flying above
New member
A very good older lens is the Nikon 70-210 mm f/4-5.6.
Check out Ken Rockwell's review.
Check out Ken Rockwell's review.
Help understanding shutter speed/F stop
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flying above
New member
A very good but older lens is the Nikon 70-210 mm f/4-5.6.
Probably can find used one pretty cheap. Check out en Rockwell's review @ Nikon 70-210mm f/4-5.6 Review
Probably can find used one pretty cheap. Check out en Rockwell's review @ Nikon 70-210mm f/4-5.6 Review
I personally would pass on that lens...
Go for the 70-210 F4 great lens for general photography/portraits. Not expensive at all, however you are dealing with an older lens, so no VR. But it is my lens of choice next to my 70-200 2.8. Not everyone needs a 2.8 lens, so the F4 do make sense.
I had a push-pull version of that lens for a few weeks. (Technically, I still have it, but it's being held together by a rubber band. It came apart on me!) The image quality was better than my Nikon 55-200 f/4-5.6, but not by a lot.
hi grandpaw, thanks for the info, that does sound a good start for me to try, i think i have been thinking about too much and get frustrated with all the info etc, i will make a note of your comments and try it out, what do you do with ISO settings, do you leave on 100 all the time or adjust at any particular scene etc, cheers and thanks everyone for the comments, much appreciated.
I try and keep the ISO as low as I can but I do raise it up as needed to keep the settings working for what I need to make the F stop and shutter work like I need. As you get comfortable doing this you can begin refining the settings you choose.
Last edited:
Bob Blaylock
Senior Member
To add my own attempt to help someone make sense of all this.
A term that I only ever recently heard was “exposure triangle”, referring to the three parameters that set the overall exposure level in a camera—Shutter speed, lens aperture size, and film/sensor sensitivity. For a given amount of illumination of the scene being photographed, there are any number of combinations among these parameters, that will produce the same exposure level. If you adjust one in a way that increases or decreases the exposure level, then you can adjust another to bring the exposure back to the same level.
It's probably useful, at this point, to mention the term “stop”. A change of one stop represents a change in exposure level by a factor of two. If you go from a shutter speed if 1/100 of a second to 1/200 of a second, then you reduce the exposure by one stop. From 1/100′ to 1/400′ reduces exposure by two stops.
The relationship between shutter speed and total exposure value is obvious. If the shutter is open half as long, it lets half as much light through. If it's open twice as long, it lets twice as much light through.
Sensor/film sensitivity is also fairly obvious. Double the ISO rating, you double the sensitivity, with the same result as doubling the total amount of light, doubling the exposure. Halve the ISO rating, you have half the sensitivity, half the exposure.
The lens' ƒ/ value is somewhat less obvious. If you look at the aperture ring of a lens that has one, you'll surely notice that every mark has a number that differs, not from the adjacent marks, but from the marks that are two marks away from it on either side, by a factor of two. This can be somewhat misleading. The numbers here are inversely proportional to the diameter of the aperture opening. What it literally represents is the ratio of the focal length to the aperture diameter. But what affects exposure is not the diameter, but the area of the aperture opening, which is proportional to the diameter squared. So if you double the diameter of the aperture, you actually increase the exposure by a factor of four, or two stops. The adjacent ticks represent increments of one stop, or of a doubling or halving of the exposure. A setting of ƒ/4 lets twice as much light in as ƒ/5.6, and four times as much as ƒ/8.
If you come from a point of view of wanting everything in the picture to be as sharp and as technically-perfect in every way, then you have to recognize that every one of the three parameters of the exposure triangle involves some sacrifice.
Shutter speed is the most obvious. If there is anything moving in the scene, then a slower shutter speed, to let more light in, will result in moving things being more blurred. A faster shutter speed will result in less motion blur, but it also lets in less light, which means you need to change one of the other parameters in order to compensate.
The aperture setting affects depth of field. A smaller aperture setting gets you more depth of field allowing more to stay in focus closer or farther from the point at which the lens is actually focussed, but it lets less light in, so you have to change one of the other parameters to compensate. A wider aperture lets in more light, but gives you less depth of field. In the above image of my lens, do you see those color-coded marks to each side of the main focus mark? Those are coded to the aperture setting numbers, and give an indication of the depth of field. As this lens is currently set, it is focussed at ten feet, with the aperture set to ƒ/11. The yellow marks, coded to match the yellow number 11 on the aperture ring, indicate that at this setting, everything from about 7 feet to about 15 feet can be expected to be in focus.* You can see that the blue marks, matching ƒ/16, are farther apart, indicating that depth of field would be even greater at that aperture setting, while the red and green marks, coded to match ƒ/8 and ƒ/4 respectively, show how the depth of field shrinks at those settings.
See my threads at http://nikonites.com/education/25599-aperture-depth_of_field-relationship-nikkor-s-50mm-f1-4-a.html and http://nikonites.com/education/2552...tionship-vivitar-85-205mm-f3-8-tele-zoom.html for some demonstrations of the relationship between ƒ stopsand depth of field.
