STOPPING DOWN THE LENS

These are 100% crops of jpeg "FINE" photos, right out of the camera with no changes in Photoshop. "Optimize Image"=Normal. They are pictures of an insulator on power lines.

With the lens at full zoom (340mm), as the lens is stopped down, the images display less ghosting and more sharpness. The magic number seems to be F/6.3. By then all ill effects are gone and you can shoot away at full zoom worry-free.

Nikon D70 with 70-200 VR + TC17EII, zoomed all the way in (340mm with the TC).

F/4.8, the fastest possible with the 1.7TC. Notice overall softness and ghosting on the wire coil (white background bleeding in).

Stopped down to F/5. Ghosting diminished, yet still apparent.

F5.6 Ghosting diminished further, still not great.

F/6.3 Ghosting apparently gone, very sharp.

F7.1 Very sharp as well, but not noticeably better than F/6.3.

F/8 Greater depth-of-field, but not any sharper than F6.3 either.

So, again, F/6.3 seems to be the magic number. Stop down to that, and you won't have any problems at full zoom.

HOME | STOP DOWN THE LENS | ZOOM OUT A BIT | COMBINE THESE METHODS | CONCLUSIONS

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