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Image capture best practices

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#1 nimitz69

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Posted 22 November 2019 - 05:24 PM

Since this is a beginner & intermediate imaging sub forum I thought it might be useful to start a ‘best practices’ thread for just the image capture portion of AP - no post processing discussion.   I continually see posts from new imagers where they are not doing some of what most experienced imagers consider mandatory, so ..... here’s a couple to get started:

 

- always take cal frames (darks, flats, bias or dark flats) - always

- if doing manual focus use a Bahtinov mask and spend whatever time is needed to get it perfect; then check refocus at least every hour, more if temps are dropping rapidly

- setup early to allow your optics to get to ambient temperature - it takes longer than you think

- always dither

- learn to use plate solving.  You’ll no longer need to waste time doing mount star aligns and you’ll always be on target when chasing fainter things

 

 

what’s on everyone else’s list?


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#2 Gipht

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Posted 22 November 2019 - 05:33 PM

and:

 

- pick a target that suits your equipment and experience level.

- plan for the correct exposure time.

- try for at least 3 hours of integration time.

- enjoy the night sky.


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#3 mikefulb

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Posted 22 November 2019 - 05:43 PM

- If possible do test runs of setting up and imaging at home before driving to a dark site and losing precious dark time.

- Bring duplicates of power and data cables.

- If possible do not update software before an imaging trip.  I lock down my software for months/years at a time if it is all working.  I only use the laptop for imaging so not as concerned about security issues via network attack vectors.


Edited by mikefulb, 22 November 2019 - 05:44 PM.

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#4 elmiko

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Posted 22 November 2019 - 06:44 PM

All very good advice! I will add... Plan your target, make sure it will fit in your imaging field of view. Pick a target that will be in view at your location and make sure it will be dark then and High enough at least 30 degrees up from the horizon so your imaging through less atmospheric muck! I try to image three hours on the east side of the the meridian, then another three on the west side of the meridian. That's six hours of data! I know it's tempting to try and bag as many targets as possible. But stick with one target and try and get at least six hours or more, it makes processing so much easier.


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#5 diggy

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Posted 22 November 2019 - 07:20 PM

Spend whatever time needed for a good polar alignment.  Invest in SharpCap Pro, which has a great PA routine; or one of the hardware gadgets to do the same.  This will greatly assist on the next item...

 

Work on getting the best guiding you can for current conditions.  PHD2 is the standard. Get it; learn to use it.  But don't obsess about the numbers.  The ultimate criteria is small, round stars in your images.

 

Put in the time to really compare current, wonderful telescope management/image capture software--SGP, Voyager, N.I.N.A., APT, etc. Pick one you can relate to. They are free or cheap and make your life a whole lot easier.

 

Have fun!


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#6 WebFoot

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Posted 22 November 2019 - 07:27 PM

To the extent possible in this very complex habit, uh, I mean hobby, keep it simple.

 

For instance, don't mess with color until you're acquiring good data through the luminance filter, and can process it reasonably well.  Obviously, this does not apply to those imaging with a DSLR or OSC.

 

Get as good a mount as you can afford; the mount is the single most important, and limiting, piece of equipment in your rig.

 

Start with as short a focal length as you can; it's much, much less demanding, on operator and equipment, to image at 3.5 arcseconds per pixel than at .5 arcseconds per pixel.

 

Mark


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#7 PeteM

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Posted 22 November 2019 - 10:33 PM

Good stuff already listed here!

 

1) Spend moonlite nights learning the nitty gritty stuff: focusing, guiding, pointing, software. Also tweaking setups or changing setups(if new).

2) If possible keep calibration frames to a minimum at a dark site. Just flats if you have a regulated cooler..darks,bias can be done at home.

3) At a dark site, go for the targets that are hard from your usually location. Meaning if you live in LP, go for the fainter stuff at the dark sites. Or objects not visible at home.

4) Finally...go to a dark sky to image if you are in a red zone or worse. You will be blown away with the quality of the data.


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#8 moonrider

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Posted 22 November 2019 - 10:51 PM

Great subject and responses!

