AN interesting idea about the SONY A7/7r and its lenses

[mdijb]

What strikes me is the new lenses for the A7 are E-mount and can be used on the NEX7.  The NEX7 lense can be used on the A7 and a in camera crop mode can be used.

It seems to me that putting an A7 lense on the smaller NEX7 would use mostly the center of the lense, its sharpest section, and the image quality should be excellent.

Putting a NEX7 lense on the A7 would result in cropping but the images is now falling on larger pixels and again image quality should be improved.

This would mean that all the lenses could be used on both cameras with benefits resulting.  Investing in the more expensive A7 lenses and using them on the NEX7 give one a lot of flexibility--the 35 MM for example would be a 50 MM on the NEX7 and should give possibly improved image quality.  These expensive lenses could be used on both cameras and be cost effective.

Is my reasoning accurate or are  there some factors I am not considering.

HMMMM!!!

MDIJB

[BernardLanguillier]

Is my reasoning accurate or are  there some factors I am not considering.

Yes, it is exactly the kind of capabilities that have been available for Nikon users between the DX and FX cameras/lenses for many years. 

Canon offers some of that too, but to a lesser extend I understand.

Cheers,
Bernard

[ErikKaffehr]

Hi,

Yes and no. An APS-C lens could be calculated for the smaller sensor. Those lenses are often sharper (per millimeter) than full format lenses. A really good lens is essentially sharp across the field, so little is gained by using the central area.

To take an example, my Sony 16-80/3.5-4.5 ZA zoom is definitively sharper at center than my 100/2.8 Minolta macro.

AFAIK, few of the NEX lenses were really good, so putting the new FE-lenses on NEX cameras may be a great idea.

Best regards
Erik

What strikes me is the new lenses for the A7 are E-mount and can be used on the NEX7.  The NEX7 lense can be used on the A7 and a in camera crop mode can be used.

It seems to me that putting an A7 lense on the smaller NEX7 would use mostly the center of the lense, its sharpest section, and the image quality should be excellent.

Putting a NEX7 lense on the A7 would result in cropping but the images is now falling on larger pixels and again image quality should be improved.

This would mean that all the lenses could be used on both cameras with benefits resulting.  Investing in the more expensive A7 lenses and using them on the NEX7 give one a lot of flexibility--the 35 MM for example would be a 50 MM on the NEX7 and should give possibly improved image quality.  These expensive lenses could be used on both cameras and be cost effective.

Is my reasoning accurate or are  there some factors I am not considering.

HMMMM!!!

MDIJB

[madmanchan]

In general you'll also get much less light falloff (image edges and corners) when using a full-frame lens on an APS-C body, especially at the wider apertures.  This makes sense from the point of view of capturing a full frame image, then cropping out the central portion.