Full frame DOF

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coldpenguin

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Yes
I have the 7d Mk I
This was a good camera for me, as I enjoyed taking photos of wildlife, that was further away that I wanted

Recently, I have been taking portraits, my new kid, and niece.
My best lens would be the 70-200L 2.8, but it is a bit too long on the 7d.
Next down is the 17-55 2.8, which is what I have been using.

I am under the impression that the DOF effect for Full frame is much stronger, zoom-to-zoom comparison.

Is there any way I can 'pretend' with the kit I have that the camera is full frame (even if it means taking a gash photo at a much longer than expected focal range, then cropping or whatever) to get a feel for what I would normally achieve (aside from getting one in/hiring)?

It appears that with the 6d, and 5d MkII the prices are becoming more reasonable for a occasional hobbyist, but it is still difficult to justify the expense of what would be a 2nd body.
 
DOF is actually Less on FF over APS-C though at shorter distances there isnt to much in it. this chart shows perfectly the differences using a canon 7D and 5D mark lll.
the only major difference is angle of view when comparing lenses over the same focal range and to get the same shot on FF over APS-C you would need to be closer with FF so the DOF will change in that respect.
As you can see anything within the first 3m distance the DOF change is marginal so shooting portrait the only real difference will be angle of view when using say a 50mm lens. on FF your angle of view will be wider thus the central object of focus will be smaller in the frame, so to compensate for that you would thus need to move closer to create the same angle of view as on an APS_C and by moving closer you of course decrease DOF.
Depth_of_field_chart.jpg
 
The difference in DoF between FF and APS-C is f/number x crop factor. 1.2 to 1.3-ish stops, depending on crop factor but one stop is near as makes no odds. So if you shoot something at f/4 on your 7D, and then at f/2.8, that will show the same difference as changing format.

The difference is noticeable for sure, but not massive. If you want really shallow DoF, then it's full frame plus some nice fast f/1.4 primes :)
 
The crop factor works so all you need to do is factor in the x1.6 (for Canon) and you can easily work out what the apertures and focal lengths will be equivalent to, APS-C to FF wise.

I think it's important to decide what you want and how to achieve it and what if anything FF would offer over your APS-C setup. If a shallow DoF look is your aim then the next question is can that look be achieved with your current kit or would you need FF. Personally with FF I often find myself struggling for more DoF and again, personally, when shooting a portrait I usually don't want one eye in the DoF and one eye out and to get some depth of field I usually therefore don't shoot a portrait anywhere near wide open.

In your position what I'd do is shoot a few portraits with the same subject and framing at different focal lengths and apertures and then review the shots and decide if I was happy or not and if not, why not. My guess is that unless you want to get shots in which very little is in the DoF you'll be able to get the look you want with your current kit.

I'd question if a 85mm f1.8 is needed, for example if you shoot with FF at 85mm and f5.6 you'd get the same look from APS-C at 55mm and f3.6 and you can get that with your 17-55mm f2.8. Shoot FF at 85mm and f1.8 and depending upon your camera to subject distance you could end up with very little in the DoF.
 
Thanks all for the replies.
I think it has helped me clarify my position and think it through. It isn't the DOF effect in the end that I want, I believe that it is actually a lens/focal length issue, and I just incorrectly 'thought' that shallower DOF will fix it. (FF fixes all problems doesn't it).

Ultimately, my 70-200 takes better pictures than my 17-55. The 17-55 isn't bad, but it just isn't as good. However, in the confines of the area I was taking photos, it just wasn't suitable.

So in reality, now I think I either need to go to FF (the 7d is a 1.6x crop, so in reality that is 112 substitute), or probably more sensibly, a lens like the 24-105 would be better.
(the lens given that I felt I was at 55mm most of the time the other day, the quality is supposedly better than the 17-55.

I will definitely try a shoot with a still-life subject and practice with the DOF/aperture see how I fare again.
 
