What focal length = 40mm lens on medium format

[Dan Dubowitz]

Lens focal length Questions
How do I calculate what lens will give me the same wide angle view of a 40mm medium format lens as a square image on 4x5 and 10x8 formats,
i.e using part of the image area 4 inch by 4 inch and 8 inch by 8 inch?
thanks
dan

[BrianShaw]

There are a large number of resources to help:

http://www.google.com/search?hl=en&s...ens+eq&aqi=g10

[BrianShaw]

This is probably easiest to use:

http://photo.net/photo/lens-table

[BrianShaw]

... or this:

pumpkin.annex.home.att.net/articles/Equiv_Focal_Length.pdf

[drew.saunders]

If you're going to crop square, the math gets much easier. Most 4x5 film holders give you an actual image in the neighborhood of 96x121mm, where your 6x6 is 56x56mm, so just divide 96 by 56 to get a 1.71x multiplier (and double that for 8x10). 40mm on 56x56 is 68mm on 96x96, and there are plenty of 65mm lenses out there, and even a really nice and really expensive Schneider 72mm lens, and plenty of 75mm lenses.

For 8x10, you have fewer choices: the 120/8 Nikkor, 150/8 Nikkor or 150/5.6 Schneider SSXL.

[aduncanson]

It is a simple proportion: X is to 4 inches as 40mm is to 56mm. Except that you should use 3.75 inches (95mm) instead of 4 inches to account for the edges of the 4x5 frame covered by the film holder.

Or equivalently, what Drew said.

[Gordon Moat]

According to the pCAM software on my Palm Pilot, a 40mm square medium format lens would be equivalent to a 65mm or 80mm, depending upon which side you chose to match on 4x5. If you were to do a 4" by 4" image, then the 65mm would be the closest.

All the 65mm lenses for 4x5 cameras have fairly minimal movement capabilities compared to longer focal lengths. If you were going to crop to 4" by 4" later, then that gives you a bit more movement room.

Ciao!

Gordon Moat Photography

[Ivan J. Eberle]

The 35mm and 40mm lenses available for MF are among the sharpest available for the format. The incredible DOF they provide (no moves necessary for sharply focused near-far compositions), coupled with the thinner and higher resolving base of MF film makes the focal length a sweet spot for MF. This might translate into results in 4x5 that will be disappointing. What exactly is it you're trying to achieve?

[Dan Dubowitz]

Ivan,
many thanks for this comment it really hits the nail on the head for me for something i couldn't quite pin down. I have shot exclusively with a 40mm hasselblad lens I bought new in 2003 until last year, Its incredible, and I couldnt fault it, I used it almost exclusively until last year when it kept coming loose, and 3 pricey hasselblad repairs have left me with a lens I shelled out a lot for and now dont trust.
Before I was doing work on books, and not printing large, now I am making prints regularly at 1.2 m x 1.2m and 2,4m x 1.2 m, for panoramas.
These are long exposure low light dark interiors (walk away with the aperture open for 10 mins) on some projects, bright external buildings on others, see www.civicworks.net , printing formerly on duratrans for light boxes, and increasingly giclee on hahne muller inkjet prints.
The trannies i have, just arent holding up to this enlargement. The 4x5 I am now shooting mostly with a 5.6 90mm schneider angulon, and a bit with a 65mm schneider angulon, ishelping me in 2 ways, I am using the front shift a lot to deal with not being able to get the camera high enough and so getting shots i need i couldnt get with the hasselblad kit i had, and I am getting a bigger negative, and the lab arent having to lay on silly amounts of sharpening to the drum scans. However, there's something I cant put my finger on yet, I always take an mf pic first, and I often prefer them! I am assuming that the lens has something to do with it, and once I get a better set of lenses for 10x8 and 4x5 this disparity may go.
(I look forward to doing contact prints-though I assume this is going to be difficult from transparencies)
Because I set the shot up currently with the mf, and i have worked with the same objective for so long, i was eager to be able to leave the tripd where it is and mount the lf camera with a comparable objective.
I had thought the zeiss biagon 75mm might me the lens for me on 4x5, but I am somewhat swayed to a 72mmxl by the reviews and extra coverage, and will now look at what there is in 65mm.
Do you think I will remain a little disappointes with what ever objective i go for in the 65mm and 130mm range compared to the mf 40mm?

[venchka]

Give the Pentax 6x7 with 45mm lens a test drive.