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Messages - Etienne

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211
To be even more clear, here is an example calculation taken from http://www.cambridgeincolour.com/tutorials/digital-camera-sensor-size.htm

212
Pointless discussion.

In practice, if you want to achieve the same depth of field on a crop as FF, you need to open the aperture on the crop camera by 1.3 stops.

Now ... let the confusion of circulars begin

213
DoF ~ focal length * aperture * subject distance
If you want to shoot the same picture using the same lens with both FF and crop sensor cameras, you need to be closer to the subject with FF camera to get the same framing and that's the only difference.


Good concise explanation!

I think of it like this:
A photographer must frame a shot. To get the same shot as a FF using the same lens on a crop camera, the photographer has to move backwards (by a factor of 1.6). Instead of 10 feet away, he must be 16 feet away. This increased focal distance increases the DOF of the shot.  Do the calculation here:   http://dofmaster.com/dofjs.html


It might be a concise explanation, but it is not good or accurate.

DOF, or CoC (they are entirely interchangeable), is a function of apparent aperture and subject magnification. Just those two. You can work out dof figures from just those two numbers. Subject magnification is a function of focal length and subject distance, as well as viewing distance and reproduction (print or screen) size.

When you put focal length and subject distance into a dof calculator all it is working out is the subject magnification on the sensor; it then needs the sensor size to work out the CoC for a given standard output, often an 8"x10" print viewed at 12".


Wrong: the dof calculator also calculates the circle of confusion. http://dofmaster.com/dofjs.html

The technical mumbo-jumbo can be ignored. Crop factor cameras used to collect the same image as a FF camera will need to open the aperture by 1.3 stops in order to get the same DOF in the final image.

This is true regardless of whether you achieve the same field of view by moving the camera back by a factor of 1.6, or whether you use a shorter focal length (by a factor of 1.6, for Canon APS-C).

Circle of Confusion calculations won't make any difference at all. Partly because the effect is so small when comparing one real-world camera to another.

214
This has been confusing for me for a long time thank you everyone for clarifying it.

Here's my new understanding.
• Physically the DOF does not change because your not changing the lens (ie. set up a shot,  switch a crop to a FF, and you'll just get a wider field of view but same DOF).
• But in practice it essentially does change (ie set up a shot, switch bodies, now move the came to have the same field of view, now the DOF of the crop camera photo will be larger. Same goes for not moving the camera and changing focal length).


Yes.

Photographers frame shots. None of the ultra-technical mumbo-jumbo about "circle of confusion" and "DOF is a function of the lens" is helpful.

Using a 50mm lens:

Framing on a FF cam at 10 feet = Framing on a crop at 16 feet

BUT the extra focal distance necessary to frame the same shot on a crop camera causes the DOF to increase. In order to get the same shallow depth of field on the crop camera, the aperture has to be opened by 1.3 stops in comparison to the FF camera.

Prove it for yourself. Go to http://dofmaster.com/dofjs.html and calculate the DOF for ( these two examples will give the same fov framing of the scene):

Crop camera with 50mm lens at f=1.8 and distance 16 feet
FF camera with 50mm lens at f=2.8 and distance of 10 feet

These two examples result in the same DOF (2.1 feet total). The crop camera needs to increase the aperture by 1.3 stops in order to get the same DOF as the FF camera.

PS ... the effect of "circle of confusion" calculations for different sensors is completely swamped by the overwhelming effect of the need to stand further back to compose with a crop camera.

215
DoF ~ focal length * aperture * subject distance
If you want to shoot the same picture using the same lens with both FF and crop sensor cameras, you need to be closer to the subject with FF camera to get the same framing and that's the only difference.


Good concise explanation!

I think of it like this:
A photographer must frame a shot. To get the same shot as a FF using the same lens on a crop camera, the photographer has to move backwards (by a factor of 1.6). Instead of 10 feet away, he must be 16 feet away. This increased focal distance increases the DOF of the shot.  Do the calculation here:   http://dofmaster.com/dofjs.html

216
I would like to buy all Canon flashes, but I find they are over-priced

217
The 50mm 1.4 is a old lens (1993) designed for film, so the effects of light drop off at the edge of a digital sensor are not compensated for.  Newer lenses do a better job of collimating the light so it comes in at a steeper angle, and the effect is less.
 
http://www.nikonians.org/html/resources/nikon_articles/body/FF_vs_DX_sized_sensors/


I don't think it's possible to collimate the light and still end up with a sharp image. There's urban-legend BS at work in that link.

