How does a Dandelion chip work with manual Nikon-mount lenses and Adaptall-2 apertures?
Asked 7/23/2013
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2 answers
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I’m trying to understand what a Dandelion chip actually changes when using an older manual lens on a Nikon D3200. The chip can be programmed with focal length and maximum/minimum aperture, but does it also affect how the camera stops the lens down?
With a chipped lens mounted, is the normal operation that the lens is held wide open by the camera’s aperture lever until exposure, then the camera moves the lever by a controlled amount to reach the selected aperture?
If so, that seems to require the lens aperture actuator to behave in a compatible way from lens to lens. How reliable is that with third-party lenses, especially a Tamron Adaptall-2 lens using a Nikon adapter?
Originally by Photography Stack Exchange contributor. Source · Licensed CC BY-SA 4.0
Photography Stack Exchange contributor
13y ago
2 Answers
1
The Adaptall 2 mount lenses do have a linear aperture actuator, otherwise they couldn't be used in Program or shutter priority mode on cameras that offered the feature(s). And they certainly did work in "P" mode on the Minolta X700. (Except for the 500mm/8, obviously.) The most complicated part of the mount adapter was the lever mechanism that went between the camera's aperture lever and the lens's aperture actuator; on some long-flange-distance mounts, there wasn't a whole lot of room inside the adapter to correct the ratio, so it would require a multistage approach.
Originally by user2719. Source · Licensed CC BY-SA 4.0
user2719
12y ago
0
Generated from our catalog & community — verify before relying on it.
The Dandelion chip mainly provides lens data/electronic identification to the camera. It does not change the lens’s mechanical stop-down behavior.
For this to work properly, the lens and adapter must already have a compatible aperture-actuation mechanism. In the case of Tamron Adaptall-2, the Nikon adapter was designed to translate the camera’s aperture lever movement to the lens actuator, including the correct relationship needed for auto exposure modes. Community experience indicates Adaptall-2 lenses use a linear aperture actuator; otherwise they could not have supported Program or shutter-priority operation on cameras that offered those modes.
So yes: the camera lever controls stop-down mechanically, and the accuracy depends on the adapter/lens mechanism being designed correctly. With Adaptall-2 Nikon adapters, that compatibility was part of the design, though the adapter mechanism itself is the critical piece because it has to convert the camera lever movement to the lens actuator movement in the right ratio.
In short: the chip doesn’t control the lever; the adapter/lens mechanics do.
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