Trying to capture milky way. Stop down vs high ISO?

uday029 · 04-13-2015, 01:16 PM

Hello all,

This coming weekend I will be trying, for the first time, to capture milky way. I am planning to use Rokinon 14mm f2.8 with my K-3.

What is better when shooting milky way? Keep the aperture at f2.8 and use lower ISO or stop down (for sharpness) and use high ISO? Rokinon 14mm is relatively soft at f 2.8, but would it matter when shooting far away stars? What is a better compromise to make? Any input is highly appreciated.

Thanks.

kenny47 · 04-13-2015, 01:21 PM

I would stop down and use high iso, but I am no expert...I've read some article about the matter where they recommended this, but I can't find it now..

Adam · 04-13-2015, 01:21 PM - **1 Like**

Originally posted by uday029

Hello all,

This coming weekend I will be trying, for the first time, to capture milky way. I am planning to use Rokinon 14mm f2.8 with my K-3.

What is better when shooting milky way? Keep the aperture at f2.8 and use lower ISO or stop down (for sharpness) and use high ISO? Rokinon 14mm is relatively soft at f 2.8, but would it matter when shooting far away stars? What is a better compromise to make? Any input is highly appreciated.

Thanks.

Generally speaking you want to use the fastest aperture possible so that the lens can gather as much light as possible. If the lens is soft at F2.8 though, use F3.5 or F4. Also, you will probably need to stack images, so IMO shooting multiple files at a low ISO is the way to go. There probably won't be enough light for you to use ISO 100, so you'll most likely be working in the 200-800 range.

My best star photos have all been either wide-open or close to wide-open.

Johnmor · 04-13-2015, 01:43 PM

Hi, i also have the k3 and have captured some nice images using ISO 1600, stop wide open f3.5 and 30 sec exp (any loger and you may get star trails) , manual focus. But as already said, take loads of pics, maybe need an astro chart app to find best area of sky, the k3 will see way more than your eye will see!
Need to find some real dark sky, no light pollution, solid tripod, im still a long way from getting it right but have enjoyed the challenge

Good luck

John

biz-engineer · 04-13-2015, 02:07 PM

Using slow shutter speed noise reduction (dark frame subtraction) should help.

mikeSF · 04-13-2015, 02:45 PM - **1 Like**

i recommend stopping down about 1 stop from wide open just to take some of the wide open softness off. I would rather trade 1 stop of ISO for 1 stop of aperture when shooting stars. Also, check out the OGPS1, as it does a fine job and you can be shooting 1.5min exposures for the MW at clean ISOs.

**stsimmer** · 04-13-2015, 02:58 PM

From Prep Work to Post-Processing: An In-Depth Star Photography Tutorial

Here is a link to an excellent primer on star photography. Read it all and follow the steps. You won't go wrong. I have the Rokinon 14 mm f/2.8. I suggest using it at f/2.8 for stars. It is a little less sharp at f/2.8, but definitely not soft. That lens is very sharp from end to end.

Good luck.

DeadJohn · 04-13-2015, 03:05 PM

Practice your first night out. Try f2.8, 3.5, and 4.0 to compare results. Try ISO 400, 800, and 1600.

30 seconds is a good exposure length to use with the 14mm. Use the countdown timer, remote control, or intervalometer to minimize camera shake.

Use liveview to focus. Remember that the info button (on the K5, the K3 might be different) zooms in. Pick a bright star and focus until it's as small as possible. Periodically recheck focus.

philbaum · 04-13-2015, 03:06 PM

Originally posted by mikeSF

i recommend stopping down about 1 stop from wide open just to take some of the wide open softness off. I would rather trade 1 stop of ISO for 1 stop of aperture when shooting stars. Also, check out the OGPS1, as it does a fine job and you can be shooting 1.5min exposures for the MW at clean ISOs.

Thank you Mike - i did't realize what a bonus that device is - uses the IBIS to track the stars - magic! Will have my order on Thursday - yea.

How to Pick a Lens for Milky Way Photography – Lonely Speck

The above is a discussion and rating of various lens types. Also it leads one to a discussion on petapixel that has even more stuff.

uday029 · 04-13-2015, 03:32 PM

Thank you all for your valuable input. Since I am just starting off, my goal for now is to capture milky way with some nice foreground. I did look into OGPS1 but it blurs the foreground as the sensor moves. I am also researching on image stacking but I am not sure if it would work as the stars keep moving and their position would change relative to the foreground? Luckily, I live within 2-3 hour driving distance to Lake Tahoe and Mono Lake which have decent dark skies and good foreground opportunities. I am using ClearDarkSky to check for sky charts.

