Problem with lens mount adapter (mamiya645/B4)
 

I have been testing a new lens adapter that allows me to use a Mamiya 645 lens on a B4 mount. It works great with lenses up to 200mm but the image is soft with my 300mm & 500mm. Both seem to work fine on a Mamiya stills camera. I am wondering if anyone has an idea of what might be going on? It is not a focus issue so much as a general softness across the whole picture. Thanks

David Wright
www.lunaseafilms.com

You might consider posting what camera / adapter / Lens / you are using for a troubleshooting starting point.

Equipment info
 

Camera - Panasonic HDX900
lens- Mamiya 645, 100mm & 210mm- work well
300mm & 500mm- soft images (not focus, just a general softness)
Adapter- Mechanical adapter allowing Mamiya 645 lens to be fitted on a B4 mount (no optics)

If I remember correctly, an adapter like that without optics will give you a 6.8 X crop,
and is best suited for macro use. Which means not all lenses will focus to infinity, and some will be unusable.

Infinity
 

I am actually on my third adapter and have had them made progressively thinner until I have one that does focus to infinity. My confusion lies around the fact that the longer lenses do not seem to work, focused on a subject that is close or far away.