Sunday, 1 November 2009

Comparing the Sigma 600mm and the Minolta 500mm f8 mirror lenses.

 

I`ve been wanting to do a comparison between my Sigma 600mm f8 mirror lens and my Minolta 500mm f8 reflex mirror lens(AF) for a while now./its not just about image quality, I`ve always wondered how much more magnification the 600mm gave when compared to the 500mm.

One of my readers left a comment about the 600mm Sigma not being very sharp. Last time I posted about re-chipping the Sigma lens. When I then took it out to do a field test, I was in a good position to get some amazing close ups of a Kestrel. However, the shots I got were disappointing.

The lens just was not as good as I had thought it was. I was sure that I would have got much better image quality from my 500mm. I thus carried out a few comparison shots.

The two shots below are taken through a window . The house is approximately 150 meters (500ft) away. It was a dull evening and since its winter here, the light is really bad. All shots are taken at ISO 400.

DSC04724

Above: Minolta 500mm f8

Sigma 600mm f8

Above: Sigma 600mm f8

There is indeed a significant magnification difference in the extra 100mm focal length offered by the Sigma. However, the image quality is not as good as the Minolta.

 

DSC04728

Above: Minolta 500mm f8

Sigma 600mm f8

Above: Sigma 600mm f8

 

The Sigma is manual focus while the Minolta is autofocus (it is the only AF mirror lens in the world). As far as I know, the Sony A200’s image stabilisation kicks in for both lenses, but it is not as effective for the Sigma as can be noticed from the blurred images. This could also do with the aperture. While both of them indicate F8 as the fixed aperture, the Minolta is known to be one of the only “true” f8 lenses. Most mirror lenses have a smaller aperture of greater than f8, although they claim otherwise. The Sigma it appears may be one of those.

 

DSC04729

Above: Minolta 500mm f8

Sigma 600mm f8

Above: Sigma 600mm f8

The above pictures show more clearly how images suffer in the Sigma as a result of lower light availability. The sharpness is an issue too. (The above images are approx 50mts away)

 

DSC04732

Above: Minolta 500mm f8

Sigma 600mm f8

Above: Sigma 600mm f8

Even at a closer range of approx 10mts away, the Minolta outperforms the sigma as seen in the above images.

Finally, with the light falling, I decided to take a few indoor shots with artificial lighting and flash. One feature that the sigma can boast of which the Minolta cannot, is its minimum focussing distance. Despite being a 600mm, it can focus fairly close. It is even labelled as a macro lens!

The below shots were taken approximately 5mts away from the subject, which is as close as the Minolta could focus.

DSC04738

Above: Minolta 500mm f8

Below: 100% crop of above pic

500mm 100pc

 

Sigma 600mm f8

Above: Sigma 600mm f8

Below: 100% crop of above pic

Sigma 600mm f8

 

Even indoors, with the added lighting the Sigma is no match for the Minolta. After these test shots one thing has become clear to me, I wont be using the Sigma for Bird Snapping if I can help it. It has made me realise just how good the Minolta 500mm F8 reflex mirror lens is. I`d rather shoot with the 500mm and crop the images….it would still give me better results compared to the sigma.


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