Sigma 17-70 macro VS Sigma 18-50 macro

Hallo guys ,

im choosing which lens buy Sigma 17-70 or Sigma 18-50 using for Nikon D80 Ikelite housing dome 8" and flat port , i appreciate your comments and suggestions ,

ciao from Italy

Max

Hallo guys ,

 

im choosing which lens buy Sigma 17-70 or Sigma 18-50 using for Nikon D80 Ikelite housing dome 8" and flat port , i appreciate your comments and suggestions ,

 

ciao from Italy

 

Max

The 18-50 supossed to be a faster lens being a 2.8 but is just 50mm in focal lenght with magnification of 1:3, the 17-70 in the other hand is a longer focal lenght and provides more magnification (1:2.3), also 17-70 is a wider lens reaching 72.4° against 69.3° on the 18-50.

I own a 17-70mm and as many people here can tell you, is a great "scout" lens, if were my choice, i choose 17-70 over 18-50.

If you want some samples of 17-70 go to my website and look for a gallery of key largo-Florida, all pics taked at 17mm. (I leave zoom gear back at home... :s)

I looked at both lenses and chose the new version of the F2.8 18-50 macro.

Before I chose, I took my camera and Sea & Sea housing in to a camera shop and fitted both Sigma lenses to see how well they matched. The 17-70 has a longer zoom extention and this meant at the 70 mm end the lens was practically touching the inside of my dome port. There would certainly not have been room for adding a filter or diopter without adding a second extension ring. I already need a 40mm ring to use the 18-50.

I felt that the less ambitious 18-50 zoom range may perform better optically when behind a dome port.

I preferred the slightly faster F2.8 18-50 even though the range is not as large. I can still focus to within 1cm of the front of a dome port. Using the lens behind a flat port has proved fairly useless. I made a zoom gear from a few tips from the 'Build your own zoom gear' from the DIY forum.

Overall I have been well pleased with this lens and can see no obvious optical flaws.

Hope that helps, Trev

You didn´t need diopters with 17-70mm in any case. (maybe a +2 for corner sharpness improvement, but never necessary). both lens perform behind any dome or flat port without the need of diopters.

Flat port for this lens is the same used with non VR version of 105mm (or the same extension ring, at least)