Can you show the same image with and without flat and dark file, and without both, along with that file?  4 images total from stack is request, would be a horrible PITA to process and post?  i.e. do you need to start over the entire stack/align process for leaving one or other out, or is it a final operation after the "heavy work" is done?

What tutorial?

Weren't you going to be putting one in this thread?  Actually, maybe just a few pictures showing the difference using a bias and flat make independently and together?  Wait, that was a demand of mine.  

You somehow twisted space-time 90 degrees.

BEFORE (2 pages ago, by @Ciraxis


AFTER Two posts above:

You mean the stars in the sky changed orientation?  Lucky you have some pictures of what it looked like before!

--ETA:  If the H?? blue/teal is at "10", change it to about 7.

I like the blue peeking out from the red in the bug's body, that's a nice take.   Just where it washes out to white, pull it down a bit.  Overall it's very detailed, I'm seeing parts I didn't know were there since you pushed it.   Still need a "stack" to see full range on computer since the display can't mimic the gradients that exist in nature, and the gases on a dark background are one of those things.   I don't know if you can do a gamma function to bump low ones up while maintaining middle or not.

That's pretty awesome!  I couldn't see it due to a snow storm.  And being asleep.

Which had the greater effect, the dark?   I can see the one dust chunk lower left vanishing, then the noise level drop.

Is the dark/bias frame removing that noise, and the flat removing dust and vignette?

I guess that is the heart of the issue, how big of impact each has if forgotten, is it salvageable using a flat or dark from a previous expedition as 'better than nothing', or does it make things worse?

Remember, I can't tell why you thought a few weren't so good, they're all better than I've seen with naked eye, so...  

That one is very nice and balanced!

Leave it, that nice cluster at top with the black above them shows a good contrast on how huge things are.

Just my opinion.  Not that I could come close to duplicating that.

That's a cool photo.    Seems there's a lot of stuff in that area, your photo is the green IC 405 box directly below Capella (~10° lower), in the right-middle top of this constellation map:



Capella is one of the very few stars I know without having to look it up or use sky view.    Generally, those are the few that have magnitude brighter or close to 0.

Thanks again to all posting images!   These photos are so much more awesome than looking through a telescope!   Even the "easy to see ones" are faint and I don't see anything like what these photos bring out.   Best comparison I can come up with is the Aurora.  It's a haze of light, but with a time lapse sequence like @NorthPolar makes, it's very awesome and seems to dominate.

The Messier objects discovered in the 1600s really blow my mind away at what astronomers were able to see prior to modern optics and without photographic 'exposure boost'   Sort of the same way that Hubble Deep Field amazes me.   According to the entry, one or more of the stars around Flaming Star have planets around them, which is extremely impressive and gives me a glimpse of the distances and magnitudes involved.

Like many others posted in this thread, this photo of Flaming Star is better than the one used on the Wikipedia page as well as many other photo results in an image search, so there's a lot of skills (and amazing equipment) in this thread, and I thank you for sharing and educating!

Question, again  Looking at information on these, Flaming Star has a binary star noticed by  movements less than 0.5 arc-seconds deviation to discover it's a twin system.  That blows my mind.    It would be equivalent of shooting a target, and realizing you "missed" by 30 thousandths of an inch at 100 yards.    Is that information gotten via drop in calibrated reticle, or is it computed with multiple photographs?

I feel stupid when I look into the abilities of astronomers and measuring.  This is more my speed - How to find Capella from the Big Dipper (I know offhand that, Arcturus, Spica, Big Dipper, basically).  Id have never guessed all this is up there, I was amazed how full of stars it was through a scope, and those 'stars' are full of stars.

@Ciraxis   Can you show me a couple photos of meridian flip and the odd shaped stars?   Good to let me know what's wrong if I decide to get into this expensive nightmare.  Sounds cheaper to buy a boat.

Some sort of dim white LED behind a spotting scope eyepiece, then point telescope toward objective of spotting scope?   I'm not sure how the photography works compared to different eyepieces for magnification.

Looking at a light through smaller scope "backwards" makes it much dimmer and apparently far away, I don't know if it would be at the infinity focus you need, is there a null lens of some sort you can add at objective that doesn't cost more than the scope itself?

