Linhof 617 - ND Filter (up or down?)

[mark_ftzsimmons]

I'm a little confused... With reference to the Schneider ND filter, surely one

would have to open up by two stops (allowing more light to hit the film)

rather than stopping down???

 

Quote... "For maximum results and definition when using SCHNEIDER CENTRE

FILTER, it is necessary to stop down down the lens by one or two full stops"

 

Many thanks...

[q.g._de_bakker]

Mark,<br><br>You are thinking about exposure, and you are right.<br><br>The quoted text however is talking about effect and quality, and suggests that you should not use the lens (with filter) wide open to achieve the utmost in that.<br>You than still have to compensate for the lightloss caused by the filter, but when doing so should avoid opening the lens to anything larger than "one or two full stops" down from wide open. Use longer shutterspeeds instead.

[jim_landecker]

They probably advise this because at the wide open aperture there will be some light fall-off due to mechanical vignetting in addition to the loss due to the lens design (which is what the filter is designed to compensate for). Stopping down a couple of stops eliminates this mechanical vignetting and will give the most even illumination on the film.

[mark_ftzsimmons]

Thanks for that... So when shooing landscapes for instance, I'll set the camera up to shoot... say f/32 and then open up further by 1.5 to 2 stops to (f/16) to compensate for the filter... I guess with any new camera it's going to be trial & error... Thanks for all your help so far.

[darcy_cote]

Yes, that is right.

you can see more about 6x17 in this group.

http://tech.groups.yahoo.com/group/6x17/

[mark_ftzsimmons]

Thanks Darcy... Much appreciated.