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Forum: Photographic Technique
01-17-2019, 02:31 PM
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Does't sound like a go-to method of recording the camera position - I'll just need to make sure I record it properly in future (compass and protractor to the rescue!)
I think I'll need to grab an O-GPS1 at some point... dang, I was hoping I could get away with my own inventiveness and as little money as possible! Ha, I feel like such a cheapskate sometimes!
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Forum: Photographic Technique
01-17-2019, 02:18 AM
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When I started my "Adventures in Astrophotography" post over in the Astrophotography group, a number of people reiterated the suggestion on using the O-GPS1 and that it'd be a worthwhile purchase, and I'm certainly being swayed by it!
So obviously it provides rudimentary tracking and GPS functionality - but what I was wondering was, if properly calibrated, does it also record the orientation of the camera (specifically the azimuth/elevation)? I was out taking pictures this morning and forgot my notepad, and I would usually record roughly where the camera was pointed so that I can find it again later in stellarium :P
I don't believe it does; just curious :P
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Forum: Photographic Technique
01-10-2019, 01:08 AM
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I'm afraid I lack photoshop - I use darktable for RAW processing and gimp for actual manipulation - though I find myself using gimp less for photos I take these days
You know something - I was reading something related to registax in that it's not really designed for dealing with full resolution images (which would certainly explain the out-of-memory errors I was getting when trying to use drizzle, resampling and any other options when stacking) - apparently autostakkert is a popular choice for the actual stacking, followed by registax for the wavelet processing (which, in the words of one eager commenter, is in fact "the shiz")
So! Cropping: what is the best (by which I mean easiest) way to crop a whole bunch of images?
Take for instances my picture of vega: it has the brightest group of stars in a corner (I placed lyra in the top right of my frame with intent on capturing some of the dimmer stars in the direction of the coathanger cluster - more for the sake of experimenting and seeing what can be drawn out of a given image rather than a deliberate attempt at anything!) - if I crop on the centre of the image, lyra will be cut off - is there a way to automatically crop, say, fifty images on a particular group of objects (or the brightest object?)
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Forum: Photographic Technique
01-08-2019, 03:45 PM
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Eeep... that... didn't go well!
For starters, it was windy as **** which did not help matters; I don't seem to be able to get them to stack right - not sure what's going on there xD
Oh well! I'll just need to try again! :P
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Forum: Photographic Technique
01-08-2019, 09:29 AM
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Totally printing that off for tonight's shoot! I'm headed to the harbour front tonight for a SCUBA lecture - BUT I plan on showing up early because it's the harbour front where I'll have panoramic view over the sea and very little light pollution from the west (obviously I'm expecting lots of diffuse skyglow from the North, East and South... but hey! I'll live with it :D My guess is a bortle-6 - let's see if I was right!) - anyway, I should be able to have a bit of fun before my lecture at 1930 :)
That was a very good shout on the bahtinov mask by the way! I had actually discovered that exact site earlier in the day and had the same day you did!
Will let you know how tonight's shoot turns out - I'll post it over in the astrophotography group so I can keep a record of my adventures :P
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Forum: Photographic Technique
01-08-2019, 01:30 AM
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Lots of good tips there - can't wait to give it a proper trying out!
I think the logic behind my using ISO100 was that "I can get away with it therefore I should" (the moon being so bright that I could afford the low ISO!) - and I think that's as far as my mental processing went :)
Ah, good shout on using a point source instead of the moon itself - I'd have tried to use the moon had you not said that (and probably gone "huh, that's not too great" afterwards).
Now I'm about to ask a n00bie question that betrays my regular photography-n00bieness too :P At my parents house (Class 4 on the Bortle scale, vs a 6/7 at my home location) there is a radio mast with a big red anti-collision beacon 5 miles away. The noobieness comes from my wondering: as far as my lens is concerned, is that at infinity focus? Would I be better using/does it have to be an astronomical object?
This question brought is brought to you by a poor understanding of infinity focus with respect to lenses (I know what infinity focus is; I do not know the specifics of how to achieve it!)
