Questions tagged [optics]

Optics is the science of light, and in photography often refers more specifically to to the properties and construction of lenses or the technical aspects of light sensors.

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6answers
163 views

Why smaller AoV APS-C has same aperture as larger AoV FF lens?

I am quite confused, FF focal length 50mm f/2.0 has aperture diameter 25mm APS-C lens 50mm f/2.0 has aperture diameter 25mm Then both lenses have same size front glass. However Angle of View for lens ...
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4answers
129 views

Decrease FF lens focal length for use on APS-C and still have it focus?

Need to convert very cheap vintage FF 50mm f/2.8 lens to work as 35mm lens for for APS-C, for having wider angle of view. Its kind of works by simply placing lens closer to camera sensor (without ...
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0answers
23 views

Samyang 10mm F2.8 UNKNOW ADAPTER? [duplicate]

I want to use this Samyang 10mm F2.8 lens on my fujifilm X mount camera. What kind of adapter I need to mount on my fujifilm X mount? Was used with a sony nex adapter: After a searching on the ...
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3answers
121 views

Projecting image on camera

I have an optical system that forms an image at various distances (25cm range) as shown in the figure here: What kind of optics is required to project this image onto a CCD camera but without having ...
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1answer
144 views

A spot on the lens inside the camera

Hello! Is there someone who has experience with this kind of "spot-on-the-lens" stuff? :) I bought a used 35 mm camera and discovered a "spot" on the lens inside. Of course, it ...
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0answers
179 views

Motion tracking/VFX: How to get needed info for iPhone camera?

Basically, I want to do VFX with my iPhone SE 2nd Generation front-facing camera. The software being used is Blender up-to-date. I'm not sure what to set Blender for in the track camera settings field,...
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2answers
136 views

Does it exist?: a Coronagraph-style LCD panel mask inside the optical lens to pass dark and block bright pixel segments?

So we know coronagraphs are just a circular mask in the center of a telescope to block the sun's bright light and allow our eyes to see into the dark around the sun. But what if this coronagraph could ...
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3answers
319 views

APS-C + speedbooster vs full frame

I own a Nikon in DX-format (Nikon name for APS-C sensor, crop factor ~1.5) and I'm considering buying a 50mm prime lens soon for it. (To be complete, my camera is a D5200, although I don't think the ...
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5answers
508 views

Telephoto lens for camera whose lens cannot be removed

Is it possible to add a lens in front of another lens to make it a telephoto lens? I have a few "fisheye" adapters that I can put in front of any lens to take a fisheye photo, but I wonder ...
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2answers
298 views

There are many f2.8 zooms for FF. Why are there so few f2/f1.8 zooms for APS-C?

APS-C/Super35 cameras are less staple for film than they were before, but are still widely used. Besides, there are quite a few semi-professional APS-C DSLRs on the market. As far as I understand, a ...
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2answers
168 views

Is there an optical/photographic reason for the difference between product and its product image?

I recently bought this wristwatch from a major online store, which was advertised with the following image: One of the reasons I picked it is were the black pointers and markers. The watch I actually ...
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6answers
238 views

How do I calculate f/stop change for teleconverter that increases lens magnification?

I'm trying to calculate the f/stop change of attaching a x2 teleconverter to a 80mm f/2.8 lens. In this instance, the teleconverter attaches to the front of the lens, and has a larger opening than the ...
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4answers
1k views

What's the practical difference between two Canon 50mm f/1.2 L lenses?

I've got an RF 50mm f/1.2 L lens for my R system. I've recently been playing with an F-1, and picked up the FD 50mm f/1.2 L lens. Obviously some of the different size is the autofocus and other ...
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4answers
177 views

Do chromatic aberrations change with distance?

I just saw the following claim on an amazon review and can't make much sense of it. Chromatic aberrations after 10 meters become significant. After 15-20 meters the picture becomes unusable. Is ...
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1answer
105 views

What causes the frosted glass effect of out-of-focus areas?

I expect that the out-of-focus areas would look like smooth gaussian blur ideally. But I found that they look like looking through frosted glass. Colors around the edges are blending with a grainy ...
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3answers
195 views

What shutter can fit a lens element with large glass?

I am building a camera using a very large front glass element for the lens (diameter is 70mm). At first, I thought I should try to find a shutter that is 70mm in diameter as well, one that can ...
2
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3answers
194 views

focal length to aperture relation while zooming - is my russian lens lying to me?