Thank you stsimmer and philbaum for the links. I am hoping it will be a good learning experience.

Thomas Cantwell · 04-13-2015, 03:36 PM

I don't think the 14mm is supposed to be soft wide open, though.

Samyang 14 mm f/2.8 ED AS IF UMC review - Image resolution - Lenstip.com

Aaron28 · 04-13-2015, 03:43 PM

I wish I could go there!! since you will be there for more than 30 seconds.......try it wide open with a low ISO 200-400......try it stopped down and bump up the ISO as you see fit
when I get me some dollars I want to get a 14/2.8 (prolly the bower version) for milky way shots and plan to start out wide open.....then I will stop down as I do have the o-gps-1
it will be a matter of experience with trial and error for me but from a good base line set up
good luck and happy shooting! definitely envy where you are goin.....I would lose my mind out there!

Na Horuk · 04-13-2015, 04:42 PM

My Samyang 14mm f2.8 (optically the same as Rokinon, just different label) is quite sharp wide open. There are two other problems it has:
a) decentering. The DoF is a little skewed, so one part of the frame is very sharp, while the other part has some CA and is a little blurred.
b) focusing. The lens is manual focus. How are you focusing it to get the milky way? If you just twist the focus ring all the way, that is not infinity. And if you put it right on the infinity mark, it is quite possible that is still not infinity. These lenses often have poorly calibrated focusing, there are even blog posts about this (and ways to fix it). Best is that you take test photos and learn where true infinity is with your specific camera and lens combination, then mark it on the lens. That way you will know where to focus when you are out in the field, in the dark.

That being said, the lens is still sharper at higher apertures than wide open. But I doubt you would have to go over f4. Then there are some other things to consider. The first is that you should use a heavy tripod and don't even move or walk around it while the exposure is being taken. Next is timer and trigger. You should use 2 sec timer as that disables SR and includes MLU. SR should be deactivated for long exposures anyway, since you are using a tripod. Using a remote trigger helps as well, as your hand will wobble the camera and tripod. Finally, if you want the stars to be sharp points, not star trails, you need to use a shutter speed that is so fast, that the trails won't be noticeable. If you have a 30 sec exposure, there will be trails. I think there was a formula for this, which was 600 / focal length = X. X is the longest exposure that you can do without startrails showing up in the photo. But this might not be accurate anymore, since modern cameras have a high pixel density.
The best way is to use a really long exposure, as long as you can get away with; with an ISO that you find to be still tolerable. Which ISO is that? Depends on camera, PP software, Noise reduction technique, and your own taste. Keep in mind that online you only see tiny astrophotos. A lot of those are riddled with noise at 100%, but you never see it because you only see a cleaned, tiny version. Noise tends to disappear when you scale down a photo.

Hope this helps. If you want more info, you should post sample photos with exif data, so we can diagnose what the problem is.

**interested_observer** · 04-13-2015, 05:12 PM - **1 Like**

Originally posted by uday029

Thank you all for your valuable input. Since I am just starting off, my goal for now is to capture milky way with some nice foreground. I did look into OGPS1 but it blurs the foreground as the sensor moves. I am also researching on image stacking but I am not sure if it would work as the stars keep moving and their position would change relative to the foreground? Luckily, I live within 2-3 hour driving distance to Lake Tahoe and Mono Lake which have decent dark skies and good foreground opportunities. I am using ClearDarkSky to check for sky charts.

Thank you stsimmer and philbaum for the links. I am hoping it will be a good learning experience.

I started doing some astro last year - both, with and with out the GPS unit. Your initial assumptions are pretty spot on. The conclusion I came to was, if you are including landscape in the foreground don't use the GPS and use the fastest lens you have available - wide open. If you are just going for the stars, use the GPS and you can use slower glass for the desired field of view. If you are going to stack, in order to stabilize (align) the stars positions, the landscape is going to blur.

Here is a thread I started about my adventure. It's more of just a running narrative (log) on both shooting and post processing. You can see that I was somewhat wandering around, trying things out, seeing what works - and doesn't. Both with and with out the GPS. It stretches across a few months. Also, the astro folks here on the Forum are absolutely wonderful. They provided a lot of post processing advice, suggestions, examples and encouragement. They had the knowledge and skill - I happened to have some relatively clear dark skies and a camera.

https://www.pentaxforums.com/forums/38-photographic-technique/263550-astrotra...out-field.html

Here are a few quick take aways, that I found during my quest....

