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06-01-2021, 06:10 PM - 2 Likes   #16
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QuoteOriginally posted by jon.partsch Quote
This is confusing to me. Are you saying that Sequator will basically shift the starts in each exposure so that they all line up, but will *not* also shift the foreground? If so this is interesting, and I may want to try this approach. It sound like it may be difficult to implement this along with additional offset frames intended for a stitched panorama. Are you suggesting this as an alternative approach to a single frame milky way scene *not* using Astrotracer?
Exactly! In using Sequator, you simply pick a shutter speed that will be short enough not to blur stars (I use about 10 seconds with an 18 mm lens on an APS-C 24 Mp sensor). Take as many shots as you like, more is better. When you process in Sequator, there is an option to "freeze ground". You will then paint over the sky and Sequator will create a mask. In processing, it will move all the stars over the top of one another from all exposures and do a simple average on the foreground with everything fixed and spit out a result. It sounds complicated but is in fact pretty foolproof and straightforward - lots ot YT videos on it. Here's one I prepared earlier (x posted from the DA*11-18 thread):



06-01-2021, 06:29 PM - 1 Like   #17
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QuoteOriginally posted by jon.partsch Quote
Yes, I was wondering what is the best exposure value to use to get (1) thin lines, (2) good color in the trails, and (3) maximize number of trails. The way I see it, there is no option for trial and error, so I need to decide on the EV that I will use and hope for the best. This is one of my primary concerns. Also, I don't see a way to use the K-1ii internal intervalometer for exposures longer than 30 seconds. If there is a way to do this, please explain.
Don't know how to multi quote, so.....
I use a Kp so don't know the K-1 II controls but they came out about the same time. On the Kp, I have a user mode set for startrails. It is based on B mode with timed shutter activated opening up the use of shutter speeds up to 20 minutes. I then have interval shooting set, minimum standby interval, all NR off. I have it set for 20 exposures of 3 minutes, ISO800 and F5.6 - but if you want to adjust this on the night, select the user mode and then change whichever settings you want - it's still much easier to remember than doing it all in one hit.

(BTW I have set up 3 user modes for night stuff - one is high ISO with NR on which I use for single exposures, composition and focus checking, the second for stacking short exposures and the third for startrails. Test them in the backyard to avoid disappointment in the field).


Don't get too hung up on ISO. Pentax use ISO invariant sensors - you can select all the images you took and push them 5 stops in post processing if you want (equiv ISO100 to 3200). ISO is only making changes AFTER the light hits your sensor - what you capture is based only on aperture and shutter speed. My approach is to stay a little on the low side as keeping control of blowing highlights (stars) is the key issue. You can also get cute in post by adjusting exposure progressively on the trails shots to get tapers on your star trails - another x-post example below:

06-02-2021, 02:44 PM   #18
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QuoteOriginally posted by gifthorse Quote
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.
Thanks again for all this additional detail. two clicks down is f/3.5. I couldn't help myself, and got the Sigma 35mm f/1.8 Art here on the forum. It should arrive tomorrow. It has a reputation of being tack sharp with no coma at f/2.8 and pretty good wide open too. I will be testing it out as well. I won't be able to get nice foregroud to the south at my first location, but this should be possible at my second location.

That's a great tip on letting the moon illuminate the foreground! I hadn't thought of that, though not sure I can stand to stay out that late. have been looking at photos online, and I can clearly tell which ones have a foreground shot during daylight and stitched in later. They look awful. I would much prefer a dark silhouette foreground to that.

QuoteOriginally posted by Grimmus Quote
Exactly! In using Sequator, you simply pick a shutter speed that will be short enough not to blur stars (I use about 10 seconds with an 18 mm lens on an APS-C 24 Mp sensor). Take as many shots as you like, more is better. When you process in Sequator, there is an option to "freeze ground". You will then paint over the sky and Sequator will create a mask. In processing, it will move all the stars over the top of one another from all exposures and do a simple average on the foreground with everything fixed and spit out a result. It sounds complicated but is in fact pretty foolproof and straightforward - lots ot YT videos on it. Here's one I prepared earlier (x posted from the DA*11-18 thread):
Grimmus, both your photos look very much like what I hope to capture, so I will take your advice seriously. As I mentioned in my reply to gifthorse above, I can clearly tell the photos online where the foreground was photographed separately under different lighting conditions and stitched in later - they look awful. I'm going to give the approach using Sequator some thought and look for some YouTube videos as you suggest.

QuoteOriginally posted by Grimmus Quote
Don't know how to multi quote, so.....
I use a Kp so don't know the K-1 II controls but they came out about the same time. On the Kp, I have a user mode set for startrails. It is based on B mode with timed shutter activated opening up the use of shutter speeds up to 20 minutes. I then have interval shooting set, minimum standby interval, all NR off. I have it set for 20 exposures of 3 minutes, ISO800 and F5.6 - but if you want to adjust this on the night, select the user mode and then change whichever settings you want - it's still much easier to remember than doing it all in one hit.

