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jefrs

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Everything posted by jefrs

  1. A CLS-CCD filter is for a modified camera with no IR filter, or an astro eyepiece camera. They can be fitted to an eyepiece and some Barlow, or the T-adaptor for the DSLR. I have an Astronomik CLS-CCD on a T7C guide cam, eyepiece screw-on. It made a significant improvement. The sensor lacks filters and the firmware of a DSLR. Using that filter with an unmodified DSLR produces rubbish results, a lot of colour shift. A DSLR needs to be set up for astro and night photography. They will get rid of a lot of the rubbish which an astro cam relies on a laptop app to do. The auto WB usually
  2. The 130SLT is not a bad telescope but the best thing about it is the mirror, The focuser wants to be taken apart, cleaned and serviced; some soft grease used, and the tension adjusted so it moves smoothly. The nylon bars on the slide may want packing with tape to reduce slop. The focussing is rack and pinion, and quite coarse, but by adding a long lever to one of the knobs, such as a battery crocodile clip can move it in small doses. Have the lock screw just touching whilst focussing to reduce slop, nip it lightly once in position. The problem with 'back focus' (which means something else
  3. First of all StarSense is an alignment tool. There are Celestron and SkyWatcher flavours. It connects by the ST4 port to the mount, it does not /need/ a laptop. It does have a USB port but that is /only/ for firmware update. With the firmware updated and its camera focussed (which is a royal pain) it can align and calibrate the mount in 15-30 seconds. Seriously, it can be that fast but it does have to be focussed. As such is it a very valuable tool for aligning the mount. The only way I could focus it was a boring iterative process of screwing the lens in an out a little at a time to find maxi
  4. Chinon (Japan) could make exceptional lenses to rival or exceed Asahi Pentax. Very good glass that will probably exceed Olympus and Nikon. I have a pair of 8x40 wide angle 9°. Chinon produced the first production autofocus camera lenses. Chinon got bought out by Kodak Japan. You should be able to compensate vision on one of the eyepieces. You may want to use a monopod or video head tripod when looking up for long.
  5. That is incorrect. It does have a 4:3 aspect but not why it is called 4/3-inch, It dates back to steam powered TV cameras and the internal diameter of the tube (valve) used in them. It is just a name. Rather like incorrectly calling full frame DSLR full frame when they're the same size as compact film. Image circle diameter of 4/3 is 21.6mm, less than an inch. Something to note though is a smaller sensor does not receive less light than a large one. When they are pulled into focus, all the light from the lens (telescope) is focussed upon it. What is important is the photoreceptor (pixel)
  6. The name "4/3" comes from the size of a TV camera tube, now pretty much obsolete. The image sensor of Four Thirds and MFT measures 18 mm × 13.5 mm (22.5 mm diagonal), with an imaging area of 17.3 mm × 13.0 mm (21.6 mm diagonal), comparable to the frame size of 110 film. (wiki). Micro Four Thirds (MFT or M43) is actually the lens fitting, the sensor is "4/3". The image circle diameter is almost exactly half that of a full frame camera, so the crop factor is X2, which effectively doubles the length of the lens, or telescope. The pixel size of the 16MP sensors is 3.75µ (slightly larger than m
  7. If you are considering 4/3 sensors then you might consider getting a Lumix G7 which may go for as little as £200 used, if you don't want to spring £1,000. Pixel size is more important than pixel count in low light. The 16MP sensor has 3.75µ pixels. The Panasonic designed Live-MOS is biased to sweep stray electrons off, unlike Sony CMOS sensors. And it is mounted on a heat sink to keep the temperature stable. The powerful processor has features to further reduce noise as it is designed to shoot movie indefinitely without overheating. Shutter speed down to 1 minute and built in interv
  8. There is the word 'stiction' that aptly describes the problem, yes it is a real word for a real problem - "the friction which tends to prevent stationary surfaces from being set in motion"
  9. Break it down to first principles. You have OTA focal length divided by eyepiece focal length giving the magnification of the telescope. Then your compact will add some magnification factor. For a camera that is the focal length of the lens (not full frame equivalent) divided by the sensor diagonal, aka image circle diameter. Multiply them together. Personally I have never managed to get a compact camera to focus on the eyepiece image, I'm told it has to be set at infinity.
  10. Simple answer (I hope) is divide focal length by the image diameter circle (the diagonal) of the camera sensor. Full frame is 43.3mm and this is the proper length of a prime lens to give 1:1 image although we normally use 50mm or 45mm. For micro four thirds the image circle diameter is 21.6mm so its 'prime' lens is 20-25mm thereabouts, and APS is somewhat variable, nominal 35mm. A typical guide camera might be a 1.2/3 sensor of 7.66mm diagonal. These give the equivalent eyepiece focal lengths when used on prime focus. Magnification is OTA focal length divided by eyepiece focal length. A
  11. Something I'm always trying to get my head around too. Also complicated by the eyepiece because they can vary in field of view as well as focal length, obviously a long eyepiece will give you a wider FoV than a short one. A camera will also change the FoV, sensor size (crop factor), whether on prime focus or eyepiece projector. This calculator may help https://astronomy.tools/calculators/field_of_view/
  12. The SLT mounts are not strong but with some proper servicing can support and move heavier weights than they were designed for. The bearings need cleaning and a good grease like Castrol used and then set up so they rotate smoothly with a very small end float. If set too tight they bind. The Stifnuts are poor, use Loctite, or they adjust themselves. The Alt clutch can be tightened but must still clutch. The motors like some attention, the muck they put in the gearboxes is not good. Plastic cogs need silicone grease, on the teeth not in a pool on the case floor. The gearboxes are like repairing a
  13. You will find various illuminator adapters here - http://www.astrokraken.fr/accessories-for-skywatcher-star-adventurer-mount-a184487612 ça plane pour moi I don't have a 3D printer and unlikely to get one. A lens hood can be simply made for the illuminator from a black plastic 35mm film can.