High ISO is your friend. Depending on how dark it is, ISO 1600 @ 30 sec is going to be a good starting point. f2.8 if you have it - and adjust from there. I really appreciate the 31Ltd at f1.8 - to the point of thinking about acquiring the Sigma 18-35/f1.8.
Bring a folding chair, and a red head lamp (REI @ ~$15-$20) and a wired shutter release, tripod and head.
Focusing and framing in the dark is more difficult than it appears. Crank up the ISO all the way to 51200 @ ~5 sec for test shots, so that you can see on the camera's rear monitor what your framing is against the landscape. You can also check your focus this way. I used an ballhead, but have since picked up an old used gearhead (Manfrotto 410), so that I can make more precise changes one axis at a time.
I like the old wide manual focus lenses, because at the end of the focus range its infinity (well for most lenses) - which makes focusing in the dark a bit easier.
Bring a laptop to down load the images to for a real quick check to see if you did something stupid, or if you see something that you might lead you to try something different before you leave.
You are going to burn through batteries.
I just started locking the mirror up, since I was not using the viewfinder, SR should be disabled.
Keep some notes of what worked and didn't, and what you want to try next time out.

uday029 · 04-13-2015, 05:24 PM

Thank you all. Looks like a lot of trial and error before I figure out the right settings.
@interested_observer: Thanks for the link to your thread. I read first few posts. In the first post you mentioned a 300 second exposure for your 4th image at ISO 1600. WOW! Now I am not sure if I can capture milky way even with ISO 3200 and f2.8 and a 30 second exposure.

04-13-2015, 01:16 PM	#1
uday029 Veteran Member Join Date: Nov 2014 Posts: 505	Trying to capture milky way. Stop down vs high ISO? Hello all, This coming weekend I will be trying, for the first time, to capture milky way. I am planning to use Rokinon 14mm f2.8 with my K-3. What is better when shooting milky way? Keep the aperture at f2.8 and use lower ISO or stop down (for sharpness) and use high ISO? Rokinon 14mm is relatively soft at f 2.8, but would it matter when shooting far away stars? What is a better compromise to make? Any input is highly appreciated. Thanks.

04-13-2015, 01:21 PM - 1 Like	#3
Adam Administrator Site Webmaster Join Date: Sep 2006 Location: Arizona Photos: Gallery \| Albums Posts: 51,594	Originally posted by uday029 Hello all, This coming weekend I will be trying, for the first time, to capture milky way. I am planning to use Rokinon 14mm f2.8 with my K-3. What is better when shooting milky way? Keep the aperture at f2.8 and use lower ISO or stop down (for sharpness) and use high ISO? Rokinon 14mm is relatively soft at f 2.8, but would it matter when shooting far away stars? What is a better compromise to make? Any input is highly appreciated. Thanks. Generally speaking you want to use the fastest aperture possible so that the lens can gather as much light as possible. If the lens is soft at F2.8 though, use F3.5 or F4. Also, you will probably need to stack images, so IMO shooting multiple files at a low ISO is the way to go. There probably won't be enough light for you to use ISO 100, so you'll most likely be working in the 200-800 range. My best star photos have all been either wide-open or close to wide-open. Adam PentaxForums.com Webmaster (Site Usage Guide \| Site Help \| My Photography) PentaxForums.com server and development costs are user-supported. You can help cover these costs by donating or purchasing one of our Pentax eBooks. Or, buy your photo gear from our affiliates, Adorama, B&H Photo, KEH, or Topaz Labs, and get FREE Marketplace access - click here to see how! Trusted Pentax retailers:

04-13-2015, 03:32 PM	#10
uday029 Veteran Member Join Date: Nov 2014 Posts: 505 Original Poster	Thank you all for your valuable input. Since I am just starting off, my goal for now is to capture milky way with some nice foreground. I did look into OGPS1 but it blurs the foreground as the sensor moves. I am also researching on image stacking but I am not sure if it would work as the stars keep moving and their position would change relative to the foreground? Luckily, I live within 2-3 hour driving distance to Lake Tahoe and Mono Lake which have decent dark skies and good foreground opportunities. I am using ClearDarkSky to check for sky charts. Thank you stsimmer and philbaum for the links. I am hoping it will be a good learning experience. Last edited by uday029; 04-13-2015 at 03:43 PM.

