Nikon PB-6 on a mirrorless digital camera: reproduction ratios change?

[_T_]

If you’re using a nikon z camera you’re at a slight disadvantage for a setup like yours as it’s flange distance is the shortest of any of the major manufacturers at 16mm.

Compared to the flange distance of the system the bellows is designed for (46.5mm) this means you’re losing about 30.5mm of extension from the nominal value of the bellows (208mm). At the required extension for 1:1 for an 80mm lens (≈160mm) this means you would only have about 17.5mm of further movement on the rail with which to focus.

Whether or not those 17.5mm are a viable distance in which to focus depends on how far from the sensor plane the frame of film is being held.

All of this being the case I definitely agree with Ian C that reclaiming the lost flange distance is the most obvious solution to this problem. Every mm of extension tube added is a mm of movement given back to the rail.

A set of extension tubes are also very affordable and readily available, especially compared to buying a different lens or finding and buying a difficult to source rail extension.

I would rig up a test where an object is held at the correct distance from the setup to allow it to be in focus and measure the distance at which it lies from the front of the lens with a ruler. Subtract that distance from the distance at which the film is held from from the front of the lens in your holder and that will give you the amount of additional movement you need and thus the length of extension tube(s) required. Or if the results show too great a distance for extension tubes, it will tell you if you really do require the additional extension of the extension rail

 

[Dan Fromm]

If you’re using a nikon z camera you’re at a slight disadvantage for a setup like yours as it’s flange distance is the shortest of any of the major manufacturers at 16mm.

Compared to the flange distance of the system the bellows is designed for (46.5mm) this means you’re losing about 30.5mm of extension from the nominal value of the bellows (208mm). At the required extension for 1:1 for an 80mm lens (≈160mm) this means you would only have about 17.5mm of further movement on the rail with which to focus.

Whether or not those 17.5mm are a viable distance in which to focus depends on how far from the sensor plane the frame of film is being held.

All of this being the case I definitely agree with Ian C that reclaiming the lost flange distance is the most obvious solution to this problem. Every mm of extension tube added is a mm of movement given back to the rail.

A set of extension tubes are also very affordable and readily available, especially compared to buying a different lens or finding and buying a difficult to source rail extension.

I would rig up a test where an object is held at the correct distance from the setup to allow it to be in focus and measure the distance at which it lies from the front of the lens with a ruler. Subtract that distance from the distance at which the film is held from from the front of the lens in your holder and that will give you the amount of additional movement you need and thus the length of extension tube(s) required. Or if the results show too great a distance for extension tubes, it will tell you if you really do require the additional extension of the extension rail

Hmm. If I'm clear on the OP's equipment, he has a PB-6 bellows. F-mount. He has a Z6 II body. Z-mount. F-mount into Z-mount does not go.

Attaching an F-mount bellows to a Z-mount body requires a a mount adapter FTZ or FTZ II. Male end, Z-mount, female end, F-mount. F-mount flange-to-sensitized surface distance is 46.5 mm. You say the Z-mount f-to-ss distance is 16 mm. So the adapter has to be 30.5 mm thick.

What have I missed?

If I understand the PB-6 correctly, fully collapsed it is 48 mm thick. Fully extended it is 208 mm thick. So, minimum front flange (female) to sensitized surface distance is 94.5 mm. Maximum is 254.5 mm.

In post #1 above the OP stated that a 50/2.8 enlarging lens on his rig (Z6 II + something + PB-6) "I still can't focus at 1:1 and I don't get the whole negative/slide on the sensor." The OP must have put an adapter between the PB-6 and enlarging lens. I don't think he's ever said what he used. If I'm right, he should tell us what he used.

Today the OP wrote, in post #23 above:

Today I have finally bit the bullet and tried my newly bought 80mm El-Nikkor. I had to extend it to around 160mm from the sensor plane to focus at 1:1, which made it impossible to focus on the negative, as there's not enough rail to get it further away! I need more rail... or I should have gotten a shorter lens (the Micro-Nikkor 55mm comes to mind). Looks like the 80mm El-Nikkor wasn't a good buy after all.

