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mftoet

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mftoet last won the day on April 4 2014

mftoet had the most liked content!

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About mftoet

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    http://www.mauricetoet.nl

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    Zoetermeer, Netherlands
  1. Thank you, Pieter. The observatory is great. The weather in current and recent winters is awful though.
  2. My first serious tricolour image in Hubble Palette (SHO) with a recently acquired ZWO ASI294MM Pro astro camera. Captured from my back garden observatory in the Netherlands. Exposure time: 3 hours (6x 600s Hα, 3x 600s OIII & 3x 600s SII) Optics: Takahashi Epsilon-180ED f/2.8 Filters: Baader-Planetarium Highspeed Mount: Astro-Physics Mach1 GTO Date: January 8, 2021 https://www.mauricetoet.nl/DeepSky/i-8j5wxHd/A
  3. I have a lot of images showing brown(ish) dark nebula. I don’t specifically try to bring out this colour or hue, it’s simply there. I always try to white balance my images on a the background sky (which can be hard to find when there’s lots of nebulosity in the frame. Furthermore I often increase the vibrance of the colours in my images by 20 to 30 in the Photoshop RAW converter. The last example is a rather interesting one: apart from what might be a gradient in the lower left corner, different hues can be distinguished in the molecular clouds: ‘50 shades of ...’?
  4. In the end: brown is dark orange. It’s also called a ‘context colour’. Here’s a YouTube video about brown not being an actual colour.
  5. That are excellent looking images! Nice to see Takahashi filled the gap between the 130 and 180 with this new edition of the Epsilon 160. The dedicated extender that’s in development also makes the 160 more versatile than its brothers. I noticed there are now lock nuts on the collimation bolts of the secondary. The adjustment/suspension of the primary mirror also differs from that of the 180. Good to see there’s an aperture mask on the (oversized) primary mirror. The 130 lacks one and therefore artefacts around bright stars (caused by the mirror clips) can occur.
  6. The colour gradients in your stack are also common with the D810a I use. There's always some green to purple hue. I think this is sensor related. The gradients can be corrected with the light pollution removal tool in AstroPixelProcessor, but sometimes needs several runs and careful placement of the calculation boxes. The issue with the bolts on the secondary mirror also sounds familiar. I think I've just finally managed to get the secondary mirror in the correct rotation opposed to the focuser (and also centred under the focuser). In my case, the dot on secondary has always been just slightly off center causing even worse star images in the corners than on your example image. Yesterday I've imaged with an ASI1600 4/3 format sensor and I no longer detect collimation error. I have to verify with the full frame D810a though. I collimate the primary mirror with the tube pointed straight upwards (to the zenith) and only use the cheshire eyepiece (not the tube with cross hairs). As Mark pointed out, you can screw the 1.25" adapter directly on the ED-corrector. That will make it easier to judge if all circles are perfectly concentric.
  7. That turned out excellent and very deep, just as you wanted.
  8. When I acquired the Epsilon-180ED, the RASA systems weren't released by Celestron. In the late analogue / early digital age, a friend of mine used an Epsilon-160. I fell in love with the crisp stars that telescope produced and promised myself I would acquire one some day. About 10 years later I ordered an Epsilon-180ED including the ridiculous expensive tube rings, base plate en 7x50 finder scope (which in the end I only use for star alignment after switching on the mount). Another thing that I like about the Epsilons (and other fast Newtonians for that matter), are the diffraction spikes. I know, you either like them or you don't. Would I consider acquiring a RASA instead of a fast Newtonian? Maybe, but probably not. A thing that would bother me is that the camera (and cables) must be placed in front of the corrector plate. I can imagine taking proper flats can be challenge with a RASA. So respect for those who manage to produce excellent images with these astrographs!
  9. Yes, you can, Richard. I suppose a 3D-printer can do the job.
  10. Thanks! The primary mirror of the Epsilon-180 has a diameter of 190 mm and has a mask / edge support with an aperture of 180 mm. A simple but clever solution to avoid undesired diffraction patterns like spikes caused by a turned down edge. (Please don't get upset by the dust on the mirror: this picture was taken just before cleaning...)
  11. Thank you Craig, Olly, Mark and Göran. @gorann: no the browns have nothing to do with light scattering in Earth’s atmosphere. It are genuine colours in these molecular clouds. You can also see the yellows and browns in dust lanes of other galaxies. I don’t know the exact (physical) reason for the colour, but probably a combination of absorption, reflection and ionisation in relation to the ratio between CO and H2 in these regions.
  12. This is my final image of a week of pursuing astrophotography at @ollypenrice's 'Les Granges' in Southern France. Captured during the last two nights. Unfortunately I had to ditch about 2 hours of subs due to focus drift when I was asleep (resting for the trip back home). This is a crop. A larger field of view can be found at https://www.mauricetoet.nl/DeepSky/i-vtgtMB4/A (and a high res of this crop at https://www.mauricetoet.nl/DeepSky/i-KmtWWpX/A Also seen are LDN 1353 & 1357, VdB 7, 8 & 9 and LBN 643 Exposure time: 7 hours, 30 minutes (5 min. subs) | Optics: Takahashi ε-180ED f/2.8 | Camera: Nikon D810a (ISO 400) | Mount: Astro-Physics Mach1 GTO | Guiding: Lacerta MGEN + Vixen 70S | SQM: 21.3 - 21.5 magnitude/arcsec² | Location: Étoile-Saint-Cyrice, France | Date: August 19 & 20, 2020 | Processing: Astro Pixel Processor, PixInsight and Photoshop CC
  13. Just keep adding data and the lovely browns will show up!
  14. Modern OSC cameras can generate astonishing or at least unexpected results, can't they @ollypenrice? This is a two panel mosaic of the familiar Veil Nebula Complex in Cygnus. Captured during one night with a Nikon D810a and Tak Epsilon-180. This camera has the same sensor as the QHY367c (i.e. the 36.3 megapixel full frame (36 x 24 mm) Sony IMX094 CMOS sensor with a pixel pitch of 4.87 microns), though not cooled. Even during warm summer nights, dark current is so low, I don't bother using dark frames. That would be quite difficult in practice, because ambient temperature can drop from 22 to 12 degrees Celsius during the night. AstroPixelProcessor did an excellent job making the mosaic. The image was rather difficult to process due to the many stars in the field of view! They obscure the nebulous features. The yellowish glow to the right of NGC 6960 (the Western part of the Veil Nebula a.k.a. the Witch's Broom) with bright star 52 Cygni is not a colour gradient but actual dust or nebulas. The same is true for the tornado shaped grey 'smudge' in the lower right corner. Exposure time: 6 hours, 25 minutes (5 min. subs) | Optics: Takahashi ε-180ED f/2.8 | Camera: Nikon D810a (ISO 400) | Mount: Astro-Physics Mach1 GTO | Guiding: Lacerta MGEN + Vixen 70S SQM: 21.3 - 21.5 magnitude/arcsec² | Location: Étoile-Saint-Cyrice, France | Date: August 18, 2020 | Processing: Astro Pixel Processor , PixInsight and Photoshop CC
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