be able to just power on stuff.

I dismantled the first cable I used yesterday which stopped working and sure enough the fuse is blown. That's an 8A fuse.

I'll hold off on doing any more testing until I get some more input.

I don't feel like an 8A fuse just blows for no reason. I'm powering from a 12 V battery which at the moment shows 12.6 V and that isn't going to suddenly unload high current unless there's a short. But where would that happen? The cables are all factory made and are not just going to switch polarity and everything is center positive.

1 hour ago, Dr_Ju_ju said:

Start by tracing the circuit with a resistance/continuity tester & ensure that there are no obvious short circuits on the input and that the incoming 12v reaches the stepper driver chips and  what I expect will be a regulator providing approx. 5v to the control components.

If all appears to be ok, go ahead & apply volts to the board & re-check the incoming and regulated voltages.  

Great advice and with the schematic below it helps so much! When applying voltage later, what sort of supply would be appropriate. I feel that I don't want to use the battery pack I normally use as it's able to supply quite a lot of current. So perhaps a mains supply with more limited current capacity is better?

55 minutes ago, malc-c said:

Julian is correct, the component is an inductor not a capacitor.

Two things can happen with these boards.  The first is that the power regulation fails, so the PIC microcontrollers stop running as they are no longer receiving 5v, which will give the "no response both axis " message in the handset, or a "time out" in EQMOD.  The second is that if the wrong cable gets connected to where the handset connects it can sometimes damage the serial port built into the PICs which gives the same response.

Power supply issues are harder to resolve, but there have been accounts (including my own HEQ5 board) where replacing the electrolytic capacitors with ones of identical value but higher voltage rating resolves the issue.  These boards run the steppers at 33v, which is IMO too close to the 35v rating of the capacitors used.

If you are interested in possible caused and fixes have a read of this thread

There has been a lot of work on reverse engineering the SW boards.... It's in french, but this is the schematic for the EQ6 power regulation that someone reverse engineered - I can't vouch for its correctness, but it should help you trace out the components, and even gives manufactures part numbers for the inductors etc.

That is so helpful, I haven't gotten all the way through but so far it seems accurate! Thank you! I've had a good look at the electrolytic capacitors and they don't show any sign of damage. Doesn't mean they're fine but none of them went pop. From the schematic I can't see the power LED, it should be D3. It would be nice to know where that comes in as it didn't light up, so it's a clue of a power supply issue but I'd like to know how much it limits the search.

EDIT:  Managed to follow the trace and saw now that it's driven off one of the PICs

28 minutes ago, malc-c said:

If you get stuck, and after replacing capacitors it still won't come to life and if your board used the 16F886's then drop me a PM and I might be able to take a look and see if I can fix the board in the same way as I've fixed the MC003 and MC004 boards for other SGL members.  The alternative will be a new replacement board at around £130 - £160  from FLO.   

I had no idea there were replacement boards. Would it really work for an older mount like mine? I've got the 16F73 I'm afraid. I really appreciate the suggestion!

1 hour ago, Dr_Ju_ju said:

I don't have one, but what I suspect you think is a capacitor is actually an inductor, which might well have blown out if there was sufficient current trying to pass through it....

You're right, of course. After seeing the L I realized it wasn't a capacitor.

1 hour ago, gajjer said:

I managed to blow mine up a couple of months ago. I was using an old power pack with banana plugs and doing it in the dark I managed to reverse power it. I was gutted but took it apart and noticed that a big capacitor was blown. ( It may have been two capacitors, I can't remember. ) The ends of the cap were blown out, so it was pretty obvious. 

Well, I swapped the capacitors for something similar ( bigger volts and bigger value ) and to my surprise it worked perfectly. One word of caution. It was quite difficult removing the capacitors. Be careful you don't damage the through plated holes of the PCB. I managed to cut the body from the leads making it easier to remove just the leads.