 

1. Have a imaging plan before you start the night.

2. Pre test every aspect of your equipment before you go out.

3. Utilize the built-in simulators in many programs to get familiar with them.


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#9 fewayne

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Posted 22 November 2019 - 11:37 PM

Don't be me.


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#10 brettkoz

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Posted 23 November 2019 - 12:18 AM

My best practices for beginners is to calibrate every time, flats, darks and bias or dark flats. Get at least 3 or 4 hours of data. Learn phd2 and how to problem solve mount/guiding issues. Learn plate solving and get eqmod figured out, sooner rather than later. Sometimes these things seem daunting, and when you finally do make the jump and learn it, you realize it wasn't nearly as hard as you had thought.
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#11 TelescopeGreg

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Posted 23 November 2019 - 01:03 AM

My two basic rules for the hobby, and for life:

 

1.  "If you find yourself in a hole, stop digging."  When things don't seem to be working properly, stop, review what you are doing, and figure out what steps you missed, or didn't do properly.  Regroup, then move forward.

 

2.  "Never let any piece of technology know you're in a hurry."  Take your time to do things right.  You'll naturally get faster / better at doing things with time and practice, but if you push too hard, you'll likely end up violating rule #1.

 

Oh, and I guess there's a third...  Errors and issues are like criminals, and secretly want to be found out.  Every image displays the fingerprints of a criminal.  Learn to look at what it's telling you.  Your equipment can teach you more than any book or video.


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#12 Stelios

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Posted 23 November 2019 - 03:07 AM

Things I could not do without:

 

Equipment: A good mount. A cooled camera. OAG. Auto-focuser. And scope(s) that match well to camera, seeing, and won't overtax the mount.

 

Preparation: I use Telescopius and/or Bracken's astrophotography atlas and targets to select targets. I then use SGP's framing and mosaic sequence to create the sequences. I always know at what point to start imaging a particular target and when to stop for the night and switch. I try to have at least one alternate in case of localized clouds.

I create dark libraries at home in advance, using a fridge. 

 

Acquisition:

Quick Polar Alignment. I use Sharpcap Pro. 

Software. I use SGP (I understand NINA and Voyager are good alternatives, and APT is close). I want something that can do autofocus, meridian flips, equipment profiles, framing and mosaics, plate-solving with rotation support, and dithering. I also use CDC (Cartes Du Ciel) as a planetarium program.

Guiding. I use OAG, and encourage everybody to switch if they can afford to, but if you can't, at least guide. Software is PhD2. I loosen guiding parameters when seeing is bad and tighten them when good. I *always* dither, every two frames (I take over 100) for broadband and every frame for narrowband. 

Focus. I use a Bahtinov mask initially, and then autofocus the rest of the night at least every half hour. Focusing is only next to guiding in importance. 

Flats panel. I use Spike-A-Flat, expensive but nice, however any panel is better than none. I take flats every time, either before or after the session. Between 1/3rd and 2/3rds of histogram exposure. 

 

 

I've been doing this a while, and it's amazing how many glitches still creep up. It's important to always have spares for everything: Spare usb cables, spare hubs, spare laptop if you can afford it, spare camera, extra batteries, extra flashlights, extra power supplies and cables, small toolkit. When all else fails, power off, reconnect everything, and reboot. Many times a loose usb or power connection can cause head-scratching catastrophes that are easily fixed by unseating and firmly re-seating everything.

 

Carry extra warm clothes. It always feels *MUCH* colder when you are sitting at the mount. Warm hat that covers ears, warm boots (and toe-warmers!) are essential. I use half-gloves (they reach halfway to elbow but leave finger tips bare) and over-gloves. Several layers of socks, long johns, and upper body wear with a long, warm windproof exterior. Be prepared for the weather to be 20 degrees colder than the forecast. It'll feel that way. 

 

Start well before dark. Give the scope time to acclimate itself, and yourself time to setup, level, balance and connect everything. Always put on CW's before the scope! And use a dew heater if there's a possibility of dew. 

