gettr
professor emeritus
Reged: 10/20/04
Posts: 505
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Hi all,
I've finally ordered the last couple of things I need to try some prime focus astrophotography. I been trying to get a list together so I can minimize the screw-ups. (I know I'm going to have more than my fair share...  ) So far there seems to be three really important things:
1. a good polar alignment
2. a good focusing technique
3. post processing
The polar alignment is something I'm going to have to work on. I usually just plop my mount down with a quick eyeball reference to Polaris.(For viewing, not photography)
Focusing is where I think I'm going to have a problem. How do you achieve a good focus? Just by looking thru the view finder on the camera?
I plan on shooting Raw images that will be processed in Adobe Photoshop Elements. I know this program doesn't have all the bells and whistles that Photoshop has, but is it enough? I don't plan on publishing anything anytime soon. 
Is there anything else that needs special emphasis? Could maybe a couple of you experienced guys list the steps you go through from setting up till you close the shutter? I've found that (for me) a check list usually starts to minimize the things that can possibly go wrong. We called it "Marine proof" when I was in the service. (Before I get flamed, that was my chosen service)
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DaveC
Pooh-Bah
Reged: 11/27/03
Posts: 1316
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first off let me say thank you for your service =)
1) check this out. this page helped me learn it.
http://www.darkskyimages.com/gpolar.html
2) a couple of choices here.
http://www.dslrfocus.com/
or
http://velatron.com/dca/articles/focus/
or
http://www.stellar-international.com/digitalfg.html
3) heres on place to start. unfortunatly a few links may be dead.
http://www.lefevre.darkhorizons.org/articles/proctutorial2.htm
heres another...
http://www.cloudynights.com/documents/photoshop.pdf
Quote:
Is there anything else that needs special emphasis? Could maybe a couple of you experienced guys list the steps you go through from setting up till you close the shutter?
thats alot of steps! takes me two hours to set up. best bet is to work out your own list as you gain experience.
good luck
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comets4tom
professor emeritus
Reged: 02/08/05
Posts: 638
Loc: Texas
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For polar alignment, my mount has a polar alignment scope built in. It works well.
For focusing, it can be complicated and/or expensive or you can use more simple already available means. I personally use the less expensive less hassle (to me) approach. I visually get the best focus I can and then take a short test exposure. I then review the image on the LCD display and use the zoom feature to check the focus. It is repeated until I am satisfied with the focus.
Others connect their camera to a laptop computer (I got a DSLR to avoid using one) and use software like DSLR focus. Focusing aids like a knife edge focuser designed for a particular camera are available and the camera may have a right angle magnifier/viewer available. These are not inexpensive.
Regarding processing, I use a version of Photoshop LE that allows me to adjust the levels of 48 bit TIFFs. I know that Elements through at least version 2 only handle 24 bit TIFFs. I am not sure about 3.0.
You will need a remote shutter release if you do not have one already. The release will help avoid camera shake on short exposures and allow you to hold the shutter open for long exposures when using the bulb setting.
Tom H.
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Vixen R200SS,Meade 2045D, Orion Explorer 90mm, Orion Starblast Imaging Reflector, Vixen Great Polaris DX with iOptron Goto Nova, Meade LX200GPS 8 Inch, AT72ED
Canon 1000D,Orion Starshoot II Monochrome, Atik 16IC
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Anonymous
Unregistered
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Reticle eyepiece for dift alignment and this HP:
http://www.darkskyimages.com/gpolar.html
Also, which camera and mount are you using?
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Tonk
Postmaster
Reged: 08/19/04
Posts: 6100
Loc: Leeds, UK, 54N
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Images Plus is very reasonabley priced (much cheaper than MaximDL etc) and is designed for DSLR astro image processing. In the course of learning to do astrophotography you will eventually need to handle dark and flat frames to calibrate your pictures (remove hot pixels etc). Images Plus at least makes doing all this very easy. You can do this work in Photoshop but it is labour intensive in that package.
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Televue 85/TRF-2008 field flattener, Meade LX200 10", Manfrotto 055SSB tripod/410 geared head/AstroTrac TT320X-AG/056 3D head, GM-8/Gemini, 10 Micron 1000 HPS, Canon 40D (unmodded), Canon 450D (modded w/Astronomiks clip-ins - UV/IR, OWB), Coronado SM60/Lunt B1200/WO diagonal, Baader Herschel Wedge
Leeds Sky Clock Ripon Sky Clock
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Anonymous
Unregistered
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Quote:
Hi all,
I've finally ordered the last couple of things I need to try some prime focus astrophotography. I been trying to get a list together so I can minimize the screw-ups. (I know I'm going to have more than my fair share... ) So far there seems to be three really important things:
1. a good polar alignment
2. a good focusing technique
3. post processing
Hi,
I am quite new to this but very experienced in making errors. Polar alignment is alot more critical for AP than I realized, well worth it to spend what seems an inordinate time working on this. I have had limited success with methods other than drift alignment. Focusing is difficult for me; I have found a Hartmann mask a cheap and functional way to get close to good focus. Also I use the "hat trick" to avoid shutter jitters. As for post processing; practice, reading and practice. One nice thing is the processing can be done when it is cloudy.
