Depth of field question csc v dslr

scottduffy

scottduffy

Messages
3,348
Name
Scott
Edit My Images
Yes
Hi Folks,

I have been reading up quite a lot on this subject since i've just bought a Fuji XE1 and i am in the process of tracking down a 56mm f1.2 lens and last night i came across a very interesting article which states that this combination has the exact same DOF to a FF dslr and 85mm f1.8 lens. Now given that this combo will have cost me in the region of £740 and you can buy a Canon 85mm f1.8 lens for around £200 or less i was wondering if any of you would pair this with a cheap FF dslr which according to the site will give the same DOF and better auto focus.

Just for clarity i'm not thinking of doing this i was just seeking opinions.
 
The theory is sound.

All things being equal, smaller sensors have larger DoF.

Which in part adds to the appeal of larger formats.
 
TBH, perhaps the numbers are the same but the Fuji lens is MUCH better than the Canon USM. Think of it as comparing the Canon 50mm 1.4 against the Sigma 50mm 1.4 ART. Both have the same numbers, but thats about it. The Fuji lens will also give you faster shutter speed or lower ISO.

The combo cost you £740 but you aren't also working in the cost of the FF camera to use the lens with so your maths is miles off. If you for example paired it with an old 5D you're looking at £400 for a used body with less functions, around the same AF, probably worse ISO performance and £200 for the lens. Total for a lower spec package at least £600.
 
Last edited:
I was thinking that with a 5d for exapmple it would be roughly the same cost. I do believe having owned 2 85mm f1.8 lenses that they're slightly over rated (runs for cover) and i would certainly hope the fuji lens is a tad better. I just thought it was very interesting that before this article i was comparing the fuji to the canon equivalent and this compared it (for DOF only) to the much cheaper 85mm.
 
scottduffy said:
I was thinking that with a 5d for exapmple it would be roughly the same cost. I do believe having owned 2 85mm f1.8 lenses that they're slightly over rated (runs for cover) and i would certainly hope the fuji lens is a tad better. I just thought it was very interesting that before this article i was comparing the fuji to the canon equivalent and this compared it (for DOF only) to the much cheaper 85mm.
Click to expand...

If you are only looking at DOF then yes, its the same DOF for similar money. Thats where the similarities end.
 
The math is good but... The modern obsession seems to be with owning kit which can achieve wafer thin DoF rather than having wide aperture lenses for reasons of exposure. I'm a bit of a fan of thin DoF myself and I take a lot of wider aperture shots but even so I think that wafer thin DoF is being done to death perhaps to the detriment of the pictures produced although obviously it's a personal artistic choice.

As I said in another thread just yesterday, for most of my picture taking life I've been struggling for more DoF not less and I actually think that for me the sweet spot for hand held shooting is MFT/APS-C rather than FF. For example when shooting with a 35mm /FF DSLR and a 50mm lens if I can get away with it for exposure I'm usually going to be shooting at apertures smaller than f5 to get peoples eyes in the DoF and once you stop a 35mm/FF DSLR down to even f2.8 the DoF you get can be easily matched by MFT or APS-C so 35mm/FF apertures smaller than f5 are going to pose no problem at all to MFT or APS-C.

My advice is to take a long hard look at your own pictures and maybe those of others too and decide what you prefer and if you really do want the DoF you get from a 35mm/FF DSLR at f1.4-f2.8 then FF is the way to go but if you prefer the look of 35mm/FF shots taken at f2.8 or smaller then you may well get the results you want from a MFT or APS-C camera. Another way to achieve very thin DoF with smaller format kit or even with slightly smaller apertures is to change your framing by using either longer lenses or by reducing the camera to subject distance. Both could give you the look you want if you are happy with the different framing.

When I had a 5D I personally avoided the Canon 85mm f1.8 as I didn't like the look it produced and instead I went for a Sigma 85mm f1.4. These days I have Minolta Rokkor and Olympus Zuiko 85mm f2 and Canon FD 85mm f1.8.

PS. another issue with using wider apertures is shutter speed. Many cameras are limited to a maximum shutter speed of 1/4000 second and shooting at wider apertures in anything like good light may require the use of ND's. That may not be a problem for many people but personally I hate fitting an ND for one shot to get the shutter speed below 1/4000 and then taking it off for the next shot because the shutter speed has fallen to 1/20 and the ISO has risen to 1600 only to find that I need the ND for the next shot! Urgh!

Sorry to ramble :D
 
Last edited:
craftysnapper said:
I owned one and thought the same thing...so I had better run for cover as well.:)
Click to expand...

Yeah, its not great but I think the 85 is okay for the money. Decent FL, fastish aperture for under £300 nothing else really for that kind of money in Canon mount so not much of a choice. I liked my Sigma 85 1.4 a lot more.
 