 

Don't drink alcohol (I'm not a teetotaler in the least, but you need all your wits when doing AP and working in low-light conditions). Do keep warm beverages at hand, and plenty of munchies. 

 

If using Windows, make sure it updates between 8AM and 5PM if you can't/won't disable them. 

Never update software just before an imaging session. Try it at home first.

 

I'm sure I've forgotten some...


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#13 the Elf

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Posted 23 November 2019 - 04:26 AM

When not plate soving have a preview of the field of view at hand, even a print showing the largest stars so that you can verify the FOV from a single sub where the object will not show up.

When using the mount alignment make sure you can identify the alignment stars. Learn the constellations and the major stars. Make sure you can identify polaris with no doubt.

Have spare batteries or a charger you can operate from your car when using a DSLR.

Have a few basic tools like screwdriver and hex wrench with you. I once found the az bolt on the tripod was loose.

If you go to remote places tell someone where you are and when you intend to come back so that your loved ones know where to search for you when the car wont start next morning.

Be prepared for wild animals, maybe have pepper spray in your pocket. I had a close encounter with a deer once. Be prepared for drunken people.

Double check the spot with a strong flashlight before you leave. Make sure you did not drop some tiny part that you will be missing next time.

In winter have two sets of glove, thin ones you can do adjustments with and thick ones for waiting. If you tend to get cold feet, stand on a piece of styrofoam.

Stay away from the scope. Walking nearby will ruin the sub.

Depending on the scope you might want to check collimation after a bumpy ride.

Stand behind the scope, not in front. Park the car behind the scope or in a distance. The warm air rising from your body or car will ruin the image.

If you can, enjoy the comfort of imaging at home. Most of the above is not a problem in that case.

Have a plan B for a second object in case plan A does not work.

Adding to Stelios: Spike-A-Flat or Aurora by Gerd Neumann.

Make sure you find enough sleep. Lack of sleep of a longer period of time can cause serious health problems.


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#14 nimitz69

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Posted 23 November 2019 - 08:52 AM

here's another one ....

 

if you're going to image from home like me then figure out a way to have a permanent setup.  an observatory would be best but a concrete pier and 365 Telegzmo cover is light years ahead of 'setup-teardown' every time.  honestly, i don't know how you guys do that - way too much work!   you will image SO much more because you've eliminated most of the overhead work.


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#15 elmiko

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Posted 23 November 2019 - 10:06 AM

Don't be me.

Lol !! funnypost.gif



#16 Madratter

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Posted 23 November 2019 - 10:43 AM

Since this is a beginner & intermediate imaging sub forum I thought it might be useful to start a ‘best practices’ thread for just the image capture portion of AP - no post processing discussion.   I continually see posts from new imagers where they are not doing some of what most experienced imagers consider mandatory, so ..... here’s a couple to get started:

 

- always take cal frames (darks, flats, bias or dark flats) - always

- if doing manual focus use a Bahtinov mask and spend whatever time is needed to get it perfect; then check refocus at least every hour, more if temps are dropping rapidly

- setup early to allow your optics to get to ambient temperature - it takes longer than you think

- always dither

- learn to use plate solving.  You’ll no longer need to waste time doing mount star aligns and you’ll always be on target when chasing fainter things

 

 

what’s on everyone else’s list?

 

I actually break the rule about calibration frames, sometimes for long periods of time. I can use darks and bias for years (and have at times). I can sometimes use flats for long periods of time too. The optics near my camera are sealed and that helps a great deal.

 

For unsealed cameras you would definitely need frequent flats. For non-temperature stabilized cameras you are probably going to need darks (and bias if you use them).


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#17 nimitz69

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Posted 23 November 2019 - 12:58 PM

 When I said you need to take cal frames every time I meant you need to have them for every image you plan to process.  Most of us have dark libraries and bias libraries if you use them (I need to do dark flats). If you have a permanent setup and don’t touch the imaging train then you could get away with reusing flats but with an observatory it’s so easy to take flats that I’d rather be safe than sorry.  If you setup and tear down every time taking flats each session is really a best practice.



