35-100mm f2.8 strange behavior

I am in the testing phase of a used Panasonic 35-100mm f2.8 v1 lens, I have a few days to determine whether or not it is working to my liking. I am using the lens on an Olympus ep5 and have noticed some strange behavior. Sometimes when I am zoomed all the way to 100mm, the focal length that my camera registers jumps around. Most of the time it seems to register either 100mm or 93mm, but on some occasions, it rapidly changes and can go all the way down to the 40mm-50mm range. When the focal length is registered incorrectly, the lens no longer focuses properly. I can get the camera to register the proper focal length if I rack the zoom back and forth a few times, but this seems to be unreliable.

Does anyone have suggestions? I would like to get this straightened out soon because I will be leaving for a trip on June 8 and was hoping to use the lens during my travels. The vendor has several other used copies of the lens available, so if I act fast, I can probably get another copy to test before the trip.

Exchange it immediately and tell the vendor about the fault.

Andrew

A risk on buying used. Try another one to see could it be better...

Desargues wrote:

I am in the testing phase of a used Panasonic 35-100mm f2.8 v1 lens, I have a few days to determine whether or not it is working to my liking. I am using the lens on an Olympus ep5 and have noticed some strange behavior. Sometimes when I am zoomed all the way to 100mm, the focal length that my camera registers jumps around. Most of the time it seems to register either 100mm or 93mm, but on some occasions, it rapidly changes and can go all the way down to the 40mm-50mm range. When the focal length is registered incorrectly, the lens no longer focuses properly. I can get the camera to register the proper focal length if I rack the zoom back and forth a few times, but this seems to be unreliable.

Does anyone have suggestions? I would like to get this straightened out soon because I will be leaving for a trip on June 8 and was hoping to use the lens during my travels. The vendor has several other used copies of the lens available, so if I act fast, I can probably get another copy to test before the trip.

What you describe sounds like a problem with the lens.  If it can't AF or focus properly, then it's pretty much useless.  I would return it for a new one or the version II brand new.  But that's just me, you may want to hold on to it for the value aspect.

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...