Dumb APS-c vs FF question

eoren1

Please humor me with this one:
I shoot with a Canon 50d and am considering the jump to full frame but concerned about losing the 'reach' I get.
For this shot, I used the 70-200/4 IS at 155mm:


Is my understanding re: FF correct in that:
If I shot with the 5D II at 155mm, I would get the same exact perspective but would have to crop to get this image? If so, would I essentially end up where I am now (as this is on a 15MP sensor)?
If I shot with the 5DII at 200mm, I might get closer to this framing/composition but would have a slightly different perspective? Though granted the 70-200 doesn't really do any distortion from 150-200...

I'm more concerned about shots like those of a full moon where I currently shoot at 200mm on an APS-C 15MP sensor and am trying to figure out if I will essentially get the exact same image from a FF sensor at 21MP if I just then cropped in Lightroom (well, pretty close - 1.6 x 15MP = 24 MP)

Thanks

cab.in.boston

You would lose a lot of pixels cropping a 5DII image to APS-C size. The crop factor does not apply to MP, it applies to effective focal length. APS-C (328 mm^2) has about 38% of the area of FF (864mm^2), thus the 50D has a much higher pixel density than 5DII (0.456 MP/mm^2 vs. 0.243). So if you crop FF down to equivalent size, you'll have roughly an 8MP image.

Other than that, my understanding is the same as yours. At 155mm, this exact image would live in the middle of a 5DII image (but of course you'd get all the benefits of lower noise per pixel, etc, from FF). You'd get a bit more compression shooting at 200mm vs. 155, and the changes in DoF that come with the longer FL as well. Unless I'm totally wrong on that, too.

paddler4

My understanding is the same as cab.in-boston's. The best explanation I have found of the DOF issue is here: http://photo.net/learn/optics/dofdigital/

Demian

You'd get a bit more compression shooting at 200mm vs. 155

Less compression. 200mm on FF has the same FOV as 125mm on crop. Depth of focus would be narrower tho


FF cameras do have some other drawbacks too. They're more susceptible to certain aberrations, and since it uses more of the lens you have to worry more about corner issues at low apertures.

Any particular reason you're considering a FF body?

eoren1

Thanks everyone. The more I think about moving to FF, the more scared I am of getting out of my comfort zone.
I have a friend who is a portrait photographer in town. She just switched from the 50D to the 5D II. She did me a favor by shooting some headshots and used her trusty 50/1.4. When I get the shots back, I saw distortions that I would normally expect at 30mm. Makes me wonder if the move up will cause me more headache than its worth.
Demian - here's a thread I started discussing my thoughts on staying with the crop body vs moving to FF
http://www.dgrin.com/showthread.php?t=212238

BoomerangNetwork.com

The positive point of not using a full frame is the bonus of magnification on all of your lenses. The negatives is that your wide angles have been limited too. Take a look at how a Fisheye lens is viewed, full frame vs APS.

Nikolai

For me, APS-C means two things:

1. x1.6 "reach" over similar MP field, and
2. a much more affordable (compared to EF L) EF-S glass line that still provides decent results.
3. well, it's also smaller and lighter, but I never cared about that :-)

However, once you start shooting with a comparable L counterpart glass on FF body you really can see the difference. E.g. EF 16-35 II L on 5D2 produces, IMHO, considerably better results than EF-S 10-22 on 7D. Granted, it also costs considerably more: $1,600 vs $800 (both new).

In OP example, snapping 50mm on FF is a bit too short for a good portrait work, methinks. You really want be above 70mm to avoid the distortion, at least for the upper body/headshots (full height/groups are different subject).

DeVerm

I didn't hesitate much other than the $$$ involved to add a 5d2 to my 7d. The great bonus is that your EF lenses multiply because you can switch them from one body to another where they perform different. I have two lenses that can only go on the 7D which is the EF-S 17-55mm IS USM and the Tokina 12-24mm. It means that I bought the 24-105mm f/4L IS USM as kit lens with the 5d2 and added the 17-40mm f/4L as wide angle to get full range on the 5d2. The 70-200mm, extenders, primes etc. all get an extra function so to say. When the 70-200mm f/2.8 IS USM goes on the 7D it always has an extender added for extra reach but on the 5D it is used without extender as a tele zoom just beyond the reach of the 24-105mm. Love the 70-200 twice as much now!

Matthew Saville

Yeah, honestly these days with the dynamic range and base ISO detail that is coming out of crop-sensor cameras, (Especially the new 7D / 60D sensor) ...Full-frame is really ONLY for people who love shallow depth or low-light high ISO stuff. I'd much rather have a crop sensor camera, if I were a hobbyist nature / adventure / landscape photographer. The ultra-wide options are even more plentiful with sharpness-for-your-dollar than on full-frame, and the telephoto options have their obvious advantage.

