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Low light/night problems with new Canon 6D
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May 31, 2017 11:57:45   #
jeep_daddy Loc: Prescott AZ
 
A good starting place for Milky Way photography is:
ISO 1600-3200,
a shutter speed of 15-20 seconds,
and the lowest (most wide open) aperture that your camera allows.
As with most astrophotography, a good wide angle lens is a must for Milky Way photography. You’ll also want to employ your camera’s noise reduction function to compensate for the high ISO.

An f/2.8 lens works best.

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May 31, 2017 12:13:20   #
SS319
 
One method to achieve focus on stars is to start with an opaque filter and drill three very small holes equidistant from each other and about 1/2 way between the edge and center of the lens. Now, point at Sirus or Vega or another really bright star, and focus to single dots. lock your focus and use for the whole sky

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May 31, 2017 12:23:28   #
bobwalder
 
JimH123 wrote:
This is the problem then. You cannot treat stars like terrestrial objects where everything within a range appears to be in focus. Stars require EXACT focus, or they go away. This is what you need to practice on. Not all cameras are equal when it comes to focusing on stars. I shoot Sony and Olympus and they are rather easy to get good star focus. But I have known Canon shooters that really struggled to see the dimmer stars for focus.

Start with a longer FL lens and practice your focus so you can see the stars. Even a 50mm will allow you to go for a few seconds without star trails, but the stars will be easier to see. But master that focusing, and then repeat, and you will have better success.

And one more thought. Some lenses don't actually go all the way to infinity. In the case of a wide angle lens, this is not likely to impact terrestrial images. But for stars, it can be a disaster, since they will not tolerate the slight focus error. You will need live view, focus magnifier at max, and a wide open aperture to check it out.

Also, wide angle lenses do not gather much light. A 20mm lens at f2.8 captures light with a 7.14mm objective. A 20mm lens at f4 is only a 5mm objective. This means that it captures 1/2 as much light. Now you lens is 11-14mm at f4. When at 11mm, the objective is 2.75mm. This is about 1/7 the amount of light as the 20mm f2.8. And this is also part of the problem of using wide angle lenses. I have done some panoramas using a longer lens and creating a wide angle effect and it works well considering how much additional light it gives you to work with. For example, a 50mm f1.4 uses an apterture of 35.7mm. Compared to the 11mm f4, it is gathering 169 times as much light! Plus, it is easier to focus.
This is the problem then. You cannot treat stars ... (show quote)


Now THAT is REALLY interesting.... and that might explain a lot given that he was using something like a 16mm or 20mm at f2.8, and I was using an 11mm at f4

Just to put the focus issue to bed - I was very happy with focus on the final images....

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May 31, 2017 13:05:42   #
JimH123 Loc: Morgan Hill, CA
 
jeep_daddy wrote:
A good starting place for Milky Way photography is:
ISO 1600-3200,
a shutter speed of 15-20 seconds,
and the lowest (most wide open) aperture that your camera allows.
As with most astrophotography, a good wide angle lens is a must for Milky Way photography. You’ll also want to employ your camera’s noise reduction function to compensate for the high ISO.

An f/2.8 lens works best.


Be sure to test 1600 vs 3200 since 3200 on one camera may look acceptable and on another camera, not acceptable at all. I have done some 1600 vs 3200 vs 6400 ISO tests and when done, I liked the 1600 ISO more than the others.

You can easily find out what shutter speed to use with a few test shots to see how much star trails you are will to accept.

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May 31, 2017 14:05:29   #
mwsilvers Loc: Central New Jersey
 
bobwalder wrote:
Just purchased a 6D so getting to know it. I took it to Big Bend to photograph the Milky Way last week and though I got some nice results I struggled with the camera. Lens was the f4 11-24mm zoom.

I was shooting alongside 2 Nikon owners and a Canon 5D MkIII owner. The Canon owner, being experienced at night photography, was helping me with exposures. He said the sensor on the 6D should get better low light results than even his.

