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2
votes
1answer
154 views

What is the largest aperture on a commercially available lens? [duplicate]

Out of pure curiosity, what is the largest aperture, or lowest f-stop, a commercially available lens has. I have seen the 50mm prime lens from canon with 1.2, but not lower than that. What are the ...
3
votes
2answers
165 views

How to compare the speed of lenses taking transmission into account?

When comparing the speed of two lenses, you almost exclusively hear about the maximum aperture. This of course makes sense, since at a certain lighting condition, a larger aperture in general allows a ...
3
votes
3answers
140 views

Differences between canon 17-85mm and 18-55mm

I was given a 450d with a canon 17-85mm lens, it has USM and image stabilzing. It has always seemed okay to me but after a few years i have decided to upgrade to the 700d, which has now come with a ...
0
votes
2answers
121 views

Why human eye doesn't exhibit aberrations?

Eye's optical system is composed of single lens and is capable of producing very sharp results, but if I use single lens (monocle) with my camera I'll get soft image.
1
vote
2answers
229 views

Does wide angle equivalent in crop sensor skew image?

I see many posts on both this forum and elsewhere the discuss the use of a wide angle on a crop sensor. For example, they discuss how at 14mm lens is 14mm on a 35mm film or full frame, but with a ...
0
votes
1answer
52 views

Exact specification of N1-CL1 Nikon Closeup lens

On nikon site (and everywhere else) I've been unable to find any exact specification of tne N1-CL1 filter lens -- only thing I need is to know the exact focal distance of this lens (or dioptres, or ...
2
votes
3answers
257 views

What does “maximum aperture” mean in a camera spec? Where can I get the full aperture range?

I own a Canon S95, and am considering getting a newer model (e.g. Canon S110 or S120), and I'm comparing the specs. According to DPReview.com, the S95 has a maximum aperture of F2.0-F4.9, and the S110 ...
3
votes
1answer
128 views

Why is the center of image smudged with magenta/white at a small aperture?

I took two pictures with a Nikon D300 and a 17-55mm f/2.8G lens. Both pictures have been taken at ISO 200, aperture f/22 and shutter speed 1/8s. I used a tripod. The only difference between the two ...
0
votes
4answers
684 views

What is the most versatile lens for the Sony NEX-6? [closed]

I received a Sony NEX-6 body (no-lens) over the holidays this year and I am looking to find the right lens to match. I am searching for the most versatile lens available for this camera. In other ...
5
votes
1answer
696 views

What makes the Zeiss Otus 1.4/55 so special?

The new Zeiss Otus 55mm f/1.4 is nearly $4000. With faster lenses from Canon (50mm f/1.2L) with autofocus, why is the zeiss lens more than twice that of the Canon counterpart?
1
vote
1answer
220 views

Size of the entrance pupil vs size of the aperture

I understand that the entrance pupil is the image of the aperture as seen from the front of the lens. However, is the size of the entrance pupil the same as the size of the effective aperture? In ...
0
votes
3answers
193 views

Can I estimate the light gathering power of a lens by measuring size of entrance pupil?

Supposing I have an unknown lens of which I don't know f/# and focal length. I want to estimate the total amount of light that my lens can collect which, I believe, is given by the solid angle that my ...
2
votes
1answer
127 views

What lens is needed to change the minimal focus distance length of my camera?

Here is my problem, I Have a scientific camera, a Sony Block FCB-EH6500, which has an automatic focus. The minimum focus distance is 1 cm when completely zoomed out and 120 cm when fully zoomed in. ...
2
votes
1answer
229 views

How do anamorphic lenses produce lens flare “streaks”?

For example: What contributes to this streaking? Why doesn't spherical lenses have this effect? How is it used in photography?
1
vote
1answer
152 views

What's the difference between a diopter and an extension tube?

It seems both allow close up shots of a subject but what are the differences both physically and in use cases?
12
votes
6answers
668 views

What lens characteristics contribute to attractive lens flare?

Some lenses give really harsh and unwanted flares. Some gives beautiful flares that add depth to an image. What's the science behind this?
1
vote
2answers
136 views

Minimum and maximum apertures

Is there such a thing as a maximum aperture that a lens can be open to? What about a minimum aperture that it can be closed to? Do these concepts even make any sense? Is there a lens with the ...
4
votes
3answers
364 views

What does it mean that a lens is x millimeters?