Hope you get it going again.

cheers

gaj

I'm not sure what could have happened to mine. I wasn't doing anything out of the ordinary and normal just plug the cigarette plug into the battery. But this time things just wouldn't quite start. I tried replugging my pegasus powerbox and that's when some sparks started flying but my guess is something was already broken by that time and caused the sparks rather than the other way around.

Thanks a lot for the soldering tip.

43 minutes ago, Pixies said:

Judging by the 'L' on the circuit board, that's an inductor. Inductance is measured in units of Henry [L]. What text is on the body of the component?

If you are going to remove it, as @gajjersays, cut the wires near the component body, so you are only trying to remove the wires when you desolder it. 

If you've never desoldered anything before, check YouTube for tips, using desoldering wick,

 

Yeah, I saw the L after I wanted to see if I could measure anything with a multimeter. I've got experience with soldering just not usually with these kinds of boards but I'm not too worried for the coil, it's quite big and easy to access.

Do you have any ideas for any troubleshooting I can do before I start desoldering. I was wondering if it was worth getting a small variable power supply and set it to some low voltage and see if I can measure the supply and perhaps find some indication of a culprit that way.

I was about to do some testing tonight and started everything up like normal when suddenly things wouldn't connect. What I saw was my Pegasus Pocket PowerBox wouldn't connect but as I later noticed it wasn't even getting power because the power cable stopped delivering which I now believe is due to the mount shorting and burning the cable. I can't see anything wrong with the cable but I've confirmed with a multimeter and trying another cable. Apart from my mount no longer turning on I also noticed that when I tried turning it on while having everything else on the serial communication with my Pocket PowerBox would fail. Of course the mount is also powered through that unit.

I'm hoping this is just a coincidence as I've just bought a new dedicated astro camera.

This is one of the older models with the RS232-port. Are there any typical components that might fail or things that are worth investigating? I don't see anything that looks damaged but one of the bigger capacitors looks a bit suspicious. Any other options for getting this back in working order?

21 hours ago, Skipper Billy said:

This is probably nearer to what you are after

https://telescopius.com/deep-sky/object/1107/andromeda-galaxy/m-31/galaxy

Click on the Altitude - Yearly tab and it shows the best time of year to image any given target.

 

 

That's perfect! I didn't know you could see it for a time of day for the whole year.

Now starts my wishlist of targets for the year. Creating a spreadsheet for planning/categorizing them and sorting for when the best time is to shoot them.

34 minutes ago, Stu said:

If you have an iPhone, there is an excellent app called Observer Pro which does exactly what you are asking.

Technically of course all objects reach their highest elevation every day of the year, there is just that inconvenient thing called daylight which gets in the way sometimes 😉. Observer Pro also shows best visibility times in terms of the lunar cycle and rise/set times too which is handy.

Right, very true! I wasn't considering the position during daylight. Unfortunately no, don't have any iPhone. Seems like an awesome app though!

25 minutes ago, Skipper Billy said:

If you use Stellarium you can locate an object then 'wind the clock' forwards or backwards by hours, weeks or months to see when its in the best place for you.

https://stellarium.org/

Yeah, I guess the best way is to check with Stellarium. I was just hoping that if I had a list of targets I'm interested in that there would be a quick way to check without really knowing what time of year they're relevant.

11 minutes ago, Gfamily said:

The height of a transit is always the same (except for solar system objects), so what's probably of interest is to know when they're due south at a good time for observing.

I'd suggest a classic planisphere as the best way to see this.

Alright, I guess I'm phrasing it a bit too general or misusing terms. From my location I would like to know what time of year an object is the highest over the horizon. For example, Orion doesn't make it over the Horizon this time of year but it gets a decent elevation around December/January.

Is it possible to find out what time of year a target will transit the highest? I know Orion is the best for me during some of the winter months but is it possible to find out after which date it starts to get lower again? I know telescopius will show transit but only for a specific date.

Thanks