7i review is a bit deceiving - What's up Phil?

Started Jun 24, 2002 | Discussions thread
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Cat 5 Contributing Member • Posts: 674
7i review is a bit deceiving - What's up Phil?

As far as the resolution tests go, I have been A/B'ing the chart shots between the f707 and the Dimage 7i to see what's up with this resolution issue. After all, if it's the same ccd it should be identical, or at least close! What did I find? The resolution of the 2 shots is, for the most part, identical. If you compare the numbers and lines on the chart you'll find that not one area of the sony's sample is even 1% sharper than the Minolta's. They are the same. The only difference is that in the extreme high resolution areas of the chart the sony begins interpolating to give the appearance of higher resolution (which should only work for extreme contrast areas) when in fact, in real world situations, this will never add to the apparent detail of the image. In fact, it kind of reminds me of the battle between 3d video accellerators...where mfgrs would tune their cards to perform exquisitely on popular benchmarks, when in fact they were underperforming in real world tasks. For the most part, both Sony's and Minolta's lenses exceed the resolution of their CCD (Minolta claims 7-megapixel+ resolution for the D5,7,7i lens)...and in real world situations they both resolve the same amount of detail (more or less). Just look at the numbers and dashes listed on the resolution chart (outside of the converging lines)...the Sony sample is identical to the Minolta's. According to Phil's comparison the sony's should be sharper. IT IS NOT! This test is grossly misleading!

Another issue is Phil's criticism of Minolta's RAW format image size. The file size is actually smaller than the TIFF size, and Phil is complaining that he can't imagine where the large file size is coming from. He says that based on the effective resolution of the CCD's output, and Minolta's 12-bit format the file size should only be 7 megabytes+. What he is overlooking is the fact that EACH PIXEL is represented by 36-bits of information (12 bits per primary - RGB), thus making each pixel a 36-bit pixel (not 12 - 12 only represents one third of the pixel - RGB remember) which would give a resulting file size of approximately 21 megabytes+. Most image formats utilize some form of compression (in the case of JPG it is lossy, in the case of TIFF it is not) and Minolta has actually managed lossless compression on their images - achiving a file size of less than half that of the original. This is, in effect, more efficient than TIFF and actually deserves merit. Minolta is preserving the original 12 bits per pixel. Why is Canon's RAW format smaller? They are only saving 8 bits per pixel (24 bit images). Why is this useful to us? If you have an underexposed image, you can adjust the levels to bring out the lost detail and still maintain 24 image quality when you export to JPG (or other 24 bit format). When you play with levels in a 24 bit image you are effectively reducing the bit depth of the image data (dynamic range). So those of you out there with complaints about Minolta's dynamic range (just look at the Nikon's! they're the worst) just learn to shoot in RAW mode, underexpose to save your highlights, and use the levels to bring back the shadow detail that appears lost. At 12-bits per primary the dynamic range is far higher than at 8 bits per primary (if you know anything about binary numbers you'll see it's exponential (4096 levels of luminance per primary compared to only 256 levels for a regular 24 bit image). By the time you squash most underexposed images you'll still exceed 24 bit color fidelity. If Minolta should get any criticism for their RAW format it's that it doesn't offer enough flexibility for extraction! Perhaps somebody knowledgeable in programming can give us an alternative - I for one will be willing to pay!

As for the noise, it really isn't that bad - but the superficial buzz about it has indeed sent me looking for an alternative to the 7i. For $1000 or less their simply isn't one. Nothing compares. So for those of you complaining about this and that, especially those of you using Phil's review to back up your arguments - learn to understand what you're reading before you start trying to influence other people's opinions. I too would like to see more metal and less plastic on the 7i, and maybe a bit better internal processing on out of camera JPGs, but for what the 7i sells for it is absolutely incredible. Especially next to the competition. And as far as Phil's review goes...he is a great photographer, and most of his opinions are valid - but where the resolution is concerened, and where RAW images are concerned I think he is very misleading.

Anyway, I hope nobody was offended by this post. I am just so sick of reading about resolution complaints and the Minolta/Sony thing that I thought I'd share my findings. Aftear all, the shots in most of the Dimage galleries are awesome. Maybe the photographer is the real issue.

Shane

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