northcoast42 Loc: Puget Sound, Washington

Here's my second attempt at Andromeda with my DSLR attached to my 127mm refractor. My last image was riddled with vertical color streaks and I never did figure out why. I tried again last night with a much better result. No color streaking! I don't have a guide camera for my reflector, just a tracking mount so I'm pretty much restricted to 60-90 sec exposures before I start seeing some elongation of the stars. I have a couple of 150 second exposures in this image and they did affect the stars a bit. I threw out a bunch of 150 and 90 second exposures. It's interesting how some frames show nice round stars while others of the same exposure length show badly elongated stars. Anyway, I'm waiting on a control panel from Meade before I can start doing guided imaging with my LX850. It's too big to do Andromeda but should be great with other targets....I hope.

Explore Scientific 127mm refractor with an unmodified Nikon D810 camera.
44 x 30 sec exposures, 8x 90 sec, 5x150 sec. All at iso1600.
30 Dark frames, 33 Bias frames, 30 Flat frames.
Aligned and stacked in Deep Sky Stacker
Processed in Pixinsight following Kayron Mercieca's tutorial.

(Download)

cessnalvr Loc: West virginia

Wow. Dont think i will ever learn this

Ronsh Loc: Floresville,Tx.

Very nice!

taffthetooth Loc: U.K

Love it, but may I ask what are dark,bias and flat frames?

skylane5sp Loc: Puyallup, WA

It's explained in the pinned subject above: "How to take a good dark and flat frame".

kelso007 Loc: Circle Pines Minnesota

I like it!

CraigFair Loc: Santa Maria, CA.

What a spectacular shot. Nice job on the processing.
Craig

SonnyE Loc: Communist California, USA

Beautiful John!
Great detail.

When I download, then zoom in, I can make out some minor trailing.
But that is nothing in view of your overall result. Amazing!

What I've found is Atmospheric disturbance is often mistaken for mechanical problems like tracking.
Also, even though my mount was on what I thought was a solid platform, would show movement if I merely moved one of my feet even slightly.
Once I got that figured out, and Ronnie (Stepping Beyond) clued me in to remote operation between two computers. That ultimately allows to be well away so the human error in the equation is reduced further.

But you are doing great by leaps and bounds!

northcoast42 Loc: Puget Sound, Washington

Here's a short guide:

Dark Frames are made at the same exposure time and ISO as the subject light frames, but with no light reaching the sensor. Their purpose is to remove the thermal noise from the light frames captured from the same imaging session. The images need to be the same exposure length, ISO and temperature as your light frames. These can be easily captured with the lens cap on your camera or telescope in place.

Flat files
Flat frames are short exposures made through the same optics used for the light frames with the camera pointed at an evenly illuminated field. They record uneven field illumination due to vignetting caused by the optics and due to partial obstructions in the light path such as dust particles on the sensor, and they are use d to remove that uneven field illumination from the light frames.

Offset/bias frames are very short exposures made with no light reaching the sensor. With a DSLR, they are taken at the fastest possible shutter speed and same ISO as the light frames, with the body, lens or telescope capped. There purpose is to remove the read noise that is present and roughly the same in every frame.

northcoast42 Loc: Puget Sound, Washington

Thanks cessnalvr. It just takes motivation and practice...just be careful, this can become addictive My first attempts at astrophotography were pretty poor but with time things improved. I'm pretty new to deep space photography so ... very steep on the learning curve but there's lots of help available on line in places like here and Stargazerslounge and Cloudynights, not to mention numerous tutorials and YouTube videos, people sharing what they know and do.

northcoast42 Loc: Puget Sound, Washington

Thanks kelso. Glad you liked the image.

stepping beyond Loc: usa eastcoast

Very nice trio , kudos John. Heat , humidity and Hurricanes have put a dampening on my enjoyment this year.

northcoast42 Loc: Puget Sound, Washington

Thanks Craig. I have to give the processing credit to Kayron Mercieca's Pixinsight tutorial. It took me step by step to the finished product, teaching me the program along the way. Pixinsight is an amazing program.

northcoast42 Loc: Puget Sound, Washington

Thanks Sonny. I think the stars would have been better if I had excluded the 150sec exposures from the stack but I wanted some of the fainter detail and I just didn't have enough of teh shorter exposures to compensate. Hopefully, when I start guiding as opposed to just tracking I won't have to limit my exposures. I was also wondering how much vibration was picked up by my moving around. Good tip. I'll have to pay attention to that in the future.

northcoast42 Loc: Puget Sound, Washington

Thanks! Sorry to hear the wx is spoiling the view. Hopefully that will calm down a bit with the coming of winter.