Nikon DX Lens Numbering Question

Zarch

Zarch

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Am I right in thinking that the numbers on DX lens aren't the actual focal lengths? That they need to be multiplied by 1.5 to get 35mm equivalents? (i'm assuming an older "standard" that is still used as the benchmark?)

If so, am I right in thinking that the 18-55 kit lens with my D3100 is actually 27-82.5?

I ask because on my old Panasonic superzoom (FZ28) it had an Wide to 18x Zoom lens which was quoted at 27-486 (35mm equiv).

So in "DX" terms, that range would be 18-324? (divided by 1.5)


I know its impossible to cover that range with my D3100 with a single lens, but just like to know I've got the figures right comparing what I had to what i've got now. :thumbs:

Thanks.
 
Zarch said:
Am I right in thinking that the numbers on DX lens aren't the actual focal lengths? That they need to be multiplied by 1.5 to get 35mm equivalents? (i'm assuming an older "standard" that is still used as the benchmark?)

If so, am I right in thinking that the 18-55 kit lens with my D3100 is actually 27-82.5?

I ask because on my old Panasonic superzoom (FZ28) it had an Wide to 18x Zoom lens which was quoted at 27-486 (35mm equiv).

So in "DX" terms, that range would be 18-324? (divided by 1.5)


I know its impossible to cover that range with my D3100 with a single lens, but just like to know I've got the figures right comparing what I had to what i've got now. :thumbs:

Thanks.
Click to expand...

not quiet - a 50 mm focal length is a 50 mm focal length regardless of format. Focal length doesn't change.

The angle of view changes so a 50mm on DX would give an equivilent field of view as a 75mm on FX (where your 1.5 multiplier comes in)
 
boyfalldown said:
not quiet - a 50 mm focal length is a 50 mm focal length regardless of format. Focal length doesn't change.

The angle of view changes so a 50mm on DX would give an equivilent field of view as a 75mm on FX (where your 1.5 multiplier comes in)
Click to expand...

Thank you...... so its the smaller DX body/sensor that messes with things.

So does this means that if you buy a 18-200 zoom lens you only get 12-133 on a DX body? :thinking: Whereas you'd get the full range on FX?
 
Zarch said:
Thank you...... so its the smaller DX body/sensor that messes with things.

So does this means that if you buy a 18-200 zoom lens you only get 12-133 on a DX body? :thinking: Whereas you'd get the full range on FX?
Click to expand...

Trust me, it's not worth bothering about.....
 
Flash In The Pan said:
Trust me, it's not worth bothering about.....
Click to expand...

LOL, I believe you......... okay without getting into the technicalities, what is the DX equivalent range that my old FZ28 superzoom was quoted as doing: 27-486 (35mm equiv).

If I decided that I wanted to cover the same range in DX lenses?
 
Zarch said:
LOL, I believe you......... okay without getting into the technicalities, what is the DX equivalent range that my old FZ28 superzoom was quoted as doing: 27-486 (35mm equiv).

If I decided that I wanted to cover the same range in DX lenses?
Click to expand...

To get 27-486mm (35mm equivalent) coverage on a DX body, you'd need DX lenses that covered 18-324mm.
 
Zarch said:
LOL, I believe you......... okay without getting into the technicalities, what is the DX equivalent range that my old FZ28 superzoom was quoted as doing: 27-486 (35mm equiv).

If I decided that I wanted to cover the same range in DX lenses?
Click to expand...

It's a bit hard to give you a direct comparison, in "optical zoom" mode your FZ28 is quoted as being 3MP, so what I think what it is doing is applying a crop factor (like saying a 50mm DX lens is equivalent to a 75mm FF one).

To give you an idea of the difference

550px-Sensor_sizes_overlaid_inside.svg.png


Your Panasonic has a 1/2.5" sensor, that's the smallest green box in the diagram and in "optical zoom" mode is only using a third of that. Now compare that with the box for the Nikon DX size.

See the difference? You're not getting more zoom or a longer focal length all your getting is part of the image captured on a tiny section of a very small sensor.
 
Apologies for interrupted, but I'd just like to say thankyou for the last few explanations.

I'm hoping to move from an FZ28 to a dSLR in the next few days, but one thing that has been a niggling concern is the phenomenal zoom capability of the FZ28. Now that it has been explained in plain English (for a simpleton like me to understand) it appears that it is cropping some of the image to make the "zoom" appear better.

So as I understand it, I can achieve a similar result on a dSLR with a smaller focal range lens by cropping the image manually (albeit in PP afterwards) and because of the larger sensor, the dSLR should give a better image than the FZ28.

Or have I misunderstood completely?
 
Chappers. said:
Apologies for interrupted, but I'd just like to say thankyou for the last few explanations.

I'm hoping to move from an FZ28 to a dSLR in the next few days, but one thing that has been a niggling concern is the phenomenal zoom capability of the FZ28. Now that it has been explained in plain English (for a simpleton like me to understand) it appears that it is cropping some of the image to make the "zoom" appear better.

So as I understand it, I can achieve a similar result on a dSLR with a smaller focal range lens by cropping the image manually (albeit in PP afterwards) and because of the larger sensor, the dSLR should give a better image than the FZ28.

Or have I misunderstood completely?
Click to expand...

Basically, yes :thumbs:
 
Flash In The Pan said:
It's a bit hard to give you a direct comparison, in "optical zoom" mode your FZ28 is quoted as being 3MP, so what I think what it is doing is applying a crop factor (like saying a 50mm DX lens is equivalent to a 75mm FF one).

To give you an idea of the difference

550px-Sensor_sizes_overlaid_inside.svg.png


Your Panasonic has a 1/2.5" sensor, that's the smallest green box in the diagram and in "optical zoom" mode is only using a third of that. Now compare that with the box for the Nikon DX size.

See the difference? You're not getting more zoom or a longer focal length all your getting is part of the image captured on a tiny section of a very small sensor.
Click to expand...

The only problem with that is that now I want a medium format system...
 
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