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Zoom reach on crop sensors
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Jan 11, 2019 10:51:40   #
bsprague (a regular here)
 
"Zoom" and "crop" are getting screwed up in this discussion because pixel count is involved. In film, it was "grains". The bigger the film the more "grains" and less "grainy" the print would be.

Technology screws all this up. A smaller sensor in one camera can have more pixels than the sensor in a larger camera. "Bridge" cameras with 1" sensors have lenses marked to provide equivalent to 35mm fields of view. The lens is not "cropping", "zooming" or "magnifying". It is projecting a field of view on a sensor.

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Jan 11, 2019 10:59:36   #
Longshadow (a regular here)
 
bsprague wrote:
"Zoom" and "crop" are getting screwed up in this discussion because pixel count is involved. In film, it was "grains". The bigger the film the more "grains" and less "grainy" the print would be.

Technology screws all this up. A smaller sensor in one camera can have more pixels than the sensor in a larger camera. "Bridge" cameras with 1" sensors have lenses marked to provide equivalent to 35mm fields of view. The lens is not "cropping", "zooming" or "magnifying". It is projecting a field of view on a sensor.
"Zoom" and "crop" are getting ... (show quote)


And the perceived effect is?

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Jan 11, 2019 11:01:19   #
joer (a regular here)
 
DebAnn wrote:
I understand that zoom lenses "reach" further on crop sensor cameras. Does a zoom lens specifically designed for a crop sensor camera have that effect? For instance, does a 55-250 mm zoom made for a crop have an effective reach of around 400 mm? Or does that only apply to lenses that work on both full frame and crop?


The lens doesn't give you more reach. Its the image enlarging when viewing. The crop sensor can provide more resolution if the pixels are more densely packed than on the FF sensor. Image noise is the price you pay.

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Jan 11, 2019 11:02:54   #
DebAnn (a regular here)
 
Generally that's what I do too. However, I am going to Africa this year - a one-time-visit - and want to take the most practical lens without going to the expense of buying a new lens.
Longshadow wrote:
I don't use a crop sensor to achieve that result, I use a crop sensor body because that's what I have.
Sometimes I wish my 18 would really be an 18.

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Jan 11, 2019 11:18:43   #
Longshadow (a regular here)
 
DebAnn wrote:
Generally that's what I do too. However, I am going to Africa this year - a one-time-visit - and want to take the most practical lens without going to the expense of buying a new lens.


I have the 18-55 and the 55-250, but years ago I purchased a Sigma 18-200, which is now my primary lens.
Yes, I lost some of the top end from the 55-250, but I've accepted the trade-off.
If the low and high ends of the 18-200 are not sufficient, I work around it.
For my old film cameras, I had six fixed focal length lenses. With the single zoom, my bag is a lot lighter now. (I also carry a 50 just in case.) I decided that the zoom is more efficient for my needs.
I'm not a pro, I've just been shooting for over 45 years.
I have a suspicion that you will want something wider than the 55 at times for your trip.

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Jan 11, 2019 11:20:49   #
bsprague (a regular here)
 
Longshadow wrote:
And the perceived effect is?
It is not perceived. It is a measured angle of view.

A story.... I was lined up along a Yellowstone NP road in a traffic jamb. I got out my M4/3 camera, long lens and $100 Costco tripod. Next to me was a petite woman who needed a custom foam carved deck in the back of her Escalade to haul her gear around. She had a boyfriend to carry it for her too. We were shooting an albino wolf (that I think has since been killed). She was after stills and I was shooting 4K video. Feeling sorry for me, she offered me a peek through her $30K setup. I returned the favor. I needed an extra camera to capture the wonerful look of confusion on her face. My field of view was narrower than hers. She could see a better "picture" of the wolf in my rig than hers.

It was not a "perceived" view. It was simply the actual angle of view resulting from my small sensor camera and appropriate lens.

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Jan 11, 2019 11:26:38   #
Longshadow (a regular here)
 
bsprague wrote:
It is not perceived. It is a measured angle of view.

A story.... I was lined up along a Yellowstone NP road in a traffic jamb. I got out my M4/3 camera, long lens and $100 Costco tripod. Next to me was a petite woman who needed a custom foam carved deck in the back of her Escalade to haul her gear around. She had a boyfriend to carry it for her too. We were shooting an albino wolf (that I think has since been killed). She was after stills and I was shooting 4K video. Feeling sorry for me, she offered me a peek through her $30K setup. I returned the favor. I needed an extra camera to capture the wonerful look of confusion on her face. My field of view was narrower than hers. She could see a better "picture" of the wolf in my rig than hers.

It was not a "perceived" view. It was simply the actual angle of view resulting from my small sensor camera and appropriate lens.
It is not perceived. It is a measured angle of vi... (show quote)

So a narrower angle of view is not perceived as being closer?