Last edited:
woof woof said:
PS. another issue with using wider apertures is shutter speed. Many cameras are limited to a maximum shutter speed of 1/4000 second and shooting at wider apertures in anything like good light may require the use of ND's. That may not be a problem for many people but personally I hate fitting an ND for one shot to get the shutter speed below 1/4000 and then taking it off for the next shot because the shutter speed has fallen to 1/20 and the ISO has risen to 1600 only to find that I need the ND for the next shot! Urgh!
Click to expand...

Good thing Fuji will be releasing an update for the X-T1 to make it 1/32000, no more 'issues' for me (not that an ND was an issue for me).
 
I'm constantly amazed by the fact that other people never have an issue shooting at wide apertures with cameras limited to 1/4000 sec when in the murky north east of England where light is hardly dazzling I need an ND for maybe one shot in three when the sun is at it's maximum 1 candle power :D
 
I don't have the ability to master FF and f1.2 lenses i just thought it was really interesting that these two combos were almost identical in the sites tests. I would love to have a go at the fuji f1.2 though with the xe1 but alas no-one seems to be selling (shamless plug). I really like some shallow DOF pictures. Not crazy shallow like one eye in focus and the rest of the head not just simply want to make my son stand out from his background at times.
 
woof woof said:
I'm constantly amazed by the fact that other people never have an issue shooting at wide apertures with cameras limited to 1/4000 sec when in the murky north east of England where light is hardly dazzling I need an ND for maybe one shot in three when the sun is at it's maximum 1 candle power :D
Click to expand...

Thats because you forgot your ISO on 6400 :p
 
I've read that too about the 56 being comparable. Having recently used a Nikon 85 f1.8 on an APS-C I can say it is totally awesome. :D Never used one on a FF though but can imagine hitting a few problems with such a shallow dof on FF.
 
The maths for framing/DoF is quite simple. To take the "same" (i.e. same DoF and field of view but ignoring resolution/look etc..) photo, stood from the same position then all you do is divide the focal length and f number by the crop factor.

So for a micro 4/3rds (since the maths is easy as the crop factor is 2) for a photograph taken at 50mm @ f2.8 on a full frame, you will get the "same" picture from a 25mm @ f1.4 on micro 4/3rds. APS-C is a 1.5/1.6 (depending on manufacturer) crop factor.
 
Cheers Andy. I had never given this too much thought to be honest. I just thought that larger sensor size equated to better image quality hence everyone's apparent rush to FF.
 
scottduffy said:
...Not crazy shallow like one eye in focus and the rest of the head not just simply want to make my son stand out from his background at times.
Click to expand...

If you can reduce your camera to subject distance and get him forward of the background you'll stand a very good chance of getting the look you want at more modest apertures. MFT or APS-C at 50 to 85mm and anything from f2.8 to even f6 should be enough.

I took this shot with an APS-C Canon 20D and a 17-85mm lens which is nothing outstanding and maybe even relatively quite a poor lens but at 85mm and f5.6 and forward of the background there's quite a bit of separation whilst the subject is mostly sharp but even at f5.6 his ears are falling out of the DoF when viewed closely and I wouldn't want the DoF to be any shallower.

 
Hi Alan,

A very good example. This is similar to what i'm aiming at although it's not always possible to have him further from the background especially indoors which is why i wanted the larger apaerture lens. It's time to just get the lens and have a play about it and see what i can produce. I'll let you know how i get on. I took some photos of my wee boy in a lovely holiday home which are in my gallery and i really liked them although i'm sure they're technically not exposed properly. I just liked them and that was the reason i wanted this set up. That might sound daft given that i got the photos i wanted with a 50d and 50mm lens but it seemed to be light in the room that made all the difference on this occasion.
 
craftysnapper said:
I owned one and thought the same thing...so I had better run for cover as well.:)
Click to expand...
I love my 85mm f/1.8. Out if the 15 lenses I own (including L lenses, tell me about it!) it's my fave by far. Ok, this or my Sigma 105mm!
 
twist said:
Yeah, its not great but I think the 85 is okay for the money. Decent FL, fastish aperture for under £300 nothing else really for that kind of money in Canon mount so not much of a choice. I liked my Sigma 85 1.4 a lot more.
Click to expand...
"Not great"?!. Jeez you must have had a bad copy, it's always been one of the better rated Canon lenses, easily up to L quality IMO!
 
odd jim said:
"Not great"?!. Jeez you must have had a bad copy, it's always been one of the better rated Canon lenses, easily up to L quality IMO!
Click to expand...

No, I had 2, they were pretty good but not great, like I said, the sigma was definitely better and so was my Nikon 85 1.8 G.
 
twist said:
No, I had 2, they were pretty good but not great, like I said, the sigma was definitely better and so was my Nikon 85 1.8 G.
Click to expand...
Just sticking up for one of my favourite lenses :)
 
You must log in or register to reply here.
Back
Top