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Posts posted by Photosbykev

  1. Comet C/2019 Y4 (ATLAS), currently 160 million kilometers away from the earth and motoring along quite nicely. This short timelapse consists of 100 x 60 second images taken over 150 minutes with a ASI533MC-Pro camera and William Optics Zenithstar 61 refractor captured with APT and post processed using PixInsight Blink for the animation. The bright star lower right is Althiba IV

    • Like 5
  2. Thank you both for confirming my thoughts on this. I suspect I won't run into any issues with stars in the corners using the small sensor on the ASI533 even if I removed the flattener. As it doesn't change the focal length of the refractor I may as well use the screw adjustment built-in to fine tune the back focus adjustment.

    17.5mm - ASI533MC-Pro camera front face to sensor

    17.5mm - Starizona filter drawer

    so I need around 32.7mm extension + 0.6 or 0.8mm for the filter thickness so approx 32.5mm extension tubes


  3. I've just acquired a ZWO533MC-Pro to mount on the back of a William Optics Zenithstar 61 refractor with the dedicated PFLAT61A flattener.

    I have been using the refractor and flattener with a Canon DSLR and have set the adjustable flattener to 12.9mm when using the T2 mount and the stars are nice an sharp corner to corner.

    Anyone using the WO61 with dedicated Flat61A adjustable flattener with a cmos camera? The back focus according to WO is 67.7mm from the rear shoulder of the flattener to the sensor BUT is this with the flattener adjustment set to zero mm adjustment rather than 12.9mm? and can I use that screw adjustment to set the back focus to exactly 67.7mm after fitting extension tubes and filter drawer in the optical path?





  4. 1 minute ago, andrew s said:

    I always take darks in the dark just to be sure. Light leaks can also be an issue for flats. 

    Regards Andrew 

    I shoot the flats immediately after the imaging session with a battery powered flat field panel so it's very dark lol. I think the flats are ok looking at them in PI, certainly not significantly different to other flats I've taken. It's only when I add the darks to the calibration stack that the image gets the curved banding across it in the lower right corner. It isn't the standard Canon sensor banding issue which I normally correct in PI anyway



  5. 16 minutes ago, cjdawson said:

    Yep, it's possible to shoot bad darks.  Light leakage would be the first culprit for that.   For a DSLR, you have two places where light can leak into the sensor, first is obviously the lens.  The second less obvious is the viewfinder.

    When shooting darks, it's important to make sure that both as properly covered and are not leaking light to ensure that dark frames really are dark, without other influences.   Putting the dSLR in a box, then putting that in a cupboard usually works, however be aware that the temperature of the dark will therefore change, as the camera will get warm and may not have the ventilation needed to keep the temperature down.

    Thank you for the input CJ

    My darks are normally very good as I do cover the refractor with it's dust cover and then slide a black fabric bag over the end to make sure the objective end of the refractor is  completely blacked out and the camera viewfinder eyepiece is covered with a custom eyepiece blank. The darks and lights sensor temperature were within 2degreesC of each other so I'm struggling with why they should be wrong. I can reshoot them, and probably will, one evening this week when the temperatures get down to around zero ambient and check the second dark set.



  6. The screen print below is of two images containing identical lights, flats and bias frames. The right hand one has a fresh set of Darks added.

    The 240 second darks were shot at the same iso, exposure and temperature on a stock Canon 5D4

    I've process the two images with exactly the same PixInsight settings (just background neutralisation,  colour calibration and stf applied to see them) DBE wasn't applied because that would affect the output for this test.

    I'm getting these strange slightly curved bands, ringed in the right hand image when I add the darks during the calibration routine

    Is it possible to shoot bad dark frames? Previous sets of darks on the same setup have worked correctly so I'm struggling to see why this dark set would be 'faulty'?