--EDIT--
I know what infinity focus is in principle (the point beyond which which light is effectively collimated (or very close to it at least) but I'm not terribly sure where that is with respect to a lens; I would assume it is at some distal point; but where is the cutoff point where the light has very suitably low divergence?
Hrm... wait... I just had a flashback to hyperfocal distances... 5 miles should definitely be beyond the hyperfocal point - does that mean if I focus on it everything beyond that should also be in focus (since I'm not worrying about things in front of that point, the moon being a little bit further away rather than close xD) - my sigma lens has hyperfocal markings on it as well... but that raises the question, when I turn it to the infinity symbol (which I always assumed was infinity-focus) - why will it not focus on perfectly on stars or the moon, which I would have assumed to have been beyond the hyperfocal distance? Is this just poor calibration on the len, wear-and-tear, or something more interesting?
--EDIT-Part-2--
Whoops! Answered my own question! "Modern" lenses focus past infinity to allow compensation for thermal expansion and for IR shooting. Not sure if my Sigma lens is "modern" but it certainly seems to go to infinity and beyond :rofl:
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Forum: Photographic Technique
01-07-2019, 12:59 AM
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That was with the tripod using a remote release and manual focus; I'm not the logic behind why I was using ISO100 though! Will keep that in mind when I'm taking my next shots - hopefully I'll have a clear sky in the near future!
I think a lot of the noise came from post processing - BUT the images were probably very slightly out of focus to begin with, which I attempted to compensate for with very novice (and no doubt heavy-handed) use of the wavelet controls - and then I emphasised any defects I had introduced from that when I cropped the image.
I'll give the stacking another go with that set of images and see if I can do a better job of the post processing - can never have too much practice! With any luck I'll get another clear night soon and I can give the image capture another go as well!
--EDIT--
Will a Batinov Mask work for/aid in focusing on the moon? I'm debating printing/cutting one out but it's a bit of effort if it won't do anything (that said, I'll still need one eventually!)
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Forum: Photographic Technique
01-06-2019, 03:07 PM
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It's been a heck of a learning curve, but I managed to stack the pictures I took on the 24th of Dec (2018) - 8x images taken on 2018-12-18 with a 300mm lens at f/11, 1/50s, ISO100 and stacked with RegiStax
It may not be great, but I like it :) I will hopefully get a bit more practice and hopefully some more moon shots in the near future :) Thank you all so much for the help! I have to say, that image came out far better than I had anticipated - yeah, it could be better (there's a lot of noise, for instance!), but for a first attempt I'm very pleased with it!
I'll no-doubt resurect this post if/when it comes time to start upgrading gear xD
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Forum: Photographic Technique
01-03-2019, 02:46 AM
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Nice - it may be my first real upgrade if I get into the field!
I've been working with only the tripod lately - just getting used to taking photos in the dark to be honest: only had one real opportunity just before xmas to photograph the moon - its' been very overcast of late! I did however down a shot of the stars just before new year... mostly because I couldn't feel my fingers and by the time I warmed up I didn't want to go outside again!
Ha! I've actually fallen in love a little with my sigma lens - took it out birdwatching the other day with a DIY red dot reflex sight on the hot shoe and it was surprisingly good, even with the 2x teleconverter (though the latter caused bad chromatic aberration, not sure if it will be useful for astrophotography) - I'll need to be on the lookout for more old glass - I keep saying I'm going to visit the local antique store (he has a table of old SLRs, a few of which must be pentax - and who knows, I might find a lens or two in there as well!)
Good call on asking questions early! I'll make sure I join the astro group today - and I'll try not to be intimidated by the masters, but I can't promise I won't be :lol:
As I mentioned earlier, I've not been out much - over the festive period - between having the flu and a nasty cold and family and Christmas-dinner-induced-food-comas, and worst of all, clouds, I've only managed to take some shots of the moon - going to use them for stacking practice!
That reminds me, can you suggest some free/freeware stacking software? I've seen/heard reccomendations for RegiStax and Deepsky Stacker but haven't really looked into them yet (what little I've done so far was aimed at getting used to photographing the sky in the dark rather than the stacking side, though I have also taken some series of shots intended for stacking, I just haven't gotten round to it yet!