Here's the issue.... everyone else was shooting at ISO 3200, f2.8 for around 20 seconds. I bumped up to ISO 6400 to make up for the extra stop (f4) but ended up with exposures of 45-50 seconds just to get results comparable to the others. When they tried light painting, they were getting some amazing results (brief 1 second flashed from LED lamps on the foreground) but my camera picked up virtually none of it.

So on the face of it, my sensor was WAY less sensitive than any of theirs. I had long xposure low noise reduction set to Auto, by the way... only on certain shots did I get the long delay as it wrote to memory card so clearly it was being used occasionally... there was no discernible difference to the exposures or results so I doubt that setting was the culprit.

So..... any ideas? Faulty camera? Faulty lens? Settings I need to look at? Or is the 6D just really bad at night photography (not something's no I would have expected based on reviews)?

Would really appreciate some help, especially from other Canon owners. REALLY not looking for "switch to Nikon" type advice, thanks :0) I need to decide quickly if I need to return camera, lens or both, or if I can fix this via camera settings

Thanks in advance
Just purchased a 6D so getting to know it. I took... (show quote)

Was everything else the same? Same mode? Same metering? What lenses were they using, especially the Canon guy. One possible culprit is light transmission. According to DXOMark, even though your lens's maximum aperure is f/4, it has a maximum tStop of 4.5! Additionally, comparing results between differently designed lenses, especially with different focal ranges, in real world conditions is difficult at best. If you could go back out with the Canon guy, as was suggested and shoot again, and then swap lenses, I think you'll find there is absolutely nothing wrong with your equipment.

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May 31, 2017 14:15:04   #
JimH123 Loc: Morgan Hill, CA
 
mwsilvers wrote:
Was everything else the same? Same mode? Same metering? What lenses were they using, especially the Canon guy. One possible culprit is light transmission. According to DXOMark, even though your lens's maximum aperure is f/4, it has a maximum tStop of 4.5! Additionally, comparing results between differently designed lenses, especially with different focal ranges, in real world conditions is difficult at best. If you could go back out with the Canon guy, as was suggested and shoot again, and then swap lenses, I think you'll find there is absolutely nothing wrong with your equipment.
Was everything else the same? Same mode? Same mete... (show quote)


Stars are point sources of light, and the f-stop value has less impact on the brightness of a star than does the area of the aperture. A 11mm at f4 has an aperture of 2.75mm. A 20mm at f4 has an aperture of 5mm. Same f-stop value, but larger aperture on the 20mm, and the stars will be brighter. This why telescopes keep being made larger and larger. If you compare the areas, you can compute the difference.

In the case of a terrestrial view, the f4 on both lens will create an image of similar brightness.

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May 31, 2017 14:22:57   #
bobwalder
 
JimH123 wrote:
Stars are point sources of light, and the f-stop value has less impact on the brightness of a star than does the area of the aperture. A 11mm at f4 has an aperture of 2.75mm. A 20mm at f4 has an aperture of 5mm. Same f-stop value, but larger aperture on the 20mm, and the stars will be brighter. This why telescopes keep being made larger and larger. If you compare the areas, you can compute the difference.

In the case of a terrestrial view, the f4 on both lens will create an image of similar brightness.
Stars are point sources of light, and the f-stop v... (show quote)


Again... I think this is the salient point here... and something that I simply did not understand until now. Thank you for this, Jim!!!

I will, of course, still go out and do the comparison testing!!! LOL

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Jun 1, 2017 03:09:28   #
JimH123 Loc: Morgan Hill, CA
 
bobwalder wrote:
Again... I think this is the salient point here... and something that I simply did not understand until now. Thank you for this, Jim!!!

I will, of course, still go out and do the comparison testing!!! LOL


I am adding a picture I took tonight using a 14mm f2.8 Rokinon lens on an Olympus EM5ii. This is a 2.0x crop type camera, so this is effectively the same FOV as a 28mm on a Full Frame. It is too early in the season for the Milky Way as that will be overhead in a couple more months. And at this focal length, not much to see in the way of galaxies. And no nebula either. But there are certainly stars to capture. I used a 4 sec shutter speed, ISO 1250 and f2.8. Also stacked 35 images, plus 10 darks to detect and remove stuck pixels. Since the dimmer stars tend to twinkle, the act of stacking tends to make them more distinct.

