Still confused: Focal Length Multiplier

[arond a.]

Yes, I searched for the answer already (here and elsewhere) but

without luck. I understand the essence of the FLM factor when

affixing 35mm format lenses to DSLR bodies. What I have not been able

to discover is whether, when looking through the viewfinder, I have to

visualize where my frame lines would be. In other words, is it

What-You-See-Is-What-You-Get through the digital viewfinder, or do I

have to estimate where my frame would ultimately be? Thanks for your

patience in answering this old, familiar question.

[ellis_vener_photography]

<I>hat I have not been able to discover is whether, when looking through the

viewfinder, I have to visualize where my frame lines would be...</I><P>No.<P><I>

In other words, is it What-You-See-Is-What-You-Get through the digital

viewfinder...</I><P>Yes. Pretty much but sometimes, depending on the camera you

capture a little more than you see in the view finder.

[phule]

<< do I have to estimate where my frame would ultimately be? >>

 

This response is as I understand viewfinders. I could be wrong, so you should take my words with a grain of salt.

 

1) A DSLR viewfinder is not electronic (or as you said "digital"). It's an optical viewfinder. Electronic viewfinders are found in so-called "prosumer" cameras like the A2, Pro1, 8700, or C-8080 (current crop of 8MP prosumers)

 

2) Very few film SLRs show 100% covered through the viewfinder so this question really doesn't change when talking about film or digital, but that's not what you're asking either...

 

3) The optical view incorporates the crop that a non-full-frame sensor gives the image. What you see is (to within a certain %) what you get. Each camera has it's own total % of coverage through the viewfinder, which you can check for on their site.

 

Shorter answer: You're thinking too hard about the crop factor. Relax. :) Go to a camera store, look through the viewfinder, take a picture, and review it. Does the coverage look the same?

[rob_malkin]

When people talk about the FLM factor its only when doing a comparison between 35mm SLR field of view and DSLR fields of view.

ie,

If you put a 50mm lens on a Nikon F100(35mm film body) you will have a certain field of view (how much of the world you could see if you put the camera on a tripod).

Put the same 50mm lens on a Nikon D100(DSLR with a 1.5x FLM factor) on the tripod (the same tripod that has not moved) and you will be able to see less of the world.

 

What you will be able to see thru the D100 viewfinder is the same as Putting a 75mm lens (50mm times 1.5) on the F100.

 

Thats it really.

The FLM factor is only realy of any use when you know what focal lenght you need on a 35mm body and would like the same on a DSLR which has a FLM(crop) factor.

 

eg,

"I love the 200mm focal lenght for sports photography on my film body. But I am not sure what one I will need when I use my DSLR."

answer, 200 devided by 1.5 = 133mm.

So to get the same field of view/perspective as a 200mm lens you will need a 133mm lens on a DSLR with a 1.5X FLM factor.

 

I am sure I have made this more complex than it realy is.

 

As for the coverage mentioned above there is no real need to worry about it with a DSLR. Your viewfinder will not show 100% of what you will end up getting on film/sensor. But with a DSLR you can check on the back if you missed a vital bit of the picture.

 

so, in summation, NO you dont need to think about the FLM factor when looking thru the viewfinder on a DSLR with a FLM factor.

 

There is no need to ever even think about FLM factors if you just shoot with a DSLR, unless you have used 35mm equipment and have a prefered focal length(lengths).

 

rob

ps, sorry for making this a bigger deal than it is, I always complicate things

[jeff_rivera5]

Have you ever shot in other formats? If so, it's the same thing. A wide angle, normal, and short telephoto are different focal lenths for each format. Well, most DSLR senors being smaller than 35mm film are like a different format. What do you want to shoot, gentle wide angle? You need a 24mm (in 6x6 you'd need a 60mm, in 4x5 a 90mm). A nice portrait lens? A 50mm would be a good start(in 6x6 a 150mm, in 4x5 a 210mm). It's really that easy.

[Greg M]

It's also easy to see when you see the flash coverage of a lens. On my EOS 3, 17-40L and 550EX, at any setting wider than 24mm I have to flip out the 17mm diffusor of the edges of the frames are dark because the flash head only covers to 24mm. Mount that same 17-40 lens on my Digital rebel though and the 550EX covers the lens all the way to 17mm without using the diffusor.