Sorry, don't want it to sound like I just have to get something, but there was definitely something not quite feeling 'comfortable' and I am trying to work out what
 
Yes, but on a 1.6x crop, the 55mm is getting to be too close for a 3 year old full-length at 4m. The 85mm would be face only almost. This is why FF is a consideration, as I would grab back some of the distance.
 
are you really wanting what is called "compression" ……. longer lenses do that

I tend to use my 100mm f2.8 hand held or 300mm f4 or sometimes f2.8 on a tripod primes for portraits on an FF Body, (and a DX one as well …. if need be)
 
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I had the Sigma 50-150 2.8 on my 40D and it was great for the kids.. MFD was just less than 1m..
 
BillN_33 said:
are you really wanting what is called "compression" ……. longer lenses do that

I tend to use my 100mm f2.8 hand held or 300mm f4 or sometimes f2.8 on a tripod primes for portraits on an FF Body, (and a DX one as well …. if need be)
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Don't think that's quite right. Compression is a result not only of focal length but camera to subject distance.

For example the "compression" you get at 400mm on FF will be exactly the same if you stand in the same spot and take the shot with a 200mm lens on MFT or 250mm on Canon APS-C or 260mm on Nikon APS-C. Come to think of it... you'll get the same compression if you stand in the same spot and take the shot with a 50mm lens and then crop it to the same FoV.
 
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minnnt said:
It's the 85mm f1.8 that fixes everything. :D
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Not really, he has 70-200 which cover the range and f2.8 is probably more than enough for portrait on aps-c sensor.

He has said 70-200 is too long, and I would hazardly guess the OP uses the 17-55 mostly on the 55mm end when shooting portraits. So I would suggest a 60mm fast prime. Which is perfect for aps-c for portraits.

The alternative is to get 24-70L 2.8 and your will have full flexibility and range cover and should you decide to go FF then the lens is fully usable.
 
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ricky1980 said:
Not really, he has 70-200 which cover the range and f2.8 is probably more than enough for portrait on aps-c sensor.

He has said 70-200 is too long, and I would hazardly guess the OP uses the 17-55 mostly on the 55mm end when shooting portraits. So I would suggest a 60mm fast prime. Which is perfect for aps-c for portraits.

The alternative is to get 24-70L 2.8 and your will have full flexibility and range cover and should you decide to go FF then the lens is fully usable.
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Excellent advice.

This is pretty much what I did. I had the Sigma 50-150 2.8 and used it for portraiture, mostly down by 50-85ish. Sold it on for a 28-70 2.8L and use the range much more than the Sigma.

But, now I'm full frame and hankering a 70-200 2.8..!
 
60mm is hardly any different to 55 and they're usually macro lenses at that length so focusing speed will be slower.

In my experience the 85mm never fails to put a smile on my face. Shooting at f1.8 even on crop gives me plenty of shallow dof and peoples faces look right rather than slightly pinched like they do at around 50mm.

I can see that the 24-70mm would work too but I crave shallow dof so a fast prime was the only option really.
 
minnnt said:
In my experience the 85mm never fails to put a smile on my face. Shooting at f1.8 even on crop gives me plenty of shallow dof and peoples faces look right rather than slightly pinched like they do at around 50mm.
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The focal length is only to blame here if you get up close and personal :D It's a camera to subject distance thing not a focal length thing. But even so, you shouldn't be getting perspective distortion with a 50mm on APS-C unless it's a macro and you're sticking it up someones nose :D
 
minnnt said:
But 50mm is 50mm whether it's FF or APS-C.
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Yes, but what causes perspective distortion is - as Alan says - subject to camera distance. The reason you get the distortion is that the closer you put someone to a camera, the more the depth of what you are photographing matters. If you put someone 10 cm from the camera, then their eye will be (say) 13cm away from it. That is 30% extra distance. If you put the same person at 100cm, the difference is now 3%. This relationship is what causes the distortion, not the focal length of the lens (unless it is a wide angle lens most which tend not to be linear in it's projection of the image). Your chosen framing causes you to pick a distance where the effect of subject to camera distance affects the look.