Every lens has different focal length in terms of millimeter so if I have a 100mm lens, what does that refer to? Does it mean the length of the lens itself is going to be 4 inches long, or does this ...
1
vote
2answers
294 views

What does it mean for a telecentric lens to be focused to infinity?

I have a question about a telecentric lens Ive been studying (for physics research!) and was wondering if you guys could help clear some cobwebs in my head. For starters, I am simplifying the TC lens ...
7
votes
5answers
598 views

Why not have the diaphragm in camera body instead of the lens?

Why is the diaphragm to control the amount of light entering the camera typically in the lens and not the camera body itself?
15
votes
2answers
702 views

Does a specific f number across all lenses denote same amount of light?

When we say a light source emits 1500 lumens of light, it does not really matter if the light source is incandescent, CFL, diode etc. Similarly, when I say f/1.8 can I assume that all lenses pass the ...
5
votes
2answers
179 views

Why do the Nikkor non-AI 135mm vs 50mm f/1.8 work differently when I look directly through the lens?

I recently purchased an old Nikkor 135 f/2.8 non-AI lens. Beautiful lens, but the closest focal distance is about five feet. I noticed that it will 'focus' at about 4 inches as well. If I hold the ...
0
votes
1answer
327 views

Where are the principal planes located in a camera lens?

I want to find locations of the principal planes of a camera lens. I have looked at the specification for my lens here and here, but did not find what I need. But there are many other parameters in ...
7
votes
3answers
612 views

What are ED elements?

I find that some lenses are indicated with the letters "ED", referring to some special type of lens element. What are ED elements, and what advantages do they bring? Note that this question isn't ...
16
votes
2answers
735 views

Do rounded edges on aperture blades improve image sharpness, and how?

In the description for the XF lenses for its new X-Pro system, Fujifilm crows: The [XF lenses] all offer precise control over depth-of-field and deliver excellent out-of-focus bokeh thanks to the ...
11
votes
4answers
2k views

What is the reference point that the focal length of a lens is calculated from?

I understand the idea of a focal length for a single lens, i e the distance from the lens to the point at which parallel rays of light converge. However, in the case of a photographic lens with ...
5
votes
3answers
4k views

Why are objects far away inverted through a lens but not through the viewfinder?

When I look through a lens the image of objects far away are inverted but when looking the the viewfinder on my camera they are not. Why is this? I am having a hard time understanding why objects far ...
2
votes
1answer
118 views

Why does an aperture crop the image when you look through a lens itself but not when you look through the viewfinder?

I have been studying lenses for two days now and the aperture is very confusing. Based on the question here it appears that the aperture should not crop the image at all but when I look through a lens ...
2
votes
2answers
1k views

Do lenses affect color fidelity?

It seems to me that my costlier (Tamron 90 f/2.8 macro) lens gives better colors than my cheap Canon 18-55 IS kit lens. So does lens matter for color quality? What physical processes are involved in ...
12
votes
2answers
2k views

Why are cine lenses so much more expensive?

For example, compare a cine lens like the Zeiss Compact Prime CP.2 50mm/T2.1 ($3,900) to a high-end DSLR lens like the Canon 50mm f/1.2L ($1418). Both are EF-mount, have the same focal length, and it ...
7
votes
3answers
385 views

What is the limiting factor in lens construction when it comes to f-stop values?

This widely praised Nikon 105mm macro lens has a maximum f-stop value of 2.8. I've held it in my hands, it's a big lens. Meanwhile, this 50mm Nikon lens can go up to f/1.2, despite being 25% cheaper ...
8
votes
1answer
1k views

How do straight edges end up curved in photos?

In the standard model for a lens straight lines in the subject of a photograph will always end up straight. However I have seen a variety of photographs in which straight lines end up being curved, ...
6
votes
1answer
358 views

What does “distortion <XX%” mean in lens specs?

I'm going to buy a lens and I would like to understand what "distortion <XX%" means. It's a vari-focal 10-60mm lens, and mentions distortion <12-1%. According to my understanding, at 10mm focal ...
21
votes
3answers
1k views

When you zoom in with a lens on an SLR why does the lens go in then out?

