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New member here with a question regarding the mysteries of focus confirmation when fitting a manual focus lens to Canon EOS type digital and film bodies. I have a fair number of M42 Pentax Takumar lenses I'd like to use on my EOS 40D or 5DMkIV digital cameras, as well as on a number of EOS film cameras.

Having the green focus confirmation light come on would be welcome, but the more I read about adapters with focus confirmation chips, the more confused I become.

For starters, is there a difference between so-called Dandelion chips and the others that claim to allow camera to confirm focus?

Something else that gives me the willies is the apparently complex process of programming the chip to one's camera based on manufacturers' instructions in bad English. What's worse - this arcane process must be done for each lens you'd want to use with the adapter! And, possibly re-done for different apertures.

Then, we have Fotodiox warning vaguely not to use such adapters with EOS FILM cameras, as they will muck up the computer or otherwise "damage" such cameras.

THUS - and please only answer if you've had FIRST HAND experience with chipped adapters and Canon EOS 5D MkIV - is there an adapter with confirmation chip that does NOT have to be "programmed" to the camera to allow focus confirmation when using MF Takumar M42 lenses on EOS digital AND film cameras.

Lastly, is it true that focus confirmation only works with certain f/ stops on a given lens?

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Sorry, I don't have the 5D Mk IV but I expect the 5D Mk III should be similar.

Not all AF confirmation chips are created equal. There are 1st gen, 2nd gen, 3rd Gen, and 4th Gen. I think only the 4th generation "EMF" versions work with some of the latest cameras from Canon. My SL1 seems to be an exception as it does work with early generation Non-EMF AF chips while my 5D3 does not.

There are even differences between the 4th generation "Dandelion" chips. I would recommend the "Euro Dandelion" sold by Tagotech and some others sellers.

It is more expensive, but is better designed, is fully programmable, and looks nicer as well. Here is a comparison from an eBay seller showing the differences between the original vs Chinese copies of Dandelion AF chips.

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I use AF confirmation chips on three of my adapted MF lenses with my SL1 and 5D Mk III.

These are the three lenses I use and the AF chips on each:

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1) Canon FDn 50mm 1.4 with Big_Is AF chip (programmed to 50mm f/1.4) (factory default)

2) Samyang 500mm 8.0 with Adplo AF chip (programmed to 500mm f/5.6) (due to f/5.6 AF limit on the SL1)

3) Samyang 14mm 2.8 with Tagotech “Dandelion” AF chip (programmed to 14mm f/2.8)

I find they all of them are not very accurate for focus confirmation at wide apertures like f/1.4 or even f/2.8 and I use Live View at 10x magnification to get the best focus. Another good option is “Focus Peaking” available on some cameras.

Later generations can be programmed to show the correct EXIF information and having the correct f/stop seems to help with exposure metering.

The warning about not working with certain f/ stops probably refers to not using f/8 lenses or even stopping down to f/8 on a faster lens with cameras that can only AF at f/5.6

I did have trouble with using 2 different Dandelion AF chips on my 7D. Here is a video showing the erratic behavior. Canon 7D Dandelion AF Chip Erratic behavior Other 7D users in the comments section report the same problems.

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Here is what I was told about the v4 chip that is working on my 5d4 and 7d:

Camera Canon "senses" the diaphragm in the chip only to a value of 5.6. Therefore it does not matter - the diaphragm in the chip changes from 1 to 22 or does not change! Camera Canon makes an exposure on the real light stream, which falls on the matrix! Camera Canon does not use a diaphragm, which is pre-programmed on a chip! Aperture and focal length, which are pre-programmed in the chip - are needed only for the camera to correctly see the distance to the subject of photography and for recording in Exif. Our chip has the function of locking the shutter (trap focus) - the Chinese chips do not know how. Our chip works on all Canon camera models. Chinese chips - no! Our chip has the right dimensions. Chinese chips are thicker and longer. Our chip has a stand-by function. In Chinese chips this function is not! The Chinese chip discharges the camera's battery - even if the camera is turned off.

My Samyang 14mm now has this chip and it is working good but the aperture can not be changed so exif is always f/2.8 and 14mm. On the chinese chips I can change the aperture so they appear in the exif data. Here a shot with my carl zeiss pancolar https://www.flickr.com/photos/gipukan/38941609704/

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