Does the ISO dial on a Minolta Auto 25 change flash power?
Asked 5/1/2020
4 views
2 answers
0
I’m using a Minolta Auto 25 flash off-camera with a Fuji X-T2. The flash has no manual power control, only an ISO/aperture distance dial. If I set the flash’s ISO dial to a higher value, such as 800 instead of 100, will the flash actually emit less light? Or is that dial only a guide for choosing aperture/distance in auto or manual use?
Originally by Photography Stack Exchange contributor. Source · Licensed CC BY-SA 4.0
Photography Stack Exchange contributor
6y ago
2 Answers
2
After glancing through a manual I found online, I would guess that the backside dial is not connected to anything electrical, and only works as a mechanical calculator for the unit's two settings:
- Auto, for constant measured light at the sensor
- Manual, for constant (full) output of the flash
But you have a digital camera, you can try it anyway!
If you only want a darker photo, use a smaller aperture or lower ISO.
If you want to balance the flash with existing light, or use a larger aperture, you can waste the flash output somehow:
- Bounce the flash from the ceiling or walls
- Make a DIY softbox or diffuser from a white plastic container
- (Why don't you want to take the flash further from the subject? You want to hand hold both the camera and the flash?)
Originally by user63032. Source · Licensed CC BY-SA 4.0
user63032
6y ago
0
Generated from our catalog & community — verify before relying on it.
No. On the Minolta Auto 25, the ISO dial does not directly change flash power. It’s essentially a guide/calculator for matching film speed (ISO), aperture, and distance.
This flash is an auto-thyristor design: in Auto mode, the front sensor measures reflected light and cuts off the flash when enough light has been returned for the selected aperture/ISO combination. In Manual mode, it fires at full power. Changing the ISO dial alone does not make the flash weaker.
So setting the flash dial to ISO 800 while the camera is at ISO 100 will not “trick” the flash into lower output in a useful standalone way; it just changes the recommended aperture/range markings you should use.
If the flash is too strong, practical options are:
- use Auto mode with the correct aperture
- stop down the lens (smaller aperture)
- lower camera ISO
- bounce or diffuse the flash
- increase flash-to-subject distance
If you need true manual power control, you’d need a different flash or an external way to reduce output.
Recommended products
UniqueBot
AI6y ago
Your Answer
Related Questions
How does flash guide number change when you reduce flash power?
What do the green, orange, and manual modes do on a National PE-201C flash?
How do you calculate manual flash power when changing flash-to-subject distance?
Does manual ISO produce less noise than Auto ISO?
Why doesn’t the guide number calculation seem to match the inverse-square law in flash exposure?