As for setting my expectations [of planets] to reasonable levels - not going to lie, I'm expecting a blurry dot/line at best :D*
*Side note about capturing a few pixels - I decided to try to appreciate the size of the mozaic image taken by voyager I as it left the solar system the other day and found out lots of cool things, looking back at earth and was amused that it had two cameras: a 1500mm, f/8.5 narrow-angle camera and a 200mm, f/3.5 wide-angle camera - and ultimately capture the image on an 800x800 pixel "sensor" (actually a vidicon tube! It's still a sensor in a utilitarian sense though!). It's quite something when you're so far away from your target that a 3.2-degree field of view is considered "wide angle" xD Really puts things in... perspective.
So! They returned 60 frames of which three (with blue, green and violet filters) were returned and combined to get the final image of Earth, as seen through the 1500mm lens from a tiny 3'757'059'000 miles away on a 41 year old vehicle travelling at 40'000 miles per hour (6'046'400'000km, 64000km/h (nearly 18 km per second) and the return signal took five and half hours to reach earth (despite traveling at the speed of light).
How cool is that!? I even found an appendix showing the specs of the cameras used! :D
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Forum: Photographic Technique
12-21-2018, 04:56 AM
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Wooo! Lots of good advice popped up over here overnight! :D
I'll start with MossyRocks post as it's a goldmine of info :D
Aye! The telescope I have is literally 2 elements (in 2 groups) - the chromatic aberration will be terrible, and that's before we get to field curvature problems! However, I have never noticed it with my eye (the brain is literally fantastic at compensating for weird things like that... human eyes are pretty bad and need a lot of post processing!)
Begging one's pardon, it's actually a Sigma 75-300mm lens (I couldn't find it because I was typing in 70-300mm!). I actually really like it - mostly because I picked it up for £10 (~$15) and it has that vintage smell I can't get enough of!
So! Stick with the lens for now - excellent! That saves me faffing around with 3D printed adapters and miscellaneous tubes!
1-good shout!
2-Currently have a half-dismantled ultra-heavy-duty tripod from an earlier project (designed to support an antenna array on a hillside during high wind for the purpose of performing moonbounce (EME) communication - and it was a heavy duty thing - made from 2x4s and welded steel - partially dismantled because I was modifying it to make each of the legs collapsable to make it easier for transport (despite it weighing a lot).
HOWEVER - that tripod is one big mutha - stable as a rock; but needs a car for transport so it's only good for back yard and car-based work (which was its original purpose). I can, however, build a much smaller variety of that which will somewhat resemble the tripods used for surveying instruments. Lightweight but with a wide splay for stability.
3-Already got one! :D
4-Good shout! I remember reading about those many, many years ago in relation to various telescopes; they aren't terribly expensive either! In fact...Aye! You can 3D print them! - score!
4(2)-I'll need to look into lenses at some point - I'm a bit lensed out at the moment though (my wallet certainly is!)
5-Now, interestingly, I was considering building a tracking mount for pointing an antenna array at amateur radio satellites a few months back - plug in the orbital parameters, hit "start" once the satellite passes the horizon and voila, the computer handles all tracking. The CAD work is all done (In fact, it is a remarkably simple design) - but it was never built because I wouldn't have enough space in my garden! The drive system, however, could easily be modified for polar tracking, and would be more than strong and powerful enough to support a decently sized telescope (it was, after all designed to support a 12-meter long axle with 2 4-metre-long antenna booms sticking out of it at right angles)
Definitely food for thought!
6-Some day! :D
So! Looks like I can get a decent chunk of that out the way myself and make a decent start!
Hrm - I don't know yet! My plan was to throw as I reasonably can at a wall and see what sticks!
It's probably easiest to go for the moon first since it's big and bright! Probably followed by a few planets, BUT at the same time I also want to try and get a shot of andromeda and the orion nebula.
So: my initial goals are for the Moon > Planets > Deep sky - by which point I should have a decent idea if I like it or not!
Oooh! More bedtime reading :D Will have a gander shortly!