One thought on this: I started tonight with the Olympus 14-40 f2.8 pro lens. It is certainly sharp enough to do stars. But it uses focus by wire. My experience with focus by wire when doing stars is that it is absolutely frustrating. After not achieving good focus, decided to switch to the Rokinon 14mm f2.8 lens which is 100% manual, and suddenly focus was so easy to do. I was using Olympus Capture using a USB interface and the live view of the camera was then displayed on my laptop. Magnified 10x and then adjusted focus. A bright star first reached the smallest size. And then some faint stars started to appear and adjusted them for max brightness.

Then I started a time lapse and had it shoot a 4 sec image once every 10 sec. After 35 images, decided I had enough and then captured 10 dark frames (same shutter time and ISO), and put the lens cap on the lens. Stuck pixels are caught by this process.

After stacking with DSS, the image needs to be stretched to increase the brightness of the stars and to darken the sky using Photoshop. Once done in Photoshop, sent to Lightroom where contrast is increased, and noise removed.

Anyway, this should give you an idea of what can be captured and give you something to shoot for.


(Download)

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Jun 1, 2017 07:25:51   #
mjmoore17 Loc: Philadelphia, PA area
 
I have found the Canon 6D to be a very good camera for the use that you described. Here is an example of Milky Way with 6D and a Canon 2.8 lens.


(Download)

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Jun 1, 2017 09:33:52   #
RRS Loc: Not sure
 
bobwalder wrote:
Thanks. I do think that he had his viewfinder turned up brighter than mine for sure, but final results on computer monitor were also strikingly different. With 11mm focal length 40-45 secs is acceptable without seeing trails. I did try bumping ISO even higher to get same 20 sec exposure they were using, BUT even by doubling ISO again I was still looking at closer to 25-30 seconds for equivalent results compared to their 20 secs.... truly weird....

Note that the situation you just quote - 1600ISO, under 30 seconds, f2.8 - is pretty much what I was seeing from the others. What I did was double the ISO to 3200 in an attempt to use same 20 sec exposure at f4.... didn't work... had to increase to 45 secs... so I was exposing for double the time as the others.

Need to check that lens is not stuck at f5.6... or camera/lens communications are broken somehow...
Thanks. I do think that he had his viewfinder turn... (show quote)


When you look at the info for your shots wouldn't the exposure value show if you were in fact at F/4.0 or f/5.6 ?

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Jun 1, 2017 09:36:00   #
amfoto1 Loc: San Jose, Calif. USA
 
bobwalder wrote:
Just purchased a 6D so getting to know it. I took it to Big Bend to photograph the Milky Way last week and though I got some nice results I struggled with the camera. Lens was the f4 11-24mm zoom.

I was shooting alongside 2 Nikon owners and a Canon 5D MkIII owner. The Canon owner, being experienced at night photography, was helping me with exposures. He said the sensor on the 6D should get better low light results than even his.

Here's the issue.... everyone else was shooting at ISO 3200, f2.8 for around 20 seconds. I bumped up to ISO 6400 to make up for the extra stop (f4) but ended up with exposures of 45-50 seconds just to get results comparable to the others. When they tried light painting, they were getting some amazing results (brief 1 second flashed from LED lamps on the foreground) but my camera picked up virtually none of it.

So on the face of it, my sensor was WAY less sensitive than any of theirs. I had long xposure low noise reduction set to Auto, by the way... only on certain shots did I get the long delay as it wrote to memory card so clearly it was being used occasionally... there was no discernible difference to the exposures or results so I doubt that setting was the culprit.

So..... any ideas? Faulty camera? Faulty lens? Settings I need to look at? Or is the 6D just really bad at night photography (not something's no I would have expected based on reviews)?