#18 Madratter

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Posted 23 November 2019 - 02:18 PM

Good clarification on the dark and bias library.

 

As for the flats, I will say that many many things make taking new ones next to mandatory. Take the camera off the telescope, change the camera angle, or tweak the collimation of your optics and you need new flats.

 

And I agree the flats really don't take very long.

 

I ended up getting new darks, bias, and flats for my session last night. The darks took over 3 hours. The bias took around a minute. The flats took about 10 to 15 minutes.


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#19 WebFoot

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Posted 23 November 2019 - 03:04 PM

I agree that flats are a necessity for each filter of each target.  But bias and darks have a good long life; I retake darks only every three months or so.

 

The key, I think, is to take lots of calibration frames (I generally take about a dozen flats for each filter for each target, and at least 35 darks and bias frames at each duration; yes, I know that software does a pretty good job of scaling darks, but the real McCoy is always better).

 

Mark



#20 Starslinger

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Posted 23 November 2019 - 03:44 PM

I've got a whopping three weeks of experience in this field... but many, many years as a photographer... and, so far, they seem to require a very similar basic workflow:

  1. Know your gear inside out and back to front
  2. Test your gear from the comfort of your own home
  3. Have a mental (or even real) checklist of gear you'll need*
  4. Carry some backup gear** if feasible
  5. Have a shooting plan
  6. Have another plan
  7. Have a third plan in case life really hates you at that moment
  8. Make sure one plan has a 'cut short' option***
  9. Make sure everything is working before you start shooting
  10. Check your plan before you stop shooting
  11. Check your gear check list when you pack up****
  12. Backup your images as soon as you can*****
  13. Get some sleep

Notes:

 

* glance back at the driveway as you drive away to make sure none of it is sitting contentedly 'not in the car'. 

** backup gear is proportional to various factors, distance from home, distance from anywhere that might supply replacement gear and uniqueness of subject. (Once in a lifetime event versus something that you could shoot again tomorrow). 

*** Think of it like a pilots 'what happens if my engine dies on take off' plan B. Or, in photography, when a subject says you've got an hour but, when they arrive, tells you they have 5 mins. 

**** glance back at your parking spot, as you drive away, to make sure none of your gear is sitting forlornly 'not in the car'. 

***** a digital asset is considered to be 'at risk' unless there are three copies of it, in three different locations i.e main storage, backup storage, offsite storage. 


Edited by Starslinger, 23 November 2019 - 03:45 PM.

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#21 Madratter

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Posted 23 November 2019 - 04:13 PM

I've got a whopping three weeks of experience in this field... but many, many years as a photographer... and, so far, they seem to require a very similar basic workflow:

  1. Know your gear inside out and back to front
  2. Test your gear from the comfort of your own home
  3. Have a mental (or even real) checklist of gear you'll need*
  4. Carry some backup gear** if feasible
  5. Have a shooting plan
  6. Have another plan
  7. Have a third plan in case life really hates you at that moment
  8. Make sure one plan has a 'cut short' option***
  9. Make sure everything is working before you start shooting
  10. Check your plan before you stop shooting
  11. Check your gear check list when you pack up****
  12. Backup your images as soon as you can*****
  13. Get some sleep

Notes:

 

* glance back at the driveway as you drive away to make sure none of it is sitting contentedly 'not in the car'. 

** backup gear is proportional to various factors, distance from home, distance from anywhere that might supply replacement gear and uniqueness of subject. (Once in a lifetime event versus something that you could shoot again tomorrow). 

*** Think of it like a pilots 'what happens if my engine dies on take off' plan B. Or, in photography, when a subject says you've got an hour but, when they arrive, tells you they have 5 mins. 

**** glance back at your parking spot, as you drive away, to make sure none of your gear is sitting forlornly 'not in the car'. 

***** a digital asset is considered to be 'at risk' unless there are three copies of it, in three different locations i.e main storage, backup storage, offsite storage. 

