Lens hoods

[Krzys]

I have a 52mm hood for 50mm lenses, 35mm format, which I want to fit on my Nikkor-W 150mm for 4x5. Am I right to assume that there will be no vignetting and that the two formats are compatible as they are the same focal length?

[Ian Grant]

I use a Pentax lens hood for a 28mm Takumar on my 150mm Sironar, I think your hood might cause vignetting if you use any movements, and a 150mm is slightly wider anyway than a 50mm lens on a 35mm camera.

Ian

[Jesper]

Personally I use the darkslide to shade the lens since I have it in my hand during exposure anyway.

[Krzys]

Clever idea, Jesper.

[RalphLambrecht]

I have a 52mm hood for 50mm lenses, 35mm format, which I want to fit on my Nikkor-W 150mm for 4x5. Am I right to assume that there will be no vignetting and that the two formats are compatible as they are the same focal length?

A 50mm lens and a 150mm lens don't have the same focal length.

[Ian Grant]

A 50mm lens and a 150mm lens don't have the same focal length.

In this case Focal length is irrelevant it's the "Angle of View" that's important.

Ian

[RalphLambrecht]

In this case Focal length is irrelevant it's the "Angle of View" that's important.

Ian

...which differs with focal length. Six of one and a half dozen of the other.

The maximum angle of view (a) can be calculated from the image diagonal (d), and effective focal length (f) as follows:

a = 2 * arctan(d/(2*f))

[Ian Grant]

...which differs with focal length. Six of one and a half dozen of the other.

Simplified:

angle = 2 * arctan(d/(2*f))

I think you've missed the point Ralph. He's comparing different film formats, a 150mm lens on 5x4 camera has a slightly wider angle of view than a 50mm on a 35mm camera, I use a 150mm on my 10x8 and that's even wider still.

Ian

[RalphLambrecht]

I think you've missed the point Ralph. He's comparing different film formats, a a 150mm on 5x4 camera has a slightly wider angle of view than a 50mm on a 35mm camera, I use a 150mm on my 10x8 and that's even wider still.

Ian

Ian

That was my question to him. He said 'as they are the same focal length'. Lenses with the same focal length have the same angle of view, independent of film format. Unfortunately, he didn't speak of two lenses with the same focal length, which is confusing. So, I'm not sure what he is after. I think you're probably right, and he meant 'equivalent focal length' and not 'same focal length'.

[Ian Grant]

He wants to know if a lens hood for a 50mm Nikon SLR is OK on his 150mm Nikkor-W (5x4) lens without vignetting, that's unlikely if he uses any movements.

Ian