Recommendation for lens for 4x5; equivelent to 28mm in 35mm format?

[Michael R 1974]

That's what I was thinking. I hope it's that simple. So in fact if you want the same angle of view as a 50mm lens in the 35mm format, your pretty close to 180mm on a 4x5. So rather than being a "normal" lens, a 150mm lens on a 4x5 camera is actually a slightly wide angle lens.

Although, I guess technically you'd have to use the width of the image area on the sheet film, so the width of the opening in the film holder. That brings the factor down closer to 3.3. Interesting.

[Marvin]

The Kodak Professional Photoguide has a nice little chart that lets you find the equivalent focal length for different formats and it goes from 35mm to 8x10. I don't guess these are available new anymore but can be found on ebay.

[ic-racer]

So let's say I'm converting a focal length in 35mm to 4x5, and I assume I will crop the 4x5 negative down to the 35mm aspect ratio. What is the conversion factor?

I agree with what MattKing posted, but also realize that that is only for infinity focus. Once you start cranking the focus on a close object the angle of view decreases. This angle of view decrease is somewhat difficult to calculate because it is proportional to the format size and subject distance. So a lot more math is needed to get equivalent focal lengths at non-infinity focus.

Real life example> I can focus my MINOX to one foot and the angle of view change from infinity is very small. If I focus my 8x10 camera to one foot, the angle of view changes to about one-half. This will have a massive effect on you calculation of equivalent focal length.

[Michael R 1974]

Thanks ic-racer. I figured I'd start with an infinity assumption, but I guess as usual it is never a simple thing...

[ic-racer]

Thanks ic-racer. I figured I'd start with an infinity assumption, but I guess as usual it is never a simple thing...

There was a thread over on the Large Format forum about selecting lenses for portraits. I wound up putting together a spreadsheet that incorporated subject distance in addition to format diagonal and focal length. It shows how focusing in for a portrait with an 11x14 camera and 'normal' lens can diminish the angle of view to the same as what you'd get with a 35mm camera and an 85mm lens. (there is only one unique subject distance where that is the case).

[keithwms]

Worrying about what exact LF focal length matches another in 35mm format is probably not going to take you anywhere useful. The first things to do is to look at the lenses that are available- the common focal lengths are the ones to look for, as you will have (1) more choice and (2a) there is more competition between different brands and (2b) you're more likely to find the right price.

I previously recommended a look at the Schneider 90/8 SA. The reason is that it is in the ballpark field of view (big aspect ratio difference notwithstanding, because there are many different ways to compute 'equivalents'), and it's a very nice lens at a good price. There are also many other 90s out there. If you go looking for a 100mm or an 80mm or something... very thin selection, if any.