Converting focal length from 35mm to 6x6

[haggai_cohen_milo]

<p>Hello to all of you guys, I am a little new with the 6x6 format. <br>

I want to know what is the equivalent to a 35 lans on a 35mm camera in the medium format world. Or even better, how do I make the conversion from what I know from 35 to 6x6 lenses. <br>

Thank you, <br>

Haggai</p><div></div>

[joe_c5]

<p>To get the same diagonal field of view, the lens on the 6x6 camera should be roughly twice the focal length of the lens on the 35mm camera. 35mm has a diagonal of 43.3mm, 6x6 has a diagonal of 84.8mm. 84.8/43.3 = 1.96.</p>

<p>Because of the difference in aspect ratio between square and 3:2, the 6x6 camera might need slightly shorter or longer focal lengths to fit the subject into the frame properly.</p>

<p>To get similar depth of field between the two cameras, the aperture should be roughly two f stops slower for the 6x6 camera.</p>

[q.g._de_bakker]

<p><a href="http://www.hasselbladhistorical.eu/HW/HWequifoc.aspx">Look here</a>.</p>

[ilkka]

Normal lens for 35mm cameras is 50mm. Normal lens for 6x6 cameras is 80mm. Conversion factor is thus 1.6. Aspect ratio is different so direct comparison is not exact, but it should give a good idea. Coverage from left to right and up-down is quite different between these formats.

[mischakoning]

<p><a href="http://www.photo.net/photo/lens-table">Look here on photo.net</a>.</p>

[tobey_bilek]

<p>No the normal lens as definel by negative diagonal is 43 mm. Figure it out. Square root of (24x24) + (36x36). 35mm cameras come with 50mm lenses, but they are not normal.</p>

 

[q.g._de_bakker]

<p>As explained on the page i linked to, the difference in aspect ratios makes it impossible to give a direct equivalent.</p>

<p>And given that different aspect ratio, there are three ways to compare focal lengths and their angle of view:<br />- diagonal,<br />- horizontal<br />- vertical.</p>

<p>Each produces a different "equivalent".</p>

<p>For numbers for each, see the page i linked to above.<br />There you will see, for instance, that the 80 mm 'normal' lens on 6x6 is equivalent to 34 mm, 43 mm and 51 mm lenses on 35 mm format, depending on what you compare.</p>

<p>So the <strong>35 mm lens on 35 mm format</strong>'s 6x6 equivalent is <strong>80 mm</strong>, if you want the same <strong>vertical angle of view</strong>.</p>

<p>For the same <strong>horizontal angle of view</strong> you get using a 35 mm lens on 35 mm format, you will need a <strong>50 mm</strong> lens on 6x6.</p>

<p>The same <strong>diagonal angle of view</strong> requires a <strong>60 mm</strong> lens on 6x6.</p>

<p>Quite a spread, isn't it? 50 mm, through 60 mm, to 80 mm.</p>

[rodeo_joe1]

<p>Oh not again! This question comes up so regularly that PhotoNet should just post a conversion table from one format to another on the front page of the website.</p>

<p>Does nobody do a quick search for the answer before they post a question?</p>

[ilkka]

<p>Normal lens for 35 mm camera is 50mm. Has been for close to 100 years now. Diagonal measurement may be different, but that is still the normal lens. Millions of 50mm lenses have been made and sold as normal lens. How many 43mm lenses have ever been made? Similarly, 80 mm is and has always been the normal lens for 6x6.</p>

<p>It has been correctly pointed out that the aspect ratios of 35mm and 6x6 differ and thus single exact comparison is impossible. The closest one can do, and the most logical comparison, is to think of 6x6 in a 6x4.5 crop. One needs to crop it that way when printing to rectangular sheet of paper and one can also put a 6x4.5 magazine on most 6x6 cameras to achieve this cropping. Most 6x4.5 cameras have 75 or 80 mm lens as normal. The diagonal for 6x4.5 is actually 70mm, so the normal is a bit longer than the actual diagonal, just like in 35mm cameras. And when compared against the 35mm diagonal of 43mm, one gets and ratio of 1.6. Exactly what I said earlier. For somebody who is new to medium format, and who wants to have some idea how his 35mm lenses compare, that should do well enough.</p>

[haggai_cohen_milo]

<p>thank you everybody for replaying. i really appreciate all your help. <br>

sorry if my question bothered anyone... </p>

<p>Haggai</p><div></div>

[q.g._de_bakker]

<p>Just ask what you want to ask.<br>

Joe could have chosen to ignore the thread, yet chose to spend his time reading and replying. Noone forces anyone to do that against his or her will.</p>

<p>Joe, i have put tables up on the web recently. Not on Photo.net. But it will not take long for people to find it.<br>

You can help reduce the number of times this question will surface by posting the link whenever it does.<br>

;-)</p>

[richard_reddy]

<p>I agree comparisons of squares and rectangles are pure folly! But 6x7cm format can be compared more closely than 6x6cm. It is very nearly a 2:1 ratio, and since I shoot in both formats, this is verified by the sense I get shooting. This gives us a key to 6x6 and 6x9 formats, which will have a smaller or larger horizontal angle of view, respectively--at a given focal length. If your not an optical engineer, forget about the diagonal and vertical view! Most everyone equates angle of view with human eyesight which tends to be around 52 degrees.<br>

By the way, this is why large format is well-loved by wide angle fanatics (yours truly). In 8x10 format a normal lens is 360mm! I shoot 5x7 and 4x5 format, and even though I know certain designs are optically equivalent, there is often difference in feeling that most everyone picks up. <br /> This gets way too subjective to offer any reasonable defense--I can only suggest others try large format. Maybe you'll see what I mean, maybe not. <br>

The good thing is that everyone takes to the new format like ducks to water, and confusion over focal length / angle of view is just a lack of experience.</p>

 

[david_smith35]

<p>The only angle of view that matters is the horizontal one. It's what you can get in the frame from left to right which is most important for the majority of pictures.</p>