I know a lens can be tested through a null lens during creation of the mirror, but don't know how it would be employed to check photography, other than a distant street/house light in an otherwise dark area.  Lots of those here, though you've got more people in your city than there are in my state, so it's likely different.

@FredMAan That's awesome.  How do you point the go-pro exactly at Polaris, just by eye?

Were these compilations over a couple different nights?  I thought it took 24 hours for stars to make a 'circle' as shown in your 8 hour stack (which is awesome, haven't seen video).   Are there more stars on other half of orbit to make it seem like they each make a full circle?

Finally, I didn't realize a Go Pro was that good for low light!  I had no idea they packed that much into $300.  4k Video, 12MP photos, GPS, WiFi, audio AND better at low light than a cheaper or older DSLR.    Looks a lot easier to carry around than my luggable camera, lens collection, batteries, etc. Maybe I'll start with one of them.

Ok, I thought Meridian flip  was in stitching or tracking mount running out of room, but it looks like one frame is fuzzy?

How do you determine the exact focus number?   I know I can adjust micro-focus on mine with an etched cards close up, I can't think of a stellar equivalent, seems like it'd be easier to build an artificial star.

Again, the composite image looks great, and I don't see any major flaws or blur, still looks better than what I can see with good binoculars.

Only thing I can think of is a heating blanket powered by inverter off car battery and extension cord if close enough to vehicle, a tent sort of observatory with propane heater, or a battery powered portable contact warming system.

If your heater isn't enough, you could DIY a bigger heater that uses a USB power pack for lots of punch, I don't know the diameter, but 5-25W in contact should do it for non-giant scopes according to that.   Could scale up and add another battery for longer runtime by swapping one out when it's low, and charging the other in the car.

Put a fleece blanket around it.  Wind Chill only matters when an item doesn't match the outside temp, the temp of that item drops faster when wind is hitting it with fresh cold air.  A blanky around the scope w/contact warmer just to keep the wind off would make a difference for body/camera temp once warmed, inside of scope > 32-35° so frost/dew can't form.

I'll throw in Battery Life Tips
If doing that, running LiIon batteries between 20% and 75% charge gives the longest life with half the capacity.   When storing, put in a fridge, I have one dedicated for batteries, super glue, epoxy, and similar things to make them store for far longer.   Optimal storage charge is 40%.  Worse thing to kill LiIon is charging to 100%, then letting it sit at room temp.  Causes faster self-discharge which increases internal resistance more than standard higher current discharge.  They're kind of the opposite of NiMH/NiCd for storage, charging, running.  They don't like to be discharged below 3.9v/cell, leaving 25% of the capacity unused, and no full charging unless it will be discharged within a day.    That's all I can contribute to the thread.   Information is from Cadex's Battery University, which is the Final Word on batteries, as they make all the analyzers for them and collect data since the 90s with every chemistry out there.  Meant for fleet maintenance, the local specialized battery store has Cadex analyzers to say what's bad pretty quickly.  Personal is a bit on the spendy side, like "maybe I'll buy a boat instead" pricing.

I understand a bit more and a bit clearer.  You're using a notebook computer to control each shot?   Does backlash in focusing exist, so that when it tries to refocus, it moved a bit, then gives up as it thinks "good as it gets' after a flip?   Mount is very stable I'm assuming there, that nothing comes a bit loose with low temperatures causing thermal shrink on some things but not others.   I'm generally thinking "what all changes after a flip",  assuming all your 'bad' images were after the flip and there were none similar prior to flip.    What all could would move slightly with the weight changing and slight vibration while turning rapidly?  Lubricants aren't as "cusiony" in the cold, backlash torque increases, sometimes backlash itself changes, as well as optical faults like fog/mist/frost on glass.

@FredMan

That is AWESOME.  Like a cut scene in a movie awesome.   I love how you can show both versions, the trails, and the frames,have both turn out excellent when presented as image or video!    Add optional captions or annotations that pop up the current time for each hour, unless you have it at 10 seconds per hour, which should be in description for people as slow as me to figure out.