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David Morison
6th October 2011, 08:56 AM
Still doing relevant tests on my newly acquired 70-300mm and a puzzling conundrum has cropped up. Objects taken with my Leica 14-150mm at maximum zoom are half the size on the final image as the same objects taken on the ED 70-300mm at 150mm. The Exifs say they are the same focal length so what is going on? Lens technologists please help.

Taken with the Leica at 150mm:

http://e-group.uk.net/gallery/data/500/PA066738.jpg (http://e-group.uk.net/gallery/showphoto.php/photo/39593)

Taken with the ED 70-300mm at 149mm:

http://e-group.uk.net/gallery/data/500/PA066737.jpg (http://e-group.uk.net/gallery/showphoto.php/photo/39592)

Will do a test later to compare the ED70-300mm at 300 with the ED 300mm f2.8.

David

sapper
6th October 2011, 09:26 AM
I have seen this question before but cannot remember the answer, sorry:-)

Ulfric M Douglas
6th October 2011, 11:15 AM
:confused:
Do both originals have the same pixel count? (So there's no digital zooming going on...)

Please post pictures from both your Olympus and your pana-leica zooms at 70mm, 150mm and Olympus 300mm to give us more evidence to work on.
A fascinating quandry! *chr

David Morison
6th October 2011, 11:16 AM
Update. The 70-300mm at 300mm has the same width of field as the ED300mm f2.8 and the Leica 14-150mm at 14mm has the same width of field as the ED7-14mm at 14mm, but the Leica at 70mm has a larger width of field at 70mm than the 700-300 does at 70mm. Also the Leica has a wider field of view at 50mm than the ED 50mm f2 Macro. So that leads me to conclude that the Leica has a smaller zoom range than is claimed and leaves me wondering if other Panasonic lenses are similar in comparison to Oly. This is a 4/3rds lens not an MFT lens and surely all lenses marketed for 4/3rds should have identical focal length characteristics. Someone must have an answer, anyone got a clue?

David Morison
6th October 2011, 11:42 AM
:confused:
Do both originals have the same pixel count? (So there's no digital zooming going on...)

Please post pictures from both your Olympus and your pana-leica zooms at 70mm, 150mm and Olympus 300mm to give us more evidence to work on.
A fascinating quandry! *chr

All originals have the same pixel count. Here are the images asked for (sorry about the tilt!):

Leica at 70mm

http://e-group.uk.net/gallery/data/500/PA066748.jpg (http://e-group.uk.net/gallery/showphoto.php/photo/39596)

Leica at 150mm

http://e-group.uk.net/gallery/data/500/PA066749.jpg (http://e-group.uk.net/gallery/showphoto.php/photo/39597)

ED 70-300 at 70mm

http://e-group.uk.net/gallery/data/500/PA066746.jpg (http://e-group.uk.net/gallery/showphoto.php/photo/39594)

ED 70-300 at 150mm

http://e-group.uk.net/gallery/data/500/PA066747.jpg (http://e-group.uk.net/gallery/showphoto.php/photo/39595)

ED 70-300 at 300mm

http://e-group.uk.net/gallery/data/500/PA066750_edited-1.jpg (http://e-group.uk.net/gallery/showphoto.php/photo/39599)

Very confused!

David

Zuiko
6th October 2011, 12:06 PM
I'm sorry, I can't think of an answer to this! :confused:

ScottMorris
6th October 2011, 01:32 PM
I wonder how accurate the graduations, both in terms of the lens barrel markings and the lens' internal reporting for the EXIF is for the 70-300. It seems more likely that it's not quite so spot on in terms of it reporting a value in the middle of its zoom range rather than the Panaleica essentially mis-selling itself. The m4/3 version of the lens was a 14-140, but that's (hopefully) completely unrelated.

Mar
18th October 2011, 01:08 PM
It might be that Panasonic is shorter at closer distances like for example Nikon 70-200 which is only around 130mm at close distances even zoomed at 200mm.

You should try comparing it outdoors focusing at targets 5-10 meters away.

Also, note that 70-300 is also a semi-macro lens making it have larger magnification than a standard tele lens at shorter distances.

Zuiko
18th October 2011, 04:31 PM
It might be that Panasonic is shorter at closer distances like for example Nikon 70-200 which is only around 130mm at close distances even zoomed at 200mm.

You should try comparing it outdoors focusing at targets 5-10 meters away.

Also, note that 70-300 is also a semi-macro lens making it have larger magnification than a standard tele lens at shorter distances.

I think you may have the answer. If the Leica is internal focusing, then it will change the focal length at short distances. It's a price to be paid for a more compact lens that doesn't change physical length when focused. :)

DJMC
18th October 2011, 05:25 PM
So long as the 14mm end and the 150mm end of the Leica appear correct, I guess the difference in between is due to inexact markings?

I find the same with my rifle scopes. On those with objective lens focus, where the front lens housing is rotated to adjust it, many of them will focus at an actual 25 yards when turned to the 50 yard mark on the housing.

:confused:

David M
18th October 2011, 11:47 PM
I think you may have the answer. If the Leica is internal focusing, then it will change the focal length at short distances. It's a price to be paid for a more compact lens that doesn't change physical length when focused. :)

Yes, and it can be a quite dramatic shortening of the focal length in super-telephotos. I used to have figures years ago but don't know where they are now.

Phill D
19th October 2011, 07:18 PM
Not sure I follow this so will have to read the thread again more carefully. I'd be interested in the figures too if you can find them. It's good to know how your kit behaves if it's not what it seems.

David M
19th October 2011, 10:19 PM
See the second FAQ here;

http://www.tamron.com/en/photolens/faq/

If I remember correctly the legacy OM 350mm has a focal length of around 300mm at its MFD.

Phill D
20th October 2011, 06:06 AM
Ah I get it now. Definitely hadn't realised that. Thanks David.
So a Sigma 150 macro would give a much more magnified image than the Leica at 150mm and say an image distance of 12 inches. I wonder if there's any way to work out what the difference is at different distances without someone with both lenses actually taking shots?