suggestions for Nikon lenses

SnapHappy32 said:

http://www.nikonusa.com/Learn-And-Explore/Nikon-Camera-Technology/g588ouey/1/The-DX-and-FX-Formats.html

PS Upgraded that coffee yet?

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I take it that you were unable to understand the link with the actual angle of view? I thought it was pretty self-explanatory.

I'll be honest I cannot believe anyone can be so dumb as to persist in claiming that a DX lens is magically marked with a different scale of focal length even after being presented with the technical details.

Do you really not understand that the DX / FX designation on a lens has nothing to do with effective focal length? All it has to do with is the size of the image circle it projects.

Or is it just too much irish in your irish coffee? Personally I don’t need to be drunk to carry on a conversation. Although it might help me follow your logic.

Go back and look real careful like. See how I listed a FX and a DX lens with the same field of focal.

According to your strange logic the following should be true.

The Nikon 35mm DX should give the same field of view as a FX 23.3mm since (FX focal length in mm) x crop factor = DX focal length.
And 23.3fx x 1.5 = 35dx
And, the FX35mm lens should give you a DX MM of
35fx x 1.5 = 52.5dx

But sadly this is not the case. MM is MM. A 35mm FX lens produces the same angle of view as a 35mm DX lens.

So back to that stupid thing you wrote...

SnapHappy32 said:

16-85mm@85mm = 2.523
50mm@50mm/75mm DX = 2.189

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Where you illustrate your lack of understanding: you clearly do not understand that the DX lens is also impacted by crop factor and gives the equivalent field of view as a 24-127.5mm "DX".
I’m going to explain it again and do try to pay attention this time.
A 50mm lens is a 50mm lens, no matter if it is FX or DX or even CX.
A 35mm lens is a 35mm lens, no matter if it is FX or DX or even CX.

Every lens is the same focal length, no matter if it is FX or DX or CX or anything else you wish to compare it to.

What changes with the lens is how large an image circle is has to project. Meaning for simplicities sake how large a sensor it has to cover. If the image circle is not large enough you get viginetting (darkening of the corners)

So if you have a DX camera you can ignore the FX DX designation on a lens since the only bearing it has with the physical size and weight of the lens (and of course cost).

Your goofy 50mm/75mm DX comment has no meaning except to illustrate your lack of understanding.

Put another way. Put that 35mm FX lens on your camera and the 35mm DX lens and they will have the same angle of view (this means they have the same focal length ).
Another concrete example:

If I put the Nikon 35mm f1.8 DX on my FX d700 I get the same focal length (angle of view) as if I used a 35mm f1.4g FX. If I flip that around and put the FX 35mm on my d90 I get the exact same field of view as when I use a 35mm f1.4g FX lens. The ONLY reason the lenses are marked FX or DX is so we can know how large the image circle it projects so that we can see if it is suitable for our FX cameras.

Ps: you really need to step back a bit. You do not know the basics and yet you are giving advice to others on how to spend their money. You should not do this until you understand this a bit better.

You know even a smart man makes mistakes. But when presented with the facts such a person steps back and looks at the facts vs his previous (mis)understanding of it. I have presented the facts to you now 3 times and you respond by sticking to your BS.

If for no other reason than learning a few basics you’ve decided to be too thickheaded to take in via words, do the following.

Go rent a FX body, a FX lens in the same FL as you have a DX lens. The 35mm 1.8dx vs the 1.4fx is an easy comparison. Then perhaps you will believe your own eyes when you refuse to believe the facts in any other way.

--

See my plan (in my profile) for what I shoot with. See my gallery for images I find amusing.

Bjorn.

You've managed to call me a lot of things. Doesn't go together nicely with the picture of a wise old man. Stop ranting, old man. Makes you seem bitter. Seriously.

Go to somewhere sunny or get the good doctor to unload some prozac on you - because you are taking this way too seriously.

And are you kidding me? From Nikon again:

"FFocal Length Multiplier For a D-SLR that uses an imaging sensor smaller than full frame (35mm film frame), the ratio of the diagonal of the camera's imaging sensor in comparison to the diagonal of a 35mm frame is the crop factor. This ratio is commonly referred to as a focal length multiplier (FLM), since multiplying a lens focal length by the crop factor or FLM gives the focal length of a lens that would yield the same field of view if used on the reference format."

And:

"Optimized for edge to edge sharpness on both FX and DX-format D-SLRs

DX-format D-SLR the angle of view is equivalent to a focal length of 52.5mm in FX/35mm format. " http://www.nikonusa.com/Nikon-Products/Product/Camera-Lenses/2198/AF-S-NIKKOR-35mm-f%252F1.4G.html

Did you get that?

