Originally Posted by barba
+1 on renting…
300 ƒ2.8 will be long ( ~480 ) for you on a 7D; if you're going to pull the trigger on this one, probably a good idea to hedge your bet and rent a FF body so the experience isn't completely lost.
+1 on renting…
300 ƒ2.8 will be long ( ~480 ) for you on a 7D; if you're going to pull the trigger on this one, probably a good idea to hedge your bet and rent a FF body so the experience isn't completely lost.
[8-)]The more I learn the more I realize how little I know about all of this.
Of course the good news is all of your recomendations are saving me some money so thats not a bad thing, thanks again
bburns, the f/2.8 doesn't turn into a f/4.5 just because it's mounted on a 7D. Only with extenders. However I agree with everything else you and everyone have said. The 70-200 is definitely the way to go.
yes, it does. Not only does a crop body multiply focal length by 1.6x, it does the same to effective aperture. I learned that in this thread:
http://community.the-digital-picture.com/forums/p/2861/22988.aspx#22988
About halfway into it it's explained.
brendan
yes, it does. Not only does a crop body multiply focal length by 1.6x, it does the same to effective aperture. I learned that in this thread:
http://community.the-digital-picture.com/forums/p/2861/22988.aspx#22988
About halfway into it it's explained.
brendan
In terms of depth of field, yes - for an identically-framed subject, because to get that framing, you must be further away. Not in terms of light-gathering ability - the sensor does not physically affect the lens, obviously, although a crop sensor only 'sees' a portion of the image circle projected by an EF lens.
According to Daniel the Great (Daniel Browning, duh!) f/4 on FF is brighter than f/4 on 1.6. You need a slower shutter speed on a 1.6 to get the same brightness. Daniel, correct me if I'm wrong [:P]
woops...I just hijacked another thread.
I do not believe this to be true. I have not noticed such a radical change in exposure values going from 35mm to a crop sensor.
f/4 is f/4. Period. A lens set to f/4 will let in a fixed amount of light, whether that lens is attached to a 1D4, a 5D2, a 7D, a T1i, or an old Elan film camera. The subsequent comments in that thread are best summed up by Daniel's statement, "Anyway, that doesn't take away from the importance of understanding what happens when the performance per area is the same and you vary the area." Key point there is we had moved on to a discussion of sensor characteristics. What comes out of the back of the lens is totally unaffected by that. To illustrate that point, you can compare any two sensors of the same size but different properties (e.g. 7D vs. 50D/T1i). Performance and light-gathering ability differ, independent of the lens.
There's no easy calculator illustrate this with amount of light, but there is with depth of field. Try the following experiment - go to the DoF calculator atDOFMaster. With the default settings on the page (50D et al. 1.6x crop body, 55mm, f/16, 10 feet from subject), you'll see a DoF of 6.61 ft. Change just the pop-up for the body to a 5D MkII, a full frame body. Now, all else being equal, the DoF is now 12.3 ft. What?!?!? Didn't we all agree you multiply the aperture by 1.6 for a crop, meaning the DoF will be thinner on FF? Why does changing the sensor from crop to FF make the DoF wider? Because of that clause about 'same framing' that I mentioned. Because of the crop factor, you are closer to the subject for a given subject framing on a FF body. With the DoF calculator, 5D MkII, 55mm, f/16, 6.25 feet from subject = 4.02 ft DoF; a ~1.6x aperture or f/25 gives a 7.44 ft DoF (the actual 1.6x would be f/25.6, but that's not an option). 6.25 ft FF framing = 10 ft framing on a 1.6x body. Settings of50D body, 55mm, f/16, 10 feet from subject gives 6.61 ft DoF, which is what f/25.6 on a FF would yield. So, for the same framing, same lens settings as above, a crop body gives a 6.61 ft. DoF, whereas a FF body gives a thinner DoF of 4.02 ft.
So, the bottom line is that a sensor does not and cannot affect the lens properties. f/4 is f/4. f/4 on a particular FF body may be 'brighter' than f/4 on a particular crop body, but then again, f/4 on a new FF body may be 'brighter' than f/4 on an old FF body. The light projected by the lens is the same, but how the sensor detects the light depends on the sensor.
And if that's not an egregious threadjack, I've never seen one... [:P]
neuroanatomist is correct – the incident light per square centimeter @ the image plane is identical regardless of sensor type used.
Collar mount a 70-200 ƒ2.8 IS on a sturdy tripod ~ 25 feet from a quantitative test subject ( i.e. ruler @ 60° ). Now take following three test shots using the same shutter speed, aperture, and iso…
1. ~200mm on a 5D ( should have a ~0.8 ft * 2 range on your ruler)
2. ~153mm ( 200 / 1.3 ) on a 1D ( ~1.0 * 2 )
3. ~125mm ( 200 / 1.6 ) on a 7D ( ~1.3 ft * 2 )
human and camera induced variability aside, the result should be nearly identical framing and exposure across all three shots with significant differences in subject DOF, Bokeh.
I stand corrected...I never really caught on to all the technical aspects of photography [:P]
OK, thread has now been un-hijacked [^]
Posting Permissions
Reply With Quote