Can't zoom in close enough

The wider my object, the less sensitive my zoom is. If my object is very narrow, I can zoom in and see my object in very close-up detail. However, if my object is very wide, the zoom is not very sensitive and the object never allows itself to be zoomed in to a very close perspective. Once I zoom in a lot, the object begins to dissappear.

Do you have any suggestions as to an algorithm that would allow equal zoom sensitivity regardless of model size?

Any input would be greatly appreciated.

I guess you should be little more clear in explaining about your model what it looks like in 3D.Place you zoom-in code here if possible.

However try playing the viewing volumes near/far planes by adjusting the distances.

Dear ClintCJM,

Your Objects are disappearing because of the viewvolume specification.You can specify viewvolume as (-w,-h,w,h,0.0,20.0) where w is the viewport width and h is the height.

Meanvalue have a look at this application