Haha, as far as I'm concerned, nobody can ever have "perfect" gear: even if I had the most expensive and miraculously effective gear in existence, I will still take bad photos until I learn how to use it - and if I don't know the basics I'll never learn how to use it properly at all! As such I always encourage people to get their work out there (regardless of the type of work: photography, painting, music, programming, literature, dance moves - I don't care! Show people!) - sure you get a few negative people who just say "yuck that's terrible" - those are people you can safely ignore - the ones you want to listen to are the ones that tell you why it's not as good as it could be, and if you get lucky, how to improve it!
In other words, as long as you like it then it's not a bad photo (unless you like it specifically because it's bad!) and nobody can take that away from you. Unpopular does not mean bad any more than popular means good (argumentum ad populum). BUT that also doesn't mean that it can't be improved - EVERY photo can ALWAYS be improved! It's just you reach a point where the improvements get more and more subtle (diminishing return on improvements).
Lol that was a bit off topic - I was merely saying I'll get posting as soon as I get a few pictures that I actually like! :D
I have a bunch of other photos awaiting upload as well - just need to fire them through darktable and we'll be good to go!
Anyhoo! I'll respond to the other posts shortly - I started with this one as it was the most in-depth!
Thanks for that :D Much appreciated!
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Forum: Photographic Technique
12-20-2018, 07:28 AM
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Ohmagod, no, I have not! That's my bedtime reading sorted! :D
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Forum: Photographic Technique
12-20-2018, 07:01 AM
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[EDIT] - If I've put this in the wrong forum, eek! Sorry!
Goooood morning ladies and gentlemen!
...Even if I'm posting this afternoon and nobody says "ladies and gentlemen" anymore!
So! I want to try my hand at astrophotography - BUT - I want to buy as little as possible to do so.
I have a 70-300mm sigma lens (the star of this thread - get it?!? ...Well I found it funny... Fine, suit yourself! :D) - I also have a 50/300 National Geographic telescope (that's a 300mm focal length with a 50mm aperture - which works out as... F/6)
So, in principle, I have enough to get started!
To start with I'm going to just use an Az-El mount (Azimuth/Elevation-only), I can upgrade my kit with a DIY barndoor tracker if I like it!
With that in mind, I believe I'm going to have to do focus stacking since I won't be compensating for the earth's rotation (and there is NOTHING about that sentence that I don't like!) - and for better results, I believe the shortest exposure time would be the most use!
With that in mind, does that mean that my sigma lens (capable of being stopped down to F/5.6 at 300mm) would actually be better for astrophotography than this particular telescope?
SO I have a rudimentary plan, and some questions! The below list will start with the lowest numbers and I'll slowly increment the development of each part if I see fit! This way I can spend as much or as little as I want!- Mounting:
- Start with lightweight generic tripod ballasted with sandbags
- Construct DIY motorised barndoor tracker
- Build heavy-duty tripod (wide and heavy base, again ballasted with sandbags, and supports for long lenses)
- Build/buy proper equatorial mount for heavy duty tripod
- Motorisation
- NC control of motors > CNC control/Tracking
- Optics:
- Sigma lens OR 50-300mm telescope?
- Teleconverter?
- Better lens OR telescope?
- Other:
- Spotting tube/iron sight
- Holographic laser sight
- Digital Tracking (via CNC)
SO my questions mostly concern optics - and I'm aware you can spend a small fortune on both telescopes and lenses!- Is the compound Sigma lens (F.5.6 at 300mm) OR the cheap, single-element 30/300 telescope (F/6 at 300mm) likely to be better?
- I know that a teleconverter multiplies the focal length at the expense of dropping down a few f-stops; will the corresponding increase in exposure time cause problems?
See, I wondered if the lens and teleconverter would be a better idea since A) I can stack them if I really want to (ew... yeah, I shuddered too:p), and B) I can use it in regular photography as well, instead of only for a niche use!
What are you folk's thoughts on this?
Note-to-self:
-ToDo: look into noise removal techniques (darkframe/flatframe) when shooting with high ISO and give it a few practice shots
-ToDo: check if in-camera high-ISO NR + long-exposure NR is preferable
-ToDo: download DeepSkyStacker for stacking + watch ScottManley ultraquick tutorial on astrophotography
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