04-13-2015, 05:12 PM - 1 Like	#14
interested_observer Loyal Site Supporter Join Date: Jun 2009 Location: Tumbleweed, Arizona Photos: Gallery \| Albums Posts: 5,707	Originally posted by uday029 Thank you all for your valuable input. Since I am just starting off, my goal for now is to capture milky way with some nice foreground. I did look into OGPS1 but it blurs the foreground as the sensor moves. I am also researching on image stacking but I am not sure if it would work as the stars keep moving and their position would change relative to the foreground? Luckily, I live within 2-3 hour driving distance to Lake Tahoe and Mono Lake which have decent dark skies and good foreground opportunities. I am using ClearDarkSky to check for sky charts. Thank you stsimmer and philbaum for the links. I am hoping it will be a good learning experience. I started doing some astro last year - both, with and with out the GPS unit. Your initial assumptions are pretty spot on. The conclusion I came to was, if you are including landscape in the foreground don't use the GPS and use the fastest lens you have available - wide open. If you are just going for the stars, use the GPS and you can use slower glass for the desired field of view. If you are going to stack, in order to stabilize (align) the stars positions, the landscape is going to blur. Here is a thread I started about my adventure. It's more of just a running narrative (log) on both shooting and post processing. You can see that I was somewhat wandering around, trying things out, seeing what works - and doesn't. Both with and with out the GPS. It stretches across a few months. Also, the astro folks here on the Forum are absolutely wonderful. They provided a lot of post processing advice, suggestions, examples and encouragement. They had the knowledge and skill - I happened to have some relatively clear dark skies and a camera. https://www.pentaxforums.com/forums/38-photographic-technique/263550-astrotra...out-field.html Here are a few quick take aways, that I found during my quest.... High ISO is your friend. Depending on how dark it is, ISO 1600 @ 30 sec is going to be a good starting point. f2.8 if you have it - and adjust from there. I really appreciate the 31Ltd at f1.8 - to the point of thinking about acquiring the Sigma 18-35/f1.8. Bring a folding chair, and a red head lamp (REI @ ~$15-$20) and a wired shutter release, tripod and head. Focusing and framing in the dark is more difficult than it appears. Crank up the ISO all the way to 51200 @ ~5 sec for test shots, so that you can see on the camera's rear monitor what your framing is against the landscape. You can also check your focus this way. I used an ballhead, but have since picked up an old used gearhead (Manfrotto 410), so that I can make more precise changes one axis at a time. I like the old wide manual focus lenses, because at the end of the focus range its infinity (well for most lenses) - which makes focusing in the dark a bit easier. Bring a laptop to down load the images to for a real quick check to see if you did something stupid, or if you see something that you might lead you to try something different before you leave. You are going to burn through batteries. I just started locking the mirror up, since I was not using the viewfinder, SR should be disabled. Keep some notes of what worked and didn't, and what you want to try next time out. Last edited by interested_observer; 04-13-2015 at 05:17 PM.

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04-13-2015, 01:21 PM	#2
kenny47 Junior Member Join Date: Sep 2012 Location: Bratislava Photos: Albums Posts: 44	I would stop down and use high iso, but I am no expert...I've read some article about the matter where they recommended this, but I can't find it now..

04-13-2015, 01:43 PM	#4
Johnmor Inactive Account Join Date: Apr 2015 Posts: 6	Hi, i also have the k3 and have captured some nice images using ISO 1600, stop wide open f3.5 and 30 sec exp (any loger and you may get star trails) , manual focus. But as already said, take loads of pics, maybe need an astro chart app to find best area of sky, the k3 will see way more than your eye will see! Need to find some real dark sky, no light pollution, solid tripod, im still a long way from getting it right but have enjoyed the challenge Good luck John

04-13-2015, 02:07 PM	#5
biz-engineer Pentaxian Join Date: Feb 2015 Photos: Gallery Posts: 12,231	Using slow shutter speed noise reduction (dark frame subtraction) should help.

04-13-2015, 02:45 PM - 1 Like	#6
mikeSF Pentaxian Join Date: Jan 2009 Location: East Bay Area, CA Photos: Gallery Posts: 6,620	i recommend stopping down about 1 stop from wide open just to take some of the wide open softness off. I would rather trade 1 stop of ISO for 1 stop of aperture when shooting stars. Also, check out the OGPS1, as it does a fine job and you can be shooting 1.5min exposures for the MW at clean ISOs.

04-13-2015, 02:58 PM	#7
stsimmer Site Supporter Join Date: Apr 2013 Location: Minnesota Photos: Albums Posts: 118	From Prep Work to Post-Processing: An In-Depth Star Photography Tutorial Here is a link to an excellent primer on star photography. Read it all and follow the steps. You won't go wrong. I have the Rokinon 14 mm f/2.8. I suggest using it at f/2.8 for stars. It is a little less sharp at f/2.8, but definitely not soft. That lens is very sharp from end to end. Good luck.

