That 1.6 Rule

[leon]

Hi guys,

I have always bought full frame cameras which have a ratio of 1-1

A friend of mine bought a new Canon 200Dmark 11 with an APSC Comos Sensor recently with a 18-55mm kit lens.

Please tell me dose the 1.6 rule still apply to these sensors or have they fixed this so that what you have on the barrel of the lens is actually the correct reading.

Otherwise 18mm becomes 28.8mm and 55 becomes 88mm

Thank you.

Leon

[Ryderscope (Rodney)]

Originally Posted by leon

Hi guys,

I have always bought full frame cameras which have a ratio of 1-1

A friend of mine bought a new Canon 200Dmark 11 with an APSC Comos Sensor recently with a 18-55mm kit lens.

Please tell me dose the 1.6 rule still apply to these sensors or have they fixed this so that what you have on the barrel of the lens is actually the correct reading.

Otherwise 18mm becomes 28.8mm and 55 becomes 88mm

Thank you.

Leon

Hi Leon, I recently went through this with my Canon 80D and confirmed that it is still necessary to multiply the zoom setting (focal length) by 1.6 for both the EF and EF-S series lenses. So indeed it is correct that your 18-55 lens is in fact a 28.8 - 88mm lens when on the APSC body.

For clarification, the EF-S series lenses for Canon are made for the APSC (crop sensor) body and will not fit on a full frame body. The EF series lenses are made for the full frame sensor body but can be fitted to the APSC sensor body. In both cases though the zoom factor is multiplied by 1.6.

I recently bought a used Canon 70-300mm EF mount zoom lens to use on my 80D body. Taking the crop factor into account it is the equivalent of a 112-480mm zoom. I also have a 18-200mm EF-S mount kit lens that came with my old 550D which is effectively a 28.8- 320mm zoom.

CS,
Rodney

[ronson]

The 1.6x multiplication factor only matters if you want to compare/relate it to a full frame sensor. 18 mm on APC-C are 18 mm. 18 mm on full frame are 18 mm. The difference is the field of view and the depth of the focus. For some people it’s easier to relate to a full frame size, probably a historical reason from the 35mm film days. I tend not to overthink it and just get used to it and enjoy the hobby

[leon]

Thank you indeed for your responses.

Leon

[bojan]

Guys... I thought we've got rid of that 1.6 nonsense a long time ago... at least on this astro-forum.



18mm focal lens is ALWAYS 18 mm.. etc..


Only field of view (FOV) is avected with sensor size.

[leon]

Yes that is true bojan, that is probably what i meant, but didn't write it very well.

Leon

[bojan]

Leon,
My apologies for being too blunt with you, perhaps I should have been more observant..
Associated term "effective focal length" to "1.6 rule" is much worse actually.
I understand that the whole thing started by someone to help users of photo-equipment "visualizing" the effects of various FL's and sensor sizes combinations to FOV.. but the result of that "help" was just more confusion instead of proper education on how things work.. And that rattles me sometimes.. not as often recently as it used to in the past

[leon]

All good mate i don't bruise easy, no apology necessary.

Leon