Bellows extension cheatsheet for SA 90 XL, SS 150 XL, 300M?

Thanks Dan,

Good point. I will start with my 150mm.

Quote:

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Originally Posted by Dan Fromm

Key magic formulas:

extension = focal length *(magnification + 1)

Extension is measured from the film plane to the lens' rear node. For most LF lenses the rear node is close to the diaphragm.

Front node to subject distance = focal length *(magnification + 1)/magnification

For most LF lenses the front node is close to the diaphragm.

effective f/ number= f/ number set * (magnification + 1)

You're going to need 600 mm extension to shoot a 300 mm lens at 1:1. Front node to subject distance will also be 600 mm. There are some subjects for which that much working distance is helpful, but in general you'd be better off using a shorter lens at 1:1.

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For just one lense, this would handy, and I found it here, contributed by “Richard” on QL’s Bellows Factor page
http://www.largeformatphotography.in...ws-factor.html

I just need one for my 150mm Super Symmar XL.

Attachment 174863

Attachment 174864
Scale and pic by Richard

Anyone have one for 150mm that I could print?

Quote:

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Originally Posted by Drew Wiley

Today I used a little gadget from Calumet. It's a little plastic crosshair card you place in the scene, then you measure the width of it on your groundglass using a special plastic ruler marked in f-stop factors. Really portable and works for all lenses. Maybe someone else is making something like this now that Calumet is gone.

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You can make your own using the download at http://www.salzgeber.at/disc/

Bob

I don't want to do any calculating in the field. The exposure disc is a good tool, but having to place it in the scene is a disadvantage, especially in the field for found and delicate foliage shots, etc. I prefer just to consult a chart.

I've got my exposure record book with me in the field and that has charts for bellows extensions for all the lenses I commonly carry (plus reciprocity adjustments, filter factors etc., etc.) I only have to measure and look up my factor. I'm attaching the charts here for those that may find them helpful.

There's one chart in mm and one in inches so you can measure how you like. Feel free to copy, modify, whatever to suit your needs.

Best,

Doremus

Very nice Doremus and I mean that 2 ways.

Beautiful chart well sized to be usable on a phone or printed. Nicely done!

A wonderful gift and accommodation for metric or imperial practitioners. Nice!

Thank you!

Thanks Doremus for sharing the chart that you developed. I appreciate your kind generosity, and this tool will help many others for a long time!

Another cheer for Doremus' chart, which is now where my phone can always find it. Many thanks.