I guess this is more a question of optics than photography but I just got an SLR with a basic 18-55 lens. I noticed that when going from 18 to 55 or 55 to 18 the lens physically comes back in and ...
8
votes
4answers
712 views

Is it possible for a lens to produce too much contrast?

I came across a complaint that a certain lens produces too much contrast. The lens was described as rendering "cartoonish" contrast when shooting a portrait with diffused light from a window, where ...
48
votes
5answers
1k views

Is there development in the world of lenses?

Now, I'm not an expert, so if this post makes you laugh, you're welcome. Still, as far as I know there are basically two components that determine the potential quality of a camera's photos: Sensor ...
4
votes
2answers
1k views

Is it normal for focal length to change while focusing?

When I change the focus distance on my Pentax 55-300mm lens, the focal length appears to change. More specifically, the lens appears to zoom in as I focus towards the minimum focusing distance. This ...
5
votes
2answers
4k views

Is the difference between a good 50mm vs 85mm lens just your distance from the subject?

I was wondering: is the difference between a 50mm f/1.8 lens and a 85mm f/1.8 lens just your distance from the subject? Let's assume that distortion is minimal; both lenses are of high quality. Does ...
25
votes
3answers
9k views

What does the number of elements and groups in a lens mean?

All lens specifications include a statement of how many elements the lens contains, and in how many groups, for example: Nikon AF-S VR Zoom-NIKKOR 70-300 mm 1:4,5-5,6G: 17 elements in 12 groups (two ...
13
votes
2answers
2k views

Why do zoom lenses and compact cameras have varied maximum aperture across the zoom range?

Why does a camera's maximum (allowed) aperture get smaller when you increase its zoom?
5
votes
1answer
739 views

Are mirror lenses appropriate for DSLR astrophotography?

There's a whole host of inexpensive mirror lenses available in the 500 mm - 800 mm range (this for example). They have slow max apertures (f/5.6-8) and a donut shaped bokeh (not a problem ...
15
votes
5answers
900 views

How do I find the aperture that produces the highest-quality images for a given lens?

I'm not talking about large aperture (f/1.8, f/2.8...), rather, about small apertures (f/18, f/20, f/23...). I read somewhere (actually I think it was on this site, but I don't exactly remember which ...
4
votes
1answer
274 views

What is the camera's influence on lenses' optical properties?

I installed my 50mm f/1.4 Nikon lens on my Olympus E-P1. I notice some properties of the lens changed — namely, magnification and DoF both increased. I understand magnification increases because of ...
22
votes
2answers
3k views

What is a zone plate?

I was looking into alternative methods of photography and I happened upon something called a 'zone plate.' Three questions: What is a zone plate? How does it work? What can I do with it?
9
votes
4answers
412 views

Why are some zoom lenses “soft” at either end of the focal length range?

As one reads about zoom lenses, a relatively common comment that comes up in reviews of some lenses (especially lower-priced lenses) is that the lens is not as sharp ("soft") at one or both ends of ...
10
votes
1answer
2k views

What are Barrel and Pincushion distortion and how are they corrected?

I have some questions regarding Barrel distortion and pincushion distortion. Since they are related I have put them in single post. I am aware that barrel distortion occurs more in wide-angle ...
11
votes
3answers
9k views

How does a spherical lens differ from an aspherical lens?

Many lenses (like the Pentax DA 15mm f/4 Limited, or the Nikon AF-S 35mm f/1.4G) are described as having "aspherical lens elements". Does this mean that regular lenses are spherical lenses? What's the ...
16
votes
6answers
2k views

Can a smaller sensor's “crop factor” be used to calculate the exact increase in depth of field?

If APS-C and similar crop-sensor digital cameras have a focal length multiplying effect such that a 50mm lens has an apparent focal length closer to the field of view of an 80mm on a full frame ...
27
votes
3answers
2k views

What does a hexagonal sun tell us about the camera lens/sensor?

In this picture, we see that the sun comes out as a hexagon. I am sure it is not arbitrary. What does the hexagon tell us about the instrument that captured the image?
30
votes
5answers
5k views

How do constant aperture lenses work?

Cheaper zoom lenses usually are faster at the wide end and slower at the long end (for example, the $150 Canon EF-S 18-55mm f/3.5-5.6). More expensive constant-aperture zoom lenses have the same ...