Focal Length Conversion Ratio: 35mm to Digital SLR

[michoumisalade]

Hi all,
I uploaded a table for the conversion of lenses from 35mm to digital SLR.
Under the Focale column, you find the traditionnal focal lenses for 35 mm. Under the other columns, you find the equivalent for each factor of conversion like 1.3, 1.5, 1.6 (Canon Digital Rebel), 1.7 and 2.
Example: for a focale of 28 mm(65 degrees of angle) you got an equivalent of 36mm(53) for a factor of conversion of 1.3. Hum... it is more easy to view that to explain it. The number between the parenthesis are the angle converted by the focal.
Anyway, take a look!

http://www.pixentral.com/show.php?picture=1zNTVDmF2vRsQwJf3KQJgMIW7usKN1

Hope this help,

[tfry]

I'm not good with numbers.... :shock:

[Wendy]

Me neither :shock: :shock:


Wendy

[GaryK]

Michoumisalade

Thanks..great range of focal lenghts, not just the typica :)

[rjam2]

Hi all,
I uploaded a table for the conversion of lenses from 35mm to digital SLR.
Under the Focale column, you find the traditionnal focal lenses for 35 mm. Under the other columns, you find the equivalent for each factor of conversion like 1.3, 1.5, 1.6 (Canon Digital Rebel), 1.7 and 2.
Example: for a focale of 28 mm(65 degrees of angle) you got an equivalent of 36mm(53) for a factor of conversion of 1.3. Hum... it is more easy to view that to explain it. The number between the parenthesis are the angle converted by the focal.
Anyway, take a look!

http://www.pixentral.com/show.php?picture=1zNTVDmF2vRsQwJf3KQJgMIW7usKN1

Hope this help,
It does more than help. I've been searching online for hours for focal length converstion tables, and not find anything nearly as good as this.

Thanks a lot.

[lowbone]

All you really need to know is what magnification factor your camera has. Pentax is 1.5 ( at least it used to be ) Canon Xt , XTi, 20D and 30D is 1.6. etc.You then take the focal length of a lens. Lets say you have a Canon 18-55 zoom lens and you are using it on your XTi. Just multiply 18-55 by 1.6 and you have a 29-88 equivilent lens. The sensor on an XTi or 20D is smaller than a 35mm negative is. It only sees part of what a 35mm format would see. That is why these are called crop cameras. A canon 5D on the other hand has a sensor the same size as a 35mm negative. There is no crop factor here and it sees exactly the same size as the negative

[rjam2]

All you really need to know is what magnification factor your camera has.

You then take the focal length of a lens. Lets say you have a Canon 18-55 zoom lens and you are using it on your XTi.

Just multiply 18-55 by 1.6 and you have a 29-88 equivilent lens.



Thanks a lot for the concise and clear added explanation, lowbone.

Some of us have been around long enough, to forget more than median aged persons ever learned in the first place. If we don't use it, we lose it. For example, I forget from immediate memory, the names of the many friends & some relatives if I've not seen or spoken to them in the last 3-6 months. I still know very well, their personality, face, background, etc. As I learn many new and interesting things, that pushes other things into the background and I get rusty on things I don't use much, like math.

Your explanation is clearer than what I'd seen in the last few days of searching. Most explanations I saw, talked about the dimensions of the 35 mm SLR negative vs the D-SLR size. I know what those sizes are for the cameras in which I'm interested. But most explanations said the conversion factor for my 2-3 prospective D-SLR's was 1.5. I divided one side dimension of the D-SLR sensor by the corresponoding side dimension of the 35 SLR negative. I didn't get 1.5 or a 50% ratio. (I forgot the area is a factor of 2 dimensions, not just one). Anyway, I tried another route. I noticed that 18 mm in the SLR world, yielded 27 mm in the D-SLR for one of my prospective cameras. And 18 x 0.5 = 9 +18 = 27. So I used that same formula to begin to calculate the conversion for each 1 mm change in SLR. Well, that was a tedious task and I gave up after about a dozen iterations. The conversion table from michoumisalad made available at a quick glance all I needed to know,.

Your method of multiplying by 1.5 in my case, makes the formula simpler than the convoluted formula I came up with. And your method is perhaps more resourceful if I don't have the conversion table with me. But when I look online for possible less expensive interchangeable lenses to use on the D-SLR, the table is far more convenient, for now.

I appreciate your suggestion. It will clearly be useful to me at some points in my future.