Nikon 300mm f/4 effects of not having 39mm drop in filter.

This is the information off of Ken Rockwell's website.

" The internal filter should remain in place because the presence or absence of the filter changes the effective (optical) distance to the film plane by a tiny amount. Don't worry about this, but please leave the filter holder in place.

The change in effective path length is the thickness of the filter x ([the filter glass' index of refraction] -1 ). A typical index of refraction is about 1.5, so you change the effective distance to the film by about half the thickness of the filter. Of course the same effect happens with filters in front of your lens, but no one notices when you change the distance to a subject by a millimeter. In lens design, moving the film plane a mm can make a difference, but not much with telephotos.

You can confirm this effect if you focus on a distant object and note the indication on the focus scale. Now remove the internal filter, refocus, and you will note that the focus scale indicates a different distance when focused on the same object. "

All information is copyrighted by Ken Rockwell at www.kenrockwell.com

Category:

Education

Tags:

• Nikon
• 300mm
• f/4
• f/2.8
• D300
• D90
• D40
• D60
• D3x
• lilkiwiguy87

[ParadigmPenguin]

Costco dog beds FTW.

[hutdockz]

Hi, Thank for sharing.

I have a question if remove filter, can 300 f/4 focus at infinity?

PS. English not my primary, sorry.