35-100mm f2.8 strange behavior

Desargues wrote:

Thanks for the advice guys. After speaking with the store's tech support, it sounds like an internal issue that is probably easy to fix. However, since I have an upcoming trip, I would like to expedite the process and will simply return the lens and purchase another copy immediately so that I can get it in time.

On a positive note, the lens is more or less what I was hoping for. It is sharp enough at f2.8, where I would be using it for portraits or interior shots, and it seems exceptionally sharp at f4-f5.6, where it will be primarily be used as a landscape lens. Hopefully the next copy is as good optically.

As for version 2, from what I have read, the new version has not improved optically, and I am on a budget (hence buying used), so I cannot justify the extra 50% premium that a new lens will cost. The additional 3 year warranty is nice, but probably not worth 50% of a used lens to me. I am hoping that this problem was a fluke.

Depending on your body that this lens will be mounted. If you use a G85/G95/G9/GH5, mk-II which supports DUAL IS-2 will give you 1~1.5 extra stops of stabilization. IIRC the improved electronics will also speed up the fps which can give faster AF speed than mk-I. A more effective stabilisation and faster AF, or more future proof might worth the extra $ if you need them.

If you will use it on a older body or a GX7/85/9 or GX8, that are DUAL IS only or the older like G6/7/GH4 etc which are lens OIS only, mk-I and mk-II makes not much difference to you. I personally bought a 12-35 mk-I because launching of mk-II had driven its price lower. 100% happy using it on GX7 (non DUAL IS)/GX85 (DUAL IS) ...

According to https://www.opticallimits.com/m43/852_panasonic35100f28?start=1, 35-100 f/2.8 is sharpest wide open (except 100mm is best @f/4). Stopping down might not see much corner improvement as per the MFT score...