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CraigT82

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Posts posted by CraigT82

  1. Just to add… if you get dew on the scope tube during a session, that’s an indicator that the tube has cooled below ambient temp and has hit the dew point temp which may be a good couple of degrees cooler than ambient, depending on the humidity. I’ve read somewhere that even temp deltas in the tube of only 0.5 degrees can start to noticeable degrade the wavefront.

    My old Fullerscope was terrible for radiating heat, the plastic tubing must have had a v. high emissivity as I used to get dew soaking the inside the tube as well as on the outside. Wrapping it up with the screwfix radiator stuff linked to earlier in the thread put a stop to that and helped the scope perform at it’s best - in my opinion that is, as I didn’t do any proper testing or data gathering to quantify the benefit of the insulation. 

  2. 3 hours ago, newbie alert said:

    Can I ask why?

    The idea is to stop the tube walls of the OTA from cooling below ambient (via radiative emission)

    The tube cooling below ambient is bad news because the air inside the tube which is in contact with the tube wall will also cool and become a source of temp deltas inside the OTA which as you probably know is a situation to be avoided. 


    Other sources of temp deltas within the tube are the mirrors, and the warmer air rising off them and this is where fans can help.

    Tue holy grail of scope cooling is to have ALL the air inside the tube at the same ambient temperature as the outside air.

     

  3. For the data rates the camera is outputting you can think of it like this:

    • When capturing in RAW8 (which is what you should be doing for planetary), 1 pixel = 1 byte.  So say you have a 400x400 RoI that's 160,000 bytes which is 0.16MB for a single frame. 

    So if you have 10MB/s of transfer rate capability you'll get 10/0.16 = 62 fps.  Obviously other factors may affect this.

    Don't think that a camera with smaller pixels will have a smaller RoI than a larger pixeled camera, and hence will have smaller files to transfer.  The smaller pixels mean a smaller RoI (in terms of square mm) but there's still the same number of pixels within that RoI, and it's the number of pixels which dictates file sizes.

    In terms of costs and affordability, have a look at used kit.  I recently sold on here a QHY462C for £175 and a rather good USB3/SSD laptop for £125.

  4. You don't need to spend more than £100 on a laptop, that's what I paid on gumtree for a used lenovo thinkpad with 2x USB3 ports and a 250gb SSD.

    Mind you with the current situation around supply used prices will probably be significantly higher at the minute. 

  5. RAW8 is is the one to use, that will produce an 8 bit capture which will appear monochrome on screen and when played back. but actually contains colour info once de-bayered (which is what Autostakkert 3 will automatically do - if you use that).

    I'm not familiar with ASICAP but I'd start off with using a high gain (say 3/4 max) and a short exposure ideally around 5ms but certainly below 10ms if you can.  The image on the screen will appear quite dim but that's ok, you can brighten it later. Pump up the gain even more if you need to - short exposures are vital.  Don't fall into the trap of trying to get the preview image on screen to look 'nice'.  If the settings are good it will look very dim and very noisy but don't worry about that. 

    I find it helps to find focus by using the debayered preview and with a lower gain and more exposure for a birghter, cleaner and colour preview image, and before capture I will set those settings back after focussing and before hitting the capture button.

     

    Good luck!

     

    • Thanks 1
  6. I love your scope! Top modding that is 👍👍👍

    Nice Jupiter... The image is suffering from atmospheric dispersion so squeezing an ADC in there would give worthwhile benefit I think, if you could? 

    As for the 8 bit captures, this is recommended as offers best frame rates and it's the stacking of thousands of frames that restores the lost bit depth (I'm some way that I don't really understand!)

  7. 58 minutes ago, GalaticBoba said:

    Thanks for the responses.

    If I go for the 290MM, how will I take a lunar photo without getting a new telescope?

     

     

    astronomy_tools_fov (1).png

    It's quite simple to do a mosaic of 2 or more images.

    In fact, the best lunar images are mosaics of smaller images stitched together to form one larger image. It is not possible to get as much fine detail in a single full disc image as you can get by shooting small sections of the moon at a time and then stitching them together in post processing.

  8. Nice images there Trevor, I think the IR lum is working well on the detail but is throwing the colour off which is unfortunately the trade off with using this technique on Jupiter. I wonder if you can reduce the opacity of the L channel to compensate whilst maintaining the extra detail?  Or indeed using the IR as R like Pete suggests? That's probably best thing to do tbh. 

     

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