I have this old soviet/russian "Granit" 80-200mm lens, connected to my Canon 550d DSLR through M42 adapter. I also have "modern" kit 18-55mm lens. What I don't get is how aperture ...
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4answers
258 views

Does a lens with this zoom range exist?

I want to buy a zoom lens for a DSLR but I want its Focal length to start from a small number (18, 55, 100, 200) and end to a very large number (1300, 2600) so it can see near and far. Also I want it ...
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1answer
251 views

How to calculate height of camera and ground coverage via geometry?

I have a GoPro7 that I will mount on a pickup vehicle to capture ground images with video capture. The camera isn't top down but has about 20 (or 30) degrees inclination from the vertical axis. I want ...
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3answers
3k views

Canon EOS R or R5 with EF-S lens

Next month, I will buy a canon EOS R5 for concert photography. I will be short on money for some months or even a whole year because of this investment. I have a lot of EF-S lenses and some EF lenses ...
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2answers
479 views

Calculating Lens Hood Dimensions

How can I calculate for a given lens, where in the periphery a theoretical lens hood would become visible? This seems dependent on the size of the front element, focal length, and possibly other ...
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4answers
331 views

Why is there an air gap between lenses and digital sensors, as opposed to continuous glass-like higher refractive index?

Thinking about ultra-fast lenses (ƒ<1), it would seem useful to have a solid+liquid medium between lens and sensor. This wouldn't have been very practical (presumably) at the time of film, but with ...
4
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1answer
183 views

Would you consider this lens (Samyang 8mm CS II) defective?

I purchased a new Samyang 8mm F3.5 UMC Fish-eye CS II today. After I made my first shot with it I immediately noticed a flaw. At f/3.5 the flare of bright objects is shifted towards the bottom (and ...
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2answers
229 views

How are wide angle lenses able to project an image onto a sensor?

The Nikon F-mount has a flange distance of 46.5mm. A 14mm lens for example has an horizontal angle of view of about 104°. How is a lens able to project an image from the rear element onto the sensor ...
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4answers
211 views

Seeming contradiction on wikipedia about rear nodal points and how the principal plane is related to focal length

There are two lines on the wikipedia pages for "cardinal points" and "focal length" that seem to contradict each other, and I would be extremely grateful if someone could explain ...
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2answers
110 views

Estimating the optical resolution of a lens

In Tony & Chelsea Northrup's recent video titled 5 Lies Camera Companies Tell You, they mention that the optical resolution of a kit lens is often lower than the resolution of the sensor at around ...
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2answers
553 views

Why is the image plane at Z = f in pinhole camera models?

Can someone show me the mathematical interpretation of why the image plane is at Z = f in the pinhole camera model? I found a possibly useful formula in Wikipedia, as shown in the figure below: My ...
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2answers
132 views

What means lens optical characteristics?

I have 12-60 Panasonic lens for mft system. I'm about to buy 12-60 Leica for the same camera, because the photos I do with my current lens feel, smartphone-ish. Depite the lenses are similar in ...
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1answer
323 views

Can you calculate lens thickness from knowing focal length and diameter?

I'm not the best at math, but I'm wondering if there is a formula to figure out the thickness of a lens from only knowing the focal length and diameter.
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2answers
245 views

Lens Magnification vs Pixel Magnification

Scenario: I take a picture with a camera that has a crop factor of 3.19. I use a 55 mm focal length equivalent for taking the photo. In the resulting image file header, it says a magnification of 0....
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3answers
662 views

What is the necessary recess on an enlarger lens board?

I have recently acquired a Meopta Belar 75mm/f4.5, to use with my Durst M605 enlarger. I was remiss in not checking the mount of this lens (M23.5) before I bought it, and have therefore ended up with ...
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2answers
222 views

No more turn left to get focus at infinity (hit the lens limit) [duplicate]

Academic question: If I run out of turn attempting to achieve an infinity focus (close, but no cigar) would I: Move the lens away from the sensor? OR Move the lens closer to the sensor?
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2answers
239 views

What's the best choice of lens from an optics surplus shop to get a Stanhope Lens-like magnifying function?

I am looking to do some experiments with my cellphone and a lens, holding the lens in contact with my cellphone lens. I'm looking for a lens that has the shortest back focal length length possible, so ...
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3answers
476 views

Why are adapters for slightly too-short backfocus lens mounts not made with just a thick glass window instead of a lens element?

