Nikkor 55-200 closer zoom than 18-250???

gl600 · Oct 1, 2009

Hello,
I recently bought the Sigma 18-250mm lens to replace my Nikkor 18-55 and 55-200 lenses.
When I took a shot with the 55-200mm @200mm and a shot with the 18-250mm @250mm the 200mm was a closer shot than the 250mm!?!?
Can anyone tell me why??? I was really excited to get some extra reach with this lens... but i get less

Also, does this mean that if I get an 18-200mm lens it will be way less zoomed in than the 55-200?
thanks!

TJ K · Oct 1, 2009

There is something wrong with you lens for sure. Bring it to a shop to get it looked at.

tirediron · Oct 1, 2009

Hmm, there's definitely something wrong, but I'm not entirely convinced that it's your lens. It may be, but IMO, it's unlikely. Did you take your comparison images from exactly the same spot, under the same conditions, using the same settings (aside from zoom)?

Goontz · Oct 1, 2009

Did you buy the lens new or used?

KmH · Oct 1, 2009

Sorry, it looks like the Sigma is 18-200 mm, not 18-250 mm.

Edit: My mistake. I found the new 18-250. :er:

gl600 · Oct 1, 2009

@tirediron: Exactly the same conditions.
@Goontz: New from amazon.

P.S. It also has a bit of an AF issue as well. Maybe I got a dud???
http://www.thephotoforum.com/forum/members/tirediron.html

fiveoboy01 · Oct 1, 2009

Can you post both photos so we can look at them?

Sounds like you may have a faulty lens.

Focal length is focal length, and if you're not getting closer at the long end of the 250 than you are with the 200, then there is something wrong.

Goontz · Oct 1, 2009

I agree, sounds like something's off with the one you got. Look into exchanging via amazon or contacting Sigma directly for warranty work.

NateWagner · Oct 1, 2009

yeah... we can't access your hard drive to see the images.

hulk · Oct 1, 2009

gl600 said:

You have to upload the pictures first to a hosting site, and then use the address with the IMG tags. imgur is my favorite.

gl600 · Oct 1, 2009

i have no idea how to do it. (uploaded to imgur... gave me a bunch of links??)

Goontz · Oct 1, 2009

gl600 said:
i have no idea how to do it. (uploaded to imgur... gave me a bunch of links??)

http://www.thephotoforum.com/forum/...forum-functions-pictoral-guide-using-tpf.html

tirediron · Oct 1, 2009

gl600 said:
@tirediron: Exactly the same conditions.
@Goontz: New from amazon.

P.S. It also has a bit of an AF issue as well. Maybe I got a dud???

Hmmm... that puts things in a bit of a different light.

Dao · Oct 1, 2009

The 18-250mm Sigma lens behave as a 18-220mm lens according to this link.

Juza Nature Photography

Take a look at the table and look for "Real Focal Length"

So if the 55-200mm is actually longer at 200mm, it may explain why. But I am not sure if that is the case. After you take the photos with both lenses, are the Exif data match with the lens settings?

I remember one forum member here found that the field of views of 70mm between 2 different Canon L lenses were not the same. (24-70mm vs 70-200mm at 70mm)

Dwig · Oct 1, 2009

The marked FL on a lens has to be taken with a grain of salt. There are a number of variables:

1. The old standard was accuracy within 5% for prime lenses and 10% for zooms. When I've seen recent test reports that actually measured the FL accurately, zooms have generally been in error by 5% or slightly more. With zooms, the minimum FL is always longer than marked and the tele end is shorter. A 10% error on a 270mm would be 243mm.

2. Almost all modern zooms change FL when focused closer than infinity. A proper comparison of lenses should be done at a working distance of at least 1000 times the focal length. A test at 100 times the FL would be reasonable. 200-250mm lenses should be compared at distances of over 20m/65ft and preferably 200m/650ft. Comparisons done at closer distances you be marked as such and should only be applied to similar distance real shooting (e.g. portrait use, ...)