EF and EFS, FF, Crop camera

I heard an 85mm lens is a great lens for portraits but if I got an 85mm on my crop body T3i I would really have a 134mm, checking camera app it says the magnification would be 2.2
I set my app to 54mm and I get 85mm with a 1.7 magnification.
I'm thinking, I know there he goes thinking again, but,
Instead of buying a new lens for a crop body camera it would be better to buy a FF camera body then get an 85mm lens for it, and stop having to do the math for a crop sensor camera.
Would appreciate some advice on the subject.
Don

You don't have to do the math, a 85mm lens will still be a 85mm on a crop, full frame, medium format or large format.

Just to be clear using a crop body doesnt turn an 85 to a 134. What it does is give the same field of view as a 134. Crop doesn't affect the lens, just the field of view. With that said, you probably ought to be more specific about which FF body and why you want to do that. FF bodies of a similar vintage to a crop body have advantages in noise but its less clear when you start factoring in newer versus older. FF nodies have an advantage in shallow depth of field necause you have to use a longer lens to achieve similar framing.

There is also nothing wrong with the 85 on a crop having the same field of view as a 135. The 135L is a fantastic portrait lens on FF and the 85 on a crop would be an inexpensive way to achieve similar framing.

So if you can sprinkle in some specifics we can probably be of more help.

DigitalDon wrote in post #17880951
I heard an 85mm lens is a great lens for portraits but if I got an 85mm on my crop body T3i I would really have a 134mm, checking camera app it says the magnification would be 2.2
I set my app to 54mm and I get 85mm with a 1.7 magnification.
I'm thinking, I know there he goes thinking again, but,
Instead of buying a new lens for a crop body camera it would be better to buy a FF camera body then get an 85mm lens for it, and stop having to do the math for a crop sensor camera.
Would appreciate some advice on the subject.
Don

I am not sure why you are talking about magnification and where you got 2.2 and 1.7 from. Those numbers don't make sense to me.

If you can afford it, then yes, but a FF camera and 85mm lens. If you want to save some money then get a 50mm lens for your crop camera.

The math isn't that hard if you want to know about the equivalent field of view from APS-C vs Full Frame. You just multiply or divide by 1.6 because a Canon Crop camera has a sensor that is 1.6 times smaller than a FF camera.

Thanks guys
I was thinking about a 6D because I want to get rid all the crop stuff.
The magnifications came from an app called SetMyCamera I don't understand them either.

DigitalDon wrote in post #17880990
Thanks guys
I was thinking about a 6D because I want to get rid all the crop stuff.
The magnifications came from an app called SetMyCamera I don't understand them either.

Step #1 IMHO would be understanding the differences between "crop" and "FF" sensors and how they effect the field of view of the lens (and how that effects DOF, distance to subject to maintain framing, perspective etc.).

The basics (i.e. 95% of what you need to know) aren't overly complicated. Once you understand it then the decision to switch camera bodies or lenses will be easier to make based on your own needs.

Hi. I found looking at some tube clips helped me to get a clearer understanding of sensor size, DOF, FL etc.

Search for "Full frame sensors vs crop sensors Karl Taylor". I think he explains it quite well.

DigitalDon wrote in post #17880990
Thanks guys
I was thinking about a 6D because I want to get rid all the crop stuff.
The magnifications came from an app called SetMyCamera I don't understand them either.

Nothing wrong with the crop stuff you have. If you can afford to keep it, do so. You'll regret selling it.

DigitalDon wrote in post #17880990
I don't understand them either.

This is precisely why you shouldn't sell / buy anything right now. Instead, focus on this.

What makes you think you need a magnification value for portrait?
Focal length doesn't change on a different size sensor. Field of view does.
Distance to subject influences the distortion you probably have read about regarding portraiture. Focal length influences distance to subject.

Can you post examples of the portraits you're doing?
Are you doing just head shots?
Full body shots?
Indoor (studio), outdoor?
Do you use lighting (and if so, what all modifiers, lights, etc, do you have)?

