Can you make a FF effective camera out of a 1.6x crop?

[Kajuah]

Loupey:

I think I understand what you're asking but I think you have it backwards.

I assume you mean if one crops a full-frame image (from a 5D) down to the same area obtained by the 1.6x crop factor camera (of a 50D), how would the images compare? Yes?

I shoot with both the 5D and 40D and I can tell you that I much prefer the image quality from the 5D (even though it is several generations older). Proof (to me at least) that the number of megapixels is just one small factor into making high quality images and not the factor as many people think. The question for you is whether you need/want the wider angle of coverage provided by the 5D.

No no, I'm sorry it was difficult to decipher...but that was not what I meant, in fact it's exactly backwards What I'm asking is:

Can I crop along the 1.6x crop line (19x14 in canon DSLRs) off of a 15 mpx image to to get the same quality of a full frame picture ?(36x24 mm) but of a smaller size (4700x3100 for example turns into 3600x2100 pixels - arbitrarily)

Can I effectively make a 15 mpx eos 50D turn into a eos 5D with 10-12 mpx size if I crop along the 1.6x arbitrary crop factor?

Eg: Crop the image down from 36x24 to 19x14 mm square in order to get a full frame quality of a print.

I know I will not be able to use full frame lenses necessarily with the camera, but can I create the effect by using non-full frame lenses in terms of image quality? By getting rid of the frayed, blurred ends of the image towards the outer edges of the picture to get a smaller image (in size) of better quality (by pixels/sharpness/color/tone/pitch).

I think photo-john has it right about what I'm asking, though I was a bit confused because I thought the XSI and the 40D shared the same APS-C sensor

Loupey:

Actually, I had the same thoughts as the original poster before I bought my 40D. I wondered if purchasing a 5D would provide the best of both worlds - 1) a full, wide angle coverage when using wide angle lenses, and 2) a cropped image comparable in terms of IQ to that provided by some APS-C bodies.

I still don't know about #2 as I've not done any side-by-side comparisions. But I ended up going my 40D/5D route since I do so much on both ends of the spectrum (wide angle and telephoto/macro).

I promised the folks in the N&W forum that I would do a side-by-side showing a full APS-C image along side a cropped FF image. I'll do that this weekend and post my findings here or other there.

That's exactly what I was wondering i'd love to see those examples, what I'm trying to do is justify buying the 50D (APS-C) over the 5D and would it make a real difference. I don't have the money (and probably won't for a few months at least) to buy the 7D (rumored to come out soon with the latest technology/nr/dust reduction/sensor cleaning/processing unit) and I was wondering if I could make the image quality from the 50D better (by cookie cutting every image to align with the point where the pixels begin to degrade (1.6x crop factor).

Thus I would lose the image size, of course, but keep the quality ?

[Photo-John]

You've still got it a little messed up. To be specific, you've got two separate problems mixed up.

One - pixel size.

Two - lens-related image quality issues.

The image quality benefits of full-frame DSLRs have to do with the larger pixels on their sensors. No matter what you do with an APS-C camera, the pixels are still smaller and if they have the same technology as a given full-frame DSLR, the full-frame camera should be better. The cropping strategy would make sense if you were cropping from a full-frame sensor where the image quality issue is usually with optical problems around the edges of the lens. The APS-C sensor crops out some of those problems. However, if you've got a cheap, crappy lens, cropping isn't going to help.

I am also skeptical of buying a 5D over a 50D just because it's full-frame. Unless you're looking for shallow depth-of-field, I don't think you're going to gain anything. Every generation of camera has better noise reduction and sensor technology. This is one area where cameras have improved considerably in the past couple of years. I haven't done a direct comparison, but I would bet the Canon XSi / 450D has equal or better image quality than the 5D just because it's much newer. High-res samples for both cameras are available in our Digital Camera Sample Photos section, if you want to compare.