PS Happily own a D700 and several FX lenses. Bought them last summer. Hardly use them. Must be killing you that a moron like me just sits on equipment like that.
And I know it does.

Ha det greit.

SnapHappy32 said:

Bjorn.

You've managed to call me a lot of things. Doesn't go together nicely with the picture of a wise old man. Stop ranting, old man. Makes you seem bitter. Seriously.

Go to somewhere sunny or get the good doctor to unload some prozac on you - because you are taking this way too seriously.

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You are going to great lengths and issuing personal insults to maintain an erroneous position.

SnapHappy32 said:

And are you kidding me? From Nikon again:

"FFocal Length Multiplier For a D-SLR that uses an imaging sensor smaller than full frame (35mm film frame), the ratio of the diagonal of the camera's imaging sensor in comparison to the diagonal of a 35mm frame is the crop factor. This ratio is commonly referred to as a focal length multiplier (FLM), since multiplying a lens focal length by the crop factor or FLM gives the focal length of a lens that would yield the same field of view if used on the reference format."

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Please read the above carefully. It refers to the field of view, and only the field of view. It does not say that the lenses are labeled with equivalent focal lengths.

SnapHappy32 said:

And:

"Optimized for edge to edge sharpness on both FX and DX-format D-SLRs

DX-format D-SLR the angle of view is equivalent to a focal length of 52.5mm in FX/35mm format. " http://www.nikonusa.com/Nikon-Products/Product/Camera-Lenses/2198/AF-S-NIKKOR-35mm-f%252F1.4G.html

Did you get that?

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I got it. It talks about the field of view.

SnapHappy32 said:

PS Happily own a D700 and several FX lenses. Bought them last summer. Hardly use them. Must be killing you that a moron like me just sits on equipment like that.
And I know it does.

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Great! Now you can test your assertion. You must have at least one FX lens that has the same labeled field of view as one of your DX lenses. Put them both on your DX camera. If your assertion that DX lenses are labeled with the FX equivalent focal lengths is correct, you will see a different field of view. If, as Bjorn contends, FX lenses and DX lenses are both marked with their actual focal lengths, you will see the same field of view.

Check it out (it's better if you use a distant scene because a lot of lenses change focal length as they focus).

--
Leonard Migliore

SnapHappy, you really should pay attention to both Bjorn and Leonard. You're not understanding it. Put a 35mm DX lens on your DX camera and look through it. Now put a 35mm FX lens on that same DX camera and look through it. You'll see that the view is exactly the same. Put both those lenses on an FX camera and they will also have the same view except the DX view will have some vignetting.

The focal length of a lens is the same on any format. That doesn't change. Only the field of view changes. That's it. A DX camera crops out a smaller rectangle from the same image that an FX camera crops out a larger rectangle of. That's all. Using terms such as "Focal Length Multiplier" and "Equivalent Focal Length" has long confused people new to digital photography. I think the users of these terms think it makes it easier to understand instead of harder.

Here's another way to look at it. If I held a 100mm lens up and held a piece of paper behind it, let's say the image gets projected on the paper. It would be a circular image that would be upside down and left to right from what the scene was. The Pentaprism rights this for the viewfinder, but just take that round image on the paper.

Now, draw on that paper a rectangle the size of an FX sensor. There's your field of view for FX. Now draw a smaller rectangle inside of the first which is the size of your DX sensor. There's that field of view. Notice the image didn't get bigger or smaller. Notice there is no magnification going on at the sensor level. Nothing magically changed when you drew that smaller rectangle. All you did was cut out a smaller image from the larger one. That's it. Nothing else. Depth of field didn't change either. That image is all that comes out of that lens hanging there.

If you always think of it this way, it's much easier to understand what crop contributes to the optical image. Where people get into trouble is how the image is enlarged from the output. When they see a DX image with the subject looking closer,they don't understand that this is the effect of digital enlarging. When they see DOF differences, the same thing is occurring. That image coming out of that lens is the same regardless. The image doesn't magically change. It can't.

--
Cheers, Craig

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Following the simple logic of numbers I'm going to give Leonards tip a try.
I do appreciate LEARNING - as long as Im tought by someone in a civil tone.
I do however make a habit of returning insults to sender. Seems fair to me.

But it shouldnt have gone to those lengths.

Anyway - appreciate the latter inputs - very informative and easily understandable. Please help me understand the following - and please do correct me if my terminology is wrong::

2 lenses. One FX. One Dx. Both set at 50mm. If I fit the FX on a DX body, and then want to replicate the excact same Angle of view with the DX lens. At which setting focal length setting will the DX lens give me the same framing of the subject as the FX?
50mm, right?

