Using 4x5 Camera but Shot with 120 Film Back, Lens equivalence?

[patrick_li2]

Using 90mm, 150mm and 300mm lens with a 4x5 camera, but shot with a

120 film back 6x6, 6x9, and 6x12, like to know the equivalence of

lens effect to a medium format (6x6 or 6x7) and a 135mm camera.

 

This is an entry level question, but it helps me to transition my

experience with 135 or 120 to large format.

 

Thanks!

Patrick

[rich long]

I think that a 90mm lens is a 90mm lens. In large format (4x5in), 90mm is a fairly wide angle. On medium format (6x6cm, say) it's about normal or just slightly wider. On 35mm, a 90mm lens is a short telephoto. All that the film back is doing is cropping the image circle from the large format lens. Or to look at it the other way, a normal lens on a 35mm camera is 50mm. A normal lens on a medium format is about 90 to 105mm, and a normal lens on a 4x5 is in the neighborhood of 150mm.

 

Or maybe I misunderstand your question. Here, read this while I get some sleep. http://www.largeformatphotography.info/lenses-primer/

[johnmarkpainter]

Patrick,

 

Imagine shooting a Portrait on a 35mm camera with a 90 lens.

 

Now...standing in the same spot, shoot with a 90 lens on a MF camera. The subject's head

is the same size...you just see more of them.

 

Standing in the same spot....a 90 on a LF camera....Subject is the same size but you can

now see their surroundings. Make sense?

 

Think of it as a Window that can change size. Everything you see out the window stays the

same size as the window gets larger. You can just see more.

 

jmp

[patrick_li2]

I am thinking about something similar to the 1.6 effect that Canon's Digital Camera has.

 

Shot a 6x6 using a 4x5 camera and a 90mm lens or any other lens - the angle of view changed vs same lens shot 4x5" - right?

 

I guess my question is not clear, hope these 2 examples help.

 

thanks!

Patrick

[michael_briggs2]

Every lens of a particular focal length (foucsed on infinity) projects the same degrees per mm of film or other sensor. If you double the size of the film and want to maintain the same angle of view, you have to double the focal length. Its simply a matter of proportions.

 

You can easily work out the focal length equivalents by measuring the diagonals of the various formats that you use. (Or the short or long dimensions, if you care more about one of those than about the diagonal.) For example, if your 6x6 film back gives a diagonal of 79 mm and you 4x5 film holders a diagonal of 150 mm, the ratio between the two is 1.90. If you like your 90 mm lens on 4x5, the equivalent on 6x6 would be 90 mm / 1.90 = 47 mm.

[leonard_evens]

I hope it is clear by now, but let me say it all over again.

 

If you use a 120 roll film back, it is just the same as if you were using the same format in a medium format camera. So if you use a 6 x 7 roll film back, that is what you will get. The fact that it is mounted on a 4 x 5 camera is not really relevant. The focal lengths you mention range from normal (for 6 x 7) to moderately long and long.

 

You might consider using 4 x 5 film instead. That is what the camera is designed for, and while it can be used with a roll film back, that does create some difficulties.

[robert_ley]

Patrick, Check out this page: http://www.viewcamera.com/images/focalchart.gif

This should clearup some of your confusion on the different focal lenths and film formats and how they relate to each other.

[ellis_vener_photography]

If you are thinking about comparable angle of view --along the long side of each

format -- for the 35mm > 6x9cm > 4x5 formats;

 

28mm > 65mm > 90mm

 

50mm > 100mm > 150mm

 

100mm > 210mm > 300mm

[brent_doerzman]

Maybe I�m missing something here, and correct me if I�m wrong, but I think what Patrick is asking (and me too) is something like this:

 

 

Set up a 4x5 camera with a 150mm lens, put on a 6x9 roll film back and shoot an image. Next, setup an actual 6x9 camera aimed at the same scene. What lens would you have to put on the 6x9 camera to create the exact same image as the first shot with the 4x5?

 

Sorry if this just confuses things, or if this question is already answered above, but I�m just trying to word it a little differently. Or, maybe it�s just too late, and I�m being tired and dense :)! Thanks!

 

Brent D

 

 

www.doerzmanphoto.com

[scott_stadler]

Brent,

The answer to your question is 150mm. You are still shooting 6x9. It is exactly the

same because you are not actually changing format size, you are still shooting

medium format.

[patrick_li2]

Brent's statement about my question is 100% hit.

 

Scott's point is right. I think I have confused with 90mm lens with 4x5 equal to 24mm lens on 135mm camera.

 

Benefit of shoting 6x9 on a 4x5 camera with a 300mm IS YOU GET A RESULTS AS 6X9 on a 120 CAMERA WITH A 300MM LENS - you don't need to buy the expensive tele lens for 4x5 to get a 300mm equivalent lens effect with a 120 CAMERA. I understand now.

 

thanks! Patrick

[brent_doerzman]

Excellent, that clears things up for me too. OK, now I really want a 120 roll film back!!! Off to E-bay! Thanks Scott.

[patrick_li2]

Actually one more benefit - the tele lens is heavy, it lower your backpack weight for field photography! Enjoy... Patrick

[michael_schiller]

Ok, maybe I'm reading this question wrong, or maybe I'm asking a different question all

together. I have a Linhof 4x5 with a 6x7 roll film back. I also have a Linhof zoom finder. I

don't have a mask for it to automatically crop the image in the finder, but as it's a zoom

finder, I should be able to say put my 90mm lens on the camera, and then set my finder to

a different focal length to have a correct (or almost so) viewfinder. So my question is: I

have 90mm, 135mm, 150mm, 210mm and 360mm lenses, what setting (or multiplier)

would I need to set the viewfinder at to use the roll film back? (I'm pretty sure with the 90 I

would use the 150 setting, but I'm not sure for the others, and if I'm even right)

 

-Mike