Also, yeah anyone who shoots headshots on a 50mm on full-frame, well, they don't really know what they're doing. A headshot should really be shot at 85-100+mm, to minimize forehead / nose distortion. Unless you're a supermodel, and even then there's a reason that many high-fashion photographers have a love affair with a 200 f/2.0 hehe.

50mm is for medium length / family portraits, and general photojournalism. It is not for headshots. I know this may shock many, but trust me! Or, don't trust me:

http://www.mcpactions.com/blog/2010/07/21/the-ideal-focal-length-for-portraiture-a-photographers-experiment/

http://www.lesjones.com/2011/06/15/effect-of-lens-focal-length-on-portraits/

=Matt=

eoren1

Thank you Matt! I would post my headshot (taken from above) but I'm fearful of showing the GINORMOUS Forehead. I was freaking out after seeing it - sure that it was a sign of my rapidly approaching baldness. I found the lesjones link afterwards and started to relax (a bit).

In her defense, she had just moved up from the crop to FF and was still playing with it. I do need to figure out how to explain this to her though.

Matthew Saville

eoren1 wrote: »

Thank you Matt! I would post my headshot (taken from above) but I'm fearful of showing the GINORMOUS Forehead. I was freaking out after seeing it - sure that it was a sign of my rapidly approaching baldness. I found the lesjones link afterwards and started to relax (a bit).

In her defense, she had just moved up from the crop to FF and was still playing with it. I do need to figure out how to explain this to her though.

Certainly understandable. As a general rule, I NEVER "scold" someone for doing something unless I've also made that mistake myself, and feel qualified to speak on the subject .

As someone with a big nose and a shrinking hairline, I do prefer to be shot at 85mm+ :-P


=Matt=

eoren1

My new avatar pic is at 200 - handed it to my wife and squatted in the middle of the street. This after going back through over 15 years of photos of me to try to convince myself my forehead really isn't that big. Now to somehow explain it to her...

Meanwhile, latest out of Canon Rumors is that there may not even be a 7D II. I find it very hard to believe that Canon would leave that area of the semi-/pro crop but it would make this discussion less important. Given a choice between a 70D and 5D III, I would choose the FF jump. Hoping the 7D II does materialize at some point to offer a path forward.

cab.in.boston

Demian wrote: »

You'd get a bit more compression shooting at 200mm vs. 155

Less compression. 200mm on FF has the same FOV as 125mm on crop. Depth of focus would be narrower tho

No. Compression is not a factor of a crop sensor. Compression is a result of the magnification of the lens itself, and the compression in the same 200mm lens image presented to different sensors will be the same on crop/FF/m4/3/MF/iPhone/etc (once you align the image to the sensor plane). The image projected to the sensor is what it is from a particular lens, the size of the sensor does not change the optics involved in producing/focusing the image. What changes is the area of the projected image circle that is actually captured. Crop sensors only take the middle ~40-45% of the circle and present it as the entire image, thus giving an impression that a longer lens was used with respect to angle/field of view. A 200mm lens on crop has the angle/field of view similar to a 300mm on FF, but it still has the DoF and compression of a 200mm lens. So, to get the same angle/field of view, you use a 300mm lens on FF, which has a narrower DoF for the same image than the 200mm lens, and the image compression will also be different due to the higher magnification of the 300mm lens.

Demian

Sorry man, compression is solely a factor of distance, which itself tends to be determined by FOV (we get closer with wide angle lenses). I took some pictures of my awful dining room; Both were taken on a full frame with different lenses, at approximately the same distance and angle, but the 24mm shot was cropped:


85mm


24mm (cropped)


The focal length obviously effects the DOF (I think I shot these at f/4) but otherwise they are identical.

cab.in.boston

Yes, you're right: we're both wrong. I was thinking that if you have the subject the same size in the image, the compression increases with longer lenses. I've done those same tests in my living room myself, where I had two objects and made them look drastically different with respect to each other by changing focal lengths, but also having to change my focus distance so that the object in the foreground was the same size in each photo. So if Eyal was to position himself such that the light tower was the same size in his image using a 200mm lens on FF as it was with his 155mm 50D image, the resulting image would be more compressed. Since he's shooting across water, however, I'm guessing that changing his location and subject distance isn't really easy. Mea culpa.

But it also wouldn't give you less compression.

Demian

cab.in.boston wrote: »

So if Eyal was to position himself such that the light tower was the same size in his image using a 200mm lens on FF as it was with his 155mm 50D image, the resulting image would be more compressed.

