Weia

Joined on Dec 2, 2011

Comments

Total: 38, showing: 1 – 20
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In reply to:

Alec: What I would like to clarify is lines per millimeter vs. line PAIRS per millimeter. Because the proper unit in the spatial frequency / lens sharpness context is a line pair per millimeter (a black line and an adjacent white line, whose loss of contrast is evaluated).

I hope this is a simple typo (like "calories" is commonly used whereas it's in fact kilocalories i.e. thousands of calories, but everyone understands). But I'm also not ruling out that we're being duped, and instead of 50 line pairs per millimeter they're actually talking about literally 50 lines, and thus 25 line pairs, per millimeter.

...Which would be a shame (from film days we know sharp lenses' spatial response extends to 100 line pairs per mm and beyond),
... and a sham (akin to the pundits in the early days of digital pledging that 6 or 8 megapixels was "film quality" - whereas Hollywood with real money riding on asset longevity, sticks to film even in the days of 4K).

It will be line pairs, as he is also speaking of 10 & 30, which cannot be lines per mm.

Link | Posted on Feb 7, 2016 at 19:22 UTC

Interesting. that '1000 times less light than on earth' is something one doesn't realise.

Link | Posted on Jul 21, 2015 at 20:45 UTC as 8th comment | 7 replies
In reply to:

CameraLabTester: If the camera was panned a little more to the left, he would have captured a DOUBLE RAINBOW (also a rare weather spectacle).

You can see the two arcs sandwiching the lightning on the left.

Here is how a FULL DOUBLE RAINBOW looks like:

http://scontent.cdninstagram.com/hphotos-xfp1/t51.2885-15/s320x320/e15/10561207_686156514850042_1344064799_n.jpg

.

A double rainbow is quite common.

Link | Posted on Jul 12, 2015 at 07:59 UTC

It's not exactly 'once'!

Link | Posted on Jul 11, 2015 at 12:41 UTC as 107th comment

Reminds me of Buster Keaton playing all instruments in an orchestra directed by Buster Keaton. Without computers quite skillful... 3 musicians at a time and 9 dancers. The Playhouse: https://www.youtube.com/watch?v=eRo36k1ipkE

Link | Posted on Jun 6, 2015 at 17:53 UTC as 32nd comment | 1 reply

"Using a Clauss precision pan-and-tilt head" That thing looks far too unstable for an 800mm.

Link | Posted on Jun 3, 2015 at 07:57 UTC as 44th comment

Distortion of the 7-14 seems to be better corrected than in my old Oly 7-14. Would like to read more about distortion of this beast.

Link | Posted on May 12, 2015 at 09:50 UTC as 19th comment | 2 replies
On article Massive $33,500 2450mm f/8 NASA lens surfaces on eBay (235 comments in total)
In reply to:

Weia: Angle of view on 57x57 mm is 1.33 degrees. Same vertical angle on full frame gives f=1031, on Canon APS/C 636 mm, on Four Thirds 559 mm. Not very special.

Thanks for the link mosc, I get it. And I can make the calculations now.

Link | Posted on May 6, 2015 at 22:12 UTC
On article Massive $33,500 2450mm f/8 NASA lens surfaces on eBay (235 comments in total)
In reply to:

Weia: Angle of view on 57x57 mm is 1.33 degrees. Same vertical angle on full frame gives f=1031, on Canon APS/C 636 mm, on Four Thirds 559 mm. Not very special.

Interesting points, although I do not understand it completely. I would love to see an article on diffraction, with many illustrations and tests. On my old Olympus E3 (10 megapixels) with an apo Sigma 150 macro f/11 is OK, but f/13 clearly is worse thanks to diffraction. F/16 gives more depth of field but in fact is worthless.

Link | Posted on May 6, 2015 at 12:28 UTC
On article Massive $33,500 2450mm f/8 NASA lens surfaces on eBay (235 comments in total)
In reply to:

Weia: Angle of view on 57x57 mm is 1.33 degrees. Same vertical angle on full frame gives f=1031, on Canon APS/C 636 mm, on Four Thirds 559 mm. Not very special.

70 mm is the width of the film, with (as in Hasselblad) perforations on both sides, leading to 57x57 or 56x56 mm.

Link | Posted on May 1, 2015 at 15:08 UTC
On article Massive $33,500 2450mm f/8 NASA lens surfaces on eBay (235 comments in total)

Angle of view on 57x57 mm is 1.33 degrees. Same vertical angle on full frame gives f=1031, on Canon APS/C 636 mm, on Four Thirds 559 mm. Not very special.

Link | Posted on Apr 29, 2015 at 15:33 UTC as 30th comment | 12 replies
On article Winds of Change: Shooting changing landscapes (63 comments in total)

A famous Dutch naturalist said about a century ago: when you cannot find a miracle within 100 meters of your door, you'll never find it.

Link | Posted on Apr 27, 2015 at 15:11 UTC as 17th comment | 1 reply
On article DPReview recommends: Best smartphone cameras (368 comments in total)

It would be nice to add to all the measure of the sensor (not all are mentioned) and the optical zoom range.

Link | Posted on Mar 30, 2015 at 10:30 UTC as 104th comment | 2 replies
In reply to:

Weia: Where can I find more about diffraction limits and sensor size? Fourthirds, APSc and full frame. Especially in macro.

DOF is independant of sensor size or pixel density, so I wonder why diffraction effects should depend on sensor size.
I need higher f-numbers because I mostly picture insects of 1-5 mm length. I've tested my Sigma apo 150 on my good old E3 and f/11 is mostly my choice. f/10 maybe is a little bit better, f/13 definitily is worse.

Link | Posted on Mar 26, 2015 at 10:48 UTC

Where can I find more about diffraction limits and sensor size? Fourthirds, APSc and full frame. Especially in macro.

Link | Posted on Mar 24, 2015 at 12:09 UTC as 13th comment | 6 replies
On article Making 'Art': We go inside Sigma's lens factory (194 comments in total)
In reply to:

brumd: Great article! It really helps me appreciate the amount of work and care that is put in making these lenses, not only Sigma, but in general.

It would be nice to be able to compare this production process with the Leica factory and their "handmade lenses": http://blog.leica-camera.com/leica-news/the-leica-manufacturing-process/

In what ways do these production processes actually differ?

"It really helps me appreciate the amount of work and care that is put in making these lenses, not only Sigma, but in general."
I was thinking the same. Every tiny part has been in someones hands, all lines and signs are printed or even drawn by hand...

Link | Posted on Mar 9, 2015 at 12:12 UTC
On article CP+ 2015 Sigma Interview - "small office, big factory" (194 comments in total)

They love optics above all, it seems. Nice read.

Link | Posted on Mar 5, 2015 at 11:58 UTC as 33rd comment

Distortion quite much, always the difficulty with these focal distances.

Link | Posted on Feb 25, 2015 at 15:17 UTC as 20th comment
On article Adobe celebrates 25 years of Photoshop (366 comments in total)
In reply to:

Weia: I left Photoshop since the cloud version is the only one. Bye bye.

I meant: I stopped wanting updates!

Link | Posted on Feb 19, 2015 at 15:15 UTC
Total: 38, showing: 1 – 20
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