Lens Dilemma

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Limitless

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Chéyne
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I have a canon 700d which is CSC camera, now my dilemma is that I want to buy a 50mm f1.2L but with the x1.6 crop factor it will bring it down to 31.25mm. I plan on buying a full frame in the future and I don't want to have to buy another set of lenses when I upgrade, so do I buy the 85mm f1.2L to achieve 53.125mm or do I buy the 50mm and adjust my photography until I buy a full frame?

Your views/opinions would be appreciated.

Cheers Chéyne
 
Ok, the 70d isn't a CSC!

It is cropped though (if thats what you meant) but you multiply it (not divide) by 1.6, so while it will always be a 50mm lens (the focal length doesn't change) the 50mm on a cropped body provides the FF / 35mm field of view equivalent of an 80mm lens.
 
To get 50mm on crop then get a 35mm lens
 
Mark twiglet said:
To get 50mm on crop then get a 35mm lens
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It's not quite that simple - it'll give a similar angle of view to a 50mm lens on FF, but the other characteristics of the 50mm will be missing, such as subject / background separation (not to be confused with depth of field) that is more obvious at longer lengths for example, as longer lengths compress camera / subject distances and wider lenses expand this visual distance.

It does give a different look to 50mm FF.
 
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odd jim said:
It's not quite that simple - it'll give a similar angle of view to a 50mm lens on FF, but the other characteristics of the 50mm will be missing, such as subject / background separation (not to be confused with depth of field) that is more obvious at longer lengths for example, as longer lengths compress camera / subject distances and wider lenses expand this visual distance.
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Eh? Are you sure?

Are you talking about the "flattening" effect of longer lenses? If you are this is down to camera to subject distance and if you shoot with 35mm on APS-C and 50mm with FF it'll look the same assuming that your camera to subject distance is the same.

Equalise the focal length and the apertures for the crop factor and the FoV and the DoF will be the same.

Also, if you shoot from the same distance with a 4mm lens and crop it to 50mm FoV the "flattening" will be the same. It's down to the FoV which leads you to increase or decrease your camera to subject distance which gives you the subject to environment relationships. It's not a focal length thing.
 
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Limitless said:
I have a canon 700d which is CSC camera, now my dilemma is that I want to buy a 50mm f1.2L but with the x1.6 crop factor it will bring it down to 31.25mm. I plan on buying a full frame in the future and I don't want to have to buy another set of lenses when I upgrade, so do I buy the 85mm f1.2L to achieve 53.125mm or do I buy the 50mm and adjust my photography until I buy a full frame?

Your views/opinions would be appreciated.

Cheers Chéyne
Click to expand...
Your camera is a DSLR with an APS-C size sensor not a CSC.

Also you're doing the crop factor the wrong way around, 50mm on a Canon APS-C will give the equivalent focal length of 80mm
 
woof woof said:
Eh? Are you sure?

Are you talking about the "flattening" effect of longer lenses? If you are this is down to camera to subject distance and if you shoot with 35mm on APS-C and 50mm with FF it'll look the same assuming that your camera to subject distance is the same.

Equalise the focal length and the apertures for the crop factor and the FoV and the DoF will be the same.

Also, if you shoot from the same distance with a 4mm lens and crop it to 50mm FoV the "flattening" will be the same. It's down to the FoV which leads you to increase or decrease your camera to subject distance which gives you the subject to environment relationships. It's not a focal length thing.
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I don't think it quite works like that (and I'm not talking about DOF here).

Also perspective is different between the two and that won't change with the crop factor (think of the perspective wide angles give for say, faces at the same relative distance to a 50mm for an extreme example).

There will be more differences between the two lenses than simple field of view.

It's different to DOF, something I was seeing today testing my 600mm, which gave a really noticeable thrown out background, giving me great subject separation even at f/8, but also a good DOF all over the subject (because I shot at f/8). Extreme example but it does demonstrate how focal lengths effect the image past the obvious.
 
