First Post: Filters for 75mm

[evanbaines]

Hi gang!

This is my first post, but I've been reading here for a while. I have done my best to search for answers to these questions, so please forgive me if I am rehashing old news.

I am pretty new to large format photography, and I had a few questions I am hoping y'all might be able to help me with.

I just purchased a Nikkor 75 SW for my Cambo 4x5 to compliment the 150 Nikkor that came with the camera. I will mostly be using this lens with B&W negative film for urban landscapes and interiors for my personal projects.

1. I already have a number of B+W MRC color filters in 67mm that I have been using with my Mamiya 7. They are not slim/WA specific filters, but I never had any issues using them with my 50mm Mamiya lens, which is quite resistant to vignetting. How likely am I to experience significant vignetting with "normal" thickness filters on the Nikkor 75mm at a functional aperture (16-32)? Obviously, I will try to test this out when I can, but if someone can give me an idea of what to expect that would be awesome.

2. I have read every bit of information I could find about center ND's for 75mm lenses, and it seems that the consensus is: crucial for transparency unless the falloff effect is desired for some reason, may or may not be an issue for negative film, and can perhaps be addressed in darkroom/PS. As I plan on using the lens with BW negative film primarily, I will be testing it before taking the plunge on a center ND. However, most of the online threads talk about the Heliopan being the best choice due to its lower cost and solid performance. I am finding that currently, the Schneider 3B is much less expensive than the Heliopan. If I find that I do want a center ND for this lens, would the Schneider be inappropriate for any reason?

Thank you for your time and wisdom!

[Gem Singer]

Nikon did not make a center filter for their wide angle lenses for a good reason.

For B&W photography, more than likely, you will find that you do not need a center filter for your Nikon/Nikkor 75 SW.

Center filters are expensive and are usually designed to be used with a specific lens.

Why spend money unnecessarily?

[evanbaines]

I'm definitely not jumping to waste my money, but I also expect to be maximizing whatever movements this lens will permit in this work, and it is my understanding that greater movements will exacerbate the light falloff issues. I want to have a contingency plan in place if I find that I do need the filter, although I hope that I won't! Were it not for the movements, I'd probably just be using my much lighter and more convenient Mamiya 7, which in many cases can offer comparable resolution to 4x5.

I know that Nikon didn't offer a center ND, but my understanding of the situation is that physical laws of light falloff create the hotspot on a non-retrofocus lens, and all large format lenses are subject to this issue. The only question is whether this particular aspect of wide angle lenses will be objectionable to a given photographer for a given application on a given recording medium.

[Leigh]

I too have the Nikor-SW 75/4.5 and shoot it fairly often.

I don't own a center filter and haven't found a need for it.

I only shoot B&W, so I have no experience with transparencies. You might need one for that film.

I use standard 67mm B+W MRC filters with mine, but only one at a time, never stacked.

- Leigh

[evanbaines]

Thank you Leigh! That's exactly what I'm looking for!

[Emmanuel BIGLER]

Hello !

You can have an idea whether your filter will induce extra vignetting or not as follows :

- setup your camera with your lens and focus on the ground glass as usual, lens wide open;
- take the ground glass off and look through the lens from the back, from the corners of the format and check what you see through the lens;

Usually at full aperture from the extreme corners you'll se a 'cat's eye', the diaphragm being obstructed by some lens elements inside the lens itself. Closing down to the working aperture (f/22 for example) the cat's eye should dissapear.
Mount the filter and check whether you can see the filter mount through the lens. If you do not see it, the filter will not induce any extra vignetting.
Not easy when the lens is stopped downn but you can check wide open and see what happens.

Regarding filters capable of handling 105°, it should be mentioned that graded center filters are usually oversized in diameter ; e.g. a 67 mm filter thread but an overall diameter of 86 mm for the glass. A 50 mm on a 6x7 format (56x70 mm, diagonal = 90 mm) covers only 84° diagonally. A modern 75 mm view camera lens can cover between 100 and 110° !!

Well the best is to take pictures and see what happens...

[Leigh]

Anothr comment re vignetting...

It's a gradual degradation, not a hard line around the image, and always worse in the corners.

If you find it objectionable on a given shot you can always crop slightly to drop out the corners.

- Leigh

[evanbaines]

Note: Thus far in testing, I haven't found either the geometric falloff or any regular B+W filter vignetting objectionable @ f/22 on FP4+, although I haven't been shooting large even-toned areas that would show the issues prominently. I'm not ruling out that I might run into issues in the future in other situations, but so far no problem.

Just wanted to throw in this update for anyone present or future who is curious.