  14. Yes! Once I got the camera refocused it's quite amazing. I set up Thursday night 07/05/20. Of course by the time it dot dark there was solid high thin cloud. I could just visually see Arcturus but little else. So I experimented. There's a LED street lamp over our back room before our patios. Despite that and the cloud and high hedge and fence it still did an Auto Align in under a minute. Adding a star to the calibration makes it want to do another Auto Align. So we did that three or four times. Despite only seeing a few stars, now focused, it competed successfully every time, quickly too. I
  15. An older thread but a good one. My StarSense was not seeing stars. I have a lot of light pollution, LED street lamps. Auto align kept failing. I read this thread and spent the night adjusting the StarSense camera focus as described above - thank you people. I found the focus point to be quite critical. I found the focus point between 15 and 24 half turns out and then narrowed it down to to around number 20. Meaning these cameras are not all the same. I then started going in quarter turns in and out and then 1/8 turns until I got maximum star count. Whereupon I lost count of turns a
  16. Using two cables to the computer may well be true with the older Hand Controller and the 'Celestron Programming Cable' with USB/Serial adaptor. The instructions seem to have been written for this older system (pic). With the USB Starsense HC the data is fed through to the camera on the RJ12 cable. I did a little experiment when I had to replace the motor board (which has its own update process) - I updated the camera with the NexStar+ Telcon serial HC attached, this did require the camera USB cable to be used, all devices were updated. The updates are reinstalled if they are already the latest
  17. Typing correction fluid (white paint in a pen) or Sharpie Silver make good night-visible marks for alignment and switches etc against dark/black surfaces. Both can be cleaned off if desired.
  18. Celestron mount with StarSense AutoAlign USB handset on Windows 10. The StartSense Camera does not need to be connected to the computer by its USB, indeed the computer and CFM will not see it. I do not know why the camera has an USB port, the computer does not recognise it. If you connect the handset by USB before turning on the telescope, the handset will light up but you will not connect to CFM. Connect Camera and handset to the telescope in usual manner, switch on whilst holding down button 7 and the Celestron key together so handset shows 'BOOTLOADER', then connect handset USB
  19. I have acquired a number of old camera lenses over the years and adapted to modern digital cameras. However long ones can also be adapted as telescopes. The M42 lens thread is M42x1mm, as used by Praktica et al. When we speak of a camera lens with a M42 thread, this is the one it will have. The T2 (or T) thread we are familiar with on telescopes is the M42x0.75mm, also known as the Taisei (the inventor) or Tamron thread. Both are ISO-metric threads, they are not interchangeable. M42x1 to DSLR camera adaptors are readily available, these lenses were mostly for 35mm compact film SLR thus b
  20. An altazimuth mount has to be horizontal so it knows where zero degrees 'horizon' is. Use a spirit level but it doesn't have to be perfect. The mount has to be levelled anyway so I have a little spirit level in the toy set. You have to take the lens cap off (always a good one) The StarSense AutoAlign has to go through a rigmarole first calibration set up - read the book, there are some how-to on YouTube. Read The Book https://s3.amazonaws.com/celestron-site-support-files/support_files/94005_starsense_autoalign_manual_february2016.pdf Watch YouTube The set up "Calibrate
  21. I am very interested. Newbury Berkshire. Can we Private Message details for payment and posting? TIA. Jeff. PM sent please reply.
  22. The 130 SLT has a clutch only on the OTA up and down, the rotate does not have a clutch at all and is fixed firmly with locators, pegs in the bottom and a key-way on the axis bolt; its bearing can be adjusted to reduce wobble. The big gear wheel is screwed to the underside by two small screws which need to be quite tight (they're not really man enough for the job), turning by hand may loosen then or strip them out. Turning the rotate by hand may damage the gears. The OTA clutch can be adjusted by the nut under the clamp. Pull the OTA clamp hand screw out to access the nut. I have the cla
  23. Thank you everyone. Yes by "Digital Camera" I mean my various micro 4/3, being mirrorless are not "SLR" but can swap lenses. Back focus is a bit different but results are very good once that is understood and they're mounted properly. Initially the lack of a mirror box meant they wanted to sit practically inside the OTA; eyepiece projection works. Lack of sensor noise on the GH4 is excellent as being developed for video the sensor is mounted on a heat sink and the LMOS is biased to sweep stray electrons off it. Likewise the G7 but the E-M5ii has a bit more noise at high ISO and likes
  24. Possible silly question. Could be a greek parliament. What stacking software to use with digital camera astro photos (and video/time lapse), in Windows 10. Looking for effective and with ease of use. Some of the software apps I've looked at are pretty old now and rather clunky.
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