Jump to content

Banner.jpg.b89429c566825f6ab32bcafbada449c9.jpg

Stub Mandrel

Members
  • Posts

    10,662
  • Joined

  • Last visited

  • Days Won

    32

Posts posted by Stub Mandrel

  1. I have a problem with my ASI120MC, which I use chiefly as a guide camera in PHD2 but also for planetary imaging and polar alignment in Sharpcap.

    Sorry for the long list of symptoms...

     

    When used for longer exposures (typically about 0.2 seconds or less) it starts losing frames.

    Sometimes it will run fine for a whole evening.

    Usually it will periodically stop generating frames, this mostly happens in PHD2. When it (rarely) happens in Sharpcap ensuring auto Turbo USB is enabled usually restores order.

    Sometimes it starts generating split frames, so the guide star is in the wrong place.

    Sometimes disconnecting the camera in software will solve it.

    Sometimes physically disconnecting the camera is needed.

    Sometimes closing the program and re-opening will help.

    Sometimes opening the camera in Sharpcap will allow it to work when I go back to PHD2.

    Occasionally a full computer restart is needed.

    Switching between 8 and 16 bit doesn't seem to do anything.

    I have reinstalled the drivers.

    Recently I reinstalled PHD2 (I already was using the latest version) after nothing else could get the camera to work (it was working in Sharpcap).

    This seems to have improved things, but the camera still occasionally starts dropping frames for a few minutes, then recovers, resulting in guiding going AWOL.

     

     

    Sorry for the lengthy description, my guess is the problem is related to PHD2 getting out of synch with the data flow from the camera - suggested by the split frames and Sharpcap's ability to work it more reliably with its more sophisticated controls.

    It may also be an ASCOM issue as a few times ASCOM has thrown a wobbly (I have tried reinstalling it) and loses my mount (HEQ5).

    What is weird is it all used to work OK and rock solid reliability - in August I did about five nights in a week each of 5-7 hours imaging without a problem, same equipment. Since then I haven't had more than one or two sessions without a problem with the camera.

    Can anyone suggest something that I could have changed unwittingly?

    Is the 'best' solution a new camera at the risk of  no improvement?

  2. 16 hours ago, wobblewing said:

    This is great.  I was thinking about making one of these for a small heritage 150p, using my 3d printer as you have.

    Did you have any problems with roller grip on the sectors in the end?   I was wondering if a 'rack and pinion' approach may help with the sector control?  That is something that could be 3d printed quite easily into the 'sector' parts.

     

    Hi,

    Just make sure the weight is concentrated near the rollers.

    I had to superglue the rubber tube onto the rollers to stop them slipping, but once that was done it worked fine. I took it along to a club observing session and also used it for some planetary imaging, even with only a rough polar alignment it was great for these uses. I don't think you could use it for long-exposure imaging without more sophisticated alignment and control.

     

    13 hours ago, AlexK said:

    To answer your question, this particular platform type is not compatible with the rack-and-pinion (actually long rack sector-and-) driving natively, because its sectors are sliding and rocking on the bearing surface as the HA changing (they are not following the ideal circle). It will be hard to implement a cog following them. 

    However, you can add such a mechanism on a separate "row" of the virtual cone instead, e.g. right behind the sectors assembly. The sectors row will take all the scope weight load, while the actual driving will be done behind them.

    This is true, by making an 'all force straight down' sector makes them unsuitable for easily being a rack, but it would be easy to print a suitable sector of a circular rack and fit it between the roller sectors.

     

    • Thanks 1
  3. 16 hours ago, wobblewing said:

    This is great.  I was thinking about making one of these for a small heritage 150p, using my 3d printer as you have.

    Did you have any problems with roller grip on the sectors in the end?   I was wondering if a 'rack and pinion' approach may help with the sector control?  That is something that could be 3d printed quite easily into the 'sector' parts.

     

    Hi,

    Just make sure the weight is concentrated near the rollers

    I had to superglue the rubber tube onto the rollers to stop them slipping, but once that was done it worked fine. I took it along to a club observing session and also used it for some planetary imaging, even with only a rough polar alignment it was great for these uses. I don't think you could use it for long-exposure imaging without more sophisticated alignment and control.

    • Thanks 1
  4. 6 hours ago, Peter_D said:

    This image from last night is probably the best so far - but would I be right in saying the dark cloudiness are artifacts from over processing?

    No! It's meant to look like that, IMHO 🙂

    Nice pic, by the way!

    • Like 1
  5. DPI for printing is much more complex than the 'use 300dpi' usually offered.

    300dpi is the general rule for books and magazines etc. that will be viewed at a comfortable reading distance. At A4 that's an image about 3600 x 2400 pixels (~8Mp). This effectively gives you what Apple calls a 'retinal display' - that is the resolution is roughly that the eye can perceive so you don't see any artefacts and maximum usable detail is presented. In practice, we often interpolate images to get this resolution (one of my roles is a magazine editor) and it's surprising what you can get away with. Photographers are often astounded that 8 megapixels is plenty for the cover of a normal UK magazine (perhaps not Vogue or National Geographic...)

    For images to be viewed at greater distances lower DPI can be fine, for example a typical pullup display may be printed at 300dpi but the pre-interpolated image may well below 100dpi and still look fabulous at a normal viewing distance. On the other hand I have produced artwork for interpretation boards and used ~600dpi for the component images and downsampled to 300dpi for the final artwork, as it would be viewed close up.

    Ideally I would aim for about 150dpi multiplied by the viewing distance in metres, but you can go lower than this. For example, many desktop computer screens used to be 90 dpi but images looked fine on them at about 1 metre distance.