 

Oh boy. I used to take photography pretty seriously. Enough so that I have done "once in a life time" events. But I NEVER agreed to do such an event ahead of time. I would shoot what the pro would allow me to shoot (assuming a pro showed up). For some weddings people were very grateful I ended up shooting it.

 

But to actually agree ahead of time to shoot a wedding and then have the backup equipment, etc. to do it - no way and my hats off to those who have the courage to do it.

 

Miss a bridesmaid coming down the isle and it is gone.

 

I was asked reasonably often to do so. People want to get stuff on the cheap if they can. I told them to hire a pro. You'll hopefully be looking at those pictures a long time. The chicken dinner or the booze will be long gone.

 

Back on topic - I think the best advice I can give people is if at all possible, get an observatory. I realize that is out of the question for many. But it takes so many of the variables out of the equation that can screw things up for the night. And it makes setup and take down so much easier. My observatory is my most important piece of equipment.


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#22 moonrider

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Posted 23 November 2019 - 04:25 PM

here's another one ....

 

if you're going to image from home like me then figure out a way to have a permanent setup.  an observatory would be best but a concrete pier and 365 Telegzmo cover is light years ahead of 'setup-teardown' every time.  honestly, i don't know how you guys do that - way too much work!   you will image SO much more because you've eliminated most of the overhead work.

I wish!!!


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#23 Starslinger

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Posted 23 November 2019 - 04:34 PM

Oh boy. I used to take photography pretty seriously. Enough so that I have done "once in a life time" events. But I NEVER agreed to do such an event ahead of time. I would shoot what the pro would allow me to shoot (assuming a pro showed up). For some weddings people were very grateful I ended up shooting it.

 

But to actually agree ahead of time to shoot a wedding and then have the backup equipment, etc. to do it - no way and my hats off to those who have the courage to do it.

 

Miss a bridesmaid coming down the isle and it is gone.

 

I was asked reasonably often to do so. People want to get stuff on the cheap if they can. I told them to hire a pro. You'll hopefully be looking at those pictures a long time. The chicken dinner or the booze will be long gone.

 

Back on topic - I think the best advice I can give people is if at all possible, get an observatory. I realize that is out of the question for many. But it takes so many of the variables out of the equation that can screw things up for the night. And it makes setup and take down so much easier. My observatory is my most important piece of equipment.

I remember doing a job in Scotland, once, many years ago (I was shooting Velvia on a Hasselblad to give it a time frame). I needed X amount of bright, cheery, diverse images from all over the west of Scotland and I had five days to do it. It was a seriously tight brief which meant up before dawn, shoot, drive, shoot, drive, shoot, drive, bed, repeat... it rained for the first three days and my number of needed shots and locations was still X.

 

For most freelance photography the old Gene Kranz line about failure not being an option pretty much holds true. Editors and creative directors move on to the next photographer in their iPhone/rolodex pretty quickly. And as Joe McNally has said, one 'ahhhhh s**t' can undo the work of multiple 'attaboys'. 



#24 the Elf

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Posted 24 November 2019 - 06:00 AM

Well, there is nothing wrong with the Bob Ross philosophy "we don't make mistakes - we only have happy accidents". If someone just grabs the gear, drives to the dark site and happily enjoys the night sky because he/she forgot the camera that's fine. But some other character might be frustrated like hell and rather want to go thru the check list to avoid this sort of "disaster". All that is offered here are points for the checklist of those who want a checklist. You don't have to.

When I was a kid my father used to travel Bavaria (the strange southern part of Germany where the Octoberfest is) and take photos of the inside of churches. When he attempted to crank back the film he realized in a moment of panic that the film had not moved at all. So he took is small bocklet and reconstructed what locations he had lost. The whole family had to follow the church tour again like a military operation to get the missing shots. That was the most recreational holliday ever. Thank good the screen on the camera will save families from doing that unless dad accidentally erases the files.... It's basicall about how you deal with the fact that you are human and make mistakes.


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#25 Starslinger

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Posted 24 November 2019 - 11:43 AM

I don't think this was a thread about “happy accidents”, or how one deals with mistakes... it was about workflow and best practises.
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