    The same effect is seen on other data sets as well using this set of darks.spacer.png


    For reference this is what I get with a basic edit from the lights/flats/bias image




  7. M42 Orion wide field with horsehead and flame nebulas. Full frame on a stock Canon 5D MkIV camera and WO61 refractor with 61A flattener and IDAS-D2 filter.

    Mounted on a belt modded HEQ5 Pro, controlled with EQMod and PHD2, data capture with APT

    A few pixels have been trimmed around the edges to remove the dithering edges.

    Very basic late night processing from 30 x 240 second and 30 x 30 second lights, plus flats and bias frames, stacked in APP and processed in PixInsight

    Size: 5.25 x 3.41 deg
    Radius: 3.129 deg
    Pixel scale: 3 arcsec/pixel


    • Like 12
  8. You don't mention it but if you are using Eqmod as well as Phd2 then the Eqmod default Ra and Dec guide speed settings are way too low at x0.1 The PHD2 recommended value for both is X0.9. If they are at x0.1 then the calibration routine won't be moving enough to complete the routine


    • Like 1
    • Thanks 1
  9. I'm just about to buy a 13.8v bench power supply for powering a HEQ5Pro and all the accessories that go with it like DSLR/Refractor/Hub/Dewstraps etc. At some point I'm going to buy a ZWO ASI 294MC-PRO camera and there isn't any information about it's power supply requirements other than 12v @ 3amps.

    Is it ok to run this camera at 13.8v (basically the same as a fully charged unloaded car battery voltage) or does the camera specifically need a regulated 12v supply?



  10. 1 hour ago, reddoss said:

    Very disappointed indeed. I was so looking forward to seeing everyone again. 

    I may go the Fforest Fields campsite  near Builth Wells instead.


    Could be busy at Fforest Fields, we're there with the dog this weekend to avoid all the firework noise and I know a lot of other people are doing the same. Forecast is rain and plenty of more rain all weekend


    • Like 1
  11. 21 minutes ago, Davey-T said:

    Nice image Kev, I've got a WOZ61 that doesn't see much use must try to set it up on the Star Adventurer while the other rig is imaging.

    Curious about the image scale 9.77, I use a Canon 60Da on mine which I think from memory gives around 2.5 as/pixel presumably the 5D has bigger pixels but your figure looks a bit high ?


    I saw that as well Dave, CCDCalc reports the scale as 3.07arc-sec/pixel which I used for my dithering calculation (6720px wide sensor and 5.36 micron pixel size).

    Okay I know why, I resized the full frame down to 2048 pixels wide for Nova to work on :) I've corrected the top post

    • Like 1
  12. Nice clear night for a few hours in the back garden 1f642.png?_nc_eui2=AeG08sMy4lcBTCwAMrD2O
    Stock Canon 5D MkIV and William Optics Zenithstar 61 with flattener on a iOptron SkyGuider Pro guided in PHD2 with ZWO ASI120mm and 30mm f/4 guidescope.

    30 x 4 minute exposures of the Deneb region, 20 darks/flats and 50 bias frames captured with APT. Calibrated and integrated in Astro Pixel Processor then finished in PixInsight and PS.

    Full frame image with 100px crop on the borders to remove the dithering artifacts.

    Center (RA, Dec): (312.884, 44.134)
    Center (RA, hms): 20h 51m 32.201s
    Center (Dec, dms): +44° 08' 03.276"
    Size: 5.56 x 3.6 deg
    Radius: 3.311 deg
    Pixel scale: 9.77 arcsec/pixel 3.07 arcsec/pixel
    Orientation: Up is 341 degrees E of N

    • Like 10
  13. Thank you folks, sounds like just the rear filter needs to come out to take advantage of normal DSLR lens as well as the refractor. I'm not too bother about AF as the camera will be dedicated to astro work so all manual anyway but obviously reaching infinity with dslr lenses is pretty important :)


    Now all I need is just one modification company to reply to my email. 3 companies emailed in the UK and not one reply so far :(



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