    The problem with most astro images is that they are often oversampled already with the finest detail being 2 or 3 pixels. They normally look fine as they are lightly blurred rather than pixellated, but it does mean they can look mushy and soft when blown up.

    One trick we often use in the magazine is to resample an image with interpolation and then apply a judicious amount of sharpening (usually just unsharp mask, but sometimes deconvolution) to bring definition to the sharp edges in the image which creates the illusion of higher resolution. This suits the sort of  images we have which are typically machines etc. but may not work as well with 'organic' shapes like people or nebulas!

    Another tip is to view your image at 100% on your computer screen i.e. one pixel per screen pixel. This allows you to 'lean in' a bit and make a fair judgement of how sharp it really is.

    • Like 1
  6. On 22/09/2020 at 00:48, kens said:

    Could you post a guide log and maybe even the debug log? 

    For instance, it could be that there is a long wait time for the mount to respond causing delays on each expsoure

    Could be, I will try and find it.

    But at the time it had been guiding as well as 0.52", ticking away every 2 seconds then .... it just fell over, sometimes a minute or more before getting a frame, and some split frames.

     

  7. On 22/09/2020 at 00:20, michael8554 said:

    Sounds like a USB bandwidth problem.

    Experiment during the day with a short USB cable, and lightly capped, so you get a grey frame with PHD2 slider adjusted, at your usual exposure.

    Try it in all your USB's with nothing else connected.

    If that works add more kit and longer cables until it starts to be "throttled". 

    Michael

    I'm using a 1.5m quality cable 😞

    I've always had best results in Sharpcap allowing it to auto-set the USB speed.

    But PHD2 doesn't have such a feature.

  8. I use a ZWO ASI120MC for guiding with PHD2.

    I never have problems finding stars, but often have issues with poor connectivity with the camera. This seems to have got worse of late.

    What happens is that the time between frames gets longer, and longer and longer...

    Reconnecting the camera, in software or by unplugging it makes no difference. Restarting PHD2 makes no difference. Restarting the computer sometimes works.

    The only thing that works reliably is:

    • Close PHD2
    • Open the camera in Sharpcap (where it invariably works)
    • Close Sharpcap.
    • Reopen PHD2 and reconnect the camera which will now work reliable for 'a period of time' which could be ten minutes or a few hours...

     

    The problem is somewhat intermittent and I have a suspicion it might be EQMOD related, not just PHD2. I am sure it isn't a camera/driver issue as it always works fine in Sharpcap. Note that 8 bit/16 bit mode doesn't seem to affect this.

     

  9. On 17/09/2020 at 10:15, Welrod50 said:

    Just a thought regards earlier post about the camera/usb possibly playing up...

    I used to use a 550d modded with a 130PDS on an EQ3 Pro a few years ago before I sold the lot to help with costs of our wedding but before doing so and after some frustration with the camera conking out randonly both when just connected and also whilst usong BYE, I discovered that when using a 10 metre USB extension cable for some reason the distance to camera seemed to lower the signal/output and after I replaced it with a usb cord with 'signal booster' attachment (still really cheap on fleabay) the problem immediately went away.

    Worth a try??!

    Scott

    10m is pretty much the limit for USB.

  10. I need to go back to my Neptune data and see if I can rescue it with better settings in PIPP.

    Meanwhile, here are five planets from last night with my 150PL, ASI120MC, 3x barlow and ZWO ADC. So far I haven't been able to improve Jupiter by drizzling, although Saturn and Mars responded well. Uranus is just a dot, so left as it was!

    00_18_17__pipp_l4_ap57_Drizzle30.png.98b4d6376e94611d0c819b8acc90b033.png

    21_40_48__pipp_l4_ap183.png.734f54698241a11199230fbca2b603da.png

    1980344010_Saturnx3.png.1b05bef9164c984b6b2fdf64de68ab2b.png

     

    22_17_15__pipp_l4_ap5.png.a8ea24ec7e8e993ab7b23d60fe0cf530.png

    00_30_20__pipp_l4_ap5.png.e1e17b2ad0bd17031cd4d2f0dc3fd91a.png

    • Like 2
  11. 19 hours ago, Jonk said:

    One thing I don’t know enough about is layers in Photoshop.

    Very easy, if the two images have the same crop, just paste one over the other. It will create a new layer and all you have to do is change its mode to 'colour' (or luminance if the more detailed image is 'on top') then adjust its transparency percentage to taste.

    If the same scale but different crops, you will need to manually line the top one up - set its transparency to 50% to facilitate this.

  12. 3 hours ago, almcl said:

    That's not quite how I understand it,  Neil.

    May be into terminology differences here, but I think that only calibration frames in the Main group are applied universally.  So if you load lights, darks and flats into group 1 (confusingly, the second group tab) then they only apply to that group.  So with multi-session stacking perhaps one should only load offset files into main and put everything else in groups 1, 2, 3 &c? 

    Sorry, I meant the main group, not group 1.

    I do think it would be helpful and intuitive if main group control frames didn't get used if there are versions in one of the numbered groups.

    Also, here's an issue I have encountered (the details are arbitary).

    1. Night one I take 150 second subs, and make flats.
    2. Night two, I take 300 second subs, but can use the same flats as nothing was changed.
    3. A week later I take 300 second subs and new flats.

    That means I need the same flats for sessions 1&2 and the same darks for sessions 2&3.

    The problem is, I can't put the same flats into group 1 and 2; ditto I can't use the darks in two groups. The only solution is to make a master flat and dark and duplicate them. This is a bit of a pain.

    It would be useful to be able to this as it often crops up when I try to combine data from earlier years with more recent data.

×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue. By using this site, you agree to our Terms of Use.