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05-30-2021, 11:02 AM | #1 |
Need advice: Star Trails and Milky Way Wide Field Planned First Attempts
Thanks to those who provided advice re: my attempts at lunar eclipse stacking! I need more astrophotography help. Again, I am a beginner with these techniques. Next weekend, I will be camping at a couple great dark sky spots in the remote Sierra Nevada mountains here in California. I would like to try a star trails shot and a wide-field milky way shot. I will be using my K-1ii and my D-FA 24-70mm f/2.8 lens and the Astrotracer function. I have read several approaches to both of these shots, so I am confused. For the milky way shot, I have read that an EV of -8 is required. Is this correct? would I get better results at an EV of -7 or -6 due to presumably decreased noise? Should I favor a long exposure or a low ISO to get the best result? Should I stack exposures? Should I take dark frames, or use the long-exposure NR in-camera? I am also considering whether it is best to shoot one frame at 24mm or 3 or 4 frames at 35mm and stich them (vertically) in post. For the star trails shot, everything I read suggests 30-second exposures. Is there any reason that I can't use a longer exposure, like 1 minute? Is it because the stars will effectively "move out" of a given pixel before that pixel is fully exposed? I am thinking of doing a 2-hour total exposure. What is the proper EV to use for this? I have read that -7 is good, but that is so close to the recommended exposure for the milky way shot that I wonder if -6, -5 or -4 would be better. Please advise! Should I use the star trails function in-camera or combine exposures later in post? I note that I will only have one try at the star trails shot for each location where I will be camping. I can try a couple different approaches for the milky way shot. At location #1, they view is likely to be towards the NNE, at location #2, the view is likely to be toward the E. I will probably shoot my foreground earlier in the evening. In anticipation of your responses, thank you! ~ Jon | |
05-30-2021, 01:43 PM - 1 Like | #2 |
Star trails are much more forgiving exposure-wise than the Milky Way. Milky Way tips:
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05-30-2021, 02:36 PM | #3 |
Site Supporter Original Poster | Star trails are much more forgiving exposure-wise than the Milky Way. Milky Way tips:
Star trails are IMO more forgiving than the Milky Way.
Thanks again!
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05-30-2021, 03:58 PM - 2 Likes | #4 |
That's the way to do it - when you are dead on, the stars almost disappear. If there are bright (human-based!) lights off in the distance, that works, too. Make sure you are on manual focus - there is nothing quite so maddening as getting the focus just right, then hitting the shutter button, and hearing the autofocus whine into operation! Practice this at home before you leave - much less nerve-wracking than worrying about missing your big opportunity while out in the boonies. ps Where are you going in the Sierra? I've spent a lot of time on the east side of the Sierra (Owens Valley), back to when I was a radio astronomy grad student at Caltech. The Caltech radio observatory is between Big Pine and Bishop. --> lots of trips between Pasadena and Big Pine. And, lots of side trips up the mountains from Lone Pine, Independence, Big Pine, and Bishop. | |
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05-30-2021, 04:27 PM | #5 |
Site Supporter Original Poster | That's the way to do it - when you are dead on, the stars almost disappear. If there are bright (human-based!) lights off in the distance, that works, too. Make sure you are on manual focus - there is nothing quite so maddening as getting the focus just right, then hitting the shutter button, and hearing the autofocus whine into operation! Practice this at home before you leave - much less nerve-wracking than worrying about missing your big opportunity while out in the boonies. Good idea. If you wind up using the internal intervalometer for shorter exposures, don't forget that a "30" second exposure is really "32" seconds (and a "15" is real;y 16)! I think there is now a mode to just take the next picture as soon as the previous one finishes, but in the older cameras, you had to tell it the interval between exposure starts, and it you put in, say, 31 seconds while using "30 second" exposures, you missed every other interval! ps Where are you going in the Sierra? I've spent a lot of time on the east side of the Sierra (Owens Valley), back to when I was a radio astronomy grad student at Caltech. The Caltech radio observatory is between Big Pine and Bishop. --> lots of trips between Pasadena and Big Pine. And, lots of side trips up the mountains from Lone Pine, Independence, Big Pine, and Bishop. ~ Jon |
05-30-2021, 04:43 PM - 1 Like | #6 |
Another hint; Include some of the foreground scenery in your shots. Yosemite is a great opportunity to do this if your Sierra trip takes you that way.. You might have to combine two exposures, one with the Astrotracer on and one with it off (for the foreground which it will blur if tracking the stars). Those two exposures (foreground and sky) might have to be different also to properly render them which is another reason to break the shot into two exposures. Just mention this so you don't get home and have only sky shots (which are nice but you can really "spice" them up with a touch of foreground included - especially if it's El Capitan or the like).
