Before the rush

Before the rush
by evan-pak

Submit your Photo
Hall of Fame

Please participate in Meta
and help us grow.

New answers tagged

0

The key difference between these two lenses is the fact that one is a zoom lens, and the other is a prime lens. Prime lenses usually offer better optical performance, at the same focal lengths, than a zoom lens. The aperture is denoted by the f-number, and the 35 has a larger aperture, denoted by it's smaller f-number, i.e., 1.8. A larger aperture gives ...


0

You cannot alter the back focal length of a lens without changing its optics. Specialized adapters exist to do this, but there is usually a large loss of image quality. Your best bet is to not use a DSLR lens, but to use a large format lens designed for use with bellows. They will have considerably longer back focal lengths and allow you the requisite ...


2

@omega Here's what you are not getting: The 36x24 measurement is the size a classic photo negative taken with 35mm film. It is a well known and accepted measurement. 35mm film was a very commonly used film for 60+ years. Because format size (sensor or film size) determines angle of view for a particular focal length lens, and because 35mm film was so common ...


0

@omega Here's what you are not getting: The 36x24 measurement is the size a classic photo negative taken with 35mm film. It is a well known and accepted measurement. 35mm film was a very commonly used film for 60+ years. Because format size (sensor or film size) determines angle of view for a particular focal length lens, and because 35mm film was so common ...


1

From the exif data: Image size is 2988 pixels height by 5412 pixel length. The file states the actual focal length is 4.8. The file states this vale is the equivalent of a 31mm lens mounted on a full frame. From this we can calculate the crop factor = 31 ÷ 4.8 = 6.4583. The diagonal of a full frame, 24mm height by 36mm length = 43.27mm. The diagonal of this ...


1

We draw imaginary line from the top and bottom of the object to the center of the lens. This traces out the image of a triangle. The base of the triangle is the distance, object to lens. The base of this triangle is the object’s height = 90 cementers X 10 = 900mm. The height of this triangle is the distance lens-to-object = 92 inches = 92 X 25.4 = 2336.8mm....


2

PPI has nothing to do with the calculation. I calculate the Note 4's 1/2.6" sensor's dimensions to be about 5.80mm × 3.27mm. So using 5.80mm as the sensor height (the image is in portrait orientation, so we need the sensor's long dimension for image height) in the equation in Matt Grum's answer in the question you linked to, and rearranging the equation to ...


2

You are missing something big. The size of the camera sensor is not mentioned. You need to know it, both in mm and in pixels. You didn't say any sizes, but Samsung says 3.7 megapixels, so if 4:3, that is 2221 x 1666 pixels. Samsung specs don't say. Your image will be this size though, you can know its pixel dimensions. The sensor mm is pretty difficult ...


1

If you use higher end lenses and 20+ MP sensor, the 2x rule is safer. Safer meaning that there are many factors. Weight distribution of your lens, your camera body, your current physical condition, your current level of adrenaline, your sniper/biathlon training etc. So it is best to watch your shots closely and develop your personal rule.


1

When should ¹/EFL become ¹/(2 × EFL) to avoid camera shake? When you plan to display at twice the magnification needed to create an 8x10 print to be viewed at distance of 10" by a person with 20/20 vision. The original 1/FL rule of thumb was based on the assumption of a 36x24mm frame of film being enlarged to an 8x10 print. Even then, if you were planning ...


0

If you had a consistent and measurable amount of camera shake, then I suppose you could determine exactly the required shutter speed, and that would depend not only on focal length, but also the lens resolution, sensor properties (crop factor, pixel resolution/density) and how large, and from what distance, you will view the final image. However the amount ...


0

I figured it out. The mistake was that the camera was poorly calibrated. That the scaling factor was about the focal length was thus just a coincidence.


-1

A numerical example For years 35mm film cameras dominated. The image size was 24mm by 36mm. let us assume we want a 20mm high image of a 2,0 m high object at a distance u in front of the camera. Provided u is at least 10 times bigger than the focal length f, the ratio of image height to object height is approximately f/u, thus 20mm/2m = f/u, hence ...


0

“Correct” perspective is not critical for most images. Portraiture is an exception. Things close to the camera reproduce large and things far from the camera reproduce small. If the camera is worked in too close, the nose reproduces too large and the ears too small. This is the dreaded facial distortion that makes portraits look weird. Factorial: An image ...


2

No. You can only get the same look by standing in the same place. Otherwise, perspective will be altered. Nothing you can do with the lens (or camera) can get around that. On a DX format camera, to get an "85mm look" — the look of an 85mm lens on a "full frame" 35mm-format camera, or FX in Nikon terms — you need a lens that's 1.5× shorter to match field of ...


0

Why are you wanting to use a macro lens for a portrait shot? Maybe you have considered this but why would you not use a 200 f2 or a 135 dc or a 70-200 f2.8? These will give the distance, sharpness, and be flattering to the person. I understand you are also showcasing product. What is your end goal? How will this be used? What size will the print be?


0

Your coverage area is 2,46 by 1.46 meters is almost an exact match of the aspect ratio 16:9 – the current standard for HD TV. I attempted to find the published angle of view for your unit which is likely model C905 720P. I was able to find that manufacture stated the diagonal angle of view is 75⁰. Now the lens labeling tells me that the focal length is 3....


7

The distance, camera to subject determines the perspective of the image. Consider, things close to the camera reproduce large, and things further away, reproduce small. If you work in too close, the nose reproduces too big and the ears too small. We are taking distortion. It is mainly distortion of the facial features that causes the subject to say, “I look ...


2

Because it is a macro, you can go closer than usual. You can use it for things like jewelry, wristwatches etc. Consider if 70mm equivalent is not too wide for headshots, though. I believe fashion photographers usually prefer flat look that is typical for longer focal lengths.


4

Focal length is focal length, macro or not. What makes a macro lens special is that it is designed to have a small closest focusing distance. This allows to take images 1:1 the size of the subject (or 1:2 in this case). Other than that, it can be used like any other lens. Is 71mm focal length too short for use cases that I am doing to shoot all of them ...



Top 50 recent answers are included