Well done with the video and info. The SRT cameras are amongst the best in 2024 for classic film cameras. The bulk of these cameras even if they have working light meters aren't as accurate as a Sekonic hand held light meter for example. Interesting, I'll give this a try with one of these cameras. Thanks Marco.
Interesting! This makes me think whether I could try to tweak those vintage Prakticas I own in a similar manner ... By the way: I also purchased my vintage cameras because I was heading for the lenses that they came with ... Carl Zeiss Jena rules!
Yeah I'd assume loads of camera have a sensor that can be tweaked. You might have some luck typing "[name of camera] service manual PDF" on Google. Some of these service manuals have procedures on how to calibrate these sensors. These instructions were intended for people assembling those cameras back in the day, but you can "make do" at home with an external light cell and a multimeter.
There is a disadvantage with this method and it is that 1.35v mercury batteries had the virtue of keeping the voltage stable until very shortly before being completely discharged, alkaline batteries go down in voltage very quickly, cameras that used mercury batteries do not have a compensation circuit since they did not need it as the discharge curve is so linear therefore even if the potentiometer is changed or the film sensitivity (ASA) is compensated by changing on the dial, little by little as the voltage of the alkaline battery goes down the precision of the camera's light meter also changes. The best solution is to connect a diode to the battery output that corrects and rectifies the voltage keeping it at 1.35v until the end of the alkaline battery's useful life. It is better to use SR44 since they are more linear in discharge than LR44.
@@marcelocampoamor4761 Thank you ! I had seen the soldering of a diode on the main circuit thing when I researched this lightmeter issue but to be honest I didn't understand it much at the time (or I didn't try to understand it). Since then I've read about the discharge curves of LR/SR/PR44 batteries and such. The voltage rectifying diode seems to be the best long term solution. I'll look into it, potentially try it and if I see no one did a video on this I'll post an update video !
Great video, do other cameras have the potentiometer to perform this hack or only this Minolta? I have a cosina csm slr. I believe I'll have to remove tha bottom cover so i can check it. 👍
So my guess would be that all old film cameras have something like this. But there might be some change as to how to tweak the light meter based on the camera model. For example, Canon's old mechanical cameras, the FT and FTb, have similar potentiometers, but the FTb has one for the low light and one for the high light. So you need to adjust each based on the light parameters. If you look on my channel, there's a video on how to calibrate the lightmeter of X-300/500/700 cameras, and it's a whole process. It's definitely trickier. Not that much harder if you take your time and understand each step of the process, but significantly tedious. The Cosina CSM SLR has an electronically controlled shutter. In those, usually the potentiometers are on a circuit board at the top of the camera, but I couldn't tell you without looking it up. Now, this camera has a 1.5V-based battery compartment. Why do you believe your light meter could be wrong? Have you checked it against a known working one? Are your pictures over/underexposed? It could be a shutter timing issue. When I bought my Minolta XD7, for example, the light meter was spot on, but thank God I serviced it before taking pictures because the shutter speeds were absolutely wrong.
I think a good rule of thumb could be: - if your camera has a "circle and needle" lightmeter system, it's likely that there's at most a couple of potentiometers (one for the high light, low light, battery check). You could get away with it by simply following the wiring and figuring out which circuit does what. A quick Google search might also yield easy-ish to follow steps. - if your camera has an "A" mode (aperture priority) and/or an LED lightmeter system, it's probably going to be slightly more complex. Usually there's 3 potentiometers: the first one does the "constant current" part of the system (called ASA inclination), the second one the A/D conversion and finally the lightmeter itself. Adjusting these is more complex, but not impossible. If you scrub through the X-500 video I have you can see what I'm talking about.
I have the same camera but needed to clean up the viewfinder from the inside so i took the top part off. After reinstalling everything the film advance lever is a bit loose (but can still be operated it just doesnt lock itself in place). Do you know what could be the issue? I built it like it was before.
Hmm. How much did you take the shutter mechanism apart? Did you pull out the shutter button (on a rod) with its washer? You don't have to in order to remove the top. If you did, you might have unscrewed the brass nut below the shutter button retaining the spring mechanism that's responsible for the "rewind" action of the lever. I've never had to fiddle with this part of the camera, so I wouldn't know how to tension this spring. I'd advise you to search "Minolta SRT 101 service manual" on Google. You can find a 43-page PDF with detailed explanations on how to service each part. You might find some information on how to tension this spring. Now all that being said, it may just be that you need to tighten the round, slippery nut on top of the shutter button (the very last one you have to screw in order to complete the reassembly).
