The Perfect Sunrise

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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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163 views

How Do DxO Lens Ratings compare between systems?

Looking for new camera system with changing lenses (DSLR or SLD) I find DxOMark also has rating for lenses: http://www.dxomark.com/index.php/Lenses/Camera-Lens-Ratings What do the results numbers ...
0
votes
1answer
351 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
756 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 ...
7
votes
5answers
701 views

What would be a good book for optics?

I would like to refresh my knowledge about optics. I studied optics back in the university but I almost forgot everything. What would be a good book to do that?
6
votes
1answer
132 views

Is there a correspondence between Tilt-Angle and the angle of the Focus-Plane?

Tilt lenses have their tilt-range specified in degrees, typically around ±8°. It seems that this number corresponds to how much a lens physically tilts along one axis. The effect is to tilt the plane ...
11
votes
3answers
505 views

How does the D800E reverse the effect of an antialiasing filter by adding another filter?

According to http://mansurovs.com/nikon-d800-vs-d800e the D800E differs from the D800 in that one of the layers of the filter reverses the effect of the initial low-pass filter. How does this work? ...
11
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5answers
8k views

What is “infinity focus”?

I have been reading a bit about astrophotography and the term infinity focus keeps coming up. What is infinity focus and how do you set the camera to infinity focus?
12
votes
1answer
222 views

What lens design limits derive from the width of the lens mount?

I'm familiar with the lens design limitations imposed by the flange-to-focal-plane distance. But what constraints are caused by the width of the lens mount (that is, the size of the hole in the ...
6
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3answers
1k views

How does a short flange back distance improve image quality?

In the description for the new lens mount for their X-Pro series, Fujifilm says: 1: Specifically designed to maximize the mirrorless design of the body, the X-Mount has a short flange back ...
16
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2answers
763 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 ...
2
votes
1answer
1k views

How does the quantity of elements and blades in a lens affect the optics?

I am trying to get a greater understanding of how lenses work. Basically I bought this lens, the Sigma 10-20 f4-5.6: The construction has really fascinated me. 14 Elements in 10 Groups?! What ...
10
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1answer
434 views

How do I design a conceptual lens schematic?

I would like to attempt to create a schematic for a simple or small compound lens, but the process seems very daunting. I have thoroughly read 'Science for the Curious Photographer: An Introduction to ...
9
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1answer
371 views

Why do mirror lenses have poor contrast?

I was reading this question on mirror lenses and the answers taught me a lot about mirror lenses. It is pretty obvious to me why they have donut bokeh (central obstruction) and why they are fixed ...
11
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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
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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
123 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 ...
7
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4answers
979 views

Do bigger focal lengths capture more light?

I never understood what the f really stands for in the f-stop values, like f/1.8. Wikipedia explains it in various articles, but I still find it very confusing. What I understand, though, is that it ...
2
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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
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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
397 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
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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, ...
11
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4answers
1k views

Is overall light gathering of a lens only dependant on aperture?

My impression is that the aperture value of a lens determines its light gathering ability, but I'm not sure I understand how it works... When considering light gathering in telescopes, it is ...
6
votes
1answer
392 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 ...
6
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3answers
4k views

What is the technical difference between focus and zooming?

This may look like a silly question but I don't know what the difference between zooming and focusing is. Zooming in will usually let me have fewer subjects in the scene while zooming out will allow ...
24
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3answers
2k 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 ...
9
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4answers
812 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 ...
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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 ...
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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 ...
10
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2answers
2k views

Why is depth of field affected by focal length?

As the focal length decreases, the depth of field increases as well. Why is this? I'm not so much interested in a physics lesson as I am interested in a simple, down-to-earth explanation.
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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 ...
0
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0answers
56 views

Different sources of noise and ways to avoid/correct those [duplicate]

Possible Duplicate: What types of noise can be present in digital photographs? I've few questions related to noise found in digital images. There are topics on this forum on underexposure ...
5
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1answer
278 views

What's the history of neutral density filters instead of aperture diaphragms in compact cameras?

Some compact cameras use neutral density filters to control light rather than aperture blades, to avoid the effects of diffraction in tiny sizes. I first heard of this as a feature of the Nokia N8 ...
6
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2answers
778 views

How are neutral density filters in compact cameras implemented?

I've read here on this very site that some compact cameras don't use aperture blades to stop down the lens and limit the amount of light hitting the sensor. Stopping down increases diffraction. ...
26
votes
3answers
10k 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 ...
20
votes
4answers
1k views

What are good advanced books on the physics and science of photography?

I am looking for books about the physics of DSLR, including modern photography optics and sensor electronics. If I already have some books on optics and electronics, I have found fairly hard to find ...
13
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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?
8
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6answers
3k views

Technically, why is the out of focus area blurred more when using a bigger aperture?

I'm wondering, technically, why and how does the out of focus areas blur more when using a bigger aperture. I think it'd help a lot if I presented a problem that's been driving me nuts for a long ...
5
votes
1answer
780 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
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5answers
934 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 ...
6
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3answers
743 views

How many blades does my lens' aperture diaphragm have when I get 12-pointed starbursts?

Here I figured that my camera has either three or six blades. But yesterday I took another shot at night with the same setup which has twelve srokes: The camera is a Canon 550D and I used the same ...
4
votes
1answer
292 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 ...
7
votes
2answers
2k views

How can a prime lens focus on more than one plane?

By definition, a prime lens is a fixed lens system with a fixed focal length. Then, simple physics tells us that it should be able to focus only on one plane (at a fixed distance) in front of it. But ...
47
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4answers
3k views

Why aren't all viewfinders 100%?

We often see that a manufacturer's high-end (D)SLR models offer a "100% viewfinder," which shows the entire exposed frame, and allows precise composition with regard to objects near the edge of the ...
34
votes
2answers
15k views

What is the difference between a pentaprism and a pentamirror?

Higher-end SLR cameras include a pentaprism to transmit the image from the lens to the viewfinder, whereas lower-end SLR cameras use a pentamirror to accomplish the same task. What are the ...
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
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4answers
433 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 ...
14
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6answers
1k views

Is there an easy way to force chromatic aberration?

A couple of months ago I was playing with my camera and a magnifying glass and I noticed that this glass produced a very soft chromatic aberration. Here's an example: (Here is the full size, 18mp ...
10
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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
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3answers
10k 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 ...
24
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3answers
2k views

Does changing the focal length change focus?

When using manual focus or back focus on D60, I sometimes zoom in the lens, set the focus, and then zoom out. Does changing the focal length (zooming out), also change the focus? In case the answer ...