Less compressed. He would be shooting at 200mm on FF, whereas the crop camera at 155mm had an equivalent FOV to 248mm on FF. When the subject occupies the same amount of the frame, then a wider FOV means less compression while a narrower FOV means more.

Demian

*beats self over head with book*

I thought the pictures would be enough...

EDIT: I'm going to restate this simply:

RULE 1: Compression is ONLY affected by the relative distance between the lens and different objects.

The ONLY effect that focal length, FOV, or anything else has on compression is forcing you to get closer or further to fill the frame with your subject.

jhefti

Demian wrote: »

Sorry man, compression is solely a factor of distance, which itself tends to be determined by FOV (we get closer with wide angle lenses). I took some pictures of my awful dining room; Both were taken on a full frame with different lenses, at approximately the same distance and angle, but the 24mm shot was cropped:


85mm


24mm (cropped)


The focal length obviously effects the DOF (I think I shot these at f/4) but otherwise they are identical.

They don't look identical to me; the front can in the 2nd shot looks bigger.

Demian

Yeah, I didn't use a tripod, so sue me.

jhefti

Demian wrote: »

*beats self over head with book*

I thought the pictures would be enough...

EDIT: I'm going to restate this simply:

RULE 1: Compression is ONLY affected by the relative distance between the lens and different objects.

The ONLY effect that focal length, FOV, or anything else has on compression is forcing you to get closer or further to fill the frame with your subject.

I don't think I am disagreeing with you...It's just that when there are several variables at work it gets a bit complicated.

That said, it is interesting to consider what causes the apparent compression in longer lenses. If you take identical shots with different FL lenses, then crop (as you did) so they have the same FOV, the compression looks similar.

cab.in.boston

Demian wrote: »

Less compressed. He would be shooting at 200mm on FF, whereas the crop camera at 155mm had an equivalent FOV to 248mm on FF. When the subject occupies the same amount of the frame, then a wider FOV means less compression while a narrower FOV means more.

Ok, I give. I understand what you're saying. I don't think well in terms of FF, I suppose, as both my cameras are DX. So I was/am thinking only about changing focal lengths, and not about what the additional component of switching sensor size as well as FL does to the image. Again, mea culpa.

eoren1

jhefti wrote: »

1/f=1/o+1/i

M=-i/o=f/(f-o)

Here f= focal length, i=distance from lens to the image, o=distance from object to the lens, and M is the magnification.

I guess it wasn't a 'dumb' question if we're throwing equations into the discussion. Thanks everyone for the lively interaction. While it has seemed like a no-brainer in the past to aim for a FF camera, I'm realizing there are a ton of little things to think about before making the jump.

jhefti

eoren1 wrote: »

I guess it wasn't a 'dumb' question if we're throwing equations into the discussion. Thanks everyone for the lively interaction. While it has seemed like a no-brainer in the past to aim for a FF camera, I'm realizing there are a ton of little things to think about before making the jump.

Not dumb at all! In fact, I have been giving a bit of thought to the exact causes of compression (and enjoying the process).

I prefer FF, though in my collection of bodies I have crop factors of 1.6, 1.3 and 1.0. They each have their place, though CF seldom enters my thinking on which bodies to use.

jmphotocraft

eoren1 wrote: »

I'm more concerned about shots like those of a full moon where I currently shoot at 200mm on an APS-C 15MP sensor and am trying to figure out if I will essentially get the exact same image from a FF sensor at 21MP if I just then cropped in Lightroom (well, pretty close - 1.6 x 15MP = 24 MP)

Seems nobody has addressed this point.

To calculate the megapixels of a Canon APS-C sensor extended to Full Frame, you have to multiply by 1.6 twice.

The reason for this is that the FF sensor is 1.6 times wider and 1.6 times taller than APS-C.

That is why the 5DII has the same pixel density as the 20D. 8.2mp x 1.6 x 1.6 = 21mp.

Take a 5DII shot (5616 x 3744), crop it to 3510 x 2340 (8.2mp) and you get an APS-C sized image.

Your 50D has the pixel density of an imaginary 38mp FF camera.

So for your full moon shot at 200mm, you'll be putting significantly fewer pixels on the moon. The fix of course, is to buy a 300mm lens, or a 1.4x teleconverter. Or just don't print bigger than 12x18".

I have a 7D and a 5DII. The difference in DOF is extremely over-hyped. The benefits to FF as far as I can tell are:

• Less noise
• Bigger view finder
• Better for pixel peeping at 100% view
• Current selection of fast primes wider than 50mm make more sense on FF
• Current selection of walk-around L zooms make more sense on FF
• You can use a 17-40L instead of a 10-22 and impress idiots with the red ring.

