Sharing lenses between N50 and D50?

In article ,
Howard Larson wrote:
I have an N50 equipped with Sigma AF zoom lenses. I was thinking of
moving into digital realm by buying a D50 body and sharing the Sigma
lenses. Are there any pitfalls in this plan?

I have never handled these Sigma lenses, nor have I handled a
N50, so I have to ask:

"Is the lens fitted with a CPU (electrical contacts on the part
which projects into the body)?"

If it has the CPU, it should work with the D50 (and with the
D70, which I do have and use).

However -- if, for metering, it depends on the AI notches in the
aperture ring, then it will probably only work in manual mode. You'll
have to use a hand-held exposure meter with it -- or establish exposure
via trial shots and "chimping" (looking at the resulting image on the
display -- and at the histogram), and adjusting exposure appropriately.

I know that my N90s uses either the CPU or the AI notches,
depending on what a lens may offer. The D70 does not use the AI
notches, other than one tab to tell the body that the lens is stopped
all the way down.

Does the 1.5x factor
mentioned in ads mean the effective focal length of the 35mm lens is
1.5x greater?

That is correct.

Enjoy,
DoN.

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"Howard Larson" wrote in message
...
I have an N50 equipped with Sigma AF zoom lenses. I was thinking of
moving into digital realm by buying a D50 body and sharing the Sigma
lenses. Are there any pitfalls in this plan? Does the 1.5x factor
mentioned in ads mean the effective focal length of the 35mm lens is
1.5x greater?


The 1.5x factor is bogus. The focal length does not change one millimeter.
The only thing that changes is that the part of the image circle which forms
the image on the sensor gets smaller, effectively giving you a cropped
image.
This means that the angle of view of a lens mounted on a D50 is smaller than
that same lens on an N50, leading to the effect of making lenses with
smaller focal length tele lenses.
DOF, tele compression, etc. etc. don't change at all.

To see the effect, take an image from your N50 and crop away about a third
horizontally and vertically (while keeping the resulting image centered).
That's what a D50 would produce with the same lens.

As to whether your lenses will work:
If they work on the N50 they should work on the D50.

In article ,
Jeroen Wenting jwenting at hornet dot demon dot nl wrote:

"Howard Larson" wrote in message
.. .
I have an N50 equipped with Sigma AF zoom lenses. I was thinking of
moving into digital realm by buying a D50 body and sharing the Sigma
lenses. Are there any pitfalls in this plan? Does the 1.5x factor
mentioned in ads mean the effective focal length of the 35mm lens is
1.5x greater?


The 1.5x factor is bogus. The focal length does not change one millimeter.

He said "effective" focal length --- which is shorthand for the
coverage to be expected.

The only thing that changes is that the part of the image circle which forms
the image on the sensor gets smaller, effectively giving you a cropped
image.
This means that the angle of view of a lens mounted on a D50 is smaller than
that same lens on an N50, leading to the effect of making lenses with
smaller focal length tele lenses.

Exactly what "effective" refers to. Most people use the focal
length as shorthand for the coverage (angle of view), because they have
lots of experience with what to expect on a full-frame 35mm camera with
given focal lengths. DOF and other such features are usually secondary
considerations.

DOF, tele compression, etc. etc. don't change at all.

The DOF, when printed to the same size, should remain pretty
constant. The smaller circle of confusion of the shorter focal length
lens needed to give the same coverage will be enlarged with the image,
giving the same effect.

To see the effect, take an image from your N50 and crop away about a third
horizontally and vertically (while keeping the resulting image centered).
That's what a D50 would produce with the same lens.

Precisely. Now -- enlarge that area to the same size print and
you should get a better idea of what will happen.

As to whether your lenses will work:
If they work on the N50 they should work on the D50.

That one I was not sure of, since I don't know whether the N50
depended on the CPU in the lenses. If it does, then the D50 should do
the same.

Enjoy,
DoN.
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"Jeroen Wenting" jwenting at hornet dot demon dot nl writes:

DOF, tele compression, etc. etc. don't change at all.

Well, there *is* no such thing as tele compression. It's where you're
standing relative to the subjects that causes that effect. Neither
the focal length nor the field of view affect the perspective.
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In article ,
Howard Larson wrote:

[ ... ]

Thanks, all, for the helpful answers.

You're welcome.

The N50 does have a set of seven contacts inside the body centered on
the 12o'clock position. The Sigma lenses have a matching set of five
contacts (two of the contact positions are not used).

That sounds like a match for the three lenses which I have with
a CPU fitted -- the "28-105mm f3.5-4.5 D", the "50mm f1.4", and the
(converted to CPU) 180mm f2.8 manual focus. As viewed from the camera,
I see one contact, two spaces, and four more contacts.

I have two zoom lenses on the N50: 28-80mm and 70-210mm. So, I
assume these lenses, when mounted on the D50, would look like a
42-120mm 105-315mm on a 35mm camera.

Yes -- at least as far as coverage is concerned. The other
focal-length related behavior (such as DOF) can lead you into endless
debates on this newsgroup.

Since the D50 comes with a
Nikkor 18-50mm zoom, I thought I would buy it as well so as to have
overlapping coverage of (in 35mm terms) 27-75mm , 42-120mm and
105-315mm .

This sounds right.

I am assuming the Nikkor digital lens with 18-50mm focal length on
the D50 would be equivalent to mounting a 27-75mm lens on a 35mm
camera.

And that 18mm wide end on the kit lens will give you the back
what you lost to the crop factor from your 28-80mm lens. I don't know
how much you use the wide angle end of your lenses, but you will have
that back, and some extra telephoto reach.

Am I interpreting this correctly or have I gone off into the weeds?

It sounds as though you have it all.

I wonder how well the 18-50mm will work on your N50? I don't
know whether it gives full coverage on a full frame. If it does, you
will have also expanded your film capabilities.

Enjoy,
DoN.

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