What is happening is that the 85mm gives you the framing you want at a distance that avoids any obvious facial distortion. If you put the 50mm on and stayed at the same spot, took the photo again, the face would not be pinched, but you'd have to crop the image to get the framing you want. I suspect you'd be happiest with a focal length of 135mm on FF as that would give you approximately the same look and feel as the 85mm on crop....
 
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minnnt said:
60mm is hardly any different to 55 and they're usually macro lenses at that length so focusing speed will be slower.

In my experience the 85mm never fails to put a smile on my face. Shooting at f1.8 even on crop gives me plenty of shallow dof and peoples faces look right rather than slightly pinched like they do at around 50mm.

I can see that the 24-70mm would work too but I crave shallow dof so a fast prime was the only option really.
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To be honest i was going to suggest 50mm 1.8 but by the sound of OP usage anything more than 2.8 is probably not gonna be much benefit.

Suggested 60mm as it will clearly perform better than the 17-55mm on the long end. And it is an effective 85mm equivalent.

85 1.8 is an over kill for OP as he said 70-200 is too long. Obviously a nice lens to have.

For the OP there is the prime lens route such as get 35mm 1.8 50mm 1.8 and 60mm 2.8 to cover the standard zoom range. A lot of faffing and probably need studio condition.

The zoom option: stick with current setup or go to 24-70L 2.8; latter can be expensive but 2nd hand can be viable also version I is cheaper as well.

85mm is obviously a nice lens but he has 70-200 to cover it and most likely doesn't need the fix focal length.
 
Can only speak from personal experience. When i bought the 85 it opened up so many more avenues for me for portraiture. I love the way it throws the background, the way it gives a true definition of the person and the fact you don't need to be Arnold Schwarzenegger to carry it. Only ever used a 70-200 f2.8 once and tbh, it's put me off ever buying one. Suppose i'd get used to it though. But i must admit the pictures it produced were awesome with nice bokeh to.

160mm @ f2.8

Dean and Louise's Wedding by David Raynham, on Flickr


85mm @ f1.8

Lily in the sun - Explored! - Thankyou. by David Raynham, on Flickr

Andy, great explanation, thankyou. :)
 
So minnnt does make a good general point,
but
and it is entirely my fault, missed my restriction. I am shooting the photo indoors, which is where on my 1.6x crop, the 70mm is too long.
For outside, I don't consider myself a He-Man, but the 70-200 f/2.8 does me well (at the mo).
(well, apart from the strange looks that is).
 
On my crop 40D I mainly shot with a 17-35mm 2.8 indoors, sometimes broke out the 50-150 2.8 if I set the backdrop up..

Now using 5Dii I use the 28-70 2.8L indoors as well as a manual 135mm 2.8 cosinon and 58mm f2 Helios indoors too.. The 17-35 is a little too wide for indoor, but landscape and nighttime is where I utilise that..
Bokeh effect behind the subject can be enhanced by making the model stand as far away from the background as possible (closer to you) to maximise the dof range..

But as stated, dof range doesn't alter all that much at the lower zoom ranges..
 
unfortunately if you want flexibility of zoom as well as shallow DoF you won't get better than f2.8 and the only thing you can do is to go with FF and get 24-70L expensive tho. that's assuming you are simply not happy with the DoF and the rest of the image qualities from the 17-55mm is fine. But personally i think you will be a marked improvement just shifting to 24-70mm and also the extra 15mm in between will give you that bit more shallower depth.
 
minnnt said:
But 50mm is 50mm whether it's FF or APS-C.
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It is but with FF you may reduce the camera to subject distance and that's when you're more likely to get perspective distortion. It's not the focal length as such... it's that a shorter focal length requires you to move closer to the subject to get the subject big in the frame... but as I said, I just can't see 50mm on APS-C leading to distorted facial features, 20mm.. yes... but 50? I doubt it very much and I can't remember 50mm leading to distortion in any of my own APS-C pictures. YMMV of course.
 
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