Panny 25mm 1.4 vs Olympus 25mm 1.8 Reviewed

Started 7 months ago | Discussions thread
draleks
Junior MemberPosts: 48
Like?
Re: T-stops
In reply to Ido S, 7 months ago

Ido S wrote:

The difference in required shutter speeds for any given aperture is caused by the T-stops of the lens. That's the amount of light that actually manages to hit the sensor, whereas F-stops represent the amount of light that goes through the aperture diaphragm. We'll have to wait on a scientific confirmation, from the folks at DxO Labs (who are in charge of the famous, and infamous, DxOMark), as well as SLR Gear, etc.

I have an alternative theory. All lenses change their focal length slightly when focusing. So the 25 mm focal length applies strictly only at infinity. Mr Wong's test shots are portrait shots with fairly short object distance. As he himself noted, Panny has a slightly narrower FOV at that distance, which implies longer focal length. Slightly longer focal length with the same aperture diameter = slightly darker image, as is observed.

This is splitting hairs in any case, the lenses are equally bright at equal f-stops for all practical intents and purposes. The most important selling point of the panny to me is that it has antireflective coating. The night shots look absolutely gorgeous with this lens.

-- hide signature --

Disclaimer: Summilux fanboy.

Reply   Reply with quote   Complain
Post (hide subjects)Posted by
MIJNew
Keyboard shortcuts:
FForum PPrevious NNext WNext unread UUpvote SSubscribe RReply QQuote BBookmark post MMy threads
Color scheme? Blue / Yellow