Help judging performance of my FE55z, FE35f2.8z horizon/infinity

Started Jul 5, 2016 | Questions thread
l_d_allan
l_d_allan Veteran Member • Posts: 5,087
Could captures of stars be used to evaluate lens performance?
1

Nephi wrote:
Can you do me favor and take an infinity shot ...

I've wondered if a lens could be validly evaluated with a carefully taken capture of a clear night sky.

Maybe some partial aspects of IQ that avoid the problems with evaluating lens IQ with landscapes?

Everything would be at infinity, and a "flat field". With different exposures you could have hundreds of brighter stars, or tens of thousands of pinpoint, high contrast points.

Each corner could have hundreds or thousands of pin-points to compare to other corners. In posts about astro-photography, coma is apparently an issue for the corners, for example.

The partial or full moon could be at least a very good "target at infinity". You might include the full or partial moon, or re-aim the lens to being away from the moon ... depending on the focal length on the lens.

If there was a "known target" like the "Big Dipper" included in the capture, automated software might be able to compare "expected" to "actual" and generate some objective numbers. Maybe the capture could be aimed so the North Polar Star was near the middle?

Even the count of how many pin-point over a certain magnitude might be informative, and maybe could be automated.

I've thought about comparing how many stars are visible within the four sided polygon of the "Big Dipper". It seems like that might have some nuggets of how lens + sensor is performing.

Or not?

 l_d_allan's gear list:l_d_allan's gear list
Panasonic Lumix DMC-TZ3 Panasonic Lumix DMC-FZ47 Canon PowerShot S110 Canon EOS 5D Mark II Canon EOS 600D +27 more
Post (hide subjects) Posted by
(unknown member)
(unknown member)
(unknown member)
(unknown member)
(unknown member)
osv
osv
osv
osv
osv
osv
osv
osv
osv
(unknown member)
Keyboard shortcuts:
FForum PPrevious NNext WNext unread UUpvote SSubscribe RReply QQuote BBookmark MMy threads
Color scheme? Blue / Yellow