Looking to lighten the load.

Longlurker

Hello all, first time post here. I've lurked here for years and have a few questions. I need to understand the limitations of the Nikon 1 system. Particularly the limitations of the sensor and lenses. I know to multiply my FF lenses x 1.4 to attain focal length for my D90 but don't know for the Nikon 1 sensor. I don't understand how- or if- the change in sensor changes depth of field. Can anyone point me to a website or enlighten me here?

My wife and I recently returned from Alaska and my back ached for a week after returning. I weighed my camera bag at just over 10 pounds. 30 years of working construction over my head has done a number on my spine. Thank You.

Elvishefer

Hi,

While this page doesn't answer your question directly, Thom Hogan's mirrorless camera site is a great place for information on the different systems out there. As a Nikon shooter, much of what he says should be relevant to you to some degree. Start here:

http://www.sansmirror.com/articles/how-do-i-choose.html

spraynpray

Hi Longlurker, welcome.

The smaller the sensor, the greater the depth of field for a given aperture, lens focal length and distance. Google DoF master and have a play with the on line depth of field calculater to build an understanding of how depth of field works.

HTH,

Symphotic

The factor for the lens equivalence is 2.7. So the 10 mm pancake lens on the Nikon 1 is the same field of view as a 27 mm lens on full frame.
The nikon 1 is an excellent system: compact, lightweight, and the frame rate and high speed video capabilities make it an exceptional value.

Gareth

The last two posts will most likely just confuse you.

First 2.7 x focal length is for FX, not DX like your D90. I think the 1.4 you stated sounds right.

Second "

The smaller the sensor, the greater the depth of field for a given aperture, lens focal length and distance.

While I agree using DoF mater is a good idea, it may not help if you don't understand what is actually happening.

Imagine a rectangle representing your D90 sensor. Then imagine a smaller rectangle inside it representing the Nikon 1 sensor. In order for the smaller rectangle to take in the same scene as the lager rectangle it is necessary to take a few steps back. The further from the subject you are the greater the DoF, and that is why smaller sensors have greater DoF when framing the same shot.

Longlurker

Thanks all. Great information. Excellent description of DoF change Gareth, that helps me a lot. DoF is something I'm finally grasping and learning to actually enjoy using.

Longlurker

After some reading, I see that 18.5 mm Nikon 1=35mm DX=50mm FF as far as angle of view- roughly 45 degrees. Giving the same perspective. Please correct me if I'm wrong.

The next question I have is whether these lenses on their respective sensor cameras, at the same Fstop, have the same Dof or not. If not, is there a calculation for that?

Longlurker

I found the answer to my question with calculations on a site by Laszlo Pusztai, written on June 13 2013. I have to do some math to see if the sensor in the Nikon 1 line along with the available lenses are capable to do what I'd like them to do in lower light.

Symphotic

Here are two snapshots using exactly the same 55mm lens, both at f2.8. The actual depth of field is the same, even though the sensors are quite different. (These were both manually focused, so the focus point is not exactly in the same place, but you should be able to see a comparison in the depth of field.) Note that the D800 image is cropped to about the same field size as the V1.

V1 (as shot):

D800 (cropped):

Longlurker

hmm, the more I read on the internet- the more confused I get.

PB_PM

The depth of field does not change, only the portion of the optics that the sensor uses changes.

Symphotic

The depth of field does not change, only the portion of the optics that the sensor uses changes.

+1!
If you will allow me one more snapshot to illustrate what Gareth says above, here is the same image with the D800, but moved closer to the subject so that it fills the same field that the V1 shot fills. Now, because I am much closer, the depth of field is narrower.

Mathematically, depth of field is calculated using only a few variables: effective aperture, circle of least confusion, and image magnification. But since image magnification varies with lens focal length and focusing distance, most photographers summarize the effect as Gareth does, which is quite proper. Spraynpray summarizes this as DOF being a function of aperture, focal length and distance. (The math is actually rather involved, so the camera companies did us a disservice by taking the quick and easy depth of field scales off the lens bodies.)

Longlurker

O.K., here goes nothing. this is what I'm taking from this. A 100mm 2.8 lense on a FF camera produces "X" DoF. Using a Nikkor 1camera, CX sensor, with a 2.7 crop factor would require a 37mm lense to give the same Field of vision and same picture as the FF at the same distance. In order for the CX sensor to achieve the same DoF as the FF sensor does, I would need to move closer to the subject or use 270mm lense.

Is my math right here? Or am I still clueless?

Symphotic

Here's the math for close focused objects (that means other than infinity):

DOF=Far Limit of Field - Near Limit of Field, of DF=FLF-NLF

Calculating the limits of field we use the "hyperfocal distance method"

The hyperfocal distance (H) = lens focal length squared /(lens f-number x 0.03) where 0.03 is the "circle of least confusion" You can vary this number if you need more or less focus in your perceived "in focus" field, but for cameras this size, 0.03 is the established number.

FLF=H x distance /(H - distance - focal length)
NLF = H x distance / H + distance - focal length)

In the photo above, my FLF using my excel spreadsheet is ~252 mm and my NLF is ~249 mm the subject was ~250 mm away, and the DOF is about 3 mm, which is what I measured.

