How to avoid star trails with Orion?

OutsideTheMatrix · Oct 5, 2016

I was wondering what is the longest shutter speed one can take pictures of the constellation Orion at without getting star trails at 14mm focal length (28mm equiv. 135)?

I was doing handheld shots at 2 sec without any trails and with the tripod I am using now I have been doing 8 sec. Is this the longest I should go to avoid trailing? I already like the results of the 8 sec more than the 2 sec because I see that star color is maintained on Betelgeuse all the way up to ISO 4000, the same as with 2 sec, except with the 8 sec exposures I capture a lot more stars. The only side effect is a much longer imaging session when you're taking 154 8 second shots over 154 2 second shots, especially since I have dark frame subtraction turned on all the time.

Rutgerbus · Oct 5, 2016

Just apply the "Rule of 500"

It is 500 divided by the effective focal length of your lens.

In your case (500/26mm)=19.2seconds.

You have to keep in mind that a wide-angle lens is more forgiving when it comes down to startrails then a telelens. (Most of the time I aply rule of 300/400 instead).

Good luck and happy starhunting

Rutgerbus · Oct 5, 2016

For your info....

It is better to set ISO to 1600-3200 (since that's were most today's cameras have their "sweet spot")

Next, turn off the in camera noise reduction/dark frame substraction (it takes too much time and can be easily corrected in software using a good set of 20 dark-frames)

Tristimulus · Oct 5, 2016

With digital the old film based 500 rule is more like 200.

The best way to avoid star trails is using a star tracker. Simple, easy, and opening up lots of new doors to the universe...

AustinMN · Oct 5, 2016

Trollmannx said:
With digital the old film based 500 rule is more like 200.

The best way to avoid star trails is using a star tracker. Simple, easy, and opening up lots of new doors to the universe...

I thought the 200 was based on crop sensor, not digital. Either way, I draw my personal line at 300 / focal length.

--
Warning: Comments may be Big Headed.
I sometimes post from the office. Company policy requires that I disclose my real name: Tom Cooper
I give out a lot more "Likes" than praise. If I praise one of your photos, consider it a rare event.

swimswithtrout · Oct 5, 2016

OutsideTheMatrix said:
I was wondering what is the longest shutter speed one can take pictures of the constellation Orion at without getting star trails at 14mm focal length (28mm equiv.

5-10 minutes +++++ !!!

Get a tracker !

The iOpteron SkyTracker is far cheaper than any lens you can buy. You're beating a dead horse trying to capture anything on a static tripod !! The $299.00 tracking mount will let you shoot forever below 100-135mm !! You can shoot up to 30" at 300mm !!!

Why do people keep buying these WA lenses expecting them to make things brighter/sharper ?? I'm not even going to bother explaining the light gathering math anymore, showing how terrible they are.

This is using my SkyTracker, from my horridly bright downtown backyard, and a Samyang 85mm lens, on a night so bright I couldn't even see the Pleiades with my naked eyes.

40 sec, ISO 400, F5. (x 180)

Rutgerbus · Oct 5, 2016

swimswithtrout said:
OutsideTheMatrix said:

I was wondering what is the longest shutter speed one can take pictures of the constellation Orion at without getting star trails at 14mm focal length (28mm equiv.

Click to expand...

5-10 minutes +++++ !!!

Get a tracker !

The iOpteron SkyTracker is far cheaper than any lens you can buy. You're beating a dead horse trying to capture anything on a static tripod !! The $299.00 tracking mount will let you shoot forever below 100-135mm !! You can shoot up to 30" at 300mm !!!

Why do people keep buying these WA lenses expecting them to make things brighter/sharper ?? I'm not even going to bother explaining the light gathering math anymore, showing how terrible they are.

This is using my SkyTracker, from my horridly bright downtown backyard, and a Samyang 85mm lens, on a night so bright I couldn't even see the Pleiades with my naked eyes.

40 sec, ISO 400, F5. (x 180)

Stunning picture and great captur of the Barnards Loop....how did you processed it? DSS, Fitswork, PI????

--
www.rutgerbus.nl
Photographic Moments
A photon only stops "existing" when it is captured by your sensor.

W5JCK · Oct 6, 2016

AustinMN said:
Trollmannx said:

With digital the old film based 500 rule is more like 200.

The best way to avoid star trails is using a star tracker. Simple, easy, and opening up lots of new doors to the universe...

Click to expand...

I thought the 200 was based on crop sensor, not digital. Either way, I draw my personal line at 300 / focal length.

OutsideTheMatrix · Oct 6, 2016

Rutgerbus said:
For your info....

It is better to set ISO to 1600-3200 (since that's were most today's cameras have their "sweet spot")

Next, turn off the in camera noise reduction/dark frame substraction (it takes too much time and can be easily corrected in software using a good set of 20 dark-frames)

--
www.rutgerbus.nl
Photographic Moments
A photon only stops "existing" when it is captured by your sensor.

