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Post by Sepiana on Dec 11, 2020 21:52:19 GMT
Looking forward to the conjunction of Jupiter and Saturn last night I took 7 photos of them. Looking at the photos in camera I thought they were all out of focus. Why did this happen? Why did they look out of focus when I looked at them in camera? |
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Post by Sepiana on Dec 11, 2020 21:54:53 GMT
How are you focusing ? Manual, back-button, or half-press the shutter ? |
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Post by Inspeqtor on Dec 11, 2020 22:52:49 GMT
Buckskin,
When focusing at Jupiter and Saturn being 2 tiny dots in the sky the only way I know of to focus on these is to MANUALLY focus on the dots. I look at the size of the dots for when they look the tiniest in size but also the brightest in light I think would be the best way to describe how I do it when the rest of the screen is totally black.
Maybe you have a better way of describing what I try and do.
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Post by BuckSkin on Dec 11, 2020 23:39:14 GMT
I am far from qualified to even comment, so take this for what it is worth.
My understanding is focus is purely a distance thing; and, once something exceeds a certain distance from the camera, everything from that point out is "infinity"
By all means don't depend on this for all of your shots until you have tested it out; but, the next time you are shooting at such distant objects, put the focus adjustment on "infinity" for a few shots and compare them to the others for sharpness.
I long depth of field = large "F-" number = will help as well; try a few using the smallest aperture/biggest F-number focused at infinity and see if that possibly helps.
Don't waste too much expensive film on my advice before testing it out.
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Post by pontiac1940 on Dec 12, 2020 0:00:30 GMT
the only way I know of to focus on these is to MANUALLY focus on the dots. I look at the size of the dots for when they look the tiniest in size but also the brightest in light That sounds about right. I presume you camera does not have focus peaking or focus magnification. These are a boon for astro photography. You can Google "focus peaking" .. here. Focus magnification blows up the scene and when used with peaking gives precise focus. One other thing when you took the Jupiter/Saturn photos what was your shutter speed? 20 seconds is about tops even with a wide angle. It depends on focal length and you should look up "The 500 Rule." The planets are moving fast enough (because of the earth's rotation) that long exposures will blur the stars and planets, especially when using a telephoto lens like for the planets. Also, are you using the self timer? I don't use a cable/shutter release (although have a good electronic one) and so set my camera in 2 or 5-second timer so the camera is steady by the time the shutter opens. Good luck! Clive See here. |
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Post by Inspeqtor on Dec 12, 2020 6:19:39 GMT
I am far from qualified to even comment, so take this for what it is worth. My understanding is focus is purely a distance thing; and, once something exceeds a certain distance from the camera, everything from that point out is "infinity" By all means don't depend on this for all of your shots until you have tested it out; but, the next time you are shooting at such distant objects, put the focus adjustment on "infinity" for a few shots and compare them to the others for sharpness. I long depth of field = large "F-" number = will help as well; try a few using the smallest aperture/biggest F-number focused at infinity and see if that possibly helps. Don't waste too much expensive film on my advice before testing it out. Hi Buckskin, Really I am also no expert in taking pictures, there are many pictures I have taken that are out of focus, too bright, too dark because I have not checked all the settings to see what setting I used the last time on my camera. I have found over the years I can't preset any camera LENS from the past or in current use to infinity and get a sharp picture from anything that is far away, even the moon. If I do set it to infinity it will be out of focus. There is a fine line of just where that infinity position is on any lens. Clive, you seem to be an active photographer, do you agree with me on this? If you do not agree then tell me I am wrong. It has been a long time since I have tested this out by turning the lens all the way to the infinity mark to a full stop on the ring to see if anything that far away will be crystal clear in tack sharp focus. Now that Buckskin has asked about this I want to try it next time I see the moon outside. It is raining here now! |
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Post by pontiac1940 on Dec 12, 2020 6:56:36 GMT
"turning the lens all the way to the infinity " Infinity has never worked for me on any lens camera combination when shooting the moon or stars. The true focus is always just a tad back from infinity. I hope to practice on Jupiter soon..before Dec 21. Interesting stuff this. Clive EDIT improvephotography.com/48584/find-focus-night-simple-step-step-guide/That is essentially what infinity focus of a lens is, where very far subjects are sharp. Finding infinity focus is a little different on each lens. Some lenses have a focus scale and even an infinity symbol (∞). The problem is that the focus rings on most modern lenses don't stop turning when they reach the infinity mark. Furthermore, infinity focus is often not actually right on the infinity symbol, but is rather somewhere just before reaching that mark on the lens. |
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Post by Inspeqtor on Dec 12, 2020 7:07:51 GMT
That sounds about right. I presume you camera does not have focus peaking or focus magnification. These are a boon for astro photography. You can Google "focus peaking" .. here. Focus magnification blows up the scene and when used with peaking gives precise focus. One other thing when you took the Jupiter/Saturn photos what was your shutter speed? 20 seconds is about tops even with a wide angle. It depends on focal length and you should look up "The 500 Rule." The planets are moving fast enough (because of the earth's rotation) that long exposures will blur the stars and planets, especially when using a telephoto lens like for the planets. Also, are you using the self timer? I don't use a cable/shutter release (although have a good electronic one) and so set my camera in 2 or 5-second timer so the camera is steady by the time the shutter opens. Good luck! Clive See here.Hi Clive, Yes my Canon 90D DOES have focus peaking, and I sometimes use it when shooting the moon. Sometimes shooting the moon if it is full enough it is just as easy to use automatic focusing. Shooting Jupiter or Saturn, those planets are so dang tiny there is not enough surface for focus peaking to work on. I do not see how shooting stars in astronomy could ever be in focus at all trying to use focus peaking. Shooting the moon when it is 1/4 or more full I shoot the moon like I would shoot anything here on earth because I am shooting daylight on the moon. If I am shooting with my telephoto lens at 600mm then the shutter speed I use is typically around 1/640 Also when shooting the moon or planets I have the OS (Canon IS) on my Sigma lenses turned off, AND I also always use my Canon RS-60E3 Remote Switch so there is no camera shake or movement from me touching the camera body when shooting pictures. I have never tried shooting the moon or planets at 20 seconds! That seems to me like there would be planetary movement from the earth's rotation and the image would be blurry! My settings for when I shot Jupiter and Saturn was this: 1/640 at f/6.3 ISO at 8000 and focal length at 600mm. What would you have used? Teach me something different to try if you think I should have done that. If I put on my 2.0 Teleconverter then my f/stop changes to f/13 when shooting the moon at 1200mm I had never heard of the 500 Rule. I learned that is for a Full Frame. The 90D is a 1.6 factor camera so do I then use 800 or 312.5? Thank you Clive! |
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Post by pontiac1940 on Dec 12, 2020 7:10:57 GMT
Hi again...
