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When you for the first time setup an off-axis adapter it can be confusing, at least it was for me. I have written down a tutorial that maybe can be of some help:
I will edit and do some complement in the text later.
A question to all you that already have an off-axis adapter, what make and model do you have ? Are you satisfaid with it ?
My image of Omega Centauri ( NGC 5139 ) has been published as the NASA APOD for the 11th of July 2017
Link to full size image on NASA site ( warning quite large - 4620 x 3720 )
Link to discussion of image on asterisk.apod.com
( credit apod.nasa.gov )
( full size image - 4620 x 3720 )
Link to original post for this image back on the 10th of June
Update 16th June:
I could not wait to tell people that I was just notified that my image of Omega Centauri will be published as a future NASA's Astronomy Picture of the Day ( APOD ) - my first ever
I will update the thread when they publish.
A deep look at Omega Centauri ( NGC 5139 )
This image is an attempt to look deeply into the the Omega Centauri globular cluster by using HDR techniques to record as many faint stars as I can whilst retaining colour and detail in the bright stars, including at the core ...
Reprocessed to bring out more faint stars and to produce a smother transition between brightness levels.
New version ( 12 June 2017 ):
Omega Centauri ( NGC 5129 )
( please click / tap on image to see lager and sharper )
Omega Centauri ( NGC 5129 )
( please click / tap on image to see full size and sharper )
Size: 58.6 x 39 arcmins,
Centre: 13h 26 min 50.4 sec, -47deg 28' 39.1''.
Orientation: up is -89.9 East of North ( ie. E^ N> ).
Orion Optics CT12 Newtonian ( mirror 300mm, fl 1200mm, f4 ).
Corrector: ASA 2" Coma Corrector Quattro 1.175x.
Effective Focal Length / Aperture : 1410mm f4.7.
Skywatcher AZ Eq6 GT.
TSOAG9 Off-Axis-Guider, Starlight Xpress Lodestar X2, PHD2 .
Nikon D5300 (unmodified) (sensor 23.5 x 15.6mm, 6016x4016 3.9um pixels).
Long Exposure noise reduction off
Blue Mountains, Australia.
Moderate light pollution ( pale green zone on darksitefinder.com map ).
9 sets of sub-images with exposure duration for each set doubling ( 1s to 240s ) all at ISO800.
Calibration: master bias, master flat and no darks.
Integration in 9 sets.
Tarantula Nebula ( NGC 2070 ) in the Large Magellanic Cloud ( LMC )
Re-processed to tweak colour balance and bring out a little more faint detail:
( click/tap on image to see full size - the above compressed version looks a little soft; the full size version is sharper )
The Tarantula Nebula ( NGC 2070 ) is the largest and brightest emission nebula in the nearby irregular galaxy, the Large Magellanic Cloud ( LMC ). At a distance of 160,000 light years away from us, the Tarantula Nebula is so bright that it would cast shadows on the Earth if were as close to us as the Orion Nebula in our galaxy.
First image with new telescope and autoguider/setup.
NGC 2070 Tarantula Nebula
Image centre RA 5h 38m 57.3s, Dec -69deg 20' 36.6" (nova.astrometry.net)
Field of view (arcmin): 58.7 x 39.2
Scale (full size image) 0.585 arcsec/pixel.
Telescope: Orion Optics CT12 Newtonian ( mirror 300mm, FL1200mm, f4 )
Corrector: ASA 2" Coma Corrector Quattro 1.175x
Effective Focal Length / Aperture ): 1410mm f4.7.
Mount: Skywatcher AZ Eq6 GT
Guiding: TSOAG9 Off-Axis-Guider, Starlight Xpress Lodestar X2, PHD2
Camera: Nikon D5300 (unmodified) (sensor 23.5 x 15.6mm, 6016x4016 3.9um pixels)
14 x 240 sec ISO400
12 x 120 sec ISO400
10 x 60 sec ISO400
11 x 60 sec ISO200
10 x 60 sec ISO100
10 x 30 sec ISO100
Pixinsight & Photoshop
20 December 2016
A lot of people have asked me about the iso setting and what is going on inside the DSLR camera.
I have tried to do a simple tutorial about this on my homepage:
Now when DSLR cameras get better and better it's not that big advantages to use high iso setting. On earlier high noise readout cameras you could raise the signal above the readoutnoise by using a high iso setting (but depends on the camera if the amplifier was good enough), but in the same time you lower the dynamic range. With a better new camera you can lower the iso setting and stretch the data in your imageprocessing software and still have the same (or almost) low signal details. And with that get a higher dynamic range (don't saturate or clip the high levels).
With my new Canon 6D I normally use iso800 but also iso 400. Modern Nikon cameras with Sony sensors are even better. Normally you can read about isoless cameras, that's the ones that can take advantage of lover iso setting. Depends on the object what to prefer.
One important thing to know, the iso setting doesn't change how many photos the camera detect, just how the camera read out the sensor.
Hope I clearify and not confuse with my tutorial.