Note that only the first three items will always be true.

The only time APS-C beats FF is when you are focal-length limited, as is the case with your moon shot and your current lenses.

eoren1

Thanks Jack
I guess the ultimate question is: is it upwards of $6000 'better'... I know only I can answer that question in the end.

Lower noise would be nice but I have only shot above 800 a handful of times with my 50D. When I did, I would just do a black/white conversion and introduce film-like grain with Silver Efex pro on purpose for that 'look'
Bigger viewfinder is nice but not $2000-more-nice
Pixel peeping, while fun, doesn't really mean that much in the end
And I'm definitely not buying a 300 or 400mm lens anytime soon...

As for walk-around, I really like the 17-55 2.8 IS for that and would have a hard time 'moving up' to the 24-70 2.8 II for so much more money.

For better or worse, I am very comfortable with the APS-C sensor and my current lens line up. I can pre-visualize which lens to use for a given shot and have found the sweet spots for each lens. As I said above, a friend recently shot me with a 50 on the 5D II and I was shocked to see distortion akin to the 30/1.4 I used on my 50D previously. It would be a big curve to get used to how the lenses 'should' work. Without a history of shooting film with an SLR, the 'real' focal length is somewhat arbitrary/irrelevant to my way of shooting/thinking.

I do sell my landscape photography in town and have never had someone look up close and comment on any noise that might be in a finished print. And in fact, I am getting ready for an individual exhibit where I have some really nice shots printed up at 18x24 without any problems.

I'm not trying to be adversarial here by the way (this sort of reads that way - sorry). Just going through the arguments spelled out here and in my head as I decide what to do.

Will wait to see what the 5D/7D upgrades bring and consider my options then.

jmphotocraft

Sounds like you are all set then. I didn't think you were being adversarial. I hope you could tell I was saying that FF is very much over-romanticized. Sure, I use my 5DII way more than my 7D, but if I could only own one camera (that exists*) it would be the 7D.

I did start with film and I still shoot it occasionally, so I feel more at home with FF. The 17-55/2.8IS is awesome and actually more useful than the 24-70. However the 17-55 is a dust vacuum. At least the one I had was and I did not use a UV filter. Sounds like that is the only aspect of APS-C that might affect you. At low ISO, you would have to print 20x30" and put your nose to it to see any difference between the 7D and 5DII. This is basically the same as pixel peeping, and I agree it is pretty meaningless.


*I am selling my 7D to save up for the 5DIII. When the 5DIII gets here I'll sell my 5DII.

eoren1

I joined Canon's CPS program mostly for that reason (dust in the 17-55) - $100/year and I get two free cleanings plus other stuff. I also really needed to get my 50D properly cleaned as I can't get dust off the sensor anymore with the Copperhill method.

As for the whole APS-C vs FF, I'm going to stay on the fence until the 5D III and 7DII/70D are announced. I'm hoping they don't put out a 20+MP APS-C - I think that's one factor that may drive me to FF as I can't imagine getting any better image quality out of more than a 15 MP sensor of that size.

jhefti

I shoot FF and crop (1.3 in my 1D bodies and occasionally 1.6 in my 50D), and I find that many other properties of the sensor are more important that pixel density. I usually get better shots with my 5DII than my 50D, even if the PP crop results in fewer pixels. Of course, maybe my lenses are better tuned to my 5DII, so who knows? Since I shoot in low light all the time, the FF is nice.

I am actually rethinking this topic in trying to decide whether to follow-up on my pre-order of a 1Dx. My mark IV works great, and though I can occasionally use the higher ISO of a 1Dx, I'm not sure it is a justification to spend that kind of money. I do shoot sports professionally, but only to get the media credential.

adbsgicom

jhefti wrote: »

I do shoot sports professionally, but only to get the media credential.

How did you go about establishing that part of the relationship? I'd like to continue growing my skills in this area, but wasn't sure how to even start going about getting on the sidelines.

jhefti

adbsgicom wrote: »

How did you go about establishing that part of the relationship? I'd like to continue growing my skills in this area, but wasn't sure how to even start going about getting on the sidelines.

I got my start by working a connection at the local newspaper, and building a portfolio from there. Basically, any way you can get access to a good college or professional team will give you a start on your portfolio. It takes some work, but usually you can find a sponsor somewhere.

adbsgicom

jhefti wrote: »

I got my start by working a connection at the local newspaper, and building a portfolio from there. Basically, any way you can get access to a good college or professional team will give you a start on your portfolio. It takes some work, but usually you can find a sponsor somewhere.

Thanks for the reply.
Sorry for the thread-jacking.