Hello,
This is a program for the Texas Instruments TI-58 and TI-59 calculators.
It's called "Auszug" (German for "extension"). It calculates the exposure adjustment when doing macro work with the lens on a bellows or extension tube. If you don't use a TTL light meter (inside the camera) you can calculate the correct exposure starting from a normal meter reading of a handhold exposure meter.
The program needs some input, all of it is in mm (milli-meters).
Focal length of lens: <length in mm> "A" (this is reqired, and initlializes "B" and "C" settings to 0)
Distance setting on lens: <distance in mm> "B" (use 0 for infinity setting)
Extension tube/bellow extension: <extension in mm> "C"
Then press "D" to calculate the extension factor. You can multiply this with the exposure time to get a correct exposure time.
Alternatively/additionally you can press "E" to get the extension factor in sqr(2) steps. Change the aperture with that many steps.
I've attached a scan of the printout of the program. And a version written by a TI-59 emulator for Windows.
If this appears somehow antique to you (programmable calculator from the 70ies), remember that you can get an emulator of this machine for your Android cell phone. And usage is straightforward. Type numbers and "A", "B", ..."E" buttons. I'd say it's quicker to access than a typical Android program with GUI.
This is the first version. I'm currently thinking about how to make it more LF-friendly. With LF lenses (or general lenses which don't have a distance setting and are mounted on a bellows) one currently has to enter as extension ("C") the actual extension minus the focal length.
Another idea for improvement is to allow medieval units for lenght (inches, feet) instead of just millimeters.
regards,
chris
LBL A X/T 0 STO 1 STO 2 X/T STO 0 RTN
LBL B STO 1 RTN
LBL C STO 2 RTN
LBL D RCL 1 EQ CE ( RCL 1 X2 / 4 - RCL 0 * RCL 1 ) INV GE CP
SQR ( CE + RCL 1 / 2 ) ± ( CE + RCL 1 ) GTO LNX
LBL CE RCL 0 LBL LNX ( ( CE + RCL 2 ) X2 / RCL 0 X2 ) FIX 1 RTN
LBL CP 1 ± SQR R/S
LBL E ( SBR D LNX / 2 LNX ) RTN
This is a program for the Texas Instruments TI-58 and TI-59 calculators.
It's called "Auszug" (German for "extension"). It calculates the exposure adjustment when doing macro work with the lens on a bellows or extension tube. If you don't use a TTL light meter (inside the camera) you can calculate the correct exposure starting from a normal meter reading of a handhold exposure meter.
The program needs some input, all of it is in mm (milli-meters).
Focal length of lens: <length in mm> "A" (this is reqired, and initlializes "B" and "C" settings to 0)
Distance setting on lens: <distance in mm> "B" (use 0 for infinity setting)
Extension tube/bellow extension: <extension in mm> "C"
Then press "D" to calculate the extension factor. You can multiply this with the exposure time to get a correct exposure time.
Alternatively/additionally you can press "E" to get the extension factor in sqr(2) steps. Change the aperture with that many steps.
I've attached a scan of the printout of the program. And a version written by a TI-59 emulator for Windows.
If this appears somehow antique to you (programmable calculator from the 70ies), remember that you can get an emulator of this machine for your Android cell phone. And usage is straightforward. Type numbers and "A", "B", ..."E" buttons. I'd say it's quicker to access than a typical Android program with GUI.
This is the first version. I'm currently thinking about how to make it more LF-friendly. With LF lenses (or general lenses which don't have a distance setting and are mounted on a bellows) one currently has to enter as extension ("C") the actual extension minus the focal length.
Another idea for improvement is to allow medieval units for lenght (inches, feet) instead of just millimeters.
regards,
chris
LBL A X/T 0 STO 1 STO 2 X/T STO 0 RTN
LBL B STO 1 RTN
LBL C STO 2 RTN
LBL D RCL 1 EQ CE ( RCL 1 X2 / 4 - RCL 0 * RCL 1 ) INV GE CP
SQR ( CE + RCL 1 / 2 ) ± ( CE + RCL 1 ) GTO LNX
LBL CE RCL 0 LBL LNX ( ( CE + RCL 2 ) X2 / RCL 0 X2 ) FIX 1 RTN
LBL CP 1 ± SQR R/S
LBL E ( SBR D LNX / 2 LNX ) RTN
