Jump to content

Stargazers Lounge Uses Cookies

Like most websites, SGL uses cookies in order to deliver a secure, personalised service, to provide social media functions and to analyse our traffic. Continued use of SGL indicates your acceptance of our cookie policy.

  • Announcements

    sgl_imaging_challenge_banner_galaxies.thumb.jpg.d7ac9ec2b53bebbaffa8a76a92120303.jpg

symmetal

Advanced Members
  • Content count

    229
  • Joined

  • Last visited

Community Reputation

143 Excellent

About symmetal

  • Rank
    Star Forming

Profile Information

  • Location
    North Cornwall
  1. In the camera circuit the 3.3V from the Canon is via a pull-up resistor in the camera shown as 50k on your web link though is probably a standard 47k. This is there to stop the camera shutter input voltage floating to an arbituary value when there is no connection to it. This is why only 68 μA flows through the shutter switch when shorted to ground. (I=V/R, = 3.3 / 47k = 70μA). Even if your Q2 resistor was fully turned on the 47k between the emitter and ground means the camera shutter input would only drop to 1.15V and not 0V. This may be too high a voltage to trigger the shutter. As bobro says remove the 47k in the emitter and connect the emitter directly to ground. This makes the base voltage a fixed 0.6V or so when Q2 is turned on rather than a changing value depending on the current through the emitter resistor. The DC current gain (hfe) of the PN2222 is only about 35 at low collector-emitter currents so the base current needs to be at least 70μA / 35 or about 2μA. R4 needs to be (3.3V - 0.6V) / 2μA or 1.3MΩ maximum. To ensure the transistor switches fully on, put around 10 times this current into the base so R4 should be 1.3MΩ / 10 or 130kΩ. Good quick estimate at 100k bobro . Also as bobro says the grounds of the camera and the PI need to be shorted together so that they work to a common reference. Your LED circuit worked because the LED and the transistor are both powered by the PI so have a common reference. The emitter of Q1 can only rise to a maximum of about 2.7V as the base can go no higher than 3.3V. If the emitter tried to go higher than 2.7V the transistor would turn off. With a drop across the LED of about 2V the current through it is limited by R1 to (2.7V - 2.0V) / 680Ω or around 1mA so it will be a bit dim. Swapping Q1 and D2 over the emitter is fixed at 0V so the full 5V is available for driving the LED with R1, so it will pass 5mA and be brighter. R2 needs to be increased to around 10k as well to avoid Q1 going 'pop'. Alan
  2. Jupiter's very low in the sky from the UK at the moment so you're looking through a lot of atmosphere and clear images will be a challenge. Aim for the highest frame rate (frames per second) as you can, 100fps or higher. I believe the 120MC is USB2 so not sure how high it will go. Set the resolution to the smallest size able to keep it in the frame for the exposure duration to keep the frame rate high. My ASI224 will go up to 200fps using USB3. Due to Jupiter's fast rotation the video length should be kept below 2 mins. Take many 1 min or so videos and experiment with keeping only the highest quality frames in Autostakkert. Try the best 5 or 10%. With luck you'll get an instance or two where the seeing allows for some good frames. From your images posted you seem to have the processing part sorted out. I've used the Astra Image deconvolution option on their plugin for Photoshop along with their other sharpening routines with good results. When Jupiter is higher in the sky the 3x barlow could be useful though I doubt it will give better results at the moment. It will give a dimmer image so you'll need more gain (higher noise) or longer exposures (lower frame rate) to compensate. Good luck. Alan
  3. Dirty eyes?

    I developed large floaters in both eyes about 5 years ago. I'd had small floaters for as long as I can remember which were a slight nuisance but the large ones made reading, and working on the computer difficult and tiring. I tried laser vitreolysis treatment which is meant to vapourise the floaters using a laser, but after half a dozen sessions there was little improvement. I had to resort to the only procedure that will remove floaters which is a vitrectomy, where the jelly like fluid inside the eye is sucked out and replaced with saline solution under local anaesthetic. I had both eyes done (six months apart) and have complete floater free vision now which is great. You have to pay to have it done privately, about £5000 an eye but for me it was worth it to have clear vision again. Alan
  4. Help! Meade lx200gps ascom phd issue