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05-30-2021, 05:50 PM - 1 Like | #7 |
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05-30-2021, 07:09 PM | #8 |
Site Supporter Original Poster | Another hint; Include some of the foreground scenery in your shots. Yosemite is a great opportunity to do this if your Sierra trip takes you that way.. You might have to combine two exposures, one with the Astrotracer on and one with it off (for the foreground which it will blur if tracking the stars). Those two exposures (foreground and sky) might have to be different also to properly render them which is another reason to break the shot into two exposures. Just mention this so you don't get home and have only sky shots (which are nice but you can really "spice" them up with a touch of foreground included - especially if it's El Capitan or the like). Longer exposures are usually better (less noisy, fewer frame to process) for both Milky Way and star trails. The longer you go, though, increases the risk of unwanted star trailing for the Milky Way. Even with star trails it's possible to go too long if the sky background causes overexposure but that's more of a problem when there's light pollution. Dark frames aren't needed for star trails since you'll be stacking. They don't hurt, but remember that dark frames need to be taken near the same temperature as the photos, so it's best to take them after your light frames when the camera has warmed up. Simple noise reduction software, without dark frames, is IMO adequate to deal with hot pixels. ~ Jon |
05-30-2021, 10:15 PM - 2 Likes | #9 |
A couple of other points to keep in mind:- Startrails - these can be taken using quite small apertures and quite low ISO's. You can comfortably get good results around ISO400 with apertures around F4 to F7.1. Maintaining good star colour and thin trails is helped by not overdoing the exposure. You should be able to set your K-1 II's intervalometer to run timed B mode exposures of more than 30 seconds and set the interval to "minimum" to minimise gaps. The stacking software (starstax or startrails) has a setting to close up the gaps. Foreground/astrotracer blending - is not always just a matter of a still shot and an astrotracer shot. If you go with a long astrotracer sky exposure, the thick blurred line at the horizon is difficult to blend with the sharp line you get from the foreground shot - unless you shift one or the other. The second problem is the difference in ambient sky colour/exposure. This can be very frustrating to blend in Postprocessing. A good fall back plan is to take plenty of short frames without the astrotracer and then use Sequator which will stack the stars and freeze the foreground. Quick and easy to do and you will have a fall back option if the postprocessing proves challenging. Around 3 to 4 minutes of exposure time for the stars at f2.8 should be enough in a dark sky area. On a dark night, you will need about 4 times the exposure for the foreground - stacking again is a good way to minimise noise before blending. My last tip is to set up user modes before you leave home and test them to make sure they are doing what you expect. It saves all the mucking around with Hi ISO NR, intervalometer settings, WB and anything else. One flick of the wheel and you know you are ready to go - and didn't forget to change something that you only find out when you are back at the computer - don't ask how I know. Good luck and clear skies as the say! | |
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05-31-2021, 12:43 AM - 1 Like | #10 |
I use the Photo Pills app on my iPad to help plan shoots. One of the great things is they provide a whole bunch of free PDF documentation on different subjects. Here is a link to the free "Milky Way Photography: The Definitive Guide (2021)" They are Pentax friendly as they even mention the Pentax K-70, KP & K1 Mark2. Page 2 & 4 has links to other more specific guides. The OP should download it and have a read. | |
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05-31-2021, 12:07 PM - 1 Like | #11 |
I would suggest to try some constellations as well. With an astrotrace these are very easy to do. The main issue is to locate them. But you do not have to fiddle with the foreground. Use a 50 mm or a 35 mm for a wider field of view. With the stellarium programm for pc, you can look up in advance witch constellations you will be seeing and which focal length you need.