PB_PM

The lens never changes focal length regardless of what camera you have it on. A 37mm lens on a Nikon 1 would give you a tighter frame, but not because it is cropping anything. You would also still get all the characteristics of a 37mm lens, not a 105mm lens. It would lack the compression of a real telephoto lens. If anything the words "crop factor" are a little misleading. The camera isn't cropping anything. The 1" sensor in the Nikon 1 is what it is. All the changes is how much of the optics are used, thus it captures less of the scene than a camera with a 35mm (FX) sensor.

Symphotic

PB_PM is quite right. If you look at my math above, you'll see that never once do we need to know the imager size or field of view to calculate depth of field, only the distance, focal length and aperture.

If you use two different focal lengths to get the same field of view on two different imager sized cameras, you will have two different depths of fields, not because the imager size is different but because the focal length is different, giving you a different magnification.

If you use the same focal length at different distances to get he same field of view, you have two different magnifications again, so you will get different depths of field.

If you use the same focal length at the same difference on the two different imager sizes, you will get the same depth of field, but different fields of view. In this case, the magnification is the same, but the FF sensor can capture more field of view.

I have used the V1 and the D800 daily since they came on the market, and it really isn't a problem. They are great cameras.

Longlurker: are you trying to get MORE depth of field, or LESS depth of field? What is your subject matter? One doesn't usually have a problem with too much depth of field when you are hiking around Alaska.

Symphotic

O.K., here goes nothing. this is what I'm taking from this. A 100mm 2.8 lense on a FF camera produces "X" DoF. Using a Nikkor 1camera, CX sensor, with a 2.7 crop factor would require a 37mm lense to give the same Field of vision and same picture as the FF at the same distance. In order for the CX sensor to achieve the same DoF as the FF sensor does, I would need to move closer to the subject or use 270mm lense.

Is my math right here? Or am I still clueless?

You can't get the CX system to get the depth of field and field of view to match the tiny depths of field available on the FX sensors without impossible apertures. That's why if you want small depths of field, you need FX or larger imagers.

If you want LARGE depths of field, you will have an easier time getting them with the smaller sensor, as you would need impossibly tiny apertures on FX to match the large depths of field available with reasonable apertures on CX.

Longlurker

"The lens never changes focal length regardless of what camera you have it on. A 37mm lens on a Nikon 1 would give you a tighter frame, but not because it is cropping anything."

"If you use the same focal length at the same difference on the two different imager sizes, you will get the same depth of field, but different fields of view. In this case, the magnification is the same, but the FF sensor can capture more field of view."

This explains what I was asking perfectly. Thank You.

My concern is being able to get a shallow enough DoF for close quarter work.

http://farm6.staticflickr.com/5498/10914953904_fdc216b4d9_z.jpg

Longlurker

DoF for any given lens at any given Fstop is the same regardless of the sensor the camera has.

Smaller sensors record less of the image at the same distance from the object. 'Maginfying' the image and giving the impression of a longer lense.

I would need a larger aperture to reduce the DoF.

Ade

The lens never changes focal length regardless of what camera you have it on. A 37mm lens on a Nikon 1 would give you a tighter frame, but not because it is cropping anything. You would also still get all the characteristics of a 37mm lens, not a 105mm lens. It would lack the compression of a real telephoto lens. ...

The last sentence is a bit misleading. Technically speaking, the focal length of a lens has nothing to do with compression. What affects compression is the location (distance) of the camera in relation to the subject.

So there is no perspective compression that comes with a "real telephoto lens". If you take the 37mm lens on a CX camera and a 105mm lens on an FX camera, and use both to shoot the same subject from the same spot, then you will get the exact same perspective compression.

In fact, since the focal length doesn't actually matter, if you were to use a third camera (say, with a wide-angle 24mm on an FX camera) to again shoot the same subject from the same spot, you will still get the exact same compression. The field of view will be much wider on the 24mm FX, but you can crop the resulting image to have the same FoV, and you still get the same compression as before because the subject-distance is the same.

Gareth

DoF for any given lens at any given Fstop is the same regardless of the sensor the camera has.
I would need a larger aperture to reduce the DoF.

I'm glad you found my explanation helpful, I understand clearly when I think of it like this (the rectangles).

Symphotic's image makes it less clear but obviously what it illustrates it true. But who frames an image with the intention of cropping out most of it if they don't have to?

You would notice a huge difference in DoF if the images were FRAMED the same and not CROPPED the same.

Your statement about DoF quoted above is true. The Nikon 1 is a great camera if you want a lot of DoF, but not if you want a shallow DoF, and the lenses available make a shallow DoF even harder to achieve.

heartyfisher

"You would notice a huge difference in DoF if the images were FRAMED the same and not CROPPED the same."

Yes and that means that the DOF is not the same depending on the the sensor size. contrary to this statement.

"If you use the same focal length at the same difference on the two different imager sizes, you will get the same depth of field, but different fields of view. In this case, the magnification is the same, but the FF sensor can capture more field of view."

Longlurker

Thank you everyone. It took me a while, but things finally clicked