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I think you need to do some reading around crop sensors and multipliers.
Watch this video. It explains and demonstrates why you multiply by 1.6 when looking at equivalent focal lengths of lenses.
View: https://youtu.be/f5zN6NVx-hY


If you have a 700D, but want to invest in a lens that will work nicely on full frame at a later date, I would suggest you go for the Canon 50mm f1.4 USM as it's much cheaper than the L f1.2, and much lighter. The 50 1.2 is a beast of a lens and it's probably not worth it at the moment, but the 50 1.4 will work nicely on your 700D and on a full frame camera. Sure it'll be the equivalent view of an 80mm lens, but that's fine once you're used it. It does take a while to get used to using a prime lens.
Alternatively, you could look at the Sigma 35mm f1.4 Art, which is a great lens (some say better than the Canon 35mm L), will cost you about £500ish (s/h probably), this would give you the equivalent view of a 56mm on full frame, so closer.

If you only have kit lenses at the moment, I would get a 50mm prime, either a cheap f1.8 or the 1.4, get used to that, then upgrade your other lenses when you find your current kit lacking.
Until you know what sort of photography you like doing, there's no point investing a lot of money on an expensive lens that you're not going to use. For example if you like night/long exposure photography, a 70-200 f2.8 is not worth having, but a 35mm f1.4 would be worth it for night shots. Likewise if you're into portraits, then a 16-35mm f2.8 isn't going to be the lens for you, but an 85mm f1.8 would be a great start.
Some lenses are very versatile: The 24-70mm f2.8 (on full frame) or the 17-55mm f2.8 IS (on crop sensor) are good all round general lenses. Wide enough aperture to be good in low light and a good zoom range to be used in many situations.

You could, hire a lens for a weekend to see you like it before buying.

As said, it does kinda depend what you're interested in photographing.
 
Mark twiglet said:
To get 50mm on crop then get a 35mm lens
Click to expand...

A 35 is a good prime to get as it will work like a 56mm on a 1.6 crop sensor like the 700d

It will have the advantage that if you upgrade to FF then 35 is still a good focal length for general purpose photography - I shoot 28mm on a 1.3x crop camera and I really like the 35 (approx) equivalent although anything between 28-50 is "good to go" for most general types of photography.
 
Thanks for the advice everyone. I'm relatively new to photography (only had my camera for a year) and I'm constantly watching YouTube videos. For some reason I thought you divided the focal length but I should've thought as it is x1.6, silly mistake!

I wrote CSC as I thought I could shorten "Crop Sensor Camera"

I'm into portraits, night, architecture and wild life, so it a pretty broad spectrum. I would rather buy a decent prime lens now instead of buying twice. I'll probably be on a full frame by the end of the year.

My plan is to get a decent prime lens and then get a 70-200 f2.8 II USM.

I would buy secondhand lenses and other gear but I don't have my post count up to the required amount so I'll just have to wait.

I look forward to more advice:ty:
 
Limitless said:
Thanks for the advice everyone. I'm relatively new to photography (only had my camera for a year) and I'm constantly watching YouTube videos. For some reason I thought you divided the focal length but I should've thought as it is x1.6, silly mistake!

I wrote CSC as I thought I could shorten "Crop Sensor Camera"

I'm into portraits, night, architecture and wild life, so it a pretty broad spectrum. I would rather buy a decent prime lens now instead of buying twice. I'll probably be on a full frame by the end of the year.

My plan is to get a decent prime lens and then get a 70-200 f2.8 II USM.

I would buy secondhand lenses and other gear but I don't have my post count up to the required amount so I'll just have to wait.

I look forward to more advice:ty:
Click to expand...
FYI CSC = Compact System Camera
 
boliston said:
A 35 is a good prime to get as it will work like a 56mm on a 1.6 crop sensor like the 700d

It will have the advantage that if you upgrade to FF then 35 is still a good focal length for general purpose photography - I shoot 28mm on a 1.3x crop camera and I really like the 35 (approx) equivalent although anything between 28-50 is "good to go" for most general types of photography.
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Not quite, as per my post above, but will provide near on the same FOV.
 
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odd jim said:
I don't think it quite works like that (and I'm not talking about DOF here).

Also perspective is different between the two and that won't change with the crop factor (think of the perspective wide angles give for say, faces at the same relative distance to a 50mm for an extreme example).

There will be more differences between the two lenses than simple field of view.

