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11-12-2018, 05:31 AM | #1 |
Astro photographers help with K1 settings
Hi Everyone looking for some help with K1 settings I believe astro tracer is not necessary under 30 secs is this correct ? Ive also turned off noise reduction to do the work in post is this better thoughts? Im basically starting out with milky way stuff so Id appreciate any advice on settings for noise reduction even post production tips any help would be appreciated. Using the 24-70mm with my k1 for nighttime shoots Ciaran | |
11-12-2018, 06:21 AM | #2 |
The “500 Rule” for astrophotography is that shutter times of under 500/F will have negligible star trailing and don't need astrotracer or a tracking mount. At 24mm that's a 21 second exposure and at 70mm, it's only a 7 second exposure. Long shutter time NR fixes noise that is hard to fix in post unless you carefully collect your own dark frames at the time you take the picture. Last edited by photoptimist; 11-12-2018 at 09:26 AM. Reason: typo because I'm human | |
11-12-2018, 08:08 AM - 1 Like | #3 |
Welcome! Exposure time depends on a number of things, including how high you want to push the ISO. I did a few astros in New Zealand in January with my K-3II using the Astrotracer, with my 10-17 fisheye at around 10-11mm (about 15-17mm FOV in K-1 money) at f3.5 and ISO400, with exposure times of 3 minutes, with no streaking. Without the Astrotracer, exposure time would have been a maximum of 45 seconds at the same focal length, meaning that to gather the same amount of light, I'd have had to use an ISO of around 1600, or even higher. This is where the Astrotracer scores, in that it gives you more flexibility with ISO if you use it. I also leave the long shutter time NR on, so that the camera automatically does a dark frame subtraction after the exposure to minimise noise. Post processing will bring out the milky way well. I use Adobe Camera Raw pas part of Photoshop CC, and enhancement can include increasing the exposure in the software by up to a stop, and increasing contrast, clarity, highlights and whites. | |
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11-12-2018, 11:34 AM - 1 Like | #4 |
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Morning - I find a lot of the settings used are somewhat based on personal preference. What others find acceptable might have a bit too much star streaking for me. Also, I see images from others who shoot off an equatorial mount for say 5 minutes and then stack multiple frames together creates wonderful colorful images, but are so bright as to be unnatural in their presentation. So, that's why I subscribe a lot of this to personal preference. The “500 Rule” for astrophotography is that shutter times of under 500/F will have negligible star trailing and don't need astrotracer or a tracking mount. At 24mm that's a 21 second exposure and at 70mm, it's only a 7 second exposure. Long shutter time NR fixes noise that is hard to fix in post unless you carefully collect your own dark frames at the time you take the picture. Personally, I moved away from the various "rules" and guidance, to a more deterministic approach. Here is a calculator that uses pixel boxes (user defined), based on sensor size, to determine the most reasonable shutter speeds to reduce star streaking or trailing. For crop sensors (K5 16MP), I like to use 4 pixel boxes (or Pixel Tolerance). For the K1, I really have only used the astrotracing capability, however the pixel sizes of the K5 and the K1 are relatively the same size, but obviously the K1 is a much larger sensor. You could probably get away with using 8 or so (but I would probably use 6 or 7). Also, I like to use the Diagonal times, as it's a combination of both the vertical and horizontal. Your question in terms of 30 seconds would produce an acceptable pixel box of ~14, which for me would create star trails that would be a bit too long. The 500 rule (using a focal length of 24 from your 24-70 lens) would have a suggested shutter speed of ~20 seconds, which would produce star trails of ~9 pixels - which for me may be a bit too long. You are going to need to experiment a bit to see what suites your eye and purposes best. I have found that having LENR enabled is very effective, at the expense of doubling the time that the camera is in use for the shot. 1 minute exposures locks the camera up for 2 minutes while it's capturing the dark frame and then subtracting it. This is the most effective, since it's guaranteed of using the same environmental factors. That said, you can also take a dark frame yourself - usually after you are done shooting a bunch of frames, and then using post processing tools to make the subtraction. It also becomes a factor of which post processing raw editor you are using. Lightroom and Photoshop are very weak here. Affinity Photo does not support this very well either. Camera One (C1) is extremely effective in cleaning up this noise with just loading the image. RawTharapee, I'm told also has a slider that effectively removes the "white dots" (as well as red and green) pretty well.You have a few choices with this....
