what is the length of a bellow extention needed for 1:1 Macro with 120mm lens on 45

I want to try Macro with my 45 cameras and I am thinking of buying a

120mm macro lens. I want to known at what bellow extension will it

give me 1:1 magnification. My cameras allow for ~390mm extension.

 

Thanks

At 1:1 you will need double the focal lenth of the lens or 240mm of bellows for your

120mm lens

But if you will shift tilt etc. then you need a bit reserve for it.

So I would go for a bellows around 30cm.

Thank you very much for the quite answers.

The posts above assume that the lensboard is in the middle of the lens, near the nodal point and diaphram, which is where you would expect to find it on a 120mm LF lens.

If you don't use exactly 1:1 reproduction ratio, you might want to know the general rule. If the scale of reproduction or magnification is M, then the bellows extension is 1 + M times the focal length f. For a reproduction ratio of 1:1, M = 1, for 1:2, M = 1/2, for 1:3, M = 1/3, for 2:3, M = 2/3, etc.

 

Many people use a scale placed in the image to determine M. You can place a ruler in the plane of exact focus and then measure its length on the gg. See also www.salzgeber.at/disc.

 

The bellows extension is measured to the so called rear nodal point. For the type of lens you are likely to be using, that will probably be pretty close to the lens board. But you can avoid worrying about that by extending M x f beyond the point at which the lens is focused at infinity.

 

You might consider studying a book like View Camera Technique by Leslie Stroebel to learn about focusing and exposure adjustment for close up photography with a view camera. If you haven't done it before, you need to learn a few tricks.

Has anyone tried using close-up filters with 4x5? Successful?

What would be best focal length to use them on? standard 150mm?

I may be a little confused about this, so those with more experience, feel free to correct. I believe you need double the focal length of extension for 1:1 with a standard lens, but (and this is were my knowlege is a little incomplete) with a Macro lens design, it should focus close enough to give you 1:1 with less bellows draw than a standard lens.

Nigel, why degrade your image quality? You can get as close as you like as long as you have the bellows and rail to spare. I just took some shots of a cactus at twice life size with my 90mm S.A. Smaller formats do not have the bellows so they need to "cheat" by sticking bits of old milk bottle bottom in front of their highly optimised, multicoated lenses - we don't! Although, having said that, more distance between the lens and subject would have been nice as I don't have the rail & bellows to use my 180 at such magnifications...

 

Peter, I believe you are refering to a telephoto lens... My understanding is that "macro lens" in LF is simply one optimised for 1:1 magnification or thereabouts.

 

Another point not mentioned: I remember reading somewhere that macro lenses have smaller image circles at lower magnifications than "normal" lenses - you may need to check the data on the lens you have in mind if you are going to use it for non-macro subjects as well.

 

Cheers,