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05-31-2021, 01:28 PM - 1 Like | #12 |
Loyal Site Supporter |
One other tiny thing that you can do right now is to remove hot pixels, tools page 4 - pixel mapping.
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05-31-2021, 06:40 PM - 1 Like | #13 |
The k1 should easily handle an ISO of 3200 or 6400. For the Milky Way, I keep the high ISO and long exposure noise reduction on. Most lenses are soft wide open so stop the lens down stops a couple of clicks to sharpen the pinpoint stars. For a little extra stability (and for safety's sake) set a gallon jug of water under the tripod and use a bungee cord or light twine to tie the tripod to the jug of water. It will keep it from shaking in the breeze or gusts from toppling the camera and it's less likely you'll accidentally knock the camera over in the dark. Been there. Done that. It sucks. Turn off autofocus and auto exposure. I think the camera has to be in the 'B' or 'Manual' mode for Astrotracer to function. Check the instruction manual. For star trails, I usually do five minute exposures and about a 400 ISO and stack them with Startrails program. Turn off high ISO and long exposure noise reduction. Changing exposure time won't affect the brightness or number of the star trails. It will only change how long the trails are. Lowering ISO or decreasing the aperture will decrease the number of trails and the converse is true. Higher ISO/wider aperture = more/brighter star trails. For night photography a remote shutter release really is needed. If you don't already have on you can use the two second self timer temporarily. For star trails, an intervalometer like the Shutterboss will let you get consistent exposures longer than 30 seconds. You'll learn how hard that is to do when you start doing star trails. The next meteor shower isn't until late July so I won't go there yet. There's more that doesn't come to mind right now but I'll try to add more as I remember it. Oh! I know. There's a lot of post processing videos on YouTube that will help with after you get the images. just search for the keywords "Milky Way" and "post processing" | |
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06-01-2021, 11:53 AM - 1 Like | #14 |
Site Supporter Original Poster | Startrails - these can be taken using quite small apertures and quite low ISO's. You can comfortably get good results around ISO400 with apertures around F4 to F7.1. Maintaining good star colour and thin trails is helped by not overdoing the exposure. You should be able to set your K-1 II's intervalometer to run timed B mode exposures of more than 30 seconds and set the interval to "minimum" to minimise gaps. The stacking software (starstax or startrails) has a setting to close up the gaps. Foreground/astrotracer blending - is not always just a matter of a still shot and an astrotracer shot. If you go with a long astrotracer sky exposure, the thick blurred line at the horizon is difficult to blend with the sharp line you get from the foreground shot - unless you shift one or the other. The second problem is the difference in ambient sky colour/exposure. This can be very frustrating to blend in Postprocessing. A good fall back plan is to take plenty of short frames without the astrotracer and then use Sequator which will stack the stars and freeze the foreground. Quick and easy to do and you will have a fall back option if the postprocessing proves challenging. Around 3 to 4 minutes of exposure time for the stars at f2.8 should be enough in a dark sky area. My last tip is to set up user modes before you leave home and test them to make sure they are doing what you expect. It saves all the mucking around with Hi ISO NR, intervalometer settings, WB and anything else. One flick of the wheel and you know you are ready to go - and didn't forget to change something that you only find out when you are back at the computer - don't ask how I know. I use the Photo Pills app on my iPad to help plan shoots. One of the great things is they provide a whole bunch of free PDF documentation on different subjects. Here is a link to the free "Milky Way Photography: The Definitive Guide (2021)" They are Pentax friendly as they even mention the Pentax K-70, KP & K1 Mark2. Page 2 & 4 has links to other more specific guides. The OP should download it and have a read. I would suggest to try some constellations as