Will reply in the morning.
Clive
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Post by Inspeqtor on Dec 12, 2020 7:12:51 GMT
"turning the lens all the way to the infinity " Infinity has never worked for me on any lens camera combination when shooting the moon or stars. The true focus is always just a tad back from infinity. I hope to practice on Jupiter soon..before Dec 21. Interesting stuff this. Clive EDIT improvephotography.com/48584/find-focus-night-simple-step-step-guide/That is essentially what infinity focus of a lens is, where very far subjects are sharp. Finding infinity focus is a little different on each lens. Some lenses have a focus scale and even an infinity symbol (∞). The problem is that the focus rings on most modern lenses don't stop turning when they reach the infinity mark. Furthermore, infinity focus is often not actually right on the infinity symbol, but is rather somewhere just before reaching that mark on the lens.Yes I totally agree with you Clive!! |
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Post by Inspeqtor on Dec 12, 2020 7:13:29 GMT
Hi again... Will reply in the morning. Clive No problem. It is my bedtime also!! |
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Post by pontiac1940 on Dec 12, 2020 17:28:51 GMT
those planets are so dang tiny there is not enough surface for focus peaking to work on. I do not see how shooting stars in astronomy could ever be in focus at all trying to use focus peaking. So your Canon does not have focus magnification then? When my Sony A7III is set to MF, when the focus ring is moved it instantly blows up the image (which can be an issue handholding a 600-mm lens...too shaky) and then focusing on stars is a snap. Don't get me wrong, I still mess up focus on occasion. Your shutter speeds are fast that motion blur (earth's rotation) is not an issue. Back to your original question, "Looking at the photos in camera I thought they were all out of focus." What were the conditions? I tried to photograph Jupiter and Saturn 2 weeks ago and they were low to the horizon and my photos were not in focus. I shot on the back deck and suspect that it was low level atmospheric distortion and/or heat waves either as I was in town with houses just below the planets or even heat from the nearby city that was also below the planets. When focusing is critical (i.e. planets/stars) and you are using a long lens, and the planets are low to the horizon, the slightest low-level atmospheric interference can affect focus. "I have never tried shooting the moon or planets at 20 seconds!" Most certainly not the moon which is very bright. I use 2- to 10-second exposures using a wide-angle lens for the Milky Way for example. |
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Post by pontiac1940 on Dec 12, 2020 17:57:41 GMT
Inspeqtor Charles, One more thing regarding focus ... The Canon 90D has an APS-C sensor and shooting at ISO 8,000 might result in soft, noisy objects and this would show up on tiny objects vs (say) a tree or building. In addition, the planets and black sky are highly contrasted which probably exacerbates the noise issue. Drop your shutter speed much lower and reduce the ISO to 1,000 if you can. Might help. Worth a try. Clive
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Post by Inspeqtor on Dec 12, 2020 19:26:50 GMT
So your Canon does not have focus magnification then? When my Sony A7III is set to MF, when the focus ring is moved it instantly blows up the image (which can be an issue handholding a 600-mm lens...too shaky) and then focusing on stars is a snap. Don't get me wrong, I still mess up focus on occasion. Your shutter speeds are fast that motion blur (earth's rotation) is not an issue. Back to your original question, "Looking at the photos in camera I thought they were all out of focus." What were the conditions? I tried to photograph Jupiter and Saturn 2 weeks ago and they were low to the horizon and my photos were not in focus. I shot on the back deck and suspect that it was low level atmospheric distortion and/or heat waves either as I was in town with houses just below the planets or even heat from the nearby city that was also below the planets. When focusing is critical (i.e. planets/stars) and you are using a long lens, and the planets are low to the horizon, the slightest low-level atmospheric interference can affect focus. "I have never tried shooting the moon or planets at 20 seconds!" Most certainly not the moon which is very bright. I use 2- to 10-second exposures using a wide-angle lens for the Milky Way for example. I can with the push of a button go to 5X or 10X zoom on the LCD screen. |
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Post by Inspeqtor on Dec 13, 2020 1:53:20 GMT
I can with the push of a button go to 5X or 10X zoom on the LCD screen. From what I remember trying, when in the 5X or 10X magnification I do not remember being able to focus using focus peaking at all. I wish The moon was out tonight and wish we did not have any clouds tonight for me to verify this thought. |
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