Good luck, while getting to the skill level of many here is a steep learning curve, one can make large leaps in image quality intitially (especially if your starting point is as low as mine!)
Good luck,
Bill
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gettr
professor emeritus
Reged: 10/20/04
Posts: 505
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Thanks for the replies all.... there is some valuable advice (and links) there. I never knew there was THAT much involved in the focusing. And I forgot about the cable...
I will be using a 20D and a LXD75. As far as the scopes go, I was going to use my WO ZS80. I was also going to try the LPI that came with my AR6 and SN10. Come to think of it, would either of these be a better platform to start from? And would it be possible to try and establish focus with the LPI and switch to the 20D?
Thanks again,
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Anonymous
Unregistered
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Quote:
Thanks for the replies all.... there is some valuable advice (and links) there. I never knew there was THAT much involved in the focusing. And I forgot about the cable...
I will be using a 20D and a LXD75. As far as the scopes go, I was going to use my WO ZS80. I was also going to try the LPI that came with my AR6 and SN10. Come to think of it, would either of these be a better platform to start from? And would it be possible to try and establish focus with the LPI and switch to the 20D?
Thanks again,
Dennis,
The cable is cheap and easy to make, although buying one is not so painful either; worth the effort/cost in either case.
My experience with the LPI is that it plus the included software is a good way to get decent lunar and planetary pics right off the bat. In time I *think* a Toucam or Firewired based cam will do better for lunar and planetary work with either a dedicated astro CCD cam or a DSLR for DSO stuff. Of course images posted here and in related forums often nix my opinions. Think the key is to use what you have and make informed decisions based off of that; suspect we would all like to start from scratch (with all invested monies refunded, of course) but get enjoyment from what you have and go from there...
Bill
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southmike
Carpal Tunnel
Reged: 11/22/04
Posts: 2844
Loc: Fayetteville, NC
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wouldn a hartman mask help get a good focus...
and if so is dslrfoucus worth the money, if you can obtain a good focus ?
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group scope pic
my refractors
LX200 10"-St120
LX200 8" f6.3-Orion 80ed
LX200 8" f10-Orion 90 Mak setup pic
Meade 102ED LXD650
Sky Watcher 100 ED Triplet prototype
Nexstar 5
etx125
etx70's
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c131frdave
Post Laureate
Reged: 01/17/05
Posts: 4376
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Dslrfocus is worth the money. Trust me on this one. There is no better way of getting sharp focus than using this software. It is a digital pixel analysis tool- giving you graphical data instead of just eyeballing it. Plus it will automate your session if you want. You can create a sequence file with multiple shots of different exposure times if you want. In other words, once you have your mount squared away, camera focused, you can order the camera to take 20 5 minute shots, 10 2 minute shots, and 5 10 minute shots (for example), and go back inside the house for a cup of coffee. Sitting by your scope for 4 hours taking the same shot over and over can get real tedious- and Dslrfocus can do it for you.
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Tak NJP
Various sizes and shapes of formed glass
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southmike
Carpal Tunnel
Reged: 11/22/04
Posts: 2844
Loc: Fayetteville, NC
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hmm i see your point..
just what i was loooking for ..thanks
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group scope pic
my refractors
LX200 10"-St120
LX200 8" f6.3-Orion 80ed
LX200 8" f10-Orion 90 Mak setup pic
Meade 102ED LXD650
Sky Watcher 100 ED Triplet prototype
Nexstar 5
etx125
etx70's
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comets4tom
professor emeritus
Reged: 02/08/05
Posts: 638
Loc: Texas
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I would think the ZenithStar 80 with your DSLR would be good to start with (especially for deep sky work)on your LXD 75 mount due to its relatively short focal length and size. You could use your LPI for guiding when doing long exposure if you had another small guide scope to mount along side the ZS 80.
I don't think you could use your LPI to focus and then switch to the 20D because they more than likely come to focus at a different point although you could in theory add a spacer to make them parfocal.
Tom H.
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Vixen R200SS,Meade 2045D, Orion Explorer 90mm, Orion Starblast Imaging Reflector, Vixen Great Polaris DX with iOptron Goto Nova, Meade LX200GPS 8 Inch, AT72ED
Canon 1000D,Orion Starshoot II Monochrome, Atik 16IC
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gettr
professor emeritus
Reged: 10/20/04
Posts: 505
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The dslrfocus software looks very functional. The website makes it sound like it will walk your dog too... It looks like extremely useful software.
Tom, using the LPI as an autoguider is something I hadn't thought of. Is it difficult to configure the software to do this? This might be all the excuse I need to either buy a new ST80 or go get the one I gave my father.
Hmmmm, more to think about....CFO (wife) and wallet are starting to get nervous
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AuroraSeeker
Pooh-Bah
Reged: 11/16/04
Posts: 1377
Loc: Philadelphia, PA
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Actually, I would take POST-PROCESSING off your list.