It's different to DOF, something I was seeing today testing my 600mm, which gave a really noticeable thrown out background, giving me great subject separation even at f/8, but also a good DOF all over the subject (because I shot at f/8). Extreme example but it does demonstrate how focal lengths effect the image past the obvious.
Click to expand...

No, you're wrong and if you try this with FF and a crop you'll see how it works.

Trust me or try it for yourself... the crop factor multiplier thingy works and 35mm or whatever you fit to a crop camera will look like the equivalent 50mm on FF and the only differences will be down to the physical stuff in the lens such as the shape of the aperture blades and the "look" created by the blades and number of elements and all that stuff but the perspective, FoV and DoF will be exactly the same if you match everything up as per the crop factor and that's FoV, aperture and camera to subject distance. Even the size of the out of focus highlights will be the same, although the shape may be different depending upon the blades.

If this wasn't the case every shot you took with a compact and its 6-17mm lens (or whatever it has) would give you big nose syndrome but that doesn't happen because it's a x6 crop and looks like a 36-102mm and at the other end of the scale all those superzooms would have massive lenses to give you that massive zoom, and they don't.

I'm sure you'll be able to Google your way to examples that'll demonstrate this to you but if not I can send or post examples from FF and MFT which will make the numbers easy as it's x2 crop.
 
woof woof said:
No, you're wrong and if you try this with FF and a crop you'll see how it works.

Trust me or try it for yourself... the crop factor multiplier thingy works and 35mm or whatever you fit to a crop camera will look like the equivalent 50mm on FF and the only differences will be down to the physical stuff in the lens such as the shape of the aperture blades and the "look" created by the blades and number of elements and all that stuff but the perspective, FoV and DoF will be exactly the same if you match everything up as per the crop factor and that's FoV, aperture and camera to subject distance. Even the size of the out of focus highlights will be the same, although the shape may be different depending upon the blades.

If this wasn't the case every shot you took with a compact and its 6-17mm lens (or whatever it has) would give you big nose syndrome but that doesn't happen because it's a x6 crop and looks like a 36-102mm and at the other end of the scale all those superzooms would have massive lenses to give you that massive zoom, and they don't.

I'm sure you'll be able to Google your way to examples that'll demonstrate this to you but if not I can send or post examples from FF and MFT which will make the numbers easy as it's x2 crop.
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I'll give it a go tomorrow with a 35 on crop and a 50 on FF to see what it looks like, but the physics doesn't make sense to me?
 
odd jim said:
Also perspective is different between the two and that won't change with the crop factor (think of the perspective wide angles give for say, faces at the same relative distance to a 50mm for an extreme example).
Click to expand...
This is the root of your misunderstanding. Perspective is controlled only by the subject-camera distance. Most people think it's something to do with the lens, but that's because when you use a longer lens you tend to increase the subject distance to preserve the composition. It's the distance that does it, not the lens.

Thought experiment. (Actually it needn't be a thought experiment. You could do this.) Put a very long lens on your camera, get a friend to stand a long way away, and take a portrait shot (1). Without moving either you or your friend, switch to a very wide angle lens and take another shot (2). Then get your friend to walk towards you until her head is the same size in the frame as it was in (1), and take a third shot (3).

Obviously in shot 2 your friend will be very small in the frame, but that doesn't matter. Crop and zoom so that the size of the head in 2 is the same as in 1 and 3. Then compare.

You'll see that 1 and 2 will be the same, but 3 is different. 3 will have the exaggerated and unflattering perspective (big nose,small ears, etc) which we typically associate with wide angle lenses, but 2 was taken with the same lens. This demonstrates that it's the distance that causes the perspective effect, not the lens.
 
StewartR said:
This is the root of your misunderstanding. Perspective is controlled only by the subject-camera distance. Most people think it's something to do with the lens, but that's because when you use a longer lens you tend to increase the subject distance to preserve the composition. It's the distance that does it, not the lens.

Thought experiment. (Actually it needn't be a thought experiment. You could do this.) Put a very long lens on your camera, get a friend to stand a long way away, and take a portrait shot (1). Without moving either you or your friend, switch to a very wide angle lens and take another shot (2). Then get your friend to walk towards you until her head is the same size in the frame as it was in (1), and take a third shot (3).