Guidenet said:

The focal length of a lens is the same on any format. That doesn't change. Only the field of view changes. That's it. A DX camera crops out a smaller rectangle from the same image that an FX camera crops out a larger rectangle of. That's all. Using terms such as "Focal Length Multiplier" and "Equivalent Focal Length" has long confused people new to digital photography. I think the users of these terms think it makes it easier to understand instead of harder.

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Practically speaking - does the smaller rectangle of the DX Imply that i will only be able to reproduce the smaller "crop" with an FX lens/body if I physically move the lens further away from the subject? Compared to where the DX setup was placed?

Guidenet said:

Now, draw on that paper a rectangle the size of an FX sensor. There's your field of view for FX. Now draw a smaller rectangle inside of the first which is the size of your DX sensor. There's that field of view. Notice the image didn't get bigger or smaller. Notice there is no magnification going on at the sensor level. Nothing magically changed when you drew that smaller rectangle. All you did was cut out a smaller image from the larger one. That's it. Nothing else. Depth of field didn't change either. That image is all that comes out of that lens hanging there.

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I actually used the illustration on Nikons site to understand this. But I get your point. What I still dont understand is why a wideangle lens' focal length changes according to the system your using it on? As far as Ive been told, i would need a 16mm DX lens to reproduce the effects of a 24mm FX lens. On medium format systems a +40mm is still considered wide angle. How is that? Looking at a compact - wideangles even starts on single digits.

SnapHappy32 said:

Following the simple logic of numbers I'm going to give Leonards tip a try.
I do appreciate LEARNING - as long as Im tought by someone in a civil tone.
I do however make a habit of returning insults to sender. Seems fair to me.

But it shouldnt have gone to those lengths.

Anyway - appreciate the latter inputs - very informative and easily understandable. Please help me understand the following - and please do correct me if my terminology is wrong::

2 lenses. One FX. One Dx. Both set at 50mm. If I fit the FX on a DX body, and then want to replicate the excact same Angle of view with the DX lens. At which setting focal length setting will the DX lens give me the same framing of the subject as the FX?
50mm, right?

Click to expand...

Right. Because they both have a focal length of 50mm. This is a physical property of the lens. Any 50mm lens, whether it's marked DX, FX or XXXX is going to give you the same angle of view.

--
Leonard Migliore

Same angle of view on the same sensor size.
--
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Bucuresti, Romania
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SnapHappy32 said:

Practically speaking - does the smaller rectangle of the DX Imply that i will only be able to reproduce the smaller "crop" with an FX lens/body if I physically move the lens further away from the subject? Compared to where the DX setup was placed?

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You have to go the other way. With the same lens, FX is going to cover a wider angle than DX because the FX sensor is bigger. To get the same framing on FX as you get on DX from the same spot, you need to have a lens on the FX camera with a focal length 1.5X that of the lens on the DX camera. That's what "crop factor" means. For example, a D7000 with a 50mm will have exactly the same field as a D700 with a 75mm that's on the same spot.

Physically moving the camera is a whole new game. When you move the camera, you're not taking the same picture. But let's say you're shooting pictures of a brick wall (that's a popular activity on this forum, but I digress). You drag out your D700 with a 50mm and take a picture of 100 bricks. Now put the 50 on a D7000. Since the sensor is smaller, you won't get as many bricks in the picture (as I figure it, you'll get 44 bricks). So you have to back off half your distance (if you were 10 feet away with the D700, you need to be 15 feet away with the D7000).

SnapHappy32 said:

SnapHappy32 said:

Now, draw on that paper a rectangle the size of an FX sensor. There's your field of view for FX. Now draw a smaller rectangle inside of the first which is the size of your DX sensor. There's that field of view. Notice the image didn't get bigger or smaller. Notice there is no magnification going on at the sensor level. Nothing magically changed when you drew that smaller rectangle. All you did was cut out a smaller image from the larger one. That's it. Nothing else. Depth of field didn't change either. That image is all that comes out of that lens hanging there.

Click to expand...

I actually used the illustration on Nikons site to understand this. But I get your point. What I still dont understand is why a wideangle lens' focal length changes according to the system your using it on? As far as Ive been told, i would need a 16mm DX lens to reproduce the effects of a 24mm FX lens. On medium format systems a +40mm is still considered wide angle. How is that? Looking at a compact - wideangles even starts on single digits.

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Repeat after me: A lens's focal length does not change with the camera that it goes on.

The focal length is the focal length, just like the lens's weight is the same regardless of what you attach it to. The angle of coverage depends on the sensor size. Compact cameras have smaller sensors, so you need shorter focal lengths to get the same angle. Medium format cameras have bigger sensors (that's what makes them medium format) so they need longer lenses to cover the sensor.

