badriaticopo2 Loc: Kane County, Illinois

Great discussion. Am learning a lot. I use Nikon but don't have any Tamron lens. But based from your experiments, it appears that there is only a problem when the subject is near the camera. IMHO i believe Tamron can't focus as closely as Nikon's or Canon's. To illustrate using zoom lenses with almost the same zoom ranges and using the same focal length like 200mm, Nikon and Canon may be able to close focus at 4 feet while Tamron can only close focus to 6 feet. This will result to a tighter close ups for the Nikon and Canon lenses compared to the Tamron's. Please check your lenses because i don't have a plan to buy the Tamron lens. Hope this helps.

K.C. Loc: Waterloo, NE

Was the older lens used on a traditional or film camera? If so, use on the digital would effectively double the focal length due to size of the capture sensor. I think one of the posts may have addressed this but I do not see follow-up conversation. With my thanks, kc

jeep_daddy Loc: Prescott AZ

They should be close though.

flashgordonbrown Loc: Silverdale, WA

WRONG! The focal length is the focal length-the fact that the Tamron is designed for use on crop sensors only means that it will not cover a full frame sensor. The crop factor is still in play.

les2297 Loc: Central OR

You guys crack me up. You are comparing macro capabilities with telephoto ratings. Apples to oranges, then you wonder why the red fruit doesn't make good orange juice

fdildine Loc: From-Bath, NY / Live-Transfer, PA

I'm as new as they come, but the only thing I see in the meta-data, is that even they both say the same resolution, image A contains almost twice as many pixels. Would this make a difference?

badriaticopo2 Loc: Kane County, Illinois

Your Nikon has a better macro capability than your Tamron. Hence the Nikon has a tighter closeup. Using the same 200mm focal length, the Nikon can focus a lot closer than the Tamron. Both are just limited by their close focusing capabilities.

chapjohn Loc: Tigard, Oregon

Aer reading the all this thread (so far), les2297 makes a lot of sense. I also learned from the posts that different focal lengths produce different results. This is a good thread with good information. I look forward to the final answer.

cecilia delacroix Loc: near Seattle

My 1st image (on page 3 of this thread) was accidentally posted twice...my apologies for any confusion. Ignore that 3rd image.

alksaki Loc: Fresno, CA

Quoted from Wikipedia http://en.wikipedia.org/wiki/Zoom_lens:
"at the extreme telephoto setting of the lens the effective focal length changes significantly while the lens is focused on closer objects. The apparent focal length can more than halve while the lens is focused from infinity to medium close-up."

It doesn't explain the cause, other than it's a design compromise of 10x zooms. The article states its a lesser problem with fixed focal length lenses. I've noticed it in a Micro-Nikkor 200mm f/4, when used at very close focusing distances. Moving the focus ring, which moves the internal lens elements, changes the field of view enough to require repositioning of the camera/tripod.

joker22joe Loc: naples fl.

this a simple answer, wtf is the big deal one lens is better and I think you are messing with every one!

Lawrence

Caranx, your right! I used the Same Camera (Canon 7D) To take all my pictures, and found you to be right. I think some of these replys Are missing your point. Like I said above, (MY FINDINGS WERE THE SAME AS YOURS).

Caranx Loc: Atlanta

Hi Joker22joe. To reiterate what I wrote very early in this topic, I don't have the time or the inclination to be "messing with every one (sic)" as you imply. I wondered when the discussion, healthy as it has been, was going to be marred by someone starting with the expletives and name calling. There isn't a need or a place for this here and the level of discourse has been sterling so far.

I am learning a lot, just as several others on the forum have opined, and if nothing else comes out of this than a better understanding of how lenses are designed or labeled by manufacturers, then some good will have been done.

I have expressed a genuine interest in finding out why there is this apparent discrepancy. Its not a matter of whether a lens is "better" than another. This appears to be an inconsistency in how the focal length of lenses are defined. Other UHH members have had similar experiences (Barny, Lawrence, Gibar to name a few) and I think we all seek better understanding.

If a lens is labeled as a 270mm lens, I think IMHO, it is reasonable to expect that it will give me more reach than a 200mm lens. What if you bought a 400mm zoom and then found that a 100mm zoom was bringing things in closer, wouldn't you question it? The answer may be quite simple, as you state in your post, but it has eluded all of us on the forum so far.

Since "this is a simple answer" to quote you, would you mind explaining this to us? I just want to understand this. Thanks

Caranx Loc: Atlanta

Thank you Lawrence. I realise some may doubt this but it I invite them to do a similar "test" as you have. I just want to know why this is so!

pigpen

I was reading reveiws on lenses before I bought the Canon 400mm"L". One reveiw compared images of a $100 bill shot with the Canon and the Sigma 150-500mm (@500mm). The magnification was almost exactly the same. The reveiwer pointed it out, but offered no explanation. The Sigma is MUCH longer than the Canon, I used to have one.

My guess is that different companies have different specs?