Here is an image, K1, 15mm, f2.8, 50 seconds, astrotracked, 3 images stitched together that shows very little to no foreground smearing. I shoot with the 15-30. I (try to) shoot very simple straight forward at 15mm (either a single image, or a 2 or 3 or maybe even 4 image stitch) using it as a reference image (throwaway test - so that I can gauge somewhat how to process the more detailed stitches). These are simple to process and stitch - usually a minute or so. Then I shoot the same scene at 30mm (which doubles the amount of light I'm able to capture compared to 15mm (same f stop, however the size of the physical aperture is substantially larger at a longer focal length), and usually shoot a 7 x 2 or 3 stitched panorama. This takes substantially longer to process - since you need to mask and composite the sky and ground elements together. Shooting with the 15-30, I do need to take in to consideration how the stars are going to track in the corners and along the edges of the frame. With UWA lenses, the stars in the corners and edges track at a faster rate than what they do in the center - just physics at work. To minimize this effect, you need to keep the shutter times below about 90 seconds. That's one reason why I stitch a lot, so I essentially only use the center of the frames with the edges dropped. Also on the sides, I can crop the edges off (so I shoot wider than what I need to). This does not affect the foreground - just the sky. Again, I shoot 2 rows - so that I'll have a bit of additional frame to crop off, if I need to. |
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11-12-2018, 11:58 AM | #5 |
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Welcome to the forum and astro photography. You can always check out the astrophotography group they are very helpful over there and some there are true masters of the art. This should help you get pointed in the right direction. It is a beginners guide I wrote focusing mostly on the technical aspects of taking astro images. Since you brought up dark frames and in camera high ISO noise reduction I will delve a bit into that aspect here. Dark frames are used to help eliminate the thermal noise in the sensor from long exposures. When you have high ISO noise reduction turned on in the camera it will take a picture of the back of the shutter (dark frame) using what ever settings you had just used for the actual picture (light frame) and then will subtract the dark frame from the light frame. Most astrophotographers turn this off and just take a series of photos with the lens cap on at the end of the session or at the end of shooting an object before changing settings. Then using a stacking program like Deep Sky Stacker (DSS) a master dark frame is created (average of all dark frames) which is then subtracted from each light frame before the light frames are stacked. The averaging eliminates a good portion of the systematic thermal noise but there will still be the truly random noise in each frame which is one of the things that stacking the light frames helps to eliminate. To gather these I put the camera in to the low speed burst mode put the lens cap on and let it blast away and collect 10-20. Low speed is chose here to better emulate the conditions in which I shoot that allow a brief cool down of the sensor between shots. Related to dark frames are what are known as bias frames and as far as I know no camera does these. Their purpose is to eliminate the noise that is introduced by the signal amp which is usually drowned out by the thermal noise from the long exposures normally done. Here you use the same ISO you used during shooting but use the fastest shutter speed your camera supports and blast away with the lens cap on. Again here I put the camera into the low speed burst mode to mimic how I have to shoot so that the brief amp cool down between shots can happen. DSS will also combine these into a master bias frame and subtract it from the light frames. Finally there are flat frames. These are used to correct for vignetting from the lens. Basically you cover the front of the lens with some white cloth shine a uniform bright light on the front of the lens and take a series of photos. Again here DSS will combine and average them and create a master flat frame which it will use to correct vignetting in each light frame before it stacks them. Unlike dark and bias frames, flat frames are lens specific instead of session specific so can be reused from one shooting session to another where that lens and camera combo was used. The most important frames to capture are the light frames so spend your efforts there for the most benefit. I usually capture the rest when I am packing up and depending on how cold it is I may not even bother as when I do winter shooting when it is near 0F there just isn't enough thermal noise to worry about. The dark frames as a pack-up everything but the camera and tripod, and the bias frames as I pack up the tripod and camera. I have never bothered with flat frames especially since I don't have a proper equatorial mount so I snap a few images and reframe frequently and any vignetting should just average out. Having not used the 24-70, I assume it is this one, I can't say how it works for astrophotography but by the numbers it looks like it stands a good chance of being a pretty good lens to start with. I shoot primes for astro and chase deep sky objects (DSOs) so zooms and the milky way I can't offer much. For processing there are lots of tutorials out there. There is a series I used that Pete_XL pointed me to a while back. I don't have the link at hand but I can post it when I get home. It is for processing DSOs but a lot of it should be applicable to what you are doing too. This reminds me that I keep wanting to write a beginners guide to astro image processing but I keep shying away from doing so because I don't feel my skills are up to snuff enough yet to not point people down the wrong path.. |