I suspect that the OP meant that whatever he's using to hold the negative being copied won't hold it far enough away from the lens. So, OP, what are you using to hold the neg?

The obvious solution for copying 35 mm slides/negs has been mentioned several times in this discussion. Z6 II + FTZ (or FTZ II) + PB-6 + 55 or 60 mm MicroNikkor + (ES-1 or ES-2 or PS-6) will do that jobs.

The obvious solution for copying a larger negative is Z6 II + FTZ (or FTZ II) + PB-6 + (any old lens, the OP's 50/2.8 enlarging lens would do, so would his 80/2.8) on a copy stand with the neg on a light box. OP, what are you trying to use to hold the larger neg?

 

[wiltw]

For simplicity of checking various distances...the film plane to object being copied at 1:1 will be 4*FL ...

• 2*FL is distance of film plane to lens optical node,
• 2*FL s the distance from lens optical node to object being copied.

 

[_T_]

Hmm. If I'm clear on the OP's equipment, he has a PB-6 bellows. F-mount. He has a Z6 II body. Z-mount. F-mount into Z-mount does not go.

Attaching an F-mount bellows to a Z-mount body requires a a mount adapter FTZ or FTZ II. Male end, Z-mount, female end, F-mount. F-mount flange-to-sensitized surface distance is 46.5 mm. You say the Z-mount f-to-ss distance is 16 mm. So the adapter has to be 30.5 mm thick.

What have I missed?

If I understand the PB-6 correctly, fully collapsed it is 48 mm thick. Fully extended it is 208 mm thick. So, minimum front flange (female) to sensitized surface distance is 94.5 mm. Maximum is 254.5 mm.

In post #1 above the OP stated that a 50/2.8 enlarging lens on his rig (Z6 II + something + PB-6) "I still can't focus at 1:1 and I don't get the whole negative/slide on the sensor." The OP must have put an adapter between the PB-6 and enlarging lens. I don't think he's ever said what he used. If I'm right, he should tell us what he used.

Today the OP wrote, in post #23 above:



I suspect that the OP meant that whatever he's using to hold the negative being copied won't hold it far enough away from the lens. So, OP, what are you using to hold the neg?

The obvious solution for copying 35 mm slides/negs has been mentioned several times in this discussion. Z6 II + FTZ (or FTZ II) + PB-6 + 55 or 60 mm MicroNikkor + (ES-1 or ES-2 or PS-6) will do that jobs.

The obvious solution for copying a larger negative is Z6 II + FTZ (or FTZ II) + PB-6 + (any old lens, the OP's 50/2.8 enlarging lens would do, so would his 80/2.8) on a copy stand with the neg on a light box. OP, what are you trying to use to hold the larger neg?

You’re right. I forgot about the adapter.

 

[fdonadio]

For simplicity of checking various distances...the film plane to object being copied at 1:1 will be 4*FL ...

• 2*FL is distance of film plane to lens optical node,
• 2*FL s the distance from lens optical node to object being copied.

BINGO!

That’s what’s happening here. PB-6’s rail is 250mm long. I need 320mm between the Z6 II sensor and the slide/negative being digitized. This can be solved by using a long extension ring, like @Ian C and @_T_ said. The camera will go further back and the bellows can be contracted a little.

I have also noticed that my problem with the El-Nikkor 50mm is the exact opposite: the bellows won’t contract enough to make the lens nodal point be 100mm away from the sensor.

Using lenses designed for Nikon cameras (Micro-Nikkors) would be the best solution, as @Dan Fromm suggests. They are designed with the flange distance in mind. Also, for 35mm, I wouldn’t need more than 60mm focal distance.

 

[fdonadio]

@gorbas and @Dan Fromm : I will be posting pictures of my set up and more detailed explanations tomorrow. It’s almost 1am here and I gotta sleep.