Question - Centering Filter

**anchored** · 13-Oct-2009, 08:28

Quick question:

Is the centering filter used for a 75mm f4.5 Grandagon-N the same as to be used for a 90mm f6.8 Caltar II-N?

Reason for question: Now have both lenses, and hopefully don't need to purchase another expensive filter.

Further note: I shoot predominantly 4x5 color film... most often Velvia 50 when light conditions are right (Provia secondary film), and a centering filter is needed at least with the 75mm lens, but hopefully not so much with the 90mm (not yet used).

Most Appreciative in Advance...

Glenn

**Leonard Evens** · 13-Oct-2009, 09:21

I'm not sure, but I think the Caltar is the same as the f/6.8 90 mm Rodenstock Grandagon M. If so, they use the same filter.

**Leonard Evens** · 13-Oct-2009, 09:25

P. S. It is is called a center filter, not a centering filter. As I'm sure you know, it corrects for the fall off of light as you move from the center to the periphery. But the correction is not complete, and in fact it corrects to different degrees for the the two lenses. It doesn't help you `center' the image in any way.

**anchored** · 13-Oct-2009, 10:00

Thanks Leonard... call that an error caused by not-thinking-whilst-typing and not caused by not-knowing-what-it-is.

I surmised this gradient filter would be different for different length lenses, but noticed on B&H the filter that is listed as an accessory for this lens is also used for various other lengths (the 75mm not being one listed), and also noted the filter suggested was also a 2.5-stop correction (same as the 75mm) and has the same thread diameter.