Tweet
Roller...Absolutely love the setup! That slider looks super rigid and adjustable, should be a great copy stand.
That said, you have a severe limitation with that setup using a 55mm Micro lens. It's possible you will never get the stand much above its minimum extension because it just won't focus at longer working distances. To explain the problem, I've got to explain magnification in an optical system, so don't go to sleep...
First, let's discuss magnification. Using a Nikon APS-C camera as example, the sensor height is ~16mm. Thus to fill the sensor with an image of a 19mm diameter Lincoln Cent, the magnification is 16/19mm, or M=0.84.
Nikon cameras have a "register" distance, ie the distance from sensor to the lens mount plane, of 46.5mm. This is the distance that any Nikon mount lenses are designed to give infinity focus. All lenses extend somewhat either inside or outside this register distance. Your 55mm Micro actually sits outside by about 8.5mm when focused at infinity, so it sits exactly 55mm from the sensor at infinity focus as a 55mm lens should.
The Nikon Bellows-2 you are using has a minimum extension of approx 50mm. This includes the physical length of the bellows "standards" and the mounts. This minimum extension adds to the "register" distance.
The critical number to calculate magnification is the Total Extension. For your system, the minimum total extension of the lens from the sensor is 46.5mm + 8.5mm + 50mm = 105mm.
The magnification of a lens system is given by:
M = (Total Extension - Focal Length) / Focal Length
With the numbers from your system, the minimum magnification is:
M = (105 - 55) / 55 = 0.91
This is more than 0.84 so is too much magnification to frame a Lincoln Cent on your sensor! And there is little you can do about it with the system you have. There are bellows available that have shorter minimum distance that you can use, but most are at least 40mm, though you really only need a few mm less to get the whole Cent in the picture.
You could use a full-frame camera, with 24mm sensor, but that's a big extra expense.
Unfortunately, your best option may be to shift over to a longer lens. For the system you've constructed, the 105mm Micro is a better choice. Working through the numbers gives a minimum magnification of 0.47 with the 105 Micro. Even this may get a bit annoying to you since you need minimum magnification of 0.42 to fill the sensor with a Dollar, but at least you have plenty of length for Cents.
An even better approach may be to use an enlarging lens instead of a Macro lens. A 105mm EL-Nikkor has very little if any lens extension, so would allow nearly infinity focus with your system. 135mm and 150mm EL-Nikkors are available as well and would allow much bigger working distances and lighting flexibility.
Hope this helps...Ray
That said, you have a severe limitation with that setup using a 55mm Micro lens. It's possible you will never get the stand much above its minimum extension because it just won't focus at longer working distances. To explain the problem, I've got to explain magnification in an optical system, so don't go to sleep...
First, let's discuss magnification. Using a Nikon APS-C camera as example, the sensor height is ~16mm. Thus to fill the sensor with an image of a 19mm diameter Lincoln Cent, the magnification is 16/19mm, or M=0.84.
Nikon cameras have a "register" distance, ie the distance from sensor to the lens mount plane, of 46.5mm. This is the distance that any Nikon mount lenses are designed to give infinity focus. All lenses extend somewhat either inside or outside this register distance. Your 55mm Micro actually sits outside by about 8.5mm when focused at infinity, so it sits exactly 55mm from the sensor at infinity focus as a 55mm lens should.
The Nikon Bellows-2 you are using has a minimum extension of approx 50mm. This includes the physical length of the bellows "standards" and the mounts. This minimum extension adds to the "register" distance.
The critical number to calculate magnification is the Total Extension. For your system, the minimum total extension of the lens from the sensor is 46.5mm + 8.5mm + 50mm = 105mm.
The magnification of a lens system is given by:
M = (Total Extension - Focal Length) / Focal Length
With the numbers from your system, the minimum magnification is:
M = (105 - 55) / 55 = 0.91
This is more than 0.84 so is too much magnification to frame a Lincoln Cent on your sensor! And there is little you can do about it with the system you have. There are bellows available that have shorter minimum distance that you can use, but most are at least 40mm, though you really only need a few mm less to get the whole Cent in the picture.
You could use a full-frame camera, with 24mm sensor, but that's a big extra expense.
Unfortunately, your best option may be to shift over to a longer lens. For the system you've constructed, the 105mm Micro is a better choice. Working through the numbers gives a minimum magnification of 0.47 with the 105 Micro. Even this may get a bit annoying to you since you need minimum magnification of 0.42 to fill the sensor with a Dollar, but at least you have plenty of length for Cents.
An even better approach may be to use an enlarging lens instead of a Macro lens. A 105mm EL-Nikkor has very little if any lens extension, so would allow nearly infinity focus with your system. 135mm and 150mm EL-Nikkors are available as well and would allow much bigger working distances and lighting flexibility.
Hope this helps...Ray
Comment