During ten days I had the opportunity to test the 24MP full frame Sony alpha 900 simultaneously with all the six classical professional zooms from the Sony / Minolta system (3.5/17-35mm G, 2.8/24-70mm Zeiss, 2.8/28-70mm G, 4-4.5/28-135mm, 2.8/80-200mm APO, and 2.8/70-200mm SSM - thanks to J. Nemecek for providing the 17-35mm G and the 28-70mm G, and thanks to Sony Overseas AG, Schlieren/Switzerland, for providing the Zeiss 24-70mm). In this section you will find test images of the following zooms at f=70mm: Minolta AF 4-4.5/28-135mm (1985), Minolta AF 2.8/28-70mm G (1993), Minolta (Sony) AF 2.8/70-200mm APO G (D) SSM (2003), and Zeiss Vario Sonnar 2.8/24-70mm ZA (2008).

The Minolta AF 4-4.5/28-135mm delivers at f8 clearly the best image quality of any zooms tested here - at a second hand price of 1/10 of the Zeiss. The contrast wide open is a bit low, but stopping down just 1/2 - 1 stop solves the problem. Be aware that some of these lenses were used heavily by professionals; their zoom mechanisms may be worn out. If you need a lens with perfect center resolution, high detail contrast and virtually no koma at f2.8 (!), or if you need the 24mm wide angle, the Zeiss Vario Sonnar 2.8/24-70mm will be appropriate - at least as long as you don't mind its weight and size;). And: the Zeiss T* coating is outstanding. If you are looking for a well balanced f2.8 "normal zoom", the Minolta 2.8/28-70mm G may be right. Its design and size fit perfectly to the alpha 900, it's smaller and lighter than the Zeiss, it offers slightly more tele range, and it is sold second hand at roughly 1/3 of the Zeiss' price. Due to it's softer image characteristics it may be more useful for portraits than the Zeiss.

All images shown here are 100% crops directly from the alpha 900. The alpha 900 settings were set to standard values. Manually converting the RAW files would preserve more detail, especially with the excellent 28-135mm lens (some photoshop examples are shown at the bottom, just scroll down).

Previous to the test, all lenses were individually and carefully adjusted with the "Micro AF" feature of the Sony alpha 900. Originally, the 28-135mm lens could not focus to infinity on the a700/a900 DSLRs. Therefore its "infinity" setting had to be adjusted prior to the test as well (by removing the thinnest metal shift between lens bayonet and lens body).

The alpha 900 was on a professional Manfrotto 055CB tripod equipped with a 3-way-head Manfrotto 410. Image stabilizer ("steady shot") was turned off, and 2s mirror lock-up was used to minimize vibrations.

The first comparison shows the four zooms wide open (jpegs directly from the alpha 900). Of course this is not entirely fair since the 28-135mm is more than one stop slower that the later f2.8 zooms; however it's the only "wide range" zoom in the group.

		Minolta AF 4-4.5/28-135mm @ 70mm, f4.5 The professional "normal range" zoom from 1985 has a remarkable performance even wide open. While the contrast is a bit low, the 28-135mm displays a lots of details even in the extreme corners of the alpha 900 full frame 24MP sensor. Much less CA's than the 70-200mm SSM and less CA's than the Zeiss 24-70mm. Remarkable indeed.
		Minolta AF 2.8/28-70mm G @ 70mm, f2.8 In 1993 the professional Minolta zoom was "state of the art" - on the high resolution sensors of both the a700 and the a900 it has some weaknesses. While size and weight of the Minolta are more agreable compared to the Zeiss, the detail resolution and contrast is worse. The images shown here reflect the general impression one can read in several internet forums: "Never completely sharp". Ruggedness, and bokeh are on par (or even better) than the current Zeiss, These are not slightly mis-focused images. The lens behaves like that, even when stopped down.
		Minolta AF 2.8/70-200mm APO G (D) SSM @ 70mm, f2.8 In 2003 Minolta introduced the new professional f2.8 tele zoom. This lens - widely recognized as one of the best f2.8 tele zooms - has its optimal performance at f=200mm. While at 200mm no CA's can be found, at f=70mm the lens has stronger CA's than any of the other lenses. They can be removed easily using "Photoshop", but it's less than perfect, of course. The detail resolution is clearly better than the 2.8/28-70mm G and at least on par with the Zeiss Vario Sonnar 2.8/24-70mm.
		Zeiss Vario Sonnar 2.8/24-70mm @ 70mm, f2.8 In the center we find a perfect detail resolution and contrast even wide open. In the corners, however, the detail resolution reaches neither the level of the 4-4.5/28-135mm nor of the 2.8/70-200mm SSM. Yet it is slightly better than the Minolta 2.8/28-70mm G. There are virtually no CA's (yet both the 28-135mm and the 28-70mm G are slightly better).

The second set of images shows 100% crops of f8 images (again jpegs directly from the alpha 900):

		Minolta AF 4-4.5/28-135mm @ 70mm, f8.0 Still clearly the best image quality: best detail resolution, virtually no CA's, and a very good contrast. See further down the same image, converted with photoshop. It's hard to believe that this is a zoom, let alone a 20 years old 28-135mm ...
		Minolta AF 2.8/28-70mm G @ 70mm, f8.0
		Minolta AF 2.8/70-200mm APO G (D) SSM @ 70mm, f8.0
		Zeiss Vario Sonnar 2.8/24-70mm @ 70mm, f8.0

Below two examples of a photoshop conversion:

		Minolta AF 4-4.5/28-135mm @ 70mm, f8.0 Photoshop conversion Camera Raw 4.6beta, Sharpening 50, Radius 0.5px, Detail 50, Blue/yellow fringe -10 Only now the incredible quality of the 28-135mm becomes obvious. Again: It's hard to believe that this is a zoom, let alone a 20 years old 28-135mm ...
		Minolta AF 2.8/70-200mm APO G (D) SSM @ 70mm, f2.8 Photoshop conversion Camera Raw 4.6beta Only color fringe corrected, no additional sharpening!
		Zeiss Vario Sonnar 2.8/24-70mm @ 70mm, f2.8 Photoshop conversion Camera Raw 4.6beta, Sharpening 50, Radius 0.5px, Detail 50 -0.5 f-stops, (highlight) recovery 50