(BTW I have set up 3 user modes for night stuff - one is high ISO with NR on which I use for single exposures, composition and focus checking, the second for stacking short exposures and the third for startrails. Test them in the backyard to avoid disappointment in the field).


Don't get too hung up on ISO. Pentax use ISO invariant sensors - you can select all the images you took and push them 5 stops in post processing if you want (equiv ISO100 to 3200). ISO is only making changes AFTER the light hits your sensor - what you capture is based only on aperture and shutter speed. My approach is to stay a little on the low side as keeping control of blowing highlights (stars) is the key issue. You can also get cute in post by adjusting exposure progressively on the trails shots to get tapers on your star trails - another x-post example below:
Again, these star trails look very much like I was hoping to capture. What is the total exposure time on this one, do you remember? I was able to determine how to set a long espouse in a user mode on my K-1ii, but there is no option to use the internal intervalometer in Bulb mode (the option no longer appears in the drive mode menu). If this is different on the KP, then I am a bit envious, but I have an external intervalometer that should work.

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This is a user mode I have called "milky way". I guess I should eliminate use of the 2-second delay as it probably makes no difference for long exposures.

I will plan a few milky way (not star trail) shots, since these don't take a lot of time. I will try single frame astrotracer, the stacking method you mention using Sequator, and a stitched version using three or four 35mm frames to cover the same approximate angle of view (in portrait orientation) as 24mm.

Star trails will be one attempt at each location, and I won't know my result until stacking later in software, but I will not sweat it too much on the absolute EV that I use. I suppose I could try a shorter exposure for short trails, like 10 minutes, to try and dial it in and avoid any blown highlights - that wouldn't take too much time.

~ Jon
06-02-2021, 09:11 PM - 1 Like   #19
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QuoteOriginally posted by jon.partsch Quote
What is the total exposure time on this one, do you remember? I was able to determine how to set a long espouse in a user mode on my K-1ii, but there is no option to use the internal intervalometer in Bulb mode (the option no longer appears in the drive mode menu). If this is different on the KP, then I am a bit envious, but I have an external intervalometer that should work.
This was 72 minutes total - 36 shots of 2 minute exposure (f6.3 and ISO800). The foreground was 10 shots at 60 seconds - importantly, after waiting for the moon to rise as per @gifthorse's approach (by which time I had been locked in but that's another story ). On the Kp I was able to set this sequence up, and take a comfortable position while the camera clicked through the 36 x 2 min exposures. Bummer the K-1 II doesn't do this but no problem if you have the external intervalometer.

There is a bloke called Richard Tatti who has a youtube channel called nightscape images - it is well done and has been a great source of information and inspiration. There are several videos where he walks through the capture of stacks, panoramas and sequator processing - you'll have to tolerate the australian accent though!

06-03-2021, 11:04 AM   #20
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QuoteOriginally posted by Grimmus Quote
This was 72 minutes total - 36 shots of 2 minute exposure (f6.3 and ISO800). The foreground was 10 shots at 60 seconds - importantly, after waiting for the moon to rise as per @gifthorse's approach (by which time I had been locked in but that's another story ). On the Kp I was able to set this sequence up, and take a comfortable position while the camera clicked through the 36 x 2 min exposures. Bummer the K-1 II doesn't do this but no problem if you have the external intervalometer.

There is a bloke called Richard Tatti who has a youtube channel called nightscape images - it is well done and has been a great source of information and inspiration. There are several videos where he walks through the capture of stacks, panoramas and sequator processing - you'll have to tolerate the australian accent though!
Thanks again, Grimmus. This stuff is golden. I think I am fairly confident on planning my shoot now. I still have some PP questions gestating in my mind, but those can wait for later. I think I have what I need to capture the best exposures I can (for a first timer, anyway), and I can worry about PP later. I am going to make a PDF of all the valuable information in this thread and write up some notes on what I specifically want to do in the field.

I am a little miffed that the K-1ii doesn't include as robust an intervalometer function as the KP that came before it. It seem like it would be simple to impliment in firmware. I hope they do so, but I can use an wired intervalometer just fine, I suspect.

I will definitely check out Richard Tatti on YouTube!

Right now, I am planning three different approaches to the Milky Way shot, and then I can evaluate the differences between methods in practice.

I think I have chosen a location in Yosemite where I can get a good shot of the southern galactic core on night 3 or 4 of my trip. I am planning star trails shots toward the north (for circular effect) and west (for "raining stars" effect). I am confident that I will get some good images out of it all, and perhaps more importantly, will learn a lot.

Thanks, everyone, for your help in this thread!!!

~ Jon
06-03-2021, 12:49 PM - 1 Like   #21
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QuoteOriginally posted by Grimmus Quote
There is a bloke called Richard Tatti who has a youtube channel called nightscape images - it is well done and has been a great source of information and inspiration. There are several videos where he walks through the capture of stacks, panoramas and sequator processing - you'll have to tolerate the australian accent though!
I hadn't realized it before, but I was already inspired to try a "stitched" Milky Way image by one of his tutorials:



This seems to be a great one on the use of Sequator in the method you are suggesting:



I am now a subscriber to his channel.

~ Jon
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