How to scan 35mm negative using digital camera ?

[runswithsizzers]

In the opening post, @Rosssiiii says he is using a Durst Neonon 50mm enlarger lens and bellows.

To fill an APS-C sensor with the image of a 35mm negative or slide requires the negative be magnified about 0.65x, so less than 1:1.

The problem I had trying to use the formulas was locating the lens node. Not marked on most lenses, so any measurement requires some guesswork. In some cases, if the calculations are only a few millimeters off, it can make the difference between whether a particular combination will work as intended, or not.

 

[wiltw]

For copying 1:1, the setup will place the item being copied at 4*FL of the taking lens, from film plane. The lens node will be at 2*FL from the film plane.

 

[runswithsizzers]

[using a 50mm lens] ... For 1:1 enlargement somewhere around 80mm give or take, but that's between nodal point of the lens and the sensor. Lens-negative distance will be around 130mm.

For copying 1:1, the setup will place the item being copied at 4*FL of the taking lens, from film plane. The lens node will be at 2*FL from the film plane.

It seems to me that these can't both be correct? If I understand correctly, @wiltw would put both the sensor-to-lens distance and the subject-to-lens distance at (50mm x2 =) 100mm for each distance, symetrical around the lens node, right?

But it is probably a moot point, because as already mentioned, the OP is copying 35mm to APS-C, so is probably not using a magnification of 1:1, but more likely about 0.65x, which is the magnification needed to fill (many/most?) APS-C sensors with the image of a 35mm negative.

However, if taking multiple overlapping shots by filling the width of the sensor with the height of the film, then the magnification will need to be very close to 1:1. (My Fuji APS-C sensor is 23.9mm wide and a 35mm frame is 24mm tall.)

 

[koraks]

It seems to me that these can't both be correct?

I should have worded my reply differently when I said "1:1". What I meant was "full frame 35mm to full-coverage APS-C". That's not really 1:1 magnification.

 

[wiltw]

It seems to me that these can't both be correct? If I understand correctly, @wiltw would put both the sensor-to-lens distance and the subject-to-lens distance at (50mm x2 =) 100mm for each distance, symetrical around the lens node, right?

But it is probably a moot point, because as already mentioned, the OP is copying 35mm to APS-C, so is probably not using a magnification of 1:1, but more likely about 0.65x, which is the magnification needed to fill (many/most?) APS-C sensors with the image of a 35mm negative.

However, if taking multiple overlapping shots by filling the width of the sensor with the height of the film, then the magnification will need to be very close to 1:1. (My Fuji APS-C sensor is 23.9mm wide and a 35mm frame is 24mm tall.)

If copy 1:1, 24mm x 36mm image would be replicated to 24mm x 36mm copied image, and the 4 * FL equation applies.

 

[runswithsizzers]

If copy 1:1, 24mm x 36mm image would be replicated to 24mm x 36mm copied image, and the 4 * FL equation applies.

Correct. But the OP wants to copy to APS-C, not 24x36mm

 

[wiltw]

Correct. But the OP wants to copy to APS-C, not 24x36mm

Yes, I was merely stating that original image size = copied image size for 1:1 scale, and that 4 * FL applies to that circumstance, while koraks noted that his so-called 1:1 was in fact not the case, so no conflicting information had been conveyed.