The remaining parameter is sensor/film sensitivity, or “speed”. With film, it has always been the case that a higher “speed” (more sensitive) film tended to be grainier, while a “slower” (less sensitive) film would have finer grain. This has a basis in physics. When there are fewer photons hitting the film, it takes bigger grains of chemical material to maintain a good chance of catching them. With digital sensors, pushing them to higher sensitivity introduces more “noise”, which isn't exactly the same effect as the coarser grain of a high-speed film, but it's easy to see them as having similar effect on the sharpness and quality of the image.
Now, all that said, you don't always want the most technically-perfect picture, with everything as sharp as possible.
For example, sometimes you want a bit of motion blur, to emphasize that an object is moving. So, you can use a slower shutter speed to get that blur, and in the deal, you get to tighten up the aperture for better depth of field and film/sensor speed for less grain/noise.
If there's a distracting background, then you may want to open up the aperture, reducing the depth of field, in order to throw that background out of focus; and in the deal, you get to tighten up on the shutter speed and film/sensor sensitivity. In fact, there's a whole branch of artistic theory about the use of out-of-focus components in a picture. Look up the term, “bokeh”.
And for some applications, in film-based photography, coarser grain is often desired for artistic purposes, to give the picture a more “vintage” look. Alas, this doesn't really translate well to digital photography. Digital sensor noise just never is able to look as good as coarse film grain sometimes can.
One more thing, concerning the use of words like “speed” and “fast”. As applied to the shutter, the terms are pretty obvious. A “faster” shutter speed means that the shutter is open for a shorter time, while a “slower” shutter speed means that it stays open longer.
These and related words are also applied to the other two parameters of the exposure triangle, in a way that is less obvious and may be more confusing.
As applied to lenses, a “faster” lens is one that has a wider maximum aperture relative to its focal length, indicated by a smaller ƒ/ number. A lens that can open up to ƒ/1.4 is twice as “fast” as one that can only open up to ƒ/2.
As applied to film (and, I suppose, to digital sensors, but I can't recall ever hearing it used in that context) a “faster” film is more sensitive to light. Film with an ISO rating of 400 is twice as “fast” as film that is ISO rated at 200.
Something that can be a bit confusing is that a faster shutter speed results in less exposure, while higher lens or film/sensor “speeds” result in more exposure.
———
* This lens was made and labeled with the assumption that it would only ever be used with the standard 35mm film format. The depth-of-field markings would be just as valid with a modern FX-format digital camera, but not with a DX-format digital camera that uses a smaller frame size. In practice, the depth-of-field would be shallower when this lens is used on a DX-format camera. Since I'm getting into such details anyway, I might as well also mention that small red dot just outside the far-side ƒ/4 depth-of-field mark. That's the infrared focusing mark. If this lens were ever used with infrared film, or an infrared-modified camera, that mark indicates how far the focus needs to be adjusted from visible light in order to compensate for the longer wavelength of infrared.
A term that I only ever recently heard was “exposure triangle”, referring to the three parameters that set the overall exposure level in a camera—Shutter speed, lens aperture size, and film/sensor sensitivity. For a given amount of illumination of the scene being photographed, there are any number of combinations among these parameters, that will produce the same exposure level. If you adjust one in a way that increases or decreases the exposure level, then you can adjust another to bring the exposure back to the same level.
It's probably useful, at this point, to mention the term “stop”. A change of one stop represents a change in exposure level by a factor of two. If you go from a shutter speed if 1/100 of a second to 1/200 of a second, then you reduce the exposure by one stop. From 1/100′ to 1/400′ reduces exposure by two stops.
The relationship between shutter speed and total exposure value is obvious. If the shutter is open half as long, it lets half as much light through. If it's open twice as long, it lets twice as much light through.
Sensor/film sensitivity is also fairly obvious. Double the ISO rating, you double the sensitivity, with the same result as doubling the total amount of light, doubling the exposure. Halve the ISO rating, you have half the sensitivity, half the exposure.
The lens' ƒ/ value is somewhat less obvious. If you look at the aperture ring of a lens that has one, you'll surely notice that every mark has a number that differs, not from the adjacent marks, but from the marks that are two marks away from it on either side, by a factor of two. This can be somewhat misleading. The numbers here are inversely proportional to the diameter of the aperture opening. What it literally represents is the ratio of the focal length to the aperture diameter. But what affects exposure is not the diameter, but the area of the aperture opening, which is proportional to the diameter squared. So if you double the diameter of the aperture, you actually increase the exposure by a factor of four, or two stops. The adjacent ticks represent increments of one stop, or of a doubling or halving of the exposure. A setting of ƒ/4 lets twice as much light in as ƒ/5.6, and four times as much as ƒ/8.
If you come from a point of view of wanting everything in the picture to be as sharp and as technically-perfect in every way, then you have to recognize that every one of the three parameters of the exposure triangle involves some sacrifice.