Well done with the video and info. The SRT cameras are amongst the best in 2024 for classic film cameras. The bulk of these cameras even if they have working light meters aren't as accurate as a Sekonic hand held light meter for example. Interesting, I'll give this a try with one of these cameras. Thanks Marco.
Interesting! This makes me think whether I could try to tweak those vintage Prakticas I own in a similar manner ... By the way: I also purchased my vintage cameras because I was heading for the lenses that they came with ... Carl Zeiss Jena rules!
Yeah I'd assume loads of camera have a sensor that can be tweaked. You might have some luck typing "[name of camera] service manual PDF" on Google. Some of these service manuals have procedures on how to calibrate these sensors. These instructions were intended for people assembling those cameras back in the day, but you can "make do" at home with an external light cell and a multimeter.
You got me work to do 😑
Hopefully that works with srT303b too...
I think it should :)
Damn lucky you, what a nice camera you have. The end all be all of Minolta's fully mechanical cameras ahah
There is a disadvantage with this method and it is that 1.35v mercury batteries had the virtue of keeping the voltage stable until very shortly before being completely discharged, alkaline batteries go down in voltage very quickly, cameras that used mercury batteries do not have a compensation circuit since they did not need it as the discharge curve is so linear therefore even if the potentiometer is changed or the film sensitivity (ASA) is compensated by changing on the dial, little by little as the voltage of the alkaline battery goes down the precision of the camera's light meter also changes. The best solution is to connect a diode to the battery output that corrects and rectifies the voltage keeping it at 1.35v until the end of the alkaline battery's useful life. It is better to use SR44 since they are more linear in discharge than LR44.
@@marcelocampoamor4761 Thank you ! I had seen the soldering of a diode on the main circuit thing when I researched this lightmeter issue but to be honest I didn't understand it much at the time (or I didn't try to understand it). Since then I've read about the discharge curves of LR/SR/PR44 batteries and such. The voltage rectifying diode seems to be the best long term solution. I'll look into it, potentially try it and if I see no one did a video on this I'll post an update video !
Great video, do other cameras have the potentiometer to perform this hack or only this Minolta?
I have a cosina csm slr. I believe I'll have to remove tha bottom cover so i can check it.
👍
So my guess would be that all old film cameras have something like this. But there might be some change as to how to tweak the light meter based on the camera model.
For example, Canon's old mechanical cameras, the FT and FTb, have similar potentiometers, but the FTb has one for the low light and one for the high light. So you need to adjust each based on the light parameters. If you look on my channel, there's a video on how to calibrate the lightmeter of X-300/500/700 cameras, and it's a whole process. It's definitely trickier. Not that much harder if you take your time and understand each step of the process, but significantly tedious.
The Cosina CSM SLR has an electronically controlled shutter. In those, usually the potentiometers are on a circuit board at the top of the camera, but I couldn't tell you without looking it up. Now, this camera has a 1.5V-based battery compartment. Why do you believe your light meter could be wrong? Have you checked it against a known working one? Are your pictures over/underexposed?
It could be a shutter timing issue. When I bought my Minolta XD7, for example, the light meter was spot on, but thank God I serviced it before taking pictures because the shutter speeds were absolutely wrong.
I think a good rule of thumb could be:
- if your camera has a "circle and needle" lightmeter system, it's likely that there's at most a couple of potentiometers (one for the high light, low light, battery check). You could get away with it by simply following the wiring and figuring out which circuit does what. A quick Google search might also yield easy-ish to follow steps.
- if your camera has an "A" mode (aperture priority) and/or an LED lightmeter system, it's probably going to be slightly more complex. Usually there's 3 potentiometers: the first one does the "constant current" part of the system (called ASA inclination), the second one the A/D conversion and finally the lightmeter itself. Adjusting these is more complex, but not impossible. If you scrub through the X-500 video I have you can see what I'm talking about.
I have the same camera but needed to clean up the viewfinder from the inside so i took the top part off. After reinstalling everything the film advance lever is a bit loose (but can still be operated it just doesnt lock itself in place). Do you know what could be the issue? I built it like it was before.
Hmm. How much did you take the shutter mechanism apart? Did you pull out the shutter button (on a rod) with its washer? You don't have to in order to remove the top. If you did, you might have unscrewed the brass nut below the shutter button retaining the spring mechanism that's responsible for the "rewind" action of the lever. I've never had to fiddle with this part of the camera, so I wouldn't know how to tension this spring. I'd advise you to search "Minolta SRT 101 service manual" on Google. You can find a 43-page PDF with detailed explanations on how to service each part. You might find some information on how to tension this spring.
Now all that being said, it may just be that you need to tighten the round, slippery nut on top of the shutter button (the very last one you have to screw in order to complete the reassembly).