Thanks for your help! One weird thing I've noticed is that no matter what ISO I use the background always becomes too bright around ISO 6400. I'm experimenting with longer shutter speeds- looks like 15 sec shutter speed is still pretty good.

My EFL is actually 28mm not 26mm so 15 sec should be around the maximum? My other question is to get pin point stars when viewing on a monitor, does the magnification need to be taken into account? I like viewing the stars at 1:1 on a 1280x1024 19" monitor, for this what should be the longest shutter speed I should use to get reasonably round stars? Thanks!

OutsideTheMatrix · Oct 6, 2016

W5JCK said:
AustinMN said:

Trollmannx said:

With digital the old film based 500 rule is more like 200.

The best way to avoid star trails is using a star tracker. Simple, easy, and opening up lots of new doors to the universe...

Click to expand...

I thought the 200 was based on crop sensor, not digital. Either way, I draw my personal line at 300 / focal length.

--
Warning: Comments may be Big Headed.
I sometimes post from the office. Company policy requires that I disclose my real name: Tom Cooper
I give out a lot more "Likes" than praise. If I praise one of your photos, consider it a rare event.

Click to expand...

The rules are merely guidelines or starting points. Try starting with the rule number you prefer (adjusted for your camera sensor). Take and view a sample image. Make shutter adjustments to taste.

The rules are based on sensor size. For the same FL of lens, the larger the sensor the more time the shutter can be open before star trails become noticeable. So if you want to use the "500 Rule" then it would break down approximately like this:

Full Frame: 500 / FL = shutter speed

APS-C (Sony & Nikon): 333 / FL = shutter speed

APS-C (Canon): 313 / FL = shutter speed

M4/3: 250 / FL = shutter speed

I personally prefer the 200 Rule because it allows for zooming to 100%. If you won't be zooming in or cropping the image then Rule 300 or even 400 might work well. So that would be:

Full Frame: 200 / FL = shutter speed

APS-C (Sony & Nikon): 133 / FL = shutter speed

APS-C (Canon): 125 / FL = shutter speed

M4/3: 100 / FL = shutter speed

Whatever rule number you decide to use, that number applies to full frame cameras. To adjust to other popular sensor sizes simply adjust the rule number (RN):

FF: RN

APS-C (Sony & Nikon): RN / 1.5

APS-C (Canon): RN / 1.6

M4/3: RN / 2

--
Jack Swinden
W5JCK, amateur radio operator
An astrophotography hobbyist and amateur radio instructor and examiner. Sony a7 and Sony a6000. https://www.flickr.com/photos/jackswinden/albums

Thanks Jack.

My other question is to get pin point stars when viewing on a monitor, does the magnification need to be taken into account? I like viewing the stars at 1:1 on a 1280x1024 19" monitor, for this what should be the longest shutter speed I should use to get reasonably round stars? Thanks!

Sounds like I should be using the 200 rule for 1:1 viewing on the monitor described above! That becomes 100/FL for M4/3? So that becomes 100/14- so it looks like the 8 sec exposures I am using are about right.

*Orion is near the Celestial Equator so would that 200 rule for 1:1 viewing still be applicable to it, Jack?

OutsideTheMatrix · Oct 6, 2016

swimswithtrout said:
OutsideTheMatrix said:

I was wondering what is the longest shutter speed one can take pictures of the constellation Orion at without getting star trails at 14mm focal length (28mm equiv.

Click to expand...

5-10 minutes +++++ !!!

Get a tracker !

The iOpteron SkyTracker is far cheaper than any lens you can buy. You're beating a dead horse trying to capture anything on a static tripod !! The $299.00 tracking mount will let you shoot forever below 100-135mm !! You can shoot up to 30" at 300mm !!!

Why do people keep buying these WA lenses expecting them to make things brighter/sharper ?? I'm not even going to bother explaining the light gathering math anymore, showing how terrible they are.

This is using my SkyTracker, from my horridly bright downtown backyard, and a Samyang 85mm lens, on a night so bright I couldn't even see the Pleiades with my naked eyes.

40 sec, ISO 400, F5. (x 180)

No, you're right, that's my next step. I was just trying to do things gradually. I already have a tracking mount for my telescope, but alas, it's an Alt Az computerized tracking mount. Although if I use this with a camera and lens combo rather than a telescope, I should be able to track longer than the 30 seconds it's good for using the telescope. I need to get a mounting bracket to mount the camera on it.

Don't you live in extremely light polluted skies (Mag 4)? That's extremely good, regardless of sky quality! No filters used? I can actually see some of the Pleaides (five or six of them) and four stars below the belt of Orion here.

OutsideTheMatrix · Oct 6, 2016

Trollmannx said:
With digital the old film based 500 rule is more like 200.

The best way to avoid star trails is using a star tracker. Simple, easy, and opening up lots of new doors to the universe...