11-12-2018, 01:18 PM - 2 Likes | #6 |
For my Astro work, I shoot with a K-1 and a Samyang 14mm f/2.8 lens. For this focal length, I can shoot 20-30 seconds without Astrotracer. With Astrotracer, I get good shots at 80-90 seconds, with some distotion in the corners due to the ultra wide-angle. For these settings, I shoot f/3.5 to get a little sharper focus and less coma distortion. I use ISO 800-1600. I rarely uses long-exposure NR because it takes so long to process between pictures, but I am sure it would help. I am still optimizing my settings, but I’d rather get 10 shots in 30 minutes than just 3-4 waiting for NR. Once I get a better handle on my ideal settings, I plan to do fewer shots but with NR turned on. I mainly do Milky Way shots. A dark sky definitely helps because it allows you to increase exposure without lots of washout from light pollution. My best shots have been in rural Maine. Dark Site Finder is a good thing. | |
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11-12-2018, 04:41 PM | #7 |
I do Milkyway shots when the sky is right. Darksky areas, new moon, cool clear conditions. I always use the Astrotracer, and I have the Long exposure NR on, I shoot raw+, ISO, 2000 -3200. But I have shot at less in areas with some light pollution. Although, I have the RAW file, I must say, the K-1 does a great job itself processing the images. This thread ,OUt Here - PentaxForums.com they are all jepg's direct from the camera. Pretty happy with them. Shot with the DFA 15-30/2.8 . | |
11-12-2018, 05:17 PM - 1 Like | #8 |
To get pinpoint stars with high mp cameras 500 rule doesn't really work. I suggest downloading Photopills app, it has the pinpoint star calculator, as well as other very useful tools such as photo planner with ability to predict where milky way would be, what phase the moon is in, what time the sunset/sunrise is etc. For my personal settings - at 15mm 2.8 I use iso 3200 and 10s exposures, and then stack them in Sequator for clean, bright exposures. I stopped using astro tracer with wide lenses due to stars trailing in corners. Stacking works best for me personally. | |
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11-13-2018, 09:21 AM | #9 |
Great image. I am shocked in that image you did not have to blend a foreground image in due to blurring by Astrotracer. How do you blend your ground and sky images when taking longer focal lenghts? This is my weakest point and frankly suck at it. Especially in images like this with the trees and the windmill. If it is in the desert, it is easier, but once trees are involved, I just plain stick with single images. Any tutorials or suggestions would be appreciated. | |
11-13-2018, 09:45 AM | #10 |
Quote: Ive also turned off noise reduction to do the work in post is this better thoughts? Quote: Im basically starting out with milky way stuff so Id appreciate any advice on settings for noise reduction even post production tips any help would be appreciated. After you know the processing basics, try longer focal lengths with the astrotracer. 70mm is long enough to start seeing details in the Andromeda Galaxy and Orion Nebula. When summer comes around again, the Sagittarius portion of the Milky Way is a great target; many colorful nebula can fit into the same frame. | |
11-13-2018, 10:01 AM | #11 |
The following comments are based on the guess that you are in the northern hemisphere. If you are "down under" or nearby then ignore. Sadly the Milky Way has gone into hiding until February(ish). My next planned Milky Way shot is not until early March. So you might want into looking into some true Astrophotography (no land) for the next few months. Peleides, Orion, Andromeda offer some great choices in winter. Maybe a longer lens for those shots. I hope this will be my first winter to try and take some of those images. I have not in the past, but want to. | |
11-13-2018, 11:53 AM - 1 Like | #12 |
Thanks for the input guys heres my attempt at the Milky Way have to say really enjoyed shooting the stars hoping to do alot more.
| |
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11-13-2018, 04:13 PM | #13 |
Loyal Site Supporter | Years ago, when I first acquired the O-GPS1 for my K5, I did an experiment to see how long I could go with the astrotracking with out having to worry about smearing the foreground elements. It seemed that 40 seconds was a good number, but I never printed anything to really know for sure. The image that I posted above, was really a happenstance. I had shot about 150 images and was ready to pack-up and go home. At the last minute, before I tore everything down, I thought that I would zoom back to 15mm and just shoot 3 vertical panels to stitch quickly and see how it turned out. That's the story. The things that I learned that were significant to me...
How do you blend your ground and sky images when taking longer focal lenghts? This is my weakest point and frankly suck at it. Especially in images like this with the trees and the windmill. If it is in the desert, it is easier, but once trees are involved, I just plain stick with single images. Any tutorials or suggestions would be appreciated. I'm in the process of changing my workflow for several reasons.