    It's possible the RJ sockets on your scope over the long periods of exposure to the elements have some surface corrosion on the contacts causing bad contact and communication problems. Working for a few weeks after changing the adaptor and now the autostar problems would lead me to suspect this. You could spray some isopropyl alcohol (IPA) into the sockets and rub the contacts with a cotton bud to see if that improves matters. As a longer solution I would get some ACF-50 spray and spray the all the contacts (plugs and sockets) with this. It leaves an 'oily' like film over the surface so afterwards wipe it off the areas you don't need covered. It cuts through corrosion and protects the metal for long periods against further corrosion. I respray all my outside connectors with it every six months or so, and haven't had any connection problems. Alan
  5. Power Tank Build Completed

    Very nicely done. If I can make a couple of suggestions, you could get some self adhesive cable-tie bases to stick to the bottom of the case to keep the cables more secure and stop them moving about, particularly the ones from the batteries to the fuse box. Also you could cut the excess cable length from the batteries, if you don't need the extra length for other uses. Alan
  6. The FITS file should be the same as the TIFF file if they are both unstretched. Here's my effort in Startools with the FITS. I usually set the manual develop slider below the default setting to avoid lifting the sky background too much. Didn't do any Decon or Sharpening as it enhanced the noise too much. I set the noise reduction more aggressive than I normally do and did a final slight stretch in Photoshop to enhance the highlights. 6 subs is not really enough to give a good S/N though. Did you use Bias or Darks when you calibrated them? Also can you go lower than -15C this time of year. Yes, bright or coloured patches at the edges are a sure sign that some more cropping needs to be done. Alan
  7. The uploaded image has already been stretched by the looks of it. Startools likes to work with linear (unstretched) data. The first thing to do in Startools is to crop off the stacking artifacts around the edges as they cause havoc with the 'Wipe' module. I normally use Photoshop to crop as it's quick but you can use the Startools 'Crop' tool to do it. Do an 'Autodev' before cropping to show up the edges clearly. The Autodev is temporary and you can reset it afterwards. Can you upload an unstretched image instead. Alan
  8. Astro-Imaging Help Requested

    Hello MattDay2u and welcome to the forum. Air turbulence in the Earth's atmosphere (called the 'seeing') causes problems for getting single sharp images of the Moon and planets, as the image 'swims' around with different areas going in and out of focus. The normal method is to do 'lucky imaging' where you take a video of the subject and use software to select and stack the best frames (the 'lucky' frames) where the seeing is momentarily good. If you switch your camera into live-view you can see the image 'swimming' about which makes focusing difficult. The best way to focus is to view a bright star using a bahtinov mask on the front of the telescope, then swing back to the moon without touching the focus again. You can take a number of manual frames using an intervalometer so you don't have to touch the camera and make the image shake. Hopefully you'll get some sharp images. It's better to switch the camera into video mode and take a 30s video. If the camera has a 'crop sensor' video mode where it uses the centre 1920 x 1080 pixels of the sensor rather than interpolate the whole frame down to the video resolution, you'll get a sharper image. You really want to shoot the video in uncompressed 'raw' mode but the Canon can't do that and you'll have to use the 'mov' format which will give compression artifacts when stacking. It should still give you a much better image than single shot though. The astro-imaging cameras like the Skyris let you shoot video in raw uncompressed mode and also let you use a cropped area of the frame to enable a higher video frame rate, very useful when imaging planets as they only occupy a small portion of the sensor. The most common cameras to use at the moment are those from ZWO. They are favourably priced compared to others and give very good results. They are USB3 so can shoot at frame rates up to 200 frames per second so can possibly 'beat' the 'seeing' distortion . There shouldn't be any need to get the FeatherTouch focuser at the moment, as using a bahtinov mask in liveview on a bright star, your existing focuser should be OK. Using a wedge putting it in Equatorial mode the image will be more stable as it will only be driving in RA rather than stepping in DEC and RA when it's in Alt/Az mode, but that isn't necessary for planets and the moon as the exposures will be very short. Equatorial mode is only really needed for long exposure imaging of DSOs. There should be an option in the Setup options of your scope controller to tell it whether it's in Alt/Az mode or EQ (wedge) mode. There are several free programs to do the image selection and stacking, Autostakkert is a good stacking program and PIPP is a useful pre-processing program as it will convert your MOV files to RAW, to use in Autostakkert. I hope that's enough to get you started. Alan
  9. Atik One Filter Wheel Failure