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Jan 11, 2019 12:52:24   #
speters (a regular here)
 
lsaguy wrote:
I'm going to go out on a limb here just to see if I understand this. Hoggers, feel free to correct me if I'm wrong (like you'd need my encouragement :-})
Putting an FX lens on a DX camera doesn't change the "reach" at all. Think of the field of view (FOV) of any lens as a conical area with a defined base length. What the FX lens does on a DX camera is give the effect of decreasomg that base to that of a, roughly, 1/3 bigger lens.
To put numbers on it. If an FX lens of, say, 300mm focal length, the base of the cone is 100 feet. Put that lens on a DX camera and the smaller sensor cuts down that base to 66 feet, the base of the cone of an FX lens of 400mm.
And now to be graded on my understanding of this phenomenon.....
I'm going to go out on a limb here just to see if ... (show quote)

You sure now how to complicate a simple matter!

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Jan 11, 2019 13:51:52   #
repleo (a regular here)
 
DebAnn wrote:
I understand that zoom lenses "reach" further on crop sensor cameras. Does a zoom lens specifically designed for a crop sensor camera have that effect? For instance, does a 55-250 mm zoom made for a crop have an effective reach of around 400 mm? Or does that only apply to lenses that work on both full frame and crop?


(a)... does a 55-250 mm zoom made for a crop have an effective reach of around 400 mm? YES - 82mm - 375mm for a Sony sensor maybe a bit more for a Canon (1.6 crop factor?)

(b)... does that only apply to lenses that work on both full frame and crop. NO.

However, if you use a FF lens on a crop sensor you will be cropping off the 'crusty bits' around the edge of the frame compared to the crop on crop.

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Jan 11, 2019 16:31:38   #
bsprague (a regular here)
 
Longshadow wrote:
So a narrower angle of view is not perceived as being closer?


Longshadow,

Not sure what we are talking about at all. "perceive" = "to attain awareness or understanding". If I look through or shoot through a telephoto lens I am aware and understand that I am limiting my view to a narrow angle. I'm not cutting out pixels, so am not "cropping". Once framed, the view doesn't change, so I'm not "zooming" any more.

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Jan 11, 2019 16:57:43   #
Longshadow (a regular here)
 
bsprague wrote:
Longshadow,

Not sure what we are talking about at all. "perceive" = "to attain awareness or understanding". If I look through or shoot through a telephoto lens I am aware and understand that I am limiting my view to a narrow angle. I'm not cutting out pixels, so am not "cropping". Once framed, the view doesn't change, so I'm not "zooming" any more.


Perception is also how something looks to the viewer. We both can look at the same thing, but may perceive something totally different about it.

The key to your interpretation is "once framed, the view doesn't change", a static condition, that is correct.
I'm talking about moving from 18mm to 100mm, a dynamic condition. You are changing the field of view going from 18 to 100. The perception is zooming.
The action of cropping a portion of an image and keeping the original canvas size will give the perception of zooming (the cropped area becomes larger). Comparing a <xx>mm lens between a full frame and a crop sensor will give the perception of having been zoomed in the crop sensor. And yes, there is a difference in the field of view between each.

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Jan 12, 2019 06:43:07   #
DAN Phillips
 
So, if I put a Sigma 150-600 on a Nikon D5000, how will that compare to when I put it on a Nikon D750?
I appreciate your help!

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Jan 12, 2019 07:19:28   #
LXK0930
 
I believe that most of the people who reply are missing several very important points:

(1) Is the focal length expressed in 35mm FF equivalent, or actual focal length? If you look at a small P&S camera, the focal length is often expressed as something like 4-12mm. This is like about 35-105mm on FF.

(2) The focal length of a lens defines not only the lens reach, but also the perspective.

A wider lens, shot from a short distance, will make front/back subjects seem far apart. Same scene, using a telephoto from a long distance, will bring front/back subjects closer together.

That is why, for example, a head portrait using a wide angle lens results in a distorted face.

Hope that this rambling helps someone.

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Jan 12, 2019 08:02:17   #
billnikon (a regular here)
 
DebAnn wrote:
I understand that zoom lenses "reach" further on crop sensor cameras. Does a zoom lens specifically designed for a crop sensor camera have that effect? For instance, does a 55-250 mm zoom made for a crop have an effective reach of around 400 mm? Or does that only apply to lenses that work on both full frame and crop?


That 400 mm reach is not a true 400mm lens on a crop sensor. It is an angle of view of a 400 mm. HOWEVER, you get more EFFECTIVE MEGAPIXELS on your subject than when using a full frame FROM THE SAME DISTANCE to the subject. ie. you don't have to crop with a cropped sensor camera as you might with a FF camera. So, you will actually have more megapixels on the subject using a cropped sensor, IF BOTH CAMERA'S HAVE THE SAME SAY 24 MEGAPIXEL CAMERA. If, on the other hand, your shooting with 45 megapixel camera, then you will be able to crop more and get a very good image.

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Jan 12, 2019 08:14:54   #
mizzee (a regular here)
 
The reach, or 35mm equivalent is dependent on the crop factor of your camera. For example, my Nikon d7000 had a crop factor of 1.5 (check the specifications section of your manual for this). So a 50mm lens on that camera was the equivalent of a 75mm. My Oly has a crop factor of 2, so my 25mm is the equivalent of a 50mm on a full frame camera which has no crop factor.

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