well. With an astrotrace these are very easy to do. The main issue is to locate them. But you do not have to fiddle with the foreground. Use a 50 mm or a 35 mm for a wider field of view. With the stellarium programm for pc, you can look up in advance witch constellations you will be seeing and which focal length you need. The k1 should easily handle an ISO of 3200 or 6400. For the Milky Way, I keep the high ISO and long exposure noise reduction on. Most lenses are soft wide open so stop the lens down stops a couple of clicks to sharpen the pinpoint stars. For a little extra stability (and for safety's sake) set a gallon jug of water under the tripod and use a bungee cord or light twine to tie the tripod to the jug of water. It will keep it from shaking in the breeze or gusts from toppling the camera and it's less likely you'll accidentally knock the camera over in the dark. Been there. Done that. It sucks. Turn off autofocus and auto exposure. I think the camera has to be in the 'B' or 'Manual' mode for Astrotracer to function. Check the instruction manual. For star trails, I usually do five minute exposures and about a 400 ISO and stack them with Startrails program. Turn off high ISO and long exposure noise reduction. Changing exposure time won't affect the brightness or number of the star trails. It will only change how long the trails are. Lowering ISO or decreasing the aperture will decrease the number of trails and the converse is true. Higher ISO/wider aperture = more/brighter star trails. For night photography a remote shutter release really is needed. If you don't already have on you can use the two second self timer temporarily. For star trails, an intervalometer like the Shutterboss will let you get consistent exposures longer than 30 seconds. You'll learn how hard that is to do when you start doing star trails. The next meteor shower isn't until late July so I won't go there yet. There's more that doesn't come to mind right now but I'll try to add more as I remember it. Oh! I know. There's a lot of post processing videos on YouTube that will help with after you get the images. just search for the keywords "Milky Way" and "post processing" I am camping again in late July, so I'll try to catch the Southern Delta Aquariids / Alpha Capricornids. Thanks for the tip! As for YouTube videos - yeah, I am totally comfortable learning the finer points of PP later on. I just want to make sure I collect the best exposures when I am in the field. complicated PP does not scare me. I can learn. ~ Jon |
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06-01-2021, 05:20 PM - 1 Like | #15 |
For an initial set up for wide field Milky Way, leave the high ISO and the long exposure noise reduction on. Turn off the auto focus. I'd start with an ISO of 1600. I'm not familiar with the D-FA 24-70 so I'd set the aperture stopped down 1 or 2 clicks (not full stops, just a click or two) from wide open. With the Astrotracer, I'd start with an exposure time of about 2 minutes. If possible, aim the camera to the South. The galactic center, the brightest part of the Milky Way, will be low in the southern sky and will rise at around 10 pm. Check the exposure. If it's overexposed, I'd decrease the ISO and try again. If underexposed, I'd increase the exposure time first and then increase the ISO if needed. The Moon will rise around 3:30 am and will be about 10% to 20% illuminated. That should illuminate the foreground without washing out the Milky Way too badly.That's a start, but be prepared to make adjustments. For star trails, I'd start with an ISO of 800. For maximum stars you'll want the lens wide open. Turn off the high ISO and the long exposure noise reduction and auto focus. Aiming the camera north, toward the North star, will give you shorter and more curved star trails. Aiming East or West will create longer and straighter trails. If you are doing 5 minute exposures, the Moon above the horizon will wash out the sky. For star trails, I use a freeware program called Startrails. It's easy to use. What you see in the sky won't look like the images you take. The camera captures a lot more than your eyes see. The sky glow in the center of my first image is a small city some 30 miles away. The glow isn't visible with the naked eye but shows in long exposures. As you get more practice it will get easier. | |
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