One important metric for a sensor is the diagonal length. For example, a full-frame FX sensor, which is 24mm X 36mm, has a diagonal of 43mm. A DX sensor has a 28mm diagonal. Point and shoots have diagonals as small as 7mm. There's lot of different medium format sizes but the old 6X6 negative has an 85mm diagonal. Over the years, it has been generally accepted that the "normal" focal length for a sensor is the same as the diagonal size. So a normal for FX would be 43mm (50mm is close enough) and a normal for DX would be 28mm (but it's easier to make a 35 so that's more common). A normal for a compact would be something like 10mm. Anything shorter than a normal is considered wide angle, and anything longer is considered telephoto.

So the 40mm lens you mentioned is indeed wide on 6X6; it's less than half the diagonal. It would be normal on FX and a very slight telephoto on DX. But it would be a real telephoto on a compact with a 10mm diagonal; you would need a focal length of 4.3 X 40 or 172mm to get the same framing on FX.

--
Leonard Migliore

Thanks for finishing the sentence correctly. I should have clarified that given the reason for the question.
--
Leonard Migliore

SnapHappy32 said:

. . .

What I still dont understand is why a wideangle lens' focal length changes according to the system your using it on?

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It doesn't change. The focal length remains the same. No matter what type of system the lens is used with, it projects the same image circle. You don't need a camera to see the image circle. Take a stiff white paper and draw two rectangles on it that are the same size as an FX and a DX sensor. This would be 24x36" for the larger rectangle, and inside it would be a smaller rectange, about 15.7x23.7" (from DPR's Sensor Size glossary page). Have someone hold an FX zoom lens in front of the paper so that it's pointed at some object, such as a parked car. Shift the paper so that the image circle surrounds the concentric rectangles. Adjust the lens's focal length (or zoom with your feet) so that the car exactly fits inside the larger rectangle. The smaller rectangle is obviously smaller than the car's image.

This is what you'd get using a DX camera and an FX camera (instead of just a lens and a piece of paper) using the same lens on both, zoomed to the same focal length, with the car at the same distance. The photo shot with the FX camera will show the entire car (barely) but the photo shot with the DX camera won't show the entire car. Now, since it's easy to obtain imaginary devices, imagine that you have two of the same computer monitors side-by-side, one displaying the FX image and the other displaying the DX image. Enlarge them both so that they fill the screen. The monitor showing the FX image will show the entire car, but the monitor showing the DX image (using greater magnification to fill the screen) will show only a little more than half of the car. If you shot both photos using the lens at 50mm then you could tell people (we assume that they know a little about photography) that the photo that shows the entire car was shot using a 50mm lens (it was), and ask them what focal length lens was used to shoot the other photo. If they assume that the same camera was used for both, a good guess would be "about 75mm", even though they would be wrong. But we know that both were shot using 50mm, and the only reason why the one shot using the DX sensor seems like it used a slight telephoto is because the "cropped" image was increased in size on the monitor. Another way of saying this is that compared with the DX photo on the monitor, the one that showed the entire car looked like a wider angle lens had been used.

SnapHappy32 said:

As far as Ive been told, i would need a 16mm DX lens to reproduce the effects of a 24mm FX lens.

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Be careful with your wording. You should have been told that you'd need to use a 16mm DX lens on a DX camera to reproduce the effects of a 24mm FX lens on an FX camera. If the 24mm FX lens was used on the DX camera, the two lenses wouldn't produce the same effects (view angles).

SnapHappy32 said:

On medium format systems a +40mm is still considered wide angle. How is that? Looking at a compact - wideangles even starts on single digits.

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The type of lens (wide angle, normal, telephoto) can not be characterized by just its focal length. Its type is a function of at least the focal length and the sensor size. Mounted on Nikon's new small sensor J1/V1 cameras, a 40mm lens would have the same view angle as a 108mm lens on an FX camera like the D700.

Mounted on a DX or FX camera (you can get lens adapters that allow this) the 40mm lens wouldn't be close to wide angle. But using the same reasoning given above, the MF +40mm lens is typically used with a much larger sensor or film frame, which gives its photos a wider angle of view than 40mm lenses mounted on DSLRs. Draw a larger rectangle on the paper mentioned above that's the actual size of the MF sensor or film frame and it will fit more into this larger frame than 40mm lenses would put inside the smaller two frames, making it a wider angle lens, but only when used with larger sensors/frames. Mount the same 40mm MF lens on an FX or DX camera and the images captured by the DSLRs will be about the same as DX cameras using 40mm DX or FX lenses, and FX cameras using 40mm FX lenses. But all three types will produce photos with different fields of view. This is really only because the images are captured by different size sensors, complicated by the fact that they are ultimately viewed at different magnifications.