Infinity-correcting adapters tend to incorporate a weak teleconverter usually. It would appear that a thick, planar optical glass window is also capable of lengthening back focus - and would probably ...
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1answer
854 views

How can i calculate the direction vector of a pixel? [closed]

So if you take a pinhole camera and make it as the origin of our plane(3D) and a pixel from the image plane and connect the two with a straight line it should make a vector, which has direction and a ...
0
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1answer
464 views

Why is there a maximum focus distance when using an extension tube? [duplicate]

I am using the Nikon D850 together with the Sigma 50mm/1.4 Art and the MEIKE MK-N-AF1-A extension tube(s). During first shots I found out that the combination not only has a minimum focus distance (...
5
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2answers
140 views

Which is better in lens hoods, felt-like material or sawtooth surface?

I have noticed that many1 Canon lens hoods contain a felt-like matte black material designed to reduce reflections. The material probably does so admirably, but tends to get dusty over time. On the ...
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1answer
164 views

What explains a lens flare "streak" on only one side of light source?

We know than an axial streak can be caused by a smudged lens that has been wiped in one direction. The following image shows both lens flare and a lens "streak." But what could explain the one-sided ...
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5answers
4k views

Why can't my custom camera body focus to far distances?

I have built a custom optical device that uses a standard C-mount lens as found on CCTV cameras. Wikipedia states that the flange-to-film distance of a C-mount lens is 17.526 millimetres. I have ...
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3answers
113 views

What techniques do higher-end lenses use to reduce astigmatism at high apertures?

I own a few lenses with a maximum aperture of f/2.8. For this question, I'll focus on two specifically: A Rokinon 14mm f/2.8, which retails around the $500 CAD mark; and A Sigma 24-70 f/2.8, which ...
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1answer
82 views

I have a Nikon D60 and two lenses: 70-300 and 18-135. Should I get a 50mm 1.8 prime? [closed]

I have a Nikon D60 and two lenses: a Tamron 70-300 mm f/4-5.6, and a Nikon 18-135 mm f/3.5-5.6. I got all of these things really cheap, and now I want to buy a prime lens. I was thinking about a 50 ...
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1answer
199 views

Are front lens focusing and unit focusing equivalent in triplet/tessar style lenses?

Some vintage tessar or triplet type lenses (eg such intended for viewfinder cameras) implement focusing by merely moving the front element or front cell. When adapting such lenses to other cameras, ...
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2answers
145 views

How can a subject stay in focus if the shot is recomposed afterwards?

I have a doubt about a procedure that I see many photographers continuously apply and they taught me. I see that, when they want to take a picture with their reflex, they do this sequence of steps: 1)...
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1answer
92 views

Lumix G85 - Black Corner regardless of lens and no hood - please help

I have owned a Panasonic Lumix G85 for about a year. This month, I've started getting a black area on the left corner of my images, which you can also see on the EVF. I can't see anything on the ...
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1answer
470 views

How to get close to 180 degrees with minimal fisheye look on iPhone X or 11?

I'm trying to film my rugby practices with my iPhone and wondering what is the best lens to use to capture the entire field without much that fish eye look? I noticed that the new iPhone 11 (Pro) ...
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2answers
55 views

How do i find the distance required to resolve a point on a page from a mobile camera?

Given all details such as focal length , aperture etc , how can i find the size of a point on a paper that is at a given distance from a mobile camera ? Or vica versa , the distance required to ...
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1answer
113 views

Ghosting artefacts in narrow DOF photographs

Snapping with a Canon EOS 600D in narrow DOF situations (for example with low f-stop numbers at long focal lenght), I get ghosting artefacts on the parts of the photograph which are out of focus. ...
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2answers
213 views

Is it possible to get green and red chromatic aberration?

In one of the hallucinating scenes in a video I have played. The vision is blurry and objects nearer the edges of the screen are green and red Now the usual chromatic aberration patterns are purple/...
0
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1answer
215 views

Can a camera be a mile long?

Could parts of a camera be spaced out over a distance rather then together to work in a way a normal camera cannot? What characteristics would this camera have over a normal camera? In the picture ...
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6answers
13k views

What is the farthest a camera can see?

At what distance can a face no longer be identified using a camera? At what distance can a figure of a person no longer be captured?

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