1.4 TC on a 1.3 crop

I'll start by saying I understand FF/1.6/1.3. I know that even though you here people saying 100mm is 100mm on FF and crops. The difference is that on a crop you are seeing just a cutout (or a portion) of the FF view, so yes 100mm on a crop is the same as ff you just see the middle cropped portion.

That aside, I also know that a 100mm lens on a 1.3 crop gives you the illusion of a 130mm view. I don't want to get in a discussion regarding 100mm is 100mm is 100mm..

My question is this, if I am using a 100mm lens and I'm using my 5D, the the FOV I'm looking at is 100mm. On a 1.3 crop it's 130mm. When I add a 1.4 TC to that, would I multiply 130mm x 1.4 which is 182mm....... or do I multiply 100mm x 1.7 (the combination of 1.3 and 1.4) which brings me to 170mm. My guess is 130 x 1.4 bringing me to 182mm

Thanks in advance for your input

doesn't matter how you multiply them. They all add up to the same, 182mm

thatkatmat wrote in post #5071013
My guess is 130 x 1.4 bringing me to 182mm

Yes. That is your field of view.

LightRules wrote in post #5071066
Yes. That is your field of view.

Thanks, that's what I figured....then I got to thinking.....

Think I'll put the beer down now and call it a night

Ummmm...so stacking a 2xTC will be 364? And I'll still lose only 1 stop? Hell ... and I'm sober!

samnz wrote in post #5071155
Ummmm...so stacking a 2xTC will be 364? And I'll still lose only 1 stop? Hell ... and I'm sober!

no, in this setup, 100*1.4*2*1.3 crop=364, but 1.4tc is 1 stop, 2tc is 2, so you loose a total of 3 stops... that beautiful f2.8 lens goes to f8

Bugger - thought it was too good to be true... thanks for the reply.

thatkatmat wrote in post #5071013
or do I multiply 100mm x 1.7 (the combination of 1.3 and 1.4) which brings me to 170mm.

I'm not sure how you figured 1.7 was a combination of 1.3 and 1.4 - it isn't. To tackle it that way, you'd multiply 1.3 x 1.4 (that's the way to combine the factors) to get 1.82 and then multiply by the FL.

thatkatmat wrote in post #5071013
My question is this, if I am using a 100mm lens and I'm using my 5D, the the FOV I'm looking at is 100mm. On a 1.3 crop it's 130mm. When I add a 1.4 TC to that, would I multiply 130mm x 1.4 which is 182mm....... or do I multiply 100mm x 1.7 (the combination of 1.3 and 1.4) which brings me to 170mm. My guess is 130 x 1.4 bringing me to 182mm

Thanks in advance for your input

Umm...isn't FOV expressed in degrees not millimetres???

He's using that to mean "the FOV he's looking at is the same FOV you'd get with an XXmm lens on 35mm format."

Jman13 wrote in post #5072136
He's using that to mean "the FOV he's looking at is the same FOV you'd get with an XXmm lens on 35mm format."

To the original poster (thatkatmat): Please read and understand Jman13's post above. This is the way that this sort of thing should be thought about and, even more importantly, written in a forum such as this.

Your comments about "the FOV I'm looking at is 100mm", for example, will totally confuse any newbies reading the forum even if you completely understand the subject.

The only purpose for using the "crop factor" calculation is to compare focal lengths used on one format camera (format referring to the size of the film frame or digital sensor). If one is not actually comparing performance of lenses on two different formats, the "crop factor" calculations should be completely eliminated from the process of choosing lenses. Too many newbies are bamboozled into thinking that they always need to calculate the "35mm film camera equivalent" performance of lenses on their Digital Rebel for no useful purpose.

Thanks Everybody,
Xarqi, guess I skipped that lesson in school
MeatyO, sorry I didn't express my thoughts too clearly, but Jman did.
Jman, exactly.
Skip, I was trying to determine the difference between using my 5D and my 1D with my newly purchased 1.4TC

thatkatmat wrote in post #5072347
Skip, I was trying to determine the difference between using my 5D and my 1D with my newly purchased 1.4TC

I knew that, and I knew that you basically understood what's involved here. I was just concerned that newbies would become confused with the way you described the field of view, etc.

My last paragraph above was primarily aimed at the newbies who read everything we write here.

Meaty0 wrote in post #5071347
Umm...isn't FOV expressed in degrees not millimetres???

A lens's area of capture at a given shooting distance is FOV...it varies with shooting distanc. The lens' AOV is constant for a specific format.

For example, a 24mm lens sees FOV of 6.2' x 9.3' at shooting distance 10', but sees FOV of 3' x 4.6' at shooting distance of 5'. Its AOV is (measured diagonally) 59 degrees (regardless of shooting distance) if used on APS-C, but it has AOV of 84 degrees when used on FF.

SkipD wrote in post #5072375
I was just concerned that newbies would become confused with the way you described the field of view, etc.

This is why it's so important to express the subject carefully.