chrisd999 wrote in post #14694648
This might be true, but I wonder why. I was contemplating picking up a used crop body to use with my new-to-me 400 5.6. Then I borrowed a 60D from a friend, and did some comparison shots with his 60D and my 5D2, and after cropping in on both (much more heavily on the 5D2 obviously) at the same subject framing, there was no apparent difference in IQ right up to nearly 100% magnification on the 5D2 shots. The only difference was there was about 50% more pixels on the 60D shot than the 5D2 at the same subject framing. Here are my findings on crop body versus full frame with the 400 5.6
Based on IQ: tie
Based on Resolution: crop body wins
Based on minimum shutter speed: full frame wins
Therefore, IMO, no need to downgrade from the 5D2 to crop body based on picture quality for same subject framing.
Now here is my question no-one answered with a lot of detail in this thread:
Assuming accurate focus could be had (either manual or auto), is the picture quality better for the 400 5.6 with 1.4x better than 400 5.6 with no 1.4x cropped (assume same framing)?
Unless you are shooting and saving as something other than Large- there is a lot of things that don't seem right in this post. And perhaps it's my understanding of terminology..
For one thing- the difference between a 7D/60D and a 5D2 - is about 2.2 times as many pixels- on target- when focal length limited/constrained. If your subject- as an image on the sensor is occupying 5mm by 5mm on a 5D2 sensor, it also will occupy 5mm by 5mm on a 60D's sensor as well, for instance. Because of the pixel density- the image will be comprised of about 2.2 times as many pixels on the 60D. My understanding looking at a crop at 100% view- is one pixel in the picture is one pixel on the monitor. So a 100% crop of a 60D - using large- will have 2.2 times as many pixels as the same image shot with the same lens on a 5D2- thus features/patterns, etc at 100% should be larger- and not the same- noticeably larger. that's my understanding of a 100% crop- so you should actually be seeing about 120% more pixels ( 2.2 x as much ) . If you reduce the magnification on the 60D image, to that of the 5D2, ie zoom out- it will look similar. However, if you take a 100% crop of the 60D, and then zoom your 5D2 so that features are similar size- you will see the 5D2 image starting to fall apart. IF you needed to crop both pictures. ONLY if you can fill the frame with the full frame- does full frame have more resolving power- i.e. if you gotta crop a lot- you'd be better off with a crop. Sorry.. I've taken pictures of the moon with a 7D followed by a 5D3- using the same lens and results are similar- much more detail - pixels on target - with the 7D.
Another thing- with such a long lens, without moving- you cannot get the same framing on a 5D2 and a 60D - using the same lens. While you can crop to similar framing- the picture from the crop camera will have more pixels supporting the picture. Don't believe it- borrow that 60D again- with the 400mm, and the 5D2, and shoot a full moon- and then crop each so that the picture is just the moon- and look at the two.. And then do a 100% view of each. There's no way the 5D2 will pull ahead.. Another thing you can do is to note the final sizes of each crop- the dimensions- and see how much more you have with the crop.
As far as your question about using a TC with your 400 f/5.6- mostly- you will have to try to see if the IQ is good enough or not. Mostly- how good the TC works is a matter of which TC, and how sharp your lens is in the first place - and how good the combo is together.. Only you really can decide if it is acceptable. I certainly would give it a try though. Heck, I'd even try a 2x TC with it as well.
EOS 5D III, EOS 7D,EOS Rebel T4i, Canon 70-200 f/2.8 IS II, Canon 24-105L, Canon 18-135 IS STM, 1.4x TC III, 2.0x TC III, Σ 50mm f/1.4, Σ 17-50 OS, Σ 70-200 OS, Σ 50-500 OS, Σ 1.4x TC, Σ 2.0x TC, 580EXII(3), Canon SX-40, Canon S100
Fond memories: Rebel T1i, Canon 18-55 IS, Canon 55-250 IS, 18-135 IS (Given to a good home)...