The two MOST important things to master first is:
1. Mount and Tracking (polar alignment)
2. Focusing (including exposure etc...i.e. taking the shot)
If the above things aren't taken into consideration, post-processing doesn't mean squat. Also, even if your processing skills are poor now, they can always be improved in the future where you can revisit shots already taken.
So right now, spend time mostly on taking the shots and getting the mount to work properly.
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http://www.danielmccauley.com/
Daniel McCauley, Astrophotographer
Southern New Jersey
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southmike
Carpal Tunnel
Reged: 11/22/04
Posts: 2844
Loc: Fayetteville, NC
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the only problem i see with dslfocus means bringing a laptop..which kinda defeats the point of me buying an st-4 and a digital rebel.
and the laptop I use has and amd64 processor and has a scary battery life. like maybe 1 1/2 hours max. so really i can only travel as far as my extension cord. I have a what is supposed to be a 10 hr battery unit for it but the first one was a dud and i havent even opened the replacement yet.
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group scope pic
my refractors
LX200 10"-St120
LX200 8" f6.3-Orion 80ed
LX200 8" f10-Orion 90 Mak setup pic
Meade 102ED LXD650
Sky Watcher 100 ED Triplet prototype
Nexstar 5
etx125
etx70's
Edited by southmike (03/26/05 11:03 AM)
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Tonk
Postmaster
Reged: 08/19/04
Posts: 6100
Loc: Leeds, UK, 54N
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You only need 10 minutes at abs most to focus with DSLRFocus. I take my laptop out to remote dark sky sites and other than focusing and downloading a few test shots - its quickly back in its warm bag! I do the shooting sequence using the Canon remote timer gizmo - that doesn't have onerous battery requirements as the battery lasts at least 1 year
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Televue 85/TRF-2008 field flattener, Meade LX200 10", Manfrotto 055SSB tripod/410 geared head/AstroTrac TT320X-AG/056 3D head, GM-8/Gemini, 10 Micron 1000 HPS, Canon 40D (unmodded), Canon 450D (modded w/Astronomiks clip-ins - UV/IR, OWB), Coronado SM60/Lunt B1200/WO diagonal, Baader Herschel Wedge
Leeds Sky Clock Ripon Sky Clock
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c131frdave
Post Laureate
Reged: 01/17/05
Posts: 4376
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If you have money to burn, you could get a servo motorized focuser to save time. You can spend about an hour at home getting a razor sharp focus, note the focuser position, and then just command the focuser to go to that position at any later date. As long as you are using the same photo equipment and the belt hasn't moved, you will get your sharp focus in about 30 seconds.
I am in the process of using DSLRfocus and Robofocus to get each of my EPs and cameras to optimum focus, log the positions of the focuser, and then have a data base for rapid focusing.
Anyway, that's a little off subject, but if your laptop is an issue, you can set up all of your equipment at home like I have described above, and then spend little time in the field with your laptop.
By the way- Dan's abosolutely right. If you don't have your mount set up right, and your focus dead on- no amount of processing, not even using $15,000 movie editing software, will get you a good image. I've tried it. I've shaved trailing stars, used special effects masks, added submasking with glows and artificial lighting, and every other movie making trick I know. All a waste of time. You can get beautiful blobs this way, but not crisp astro images. Master your mount and get your razor sharp focus. The rest will come easily enough with practice and tips here on CN.
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Tak NJP
Various sizes and shapes of formed glass
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Blueshark928
Carpal Tunnel
Reged: 02/19/04
Posts: 2853
Loc: Crownsville, MD
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If your starting out here, and still deciding which software to use, may i suggest Images Plus. IP now has the focus routines and bulb exposure camera control for Canon and Nikon DSLRs. Not to mention its a full astro image processing software designed with DSLR in mind.
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John
SV-102APO
SV-80/9d
Losmandy G11
HX-916
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Blueshark928
Carpal Tunnel
Reged: 02/19/04
Posts: 2853
Loc: Crownsville, MD
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Quote:
the only problem i see with dslfocus means bringing a laptop..which kinda defeats the point of me buying an st-4 and a digital rebel.
I shouda read this part....
What you need is a Stilletto IV ronchi/knife edge focuser.
Peruse here
Stilletto web site
You will also need a 12v car adaptor power cable for your 300d too. And a couple of CF cards to boot.
--------------------
John
SV-102APO
SV-80/9d
Losmandy G11
HX-916
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southmike
Carpal Tunnel
Reged: 11/22/04
Posts: 2844
Loc: Fayetteville, NC
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hmm another thing to spend money on.....
just when there was light at the end of tunnel.
--------------------
group scope pic
my refractors
LX200 10"-St120
LX200 8" f6.3-Orion 80ed
LX200 8" f10-Orion 90 Mak setup pic
Meade 102ED LXD650
Sky Watcher 100 ED Triplet prototype
Nexstar 5
etx125
etx70's
|
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