    Yes, you're right Ray, the Atik One has the same orange ring. The motor drive is held in contact with it by a spring which you push back to remove the carousel. Alan
  10. Flat Field Analysis

    Nice and flat field there Aidan so your spacing is spot on. The error it's displaying is a slight equal tilt in x and y leading to the 44 degree direction shown. I think it incorporates tilt errors as part of the overall 'curvature' error which I believe relates to the variation in FWHM compared to the average FWHM. How it derives the figure of 11.1% I'm not sure. In a previous post you said you had a tilt adjuster in the image train. Depending on where the camera rotation adjustment is done in your image train you can narrow down which section is introducing the tilt by taking an image with the camera rotated 90 degrees and seeing if the tilt moves to the other two corners or stays the same. The camera rotator can be a cause of the tilt and you end up with varying tilt errors as you rotate the camera which is a real pain. If you instead leave the camera at a fixed rotation you can use the tilt adjuster, if you can adjust it without removing it from the image train. Your stars are round all over the field and the tilt errors just cause one corners stars to be a bit larger than the opposite corner, though still round. The error is pretty small and is probably hard to see so it may be worth leaving it as it is and be happy with the result you've got. I've just noticed that only 189 stars were used in the CCDI test. This may not be enough to give a reliable indication so it's worth trying to get more usable stars in the image. Pointing at an area of the Milky Way without large area of nebulosity can give you 2000 stars or more. I tend to point around Cassiopeia for my tests. Alan
  11. Power & Cables

    A cheaper alternative to the Tracer although significantly heavier is a lead acid battery either the sealed lead acid which you can get up to 75Ah or a standard leisure battery which are available from 75Ah to 180Ah. Alan (another one )
  12. Atik One Filter Wheel Failure

    Download the Atik One manual from their website here. It shows you how to remove the front cover and remove the filter wheel in order to change the filters. This should give you an indication of what is causing your problem. You need 1.5mm and 2mm allen (hex) keys to do this. They were supplied with the camera. The motor is held against the filter wheel by a spring. It may be the spring has detatched, or the micro-switch which engages with the indents on the filter wheel to indicate which filter is in position has got stuck. Hopefully it's nothing too serious. Alan
  13. That looks much better Aidan. If I could get that on my ZS61/ASI1600 I'd be more than happy. Looks like you've got the hang of CCDI now. Have you finally tried it with the camera rotated 90 degrees to check that the sensor is not tilted WRT the camera body. If you've no need to rotate the camera then there's no problem. There are only a couple of objects I'd consider rotating the camera for, otherwise it stays fixed with long side parallel to RA. Which tilt adaptor did you get out of interest? The ones I've seen need space to get screwdrivers in to adjust which often isn't possible with them in place. Alan
  14. Hi Peter, the plug you got from Maplins is the wrong size. It has a pin diameter of 2.5mm and outside barrel diameter of 5.0mm. The correct size is a barrel diameter of 5.5mm. 5.5mm is much more common than 5.0mm. Assuming this LX90 pinouts diagram is correct. The right part from Maplin would then be HH62S for the short barrel plug or HH63T for the long barrel plug. The 5.0mm barrel plug you have will fit in the power socket but will be a loose fit and cause an intermittent connection. It is also the short barrel length version. If you still have the the original broken plug you can compare the length to see which is the best match. Or stick something non-metallic down the socket hole like a toothpick to gauge its depth and match it that way. Long or short barrel will both work but a long barrel in a short socket will stick out a bit and not look so neat. A short barrel in a long socket looks good and will work though may not have a good area of contact. Alan
  15. Peter, JP6 is the 2 pin connector at the bottom left of the diagram just above the label 'Batteries'. Another thought is if you've had batteries in there for a long time not being used they may possibly have leaked and caused some corrosion of the battery contacts and leading to a bad connection. Take the batteries out and inspect the battery contacts on the holder in the scope to check they're still clean bare metal before you go to the trouble of getting access to the rear of the power panel. Alan
×