Would really appreciate some help, especially from other Canon owners. REALLY not looking for "switch to Nikon" type advice, thanks :0) I need to decide quickly if I need to return camera, lens or both, or if I can fix this via camera settings

Thanks in advance
Just purchased a 6D so getting to know it. I took... (show quote)


I'd guess that 98 out of 100 "camera problems" are no fault at all of the camera or lens... but are due to the user doing something wrong.

If you could post them, it would be very helpful to see one or more of the "faulty" images with EXIF still attached.

You mention 20 second exposures and that should always cause Long Exposure Noise Reduction to operate when it's set to "Auto" (or "Enabled"). Set to that, LENR should activate with any exposure of 1 second or longer.

Are you aware how LENR works? It's actually two "exposures" of the same length, one right after the other. The first is the "usual" exposure where the shutter opens and an image is recorded. The second that immediately follows is a "blank" that the camera does with the shutter closed, which it then uses to detect noise, which is then "subtracted" from the first image. So a 20 second exposure will take at least 40 seconds, for example. any exposure with LENR applied will take twice as long as it's setting on the camera.

That explains why your "exposures" were taking so much longer than the other people... they probably didn't have LENR enabled.(I would probably turn it off for star field shots, too.... but you should ask them.)

Here's the tricky part... If you forget what's happening and cancel the second "shutter closed" exposure for any reason (such as by turning off the camera), the camera will dispose of BOTH the LENR and the original image!

If you try to "light paint" during the LENR "blank" shot with the shutter closed, your efforts won't be recorded.

Generally speaking, the 6D is a very low noise/high ISO capable camera. One of the best. Should have been able to shoot without LENR, at at 6400.You might give it a try.

The main reason many night shooters use f/2.8 lenses is not necessarily that they use the lens wide open... In fact they may stop the lens down to an optimal f-stop for best edge-to-edge sharpness with the particular lens they're using. (You should test your lens to see what it's optimal f-stop is.)

Many users might choose an f/2.8 (or faster) lens for a brighter viewfinder. But with DSLRs, Live View and Exposure Simulation might be a good substitute.

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Jun 1, 2017 09:39:55   #
Ny5y Loc: Mississippi
 
Also your length of exposure is 500 divided by the length of the lens, you probably know this. The f2.8 lens makes a big difference too!

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Jun 1, 2017 10:05:45   #
catchlight.. Loc: Wisconsin USA- Halden Norway
 
$3000.00 lens...

Consider more hands on practice before you jump to conclusions. Learn the craft and learn how to use your equipment. The 11-24 f/4L is an unbelievably sharp and excellent choice.

Hand it over to one of your canon friends and see what happens and also spend some time on tutorials.

...and cap the viewfinder.

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Jun 1, 2017 11:17:59   #
lowkick Loc: Connecticut
 
You didn't say what the focal length of the lenses the other shooters were using. If they were longer lenses than yours it will make a difference. The more powerful the magnification, the stronger the light from the stars will be hitting the sensor. Keep in mind that your f/4 lens is a full stop smaller opening than their f/2.8 (meaning it lets in 1/2 the amount of light at any given shutter speed). So, between a smaller aperture and lower magnification, you will have quite different results from the others.

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Jun 1, 2017 12:08:20   #
JimH123 Loc: Morgan Hill, CA
 
lowkick wrote:
You didn't say what the focal length of the lenses the other shooters were using. If they were longer lenses than yours it will make a difference. The more powerful the magnification, the stronger the light from the stars will be hitting the sensor. Keep in mind that your f/4 lens is a full stop smaller opening than their f/2.8 (meaning it lets in 1/2 the amount of light at any given shutter speed). So, between a smaller aperture and lower magnification, you will have quite different results from the others.
You didn't say what the focal length of the lenses... (show quote)


True for terrestrial objects. Not exactly true for stars, which are point sources of light. The main determining factor for stars is aperture size, as explained earlier. A 20mm f4 lens has an aperture on 5mm, or an area of PIxR^2 = 19.625mm^2.
A 11mm f4 lens has an aperture of 2.75mm, or an area of 5.94mm^2. It is this difference in area that determines how much light is gathered. In this case, 3.3x more light for the 20mm lens.

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