Obviously in shot 2 your friend will be very small in the frame, but that doesn't matter. Crop and zoom so that the size of the head in 2 is the same as in 1 and 3. Then compare.

You'll see that 1 and 2 will be the same, but 3 is different. 3 will have the exaggerated and unflattering perspective (big nose,small ears, etc) which we typically associate with wide angle lenses, but 2 was taken with the same lens. This demonstrates that it's the distance that causes the perspective effect, not the lens.
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Yes that makes sense.

But back to my original point, would the longer lens not throw the background out significantly more, as per my suggestion previously? So even on a crop, the shorter lens would render them image differently to the "equivalent" lens on the FF body (35/50)?
 
odd jim said:
But back to my original point, would the longer lens not throw the background out significantly more, as per my suggestion previously? So even on a crop, the shorter lens would render them image differently to the "equivalent" lens on the FF body (35/50)?
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Sorry, you've lost me now. Previously you said:
odd jim said:
I don't think it quite works like that (and I'm not talking about DOF here).
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But if you're talking about "throwing the background out", surely you are talking about depth of field? Or have I misunderstood?
 
StewartR said:
Sorry, you've lost me now. Previously you said:

But if you're talking about "throwing the background out", surely you are talking about depth of field? Or have I misunderstood?
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No, that's my poor choice of words and poor way of explaining what I was trying to say. The background being thrown out is of course affecting depth of field, which is influenced by (relative) focal length at the same distance at the same aperture. The issue being that sensor crop factor won't change that, only the field of view. So using equivalent FOV on a crop (in the original case a 35 on a crop to simulate 50 on an FF) will still render the image differently.
 
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Personally, I would invest in the 17-55 f2.8 as this is a VERY useful lens on a crop body. The 50mm lenses do a job, but I think you'll get much more use from the excellent quality and range of the 17-55. Just a thought.
 
Jim, honestly, you can go mad thinking about all this and 10 minutes with a camera and either a zoom or a couple of primes will sort all this out quicker and prevent your brain from melting with it all.

If you can take a shot twice, once at long zoom and then at much shorter without changing position you should then be able to crop the wide shot to the field of view of the long and the pictures will look the same except for the resolution as you've cropped the wider shot.

Luckily for my brain I have FF and MFT so the numbers are easy to compare and I can confirm that both setting aperture and focal length for the crop factor works when comparing formats as does taking two shots from the same distance on one format.

I think it's much easier to see this for yourself rather than attempt through theory to contradict what many of us have been told.
 
Here you go. A Chinese dragon against the outside world including the neighbours washing :D

This is MFT at 17mm f4 and 35mm f8 for full frame equivalent of 35mm f8 and 70mm f16.

35mm f8 whole image shot...



17mm f4 shot but cropped to 35mm field of view...



17mm full image...



Hopefully you can see that at the same distance if the crop factors are accounted for the pictures will look the same (excepting resolution...)

Therefore 35mm on APS-C will look similar to 50mm on FF and the only differences should be down to differences in lens design and construction.
 
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Ok that's pretty definitive, my brain is still trying to relate the physics though!
 
Noone's stated the obvious yet...I don't think

As the 700D is APS-C her lens will be EF-S, so Chéyne should be beware that if she is getting a lens for her 700D that she does not accidentally buy an EF-S lens or the Tamron/Sigma equivalents that are intended for APS-C only and will not work on FF.....
 
welshwizard645 said:
Noone's stated the obvious yet...I don't think

As the 700D is APS-C her lens will be EF-S, so Chéyne should be beware that if she is getting a lens for her 700D that she does not accidentally buy an EF-S lens or the Tamron/Sigma equivalents that are intended for APS-C only and will not work on FF.....
Click to expand...
A good APS-C lens such as the 17-55 f/2.8 hold their value very well, so when that time comes she shouldn't loose out financially. She should get the most appropriate lens for her current needs even if that means getting a cropper lens only. Unless the FF upgrade is imminent of course.
 
Thanks for all your replies, I will be upgrading to a full frame within the year so I would rather buy an EF lens so I can use it on the FF.

It's he by the way ;)
 
Sorry, I said "she" because Welshwizard did, not sure where it came from!
 
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