Shutter speed is the most obvious. If there is anything moving in the scene, then a slower shutter speed, to let more light in, will result in moving things being more blurred. A faster shutter speed will result in less motion blur, but it also lets in less light, which means you need to change one of the other parameters in order to compensate.
The aperture setting affects depth of field. A smaller aperture setting gets you more depth of field allowing more to stay in focus closer or farther from the point at which the lens is actually focussed, but it lets less light in, so you have to change one of the other parameters to compensate. A wider aperture lets in more light, but gives you less depth of field. In the above image of my lens, do you see those color-coded marks to each side of the main focus mark? Those are coded to the aperture setting numbers, and give an indication of the depth of field. As this lens is currently set, it is focussed at ten feet, with the aperture set to ƒ/11. The yellow marks, coded to match the yellow number 11 on the aperture ring, indicate that at this setting, everything from about 7 feet to about 15 feet can be expected to be in focus.* You can see that the blue marks, matching ƒ/16, are farther apart, indicating that depth of field would be even greater at that aperture setting, while the red and green marks, coded to match ƒ/8 and ƒ/4 respectively, show how the depth of field shrinks at those settings.
See my threads at http://nikonites.com/education/25599-aperture-depth_of_field-relationship-nikkor-s-50mm-f1-4-a.html and http://nikonites.com/education/2552...tionship-vivitar-85-205mm-f3-8-tele-zoom.html for some demonstrations of the relationship between ƒ stopsand depth of field.
The remaining parameter is sensor/film sensitivity, or “speed”. With film, it has always been the case that a higher “speed” (more sensitive) film tended to be grainier, while a “slower” (less sensitive) film would have finer grain. This has a basis in physics. When there are fewer photons hitting the film, it takes bigger grains of chemical material to maintain a good chance of catching them. With digital sensors, pushing them to higher sensitivity introduces more “noise”, which isn't exactly the same effect as the coarser grain of a high-speed film, but it's easy to see them as having similar effect on the sharpness and quality of the image.
Now, all that said, you don't always want the most technically-perfect picture, with everything as sharp as possible.
For example, sometimes you want a bit of motion blur, to emphasize that an object is moving. So, you can use a slower shutter speed to get that blur, and in the deal, you get to tighten up the aperture for better depth of field and film/sensor speed for less grain/noise.
If there's a distracting background, then you may want to open up the aperture, reducing the depth of field, in order to throw that background out of focus; and in the deal, you get to tighten up on the shutter speed and film/sensor sensitivity. In fact, there's a whole branch of artistic theory about the use of out-of-focus components in a picture. Look up the term, “bokeh”.
And for some applications, in film-based photography, coarser grain is often desired for artistic purposes, to give the picture a more “vintage” look. Alas, this doesn't really translate well to digital photography. Digital sensor noise just never is able to look as good as coarse film grain sometimes can.
One more thing, concerning the use of words like “speed” and “fast”. As applied to the shutter, the terms are pretty obvious. A “faster” shutter speed means that the shutter is open for a shorter time, while a “slower” shutter speed means that it stays open longer.
These and related words are also applied to the other two parameters of the exposure triangle, in a way that is less obvious and may be more confusing.
As applied to lenses, a “faster” lens is one that has a wider maximum aperture relative to its focal length, indicated by a smaller ƒ/ number. A lens that can open up to ƒ/1.4 is twice as “fast” as one that can only open up to ƒ/2.
As applied to film (and, I suppose, to digital sensors, but I can't recall ever hearing it used in that context) a “faster” film is more sensitive to light. Film with an ISO rating of 400 is twice as “fast” as film that is ISO rated at 200.
Something that can be a bit confusing is that a faster shutter speed results in less exposure, while higher lens or film/sensor “speeds” result in more exposure.
———
* This lens was made and labeled with the assumption that it would only ever be used with the standard 35mm film format. The depth-of-field markings would be just as valid with a modern FX-format digital camera, but not with a DX-format digital camera that uses a smaller frame size. In practice, the depth-of-field would be shallower when this lens is used on a DX-format camera. Since I'm getting into such details anyway, I might as well also mention that small red dot just outside the far-side ƒ/4 depth-of-field mark. That's the infrared focusing mark. If this lens were ever used with infrared film, or an infrared-modified camera, that mark indicates how far the focus needs to be adjusted from visible light in order to compensate for the longer wavelength of infrared.
Bob Blaylock
Senior Member
I agree. Sensor noise never looks good, so when I can, I try to keep the ISO setting at its minimum, increasing it only if I need a faster shutter and/or a smaller aperture than I can get at the base ISO, to the degree that it's worth the increased sensor noise for the sake of the other settings.
What I did in my posts were to make it as simple as I could to get you going without loading you down with too much detail and information to keep you from getting overwhelmed and confused. As you get the basics down you can add to the knowledge you have and get a little more advanced. Keep it simple and make it fun. As your experience gets expanded so will your knowledge and abilities. Don't try to do to much to quickly or you may get discouraged. Good luck, Jeff Impey