# Tag Info

29

The lens does not actually turn into a different focal length, since that's a real, physical property of the optics that can't be changed without more optics. So from that point of view, the answer is a definitive no. However, when you get to the question of is it effectively the same in terms of magnification, the answer is "pretty much, given some ...

17

The crop sensor does not change any property of the lens - but by seeing just the center of the image it makes it look like everything is multiplied by the crop factor. The focal length does not change - but by looking only at the center of the image makes it look similar to what you get by using a longer lens. The magnification also does not change, a ...

13

I do believe there are some formulas you can use. To Matt Grum's point, I have not tested these with zoom lenses, and to my current knowledge, they apply only to prime (fixed focal length) lenses. You did not specifically specify zoom lenses, so... The simplest way to calculate the magnification of a lens is via the following formula: Magnification = ...

8

Sorry, no; the magnification designation of a macro lens is the ratio of the physical size of the object to the size it appears on the sensor, meaning at 1:2 magnification, the image of the object would be half life size on the sensor (so e.g. a 2cm diameter coin would have an image 1cm wide on the sensor). Of course being a smaller sensor, the image would ...

7

You can use this calculator to play around... http://www.eosdoc.com/manuals/?q=jlcalc I got close enough on a 1.3x crop just adding all three kenko extension tubes behind my Canon 100L macro. According to the calculator, that gave me a magnification of 1.45 (and then multiply by 1.25 to give 1.8). That's at .25m. Keep in mind the lens plus body ...

6

Only way I could think of is MagicLantern. I installed it on my 1100D yesterday night and I instantly wanted to disable that feature.

6

I think it can be described, in fact Wikipedia has the relevant formula: 1/S1 + 1/S2 = 1/f Where S1 is the distance from the subject to the front nodal point, S2 is the distance of the rear nodal point to the sensor, and f is the focal length. Since extension tubes increase S2, it then allows you make S1 smaller, thus you can focus much closer to the ...

6

After a little research online, I have found two corroborating pieces of info. Firstly: The shorter the focal length of the lens used, the more magnification results. A 50mm reversed will give about life-size reproduction, while a 20mm gives 3X or 4X. http://www.cameraontheroad.com/2000/07/closeup-photography-ways-to-get-close/ Secondly: the most ...

6

Putting aside some of the details of this and strictly speaking, shooting something that is 0.15 m tall and 500 meters away on a full-frame camera will require a nearly 100,000mm long lens (which doesn't exist, or at least isn't generally available). Two lines of text tall might be 0.3 m and needs a 53,000mm focal length (which doesn't exist). Ten lines of ...

6

Focal Length controls the field of view in front of the lens. A longer focal length has a narrower field of view than a shorter one. Behind the lens, it is designed to project this image to a certain size and distance, as given by camera mount specifications. So we perceive this narrower field of view as having more "reach" as you can see farther into the ...

6

I think the answer you seek is in terms of "angular magnification" as it is used with binoculars. In the world of binoculars there is a number that is referred to as "magnification". For example a 10×45 set would offer 10× magnification (and a 45mmØ ocular). This means that the subject appears 10 times closer than with the unaided eye. This isn'...

5

This is not "obviously irrelevant to normal photography" at all; we just don't normally worry about the sort of precision that you'll need to deal with. There are two numbers that we ordinarily take at face value, knowing that they're slight fibs: the focal length of the lens (which is usualy rounded to a "friendly" value except on data sheets), and the ...

5

Leica 10X binoculars show a field-of-view of 6.7°. This is slightly wider than a 400mm lens on a full-frame camera. The Panasonic FZ1000 has an equivalent 25-400mm zoom, so at its maximum it will appear slightly more zoomed-in than the binoculars, showing a 6.1° angle-of-view. The angle-of-view is the best way to compare these two because other measures ...