04-13-2015, 03:05 PM	#8
DeadJohn Pentaxian Join Date: Jan 2011 Location: New York Posts: 4,833	Practice your first night out. Try f2.8, 3.5, and 4.0 to compare results. Try ISO 400, 800, and 1600. 30 seconds is a good exposure length to use with the 14mm. Use the countdown timer, remote control, or intervalometer to minimize camera shake. Use liveview to focus. Remember that the info button (on the K5, the K3 might be different) zooms in. Pick a bright star and focus until it's as small as possible. Periodically recheck focus.

04-13-2015, 03:06 PM	#9
philbaum Veteran Member Join Date: Oct 2007 Location: Port Townsend, Washington State, USA Posts: 3,659	Originally posted by mikeSF i recommend stopping down about 1 stop from wide open just to take some of the wide open softness off. I would rather trade 1 stop of ISO for 1 stop of aperture when shooting stars. Also, check out the OGPS1, as it does a fine job and you can be shooting 1.5min exposures for the MW at clean ISOs. Thank you Mike - i did't realize what a bonus that device is - uses the IBIS to track the stars - magic! Will have my order on Thursday - yea. How to Pick a Lens for Milky Way Photography – Lonely Speck The above is a discussion and rating of various lens types. Also it leads one to a discussion on petapixel that has even more stuff.

04-13-2015, 03:36 PM	#11
Thomas Cantwell Inactive Account Join Date: Feb 2015 Posts: 52	I don't think the 14mm is supposed to be soft wide open, though. Samyang 14 mm f/2.8 ED AS IF UMC review - Image resolution - Lenstip.com

04-13-2015, 03:43 PM	#12
Aaron28 Pentaxian Join Date: Jan 2015 Location: Huntsville, Al Posts: 7,131	I wish I could go there!! since you will be there for more than 30 seconds.......try it wide open with a low ISO 200-400......try it stopped down and bump up the ISO as you see fit when I get me some dollars I want to get a 14/2.8 (prolly the bower version) for milky way shots and plan to start out wide open.....then I will stop down as I do have the o-gps-1 it will be a matter of experience with trial and error for me but from a good base line set up good luck and happy shooting! definitely envy where you are goin.....I would lose my mind out there!

04-13-2015, 04:42 PM	#13
Na Horuk Veteran Member Join Date: Feb 2012 Location: Slovenia, probably Photos: Gallery \| Albums Posts: 11,186	My Samyang 14mm f2.8 (optically the same as Rokinon, just different label) is quite sharp wide open. There are two other problems it has: a) decentering. The DoF is a little skewed, so one part of the frame is very sharp, while the other part has some CA and is a little blurred. b) focusing. The lens is manual focus. How are you focusing it to get the milky way? If you just twist the focus ring all the way, that is not infinity. And if you put it right on the infinity mark, it is quite possible that is still not infinity. These lenses often have poorly calibrated focusing, there are even blog posts about this (and ways to fix it). Best is that you take test photos and learn where true infinity is with your specific camera and lens combination, then mark it on the lens. That way you will know where to focus when you are out in the field, in the dark. That being said, the lens is still sharper at higher apertures than wide open. But I doubt you would have to go over f4. Then there are some other things to consider. The first is that you should use a heavy tripod and don't even move or walk around it while the exposure is being taken. Next is timer and trigger. You should use 2 sec timer as that disables SR and includes MLU. SR should be deactivated for long exposures anyway, since you are using a tripod. Using a remote trigger helps as well, as your hand will wobble the camera and tripod. Finally, if you want the stars to be sharp points, not star trails, you need to use a shutter speed that is so fast, that the trails won't be noticeable. If you have a 30 sec exposure, there will be trails. I think there was a formula for this, which was 600 / focal length = X. X is the longest exposure that you can do without startrails showing up in the photo. But this might not be accurate anymore, since modern cameras have a high pixel density. The best way is to use a really long exposure, as long as you can get away with; with an ISO that you find to be still tolerable. Which ISO is that? Depends on camera, PP software, Noise reduction technique, and your own taste. Keep in mind that online you only see tiny astrophotos. A lot of those are riddled with noise at 100%, but you never see it because you only see a cleaned, tiny version. Noise tends to disappear when you scale down a photo. Hope this helps. If you want more info, you should post sample photos with exif data, so we can diagnose what the problem is.

04-13-2015, 05:24 PM	#15
uday029 Veteran Member Join Date: Nov 2014 Posts: 505 Original Poster	Thank you all. Looks like a lot of trial and error before I figure out the right settings. @interested_observer: Thanks for the link to your thread. I read first few posts. In the first post you mentioned a 300 second exposure for your 4th image at ISO 1600. WOW! Now I am not sure if I can capture milky way even with ISO 3200 and f2.8 and a 30 second exposure.