I'v pretty much decided to go with PTGui Pro. It does everything well and also has some limited masking ability built in. Several years ago, they solved their oversampling problem (which usually manifests itself with low light imagery).So, I'm thinking Camera 1 for raw editing with its superior noise reduction (white dot) capability, and PS for masking, compositing and stitching. In terms of use, when I shoot the images - the first row is level with the horizon and stitches as a cylinder. The second row is canted (tilted up at about 30 degrees) and stitches as a sphere. I'm shooting off of a pano head (Nodal Ninja 3) So, if I stitch the foreground as a row standalone and then stitch the sky, neither row will match up perfectly. You need to stitch them together all at once. Also, when I shot, I also shot 2 sets of images for the sky row. One set as the foreground - 2 minute images of the tree and windmill for best detail and low noise, and a second set for the sky 50 second astrotracked images. My thinking is to mask the sky out on the tree / windmill foreground image set, then mask the tree/windmill out of the sky image set. Then PS when stitching and compositing should (hopefully) set the masked in parts in to the masked out areas. That should be as perfect as I think I can get. One of my (minor) complaints about C1 was the colors appeared to be slightly better in LightRoom - especially the greens. I just came across this video yesterday by accident that I believe shows how to make the color adjustments. Also, just a side note. I've been shooting 50 second astrotracked images to ensure the edges and corners have as little star trailing as possible. I'v tried out 60, 70 and 90 seconds. 90 sec has a tad more than what I really want, and 70 sec images appears to look like 50 seconds for trailing, but with more star color and lower noise. So, I think I will be pushing astrotracking out to 70 seconds. I do think that 70 second astrotracked images will smear the foreground too much. The day before I go out and shoot the MW, I post process the last time I shot the MW or at the same location. This reminds me of the problems I having and I start thinking about possible changes or additions to shooting that location. |
11-13-2018, 07:59 PM | #14 |
Hi Tom, Thanks for the complement, but I need to thank you for using your K1mkII and taking the night images in your back yard at the low ISO end. That was the final item I needed to just stay with the K1 and not mod it to the mkII. The K1 does everything I need - and more. So, thanks again. Years ago, when I first acquired the O-GPS1 for my K5, I did an experiment to see how long I could go with the astrotracking with out having to worry about smearing the foreground elements. It seemed that 40 seconds was a good number, but I never printed anything to really know for sure. The image that I posted above, was really a happenstance. I had shot about 150 images and was ready to pack-up and go home. At the last minute, before I tore everything down, I thought that I would zoom back to 15mm and just shoot 3 vertical panels to stitch quickly and see how it turned out. That's the story. The things that I learned that were significant to me...
Well, actually this is in the desert. This was taken in the desert, about 70 miles east of Phoenix off of highway 60 about 5 miles before the little town of Superior (the light dome off to the left). It's in the US Forest Service - National Forest. The light dome off to the right is an open pit Ray mine, 40 miles away. There is this little gully, gulch, draw, valley or whatever you wish to describe it as - of about 4 acres (measured off of google earth) with oak trees that has been somewhat fenced in, as a cattle pen for roundup - with a windmill for water and a cattle chute for loading. You can even see the barb wire in the image running down to the bottom of the gully next to the windmill. It's a nothing washed out image during the day, but at night, it just works. I'm in the process of changing my workflow for several reasons.
I'v pretty much decided to go with PTGui Pro. It does everything well and also has some limited masking ability built in. Several years ago, they solved their oversampling problem (which usually manifests itself with low light imagery).So, I'm thinking Camera 1 for raw editing with its superior noise reduction (white dot) capability, and PS for masking, compositing and stitching. In terms of use, when I shoot the images - the first row is level with the horizon and stitches as a cylinder. The second row is canted (tilted up at about 30 degrees) and stitches as a sphere. I'm shooting off of a pano head (Nodal Ninja 3) So, if I stitch the foreground as a row standalone and then stitch the sky, neither row will match up perfectly. You need to stitch them together all at once. Also, when I shot, I also shot 2 sets of images for the sky row. One set as the foreground - 2 minute images of the tree and windmill for best detail and low noise, and a second set for the sky 50 second astrotracked images. My thinking is to mask the sky out on the tree / windmill foreground image set, then mask the tree/windmill out of the sky image set. Then PS when stitching and compositing should (hopefully) set the masked in parts in to the masked out areas. That should be as perfect as I think I can get. One of my (minor) complaints about C1 was the colors appeared to be slightly better in LightRoom - especially the greens. I just came across this video yesterday by accident that I believe shows how to make the color adjustments. Also, just a side note. I've been shooting 50 second astrotracked images to ensure the edges and corners have as little star trailing as possible. I'v tried out 60, 70 and 90 seconds. 90 sec has a tad more than what I really want, and 70 sec images appears to look like 50 seconds for trailing, but with more star color and lower noise. So, I think I will be pushing astrotracking out to 70 seconds. I do think that 70 second astrotracked images will smear the foreground too much. The day before I go out and shoot the MW, I post process the last time I shot the MW or at the same location. This reminds me of the problems I having and I start thinking about possible changes or additions to shooting that location. | |
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