I was just trying to do things gradually. I already have a tracking mount for my telescope, but alas, it's an Alt Az computerized tracking mount. Although if I use this with a camera and lens combo rather than a telescope, I should be able to track longer than the 30 seconds it's good for using the telescope. I need to get a mounting bracket to mount the camera on it. You're right though and looking around camera tracking mounts are cheaper than a lens I was considering getting! Question.....do I need to power them with batteries or AC power or what? My computerized mount needs 8xAA batteries or AC power.

swimswithtrout · Oct 6, 2016

OutsideTheMatrix said:
swimswithtrout said:

Click to expand...

Don't you live in extremely light polluted skies (Mag 4)? That's extremely good, regardless of sky quality! No filters used? I can actually see some of the Pleaides (five or six of them) and four stars below the belt of Orion here.

Ummmmmmmm...... The Pleiades are no where near this frame . This is an 85mm lens and barely fits in M42, Orions Belt/ Horsehead nebula, and Barnards Loop. Time to go back to Star/Constellation ID 101.

This is the Pleiades, with Comet Lovejoy, using my old D7100 and 135mm lens on the litttle iOptron SkyTracker, and then with my big 8". Tracking is your friend.

OutsideTheMatrix · Oct 6, 2016

swimswithtrout said:
OutsideTheMatrix said:

Don't you live in extremely light polluted skies (Mag 4)? That's extremely good, regardless of sky quality! No filters used? I can actually see some of the Pleaides (five or six of them) and four stars below the belt of Orion here.

Click to expand...

Ummmmmmmm...... The Pleiades are no where near this frame . This is an 85mm lens and barely fits in M42, Orions Belt/ Horsehead nebula, and Barnards Loop. Time to go back to Star/Constellation ID 101.

This is the Pleiades, with Comet Lovejoy, using my old D7100 and 135mm lens on the litttle iOptron SkyTracker, and then with my big 8". Tracking is your friend.

Lol you need a lesson in Humility 101 and perhaps a bit of reading comprehension skills ;-) I'm pretty good with constellations and astronomy in general (since that is my primary interest, not photography) especially since I already knew all the constellations when I was 9 years old and knew all about the H-R diagram and the way stars get classified, quasars, black holes, neutron stars, all that sort of thing.

What I said was I can "see..................HERE" meaning from my location, NOT in your image. I was commenting on the level of light pollution here late at night. Before midnight it's MUCH worse. I wouldn't be impressed if I could see them in your image, because any old camera can do that.

jrsm · Oct 6, 2016

Going back to your original request regarding exposure time. 25 seconds with a 14mm lens is too long. You will get trails. The 500 rule does not work with digital cameras. A 300 or 200 rule is more satisfactory. I would suggest a minimum 15 seconds or less. While a tracker is useful, if you don't have one, then you need short exposures and then stack them. I am not sure what ISO you are using , but you can get away with 3200 and use darks and bias frames and then stack your images (raw files) in a program like deep sky stacker and then an editor like photoshop. It is a lot of images but if you take hundreds, they add up. Look at some you tube videos on astrophotography without a tracker.

If you are in a severely light polluted area you may not be able to use an exposure longer than 15 seconds because of the skyfog. M42 is quite bright so your may have better results with this object than more faint ones.

OutsideTheMatrix · Oct 6, 2016

jrsm said:
Going back to your original request regarding exposure time. 25 seconds with a 14mm lens is too long. You will get trails. The 500 rule does not work with digital cameras. A 300 or 200 rule is more satisfactory. I would suggest a minimum 15 seconds or less. While a tracker is useful, if you don't have one, then you need short exposures and then stack them. I am not sure what ISO you are using , but you can get away with 3200 and use darks and bias frames and then stack your images (raw files) in a program like deep sky stacker and then an editor like photoshop. It is a lot of images but if you take hundreds, they add up. Look at some you tube videos on astrophotography without a tracker.

If you are in a severely light polluted area you may not be able to use an exposure longer than 15 seconds because of the skyfog. M42 is quite bright so your may have better results with this object than more faint ones.

The longest I tried so far was 15 sec but based on what Jack said about 1:1 viewing, I think I should limit myself to 8 sec for now. You are quite right that longer than 15 sec, and sky fog starts to drown out the signal. What's particularly interesting is that high ISO seems to be more vulnerable to sky fog than longer shutter speeds are- for example, I can shoot up to ISO 3200 at any shutter speed, but when I go over that number, regardless of the shutter speed (I tested 2, 4, 8 and 15 sec) the sky starts to change color. I wonder why that is?

I also noticed that higher than ISO 1600 makes star colors fade so I've been sticking to ISO 800 and 1600 for now. Interestingly enough, increasing the shutter speed does not have this effect (up to the 15 sec I tried anyway.)

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How to avoid star trails with Orion?

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