5

The magnification will indeed depend on your reversing hardware. The more distance you put between the lens and the body, the higher the magnification. The exact formula is: magnification = lens_to_sensor_distance / focal_length - 1 The problem is that the distance from the lens to the sensor has to be measured from the relevant principal plane of the ...

5

You should be fine stacking on a whole set of extension tubes. You will increase diffraction, however you'll also be magnifying your subject by a greater factor, possible several times more...so fine details will still stand out more than they would at a lower magnification level because the effects of diffraction remain smaller than the magnified details (...

4

The depth of field, as defined by the aperture, also does not change. The only reason it is larger (more in focus) than on a full frame sensor, is because of the cropping factor, the person must move backward (or zoom out) to achieve frame something the same within the image. In other words, if you had a full frame body setup with a 50mm lens at F/1.8 aimed ...

4

edit to respond to follow up questions given you know the effects of a tube of a certain length on a certain lens you can work out the missing values from John's equations you should be able to get an estimate of the effect of a different length tube. Again the values will be subject to the foibles of the lens focussing method, but should give you a good ...

4

I'm afraid you cannot determine that magnification ratio mathematically. Peter Forsell's great Math for macro photographers page contains lots of macro magnification ratio calculations for different scenarios, but in the section about the reversed lens, he claims the following: We cannot directly calculate the zero extension magnification (Zm) of the ...

4

Zoom is zoom and magnification is magnification. Apples and oranges. Optical Magnification is the ratio between the apparent size of an object (or its size in an image) and its true size. It is calculated with the following formula: M = (di - f) / f with di as found in the following image: Zoom is the ratio of focal length as you mention it in ...

3

Yes, a bellows set should be able to give you 1:1, unless it's too deep when collapsed. In that case, it's not that you can't get up to 1:1, but that you won't be able to get down to 1:1 with the lens nominally adjusted to infinity focus; your magnification will always be greater than 1:1. In both cases (the dedicated Adaptall extension tube and the bellows) ...

3

The answer to your question generally is yes. However as you mention, the ratio of how much of the overall image your subject takes up will depend on your sensor size. What you do have to watch out for is that the "35mm equivalent focal length" should not be used but the actual focal length as quoted on the camera specs - this is usually something in the ...

3

I once asked this and got many confusing answers, but in the end I understood it, and I will try to explain it as simply as I can: Nothing about the lens is ever changed. It is not a Transformer after all, so every property of it remains the same. A photo taken with an APS-C camera is like taking photo on a Full-Frame camera and then printing it out, and ...

3

My Nikon 105mm drops from f/2.8 to f/4.5 at closest focus, so that sounds right. A post at betterfamilyphotos has a post where they say (emphasis mine): You would imagine that using a macro lens is the same as using a normal lens, and you would be right except that with a macro lens when you get close to 1x magnification, you start losing light. My ...

3

When a macro lens has a reproduction ratio of 1:1 an object with a given size will be reproduced at the image plane at the same size. This is irrespective of the focal length. The only difference is that a longer focal length will afford you the ability to achieve that reproduction ratio at a greater distance than the shorter focal length. The precise ...

2

First of all, adding extension tubes will bring the front of lens further from body, while bringing focused plane closer. There's a limit how much you can extend until your lens won't physically fit between focused plane and camera body. A 35mm macro lens already is very close focusing, so the physical length of the lens limits how much you can extend it. ...

2

Use a second camera, preferably a P/S with a small aperture. Take a picture through the viewfinder of your main camera, then a second picture of whatever your main camera is aimed at, and from the same distance. Be careful to use the exact same focal length for both pictures. Now you just have to compare the sizes of the two images. Take a random element ...

2

Yes, they are independent of sensor size. Even if the subjects appear to be bigger or nearer on a smaller sensor because of the larger pixel density, the subject's size on the sensor is the same regardless of sensor size. To elaborate: If a subject occupies 3mm of a sensor, it will occupy 3mm even if you change the sensor size, given that you keep the ...

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