Sigma 18-250 OS HSM Vs Nikon 55-200 AF-S

[biggles1979]

I hope someone can help me out here...

I have a Nikon D3100 and have been using the kit 18-55 VR and 55-200 (non-VR) lenses, both Nikon, and a few days ago got the Sigma 18-250 OS HSM DC lens.

I am fairly happy with the new lens in that it gives me the flexibility of both my old lenses in one and more - being 250mm reach over the 200 of the Nikon, or so I thought, when I have just made a comparison on the zoom on an object roughly 1 meter away the 200mm zoom on the Nikon gave a much closer image than the 250mm of the Sigma - how can this be so?

I will do some more tests this evening on different distances & lens lengths but am a bit worried as I got this as a 'do it all' for a holiday and am leaving in 2 weeks - what to do? return it and keep with what I have? I could just hire one for the holiday (Nikon 18-200) which I didn't even know I could do before reading here today.

Thanks for any help or advice, Ian

P.S. You might be able to tell that I am only a beginner with this type of camera but I'm keen to learn!

 

[casts_by_fly]

some lenses shorten their focal length (and thus magnification) when you focus on very close objects. The 55-200 doesn't. The sigma must. That will be the difference in image magnification.

Thanks,
Rick

 

[biggles1979]

Hi,

Thanks for the reply - I found a reference to this on another post here: http://www.talkphotography.co.uk/forums/showpost.php?p=3923145&postcount=2 which directed me to another site for an explanation...

I am a little relieved as I was quite happy with the lens as an all-rounder then when I noticed this I was more than a little disappointed! So much to learn


Ian