There is no correct focal length for portraiture.

Maybe you can provide examples of what you're trying to achieve?

Very best,

Thanks to all of you for your help
Lets take an example of what I am trying to understand about FF vs Crop, say I am doing Boudoir photography and I have a FF camera and a crop sensor camera and a 50mm lens.

Now I put my FF camera on a tripod with the 50mm lens, camera in portrait standing vertical on the tripod, I move the tripod to fill the frame with the mattress , take a picture, then I change to my T31 crop body camera, tripod hasn't been moved, I take the same 50mm lens put it on my T3i, take a picture.

Not having a FF camera and a Crop sensor camera to see what is happening in real time is where all the tech talk gets complicated for me. So, if you would in simple terms tell me what is going to happen in the above example, I know I will have questions to your replies, so I will ask then when you reply, so that I don't wander all over the place with so many questions that is going to leave everyone wondering what the hell is he talking about.

Thanks
Don

In your example, you would have to take a few steps back with the crop/50mm to get the same field of view.
On a crop, take yours lens and multiply 1.6. (50 x 1.6 = 80) 50mm on a crop is roughly the same field of view as a 80mm on a full frame. Whatever crop lens you have just multiply it by 1.6 and it gives you the equivalent field of view on a full frame.

delta0014 wrote in post #17881342
In your example, you would have to take a few steps back with the crop/50mm to get the same field of view.
On a crop, take yours lens and multiply 1.6. (50 x 1.6 = 80) 50mm on a crop is roughly the same field of view as a 80mm on a full frame. Whatever crop lens you have just multiply it by 1.6 and it gives you the equivalent field of view on a full frame.

Good info and a different way to think about this too, if you have a zoom: If you shoot a zoom on an APS-C , and then use that zoom on the FF from the same distance, just zoom in 60% more, provided your lens has that much left, to get the same framing.

If your lens doesn't have that, then you are reach-limited, and this is one of the reasons people have a crop body (provided it has greater pixel density than their FF) in their bag.

For example, having a 5DS and a 7D wouldn't do much for you, because the 5DS cropped down to what the 7D provides for a view nets you actually a bit larger result than the 7D, resolution-wise. (50mpx / (1.6 ^2) = 20mpx vs the 18mpx on the 7D). At this point, the decision then falls to featuresets only.

If Canon produced a FF body that was 50mpx, but had the 65 AF point AI Servo and burst/FPS stats of the 7D2, there would be little reason to buy a 7D2 except for the less expensive, lighter, smaller but capable EFS lenses.

delta0014 wrote in post #17881342
In your example, you would have to take a few steps back with the crop/50mm to get the same field of view.
On a crop, take yours lens and multiply 1.6. (50 x 1.6 = 80) 50mm on a crop is roughly the same field of view as a 80mm on a full frame. Whatever crop lens you have just multiply it by 1.6 and it gives you the equivalent field of view on a full frame.

Thanks delta0014

Now when I take the few steps back I thinking the mattress and model (full size skeleton haha) is going to get smaller and I'm going to start getting more of the room in the picture, which I will have to crop out in Lightroom, I read some where that cropping in Lightroom or other software you are going to start to losing information.
With a FF camera if I fill the frame then there shouldn't be any cropping, nothing getting smaller. Is that right?
Thanks
Don

No,
If you take a few steps back with the crop, you're still gonna fill the frame as you would with a full frame a few steps closer.

Just remember any time you move instead of using the lens to zoom in/out, you are changing your perspective. For this type of gig, you want to play with all kinds of angles, and once you get the angle you want with the background you want, then you are going to want to fine-tune using a zoom lens, most likely.

And I wouldn't get all hung up about cropping out parts of the image, it is better to shoot a bit loose, and then crop, especially if you are new at shooting something. Once you get experience, you can get a bit more surgical on your composition in-camera. Don't worry about cropping away small parts of the image, you will still have more than enough to print large if you ever want to.