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Nikon 750D test Rosette Nebula

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Picked up 750D package w included Nikkor 24-120 f4G ED VR zoom lens.  The fancy abbreviations got me.  Was excited to try it out last night being first time using full frame DSLR.  Piggy backed on my Nexstar 5SE alt/az mount.  Decided to image a nebula for first time and Rosette was just rising to the East.   To balance weight of the Nikon I had to shift tube all the way backward as far as I could, so there was no possibility of imaging > 70 deg up.  

Obsticles last night. = Light from little town to East, spotty clouds & don't polar align Nexstar alt/az with wedge (alignment failed) don't bother trying anymore.  Just do two star alignment then sync imaging area.. 

Observations. =

1.  Took 16 x 120 sec subs & 5 x 60 sec subs to test things out.  (120mm / f5 / iso 1600) no darks/bias/flats.  Below are 4 subs from the session.

2.  7 out of 16 - 120 sec subs had pin point stars. Only 1 out of 5 - 60 sec subs had decent stars.  Soooo, all I have to do is double whatever  # of 2 min images I want with this set up and i'm golden !

3.  Happy to see faint red from Rosette even in raws, I didn't stack them due to clouds and trees in images, just took a sub into lightroom / adjusted white balance / messed with other sliders. 

4.  Like everything about camera from double memory cards to tilt screen on the back.  Camera feels great in your hand, good grip and rip, intuitive, lens will be nice for travel.

5.  Once T-mount arrives will see how images look through Nexstar (if I can get it balanced) All I need now is good refractor and mount.

I'm looking through previous DSLR & nebula posts, if any nebula DSLR tip threads you can steer me (or tips in general) greatly appreciated.

Enjoy !







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It's visible there :)

What comes to my mind is that you don't need to use that high ISO because the data is there with lower sensitivity as well. High ISO camera just multiplies the signal, wanted and unwanted (noise).

Here's one test to show that effect with D600:


This had led my use max ISO500 with my D600 and ISO400 with my D5100.

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Just FYI.

Have a look at your in-camera high ISO noise reduction settings. I have the D800 and with High ISO NR turned off, the camera still does noise reduction with ISO set at 1600 or higher, in other words the camera automatically takes dark frames.

Apart from taking longer to save to your card, to some extent it takes some control of your NR out of your hands. I'm still very new to this but I'm going to try ISO800 as a maximum benchmark and take multiple shots, and some darks as well.

As HK said the higher the ISO, the more unwanted noise. From my limited understanding of this subject 2x1min subs @ ISO400 will capture the same detail as 1x1min sub @ ISO800, but without the additional noise.

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From my limited understanding of this subject 2x1min subs @ ISO400 will capture the same detail as 1x1min sub @ ISO800, but without the additional noise.


This goes actually against that logic - at least with Exmor sensors.

1x1 min ISO400 sub will have the same amount of captured photons as the 1x1 min ISO800 or 1x1 min ISO6400. The higher sensitivity just multiplies the signal in camera for both wanted and unwanted signal (noise).

As long as you’re above the unity gain ISO (1 photon = 1 ADU), the increase of the sensitivity doesn’t create any higher wanted signal. It just makes it better visible, but you can do the same and with better results in PP.

Therefore my recommendation is to stay at ISO500 with current Nikon full frame models. This helps you also utilize larger dynamic range.

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