Film lens no good for digital???

[Gadgit]

I was talking to a friend who shot film some time ago and now has a D700. He was telling me that his older Nikon 700 2.8 (not sure what model) lens, which was made for film has some of the colours out of focus. This didn’t make sense to me so he explained that film has different layers for the different colours and that the lens was made to focus the different colours at different points. Digital needs the colours to be focused at the same point.

Is this for real? Maybe someone will get a good laugh from this thread.

[ATJ]

Wow, a 700mm f/2.8 lens? That would be a huge mother.

I didn't even know Nikon made any 700mm lenses, only 600mm and 800mm. The largest aperture would have been f/4 on a 600mm lens.

The bit about a lens needing to focus different colours on different layers sounds like BS to me. It sounds more like the lens has chromatic aberrations

I have a bunch of lens which worked on my film cameras and were fine on my digital cameras.

[Matt. K]

He's talking about chromatic aberration....the inability of some lenses to focus red,blue and green at the same point. This affects film in the same way it affects a digital sensor. Most Nikkor lenses are very well corrected against this fault so there should be little problem with using the lens on a digital camera. I'm guessing you mean a 200mm F2.8? There is no such creature as a 700mm F2.8.......yet.

[gstark]

What Matt says is correct.

But let's take it a bit further: do you have a camera onto which the lens may be mounted? If so, finding the answer to the question could not be any easier: just take some shots with the lens and see for yourself.

If the lens is, indeed, a Nikkor of some sort, I would be very surprised if there were any real issues. Of greater concern would be the compatibility of the lens, but if it's an Ai or later, (mid 70's) then there should not be any issues at all.

[surenj]

700mm F2.8.......yet.

You'll need to buy a hummer or something to mount this on the back like a rocket launcher.

[Gadgit]

Sorry, I've just realised that I wrote 700 2.8 and should have put 300 2.8. My only excuse is that I've been looking up a lot of info on the D700 lately.

[Gadgit]

Now that I've got the 700 - 200 mistake corrected I will reply to the replies
CA seems to make sense. The impression I got was that this problem wasn't an issue using film (and therefore a different camera).
Gary, I'm sure that the lens is newer than mid 70's. He said that he had to order it and Nikon were only importing a few into the country. He's about 37, so unless he got it at a very young age, it would be later than mid 70's.
I may have to borrow it to see for myself.

Thanks to all for your replies.

[aim54x]

Sounds rather funny to me as well. A Nikkor should not have the CA issues being described, esp if it is a 2.8. Film lenses are great on digital, love the Ai 135mm f/2.8 on my digital bodies.

[Mr Darcy]

I am going to go against the flow here.
If you look at film undar a microcope, it is composed of layers stacked vertically (from the point of view of the light hitting it.) Each layer has a different chemical compostion that respnds to a different wavelength of light Thus each colour SHOULD focus on a different plane.
Now consider a digital sensor. Here, all colour receptors are on the same surface. so every colour SHOULD focus onthe same plane.

This means in theory that the CA response of any lens should be different when you compare Film to Digital. Now IF the lens in question was cunningly optimised for CA performance by deliberately getting the different colours to focus precisely on the different layers then the CA performance in digital may well be degraded when compared to its peformance on film.

This of course is subject to a number of caveats:

The lens was designed this way
The thickness of the film is significant optically
All the receptor sites on a digital sensor are on the same plane
The curvature of the focussed image is negligible
All films order the layers in the same way
and so on

I don't know the answers to any of these.

The only way to confirm is to test. Let us know the results.

[gstark]

Greg,

I think I can offer a little more confusion for you here ...

If you look at film undar a microcope, it is composed of layers stacked vertically (from the point of view of the light hitting it.) Each layer has a different chemical compostion that respnds to a different wavelength of light Thus each colour SHOULD focus on a different plane.

And if you're shooting B&W film there are how many layers?

[Mr Darcy]

Greg,

I think I can offer a little more confusion for you here ...

If you look at film undar a microcope, it is composed of layers stacked vertically (from the point of view of the light hitting it.) Each layer has a different chemical compostion that respnds to a different wavelength of light Thus each colour SHOULD focus on a different plane.

And if you're shooting B&W film there are how many layers?

And just how important is chromatic aberration on B&W film?

[aim54x]

Greg,

I think I can offer a little more confusion for you here ...

If you look at film undar a microcope, it is composed of layers stacked vertically (from the point of view of the light hitting it.) Each layer has a different chemical compostion that respnds to a different wavelength of light Thus each colour SHOULD focus on a different plane.

And if you're shooting B&W film there are how many layers?

And just how important is chromatic aberration on B&W film?

wouldnt CA be apparent in B&W in the terms of soft edges?

Greg you have a good point about stacked layers on colour film...but are slide and negative films stacked the same way? would they really have bothered?

[ATJ]

http://www.naturfotograf.com/lens_tele.html

For 300 mm f/2.8 Nikkor ED-IF

In common with other ED-IF designs from the same era, the 300/2.8 does show some peripheral colour fringing used on the D2X and D3. Image sharpness suffers as well. Post-processing can mitigate this issue to some extent, but I have to admit that the modern 300 mm designs should be preferred with these modern cameras.

[ATJ]

If you look at film undar a microcope, it is composed of layers stacked vertically (from the point of view of the light hitting it.) Each layer has a different chemical compostion that respnds to a different wavelength of light Thus each colour SHOULD focus on a different plane.
Now consider a digital sensor. Here, all colour receptors are on the same surface. so every colour SHOULD focus onthe same plane.

While this is true... there are only 3 layers on colour film and it would generally not be possible to have those 3 colours focus differently while maintaining other combinations.

For example, colour negative film has yellow, magenta and cyan layers which react to blue, green and red light respectively. So, which layer do you focus yellow light on? Yellow light is a distinct wavelength (around 570nm) and as such could only be focused on one layer.