218
Thanks! I'm holding off on all accessories until I actually get my EOS-M in hand, which may be another week or two since I ordered a couple of hours before the end of sale. My order might get cancelled due to lack of inventory and I don't want to get stuck with accessories I can't use.

Makes sense.  I ordered a couple of hours after the beginning of the sale, and have been enjoying my EOS M for several days now.  A second battery and a couple more SDHC cards are being delivered today.

How do you like it so far? I'm tempted to buy some batteries, cards, and the adapter in preparation for delivery of the M.

I'm planning to use it as a pocket camera, but I am seriously hoping that Canon comes out with a sharp 15mm f/2.8 for the M, and some other neat little primes.

219
The cheap eBay adapters are knock-offs, not Canon. Are they well made? I'm told the Canon one is very strong. That's important if you're attaching a $2000 + lens to it.

Anyone have experience with the cheap knock-offs?

There are apparently some OEM adapters from eBay - the adapter is sold as part of an EOS M kit in some locations, so they are sold as the equivalent of white box versions.

I have the OEM, it's very robust.  One difference I noticed from images of the knock-offs is that the tripod foot isn't the video style with the hole for the anti-rotation pin.

Thanks! I'm holding off on all accessories until I actually get my EOS-M in hand, which may be another week or two since I ordered a couple of hours before the end of sale. My order might get cancelled due to lack of inventory and I don't want to get stuck with accessories I can't use.

220
I just ordered mine from Amazon - and was able to use rewards points.

The Canon lens adapter is available on eBay from several highly rated vendors at very attractive prices.

The cheap eBay adapters are knock-offs, not Canon. Are they well made? I'm told the Canon one is very strong. That's important if you're attaching a $2000 + lens to it.

Anyone have experience with the cheap knock-offs?

221
Lenses / Re: New Tilt-Shifts in 2014, Other EF Lenses in 2013 [CR2]
« on: July 11, 2013, 09:31:33 PM »
Please include a 50mm f1.4 or a 50mm f2 IS!!

+1

222
EOS-M / Re: Canon EOS M II
« on: July 11, 2013, 08:52:10 PM »
I personally think that we do not need a new M body that urgent.  What we need is a more comprehensive M system – more lenses and accessories available.  The EOS M should not be only a backup camera for the EOS DSLR.  It is nice that I can put the L lenses to my M body once in a while, but I prefer to use it with more choice of smaller lenses as my daily camera.

+1 here ... I'd like a 15mm f/2.8 pancake and a 50 mm f/2 IS

That would give FF equiv 24mm, 35mm (the 22mm f/2),  and 80mm in a really small light package for travel!

223
Most of us would buy FF if we can afford it - right?

Eventually, we all (myself included) need to realize that there is no such thing as most of us.
just because you can afford something does not mean that you can justify buying it. Perhaps if the RX-1 was 24 or 28mm I'd be a little more tempted. When the lens comes off, i'll definitely bite.

Just been looking at some rx-1 reviews. For me I can't see why it costs $3k. The AF is still contrast detection right? Can't be all that faster than the EOS M, can it? And no removable battery?? No charger in the box? Just a USB cable? How is that useful for travel?

Quite happy knowing I have something that costs $299 and does pretty much the same thing. (Takes puctures). Full frame? So what.

I'm extremly happy that I got EOS-M for $299 through BH - great little camera for still shooting.

If bigger sensor is not so much important in photography, then why not settle for 4/3 or smaller. I can't describe the feeling of holding such a small camera(RX-1) that produce stunning photos. I'm shooting with 5D III with latest L lenses and I'm still amaze with RX-1. Hope Canon will have some thing similar + be able to swap lenses.

I agree...@ $2800 Sony should include all accessories you mentioned. Removeable battery is included, not the wall charger.

For me $3000 is too much for a pocket camera just so I can carry it everywhere even if it is FF, especially since it's stuck at 35mm forever.

But $300 is just fine. Bonus: it shoots great video, and can accept all my other lenses in a pinch, with the adapter. And APS-C is not too shabby to have in your pocket and not have to worry about it at all.

224

I am such a sucker for a sale!  :o
 
I wasn't going to buy into the old tech, but I pushed the button because of price.

225
EOS Bodies / Re: The Next EOS M Camera(s) [CR1]
« on: July 08, 2013, 10:25:34 AM »
 BTW ...

How about focus peaking and a swivel screen ?

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