Dimitris Servis

Dimitris Servis

Lives in Switzerland Switzerland
Has a website at www.coloraberration.com
Joined on Sep 27, 2009

Comments

Total: 151, showing: 1 – 20
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On Massive $33,500 2450mm f/8 NASA lens surfaces on eBay article (234 comments in total)
In reply to:

Dimitris Servis: "The aperture, f/8, is likely fixed." DPR, it wouldn't be a bad idea to explain what f8 really, really means to people...

People reading this article will not buy this lens

Direct link | Posted on May 9, 2015 at 19:24 UTC
On Massive $33,500 2450mm f/8 NASA lens surfaces on eBay article (234 comments in total)
In reply to:

mosc: It's no accident that telescopes describe the aperture size rather than the focal length and f-stop. At infinite focus, the focal length and f-stop are both means to the same ends: More light from a small object that doesn't fill the frame. A FF DSLR focused at infinity would get very similar detail out of a 600mm f4 lens as it would a 1200mm f8 lens. They're both 125mm aperture size lenses, more commonly described as 5" telescope.

This thing can be described in the very confusing magnitudes of 2450mm f8 for a 0.50 crop (compared to FF) camera or a 1225mm f4 FF lens or better yet just a 12" aperture reflector with a rather large mount built in. 12" reflector telescopes are for sale on amazon for little more than $1,000 that are probably pretty close to this optically

Though I suppose the lens may be capable of adjusting it's focal distance to something shorter than infinity? If so that's a lot more engineering for your dollar.

Telescopes are specified by clear aperture size and f number from which you can calculate the focal length. The diameter of a photographic lens cannot be easily used in this context.

For the rest I am not sure I understand what you are trying to say and what it has to do with crop factors, but I am not sure you understand either...

What is "focal distance" to you and what distance shorter than infinity would you expect a 2450mm lens to focus on?

Direct link | Posted on May 2, 2015 at 07:27 UTC
On Massive $33,500 2450mm f/8 NASA lens surfaces on eBay article (234 comments in total)

"The aperture, f/8, is likely fixed." DPR, it wouldn't be a bad idea to explain what f8 really, really means to people...

Direct link | Posted on May 2, 2015 at 06:31 UTC as 8th comment | 2 replies
On Massive $33,500 2450mm f/8 NASA lens surfaces on eBay article (234 comments in total)

Why not this?

http://www.meade.com/products/telescopes/lx850/lx850-acf-14-f-8.html

Direct link | Posted on May 2, 2015 at 06:20 UTC as 9th comment | 1 reply
On Using third-party lenses on Sony Cyber-shot a7 / a7R article (503 comments in total)
In reply to:

Dimitris Servis: A word of caution: do not put junk store lenses on your camera unless inspected for fungi. A contaminated lens may contaminate your camera and every lens you put on it.

So then give it a try :)

Direct link | Posted on Apr 24, 2015 at 07:43 UTC

Took my D750 for fixing the flare issue to the Nikon Swiss repair center. Got it back exactly the same, only with a white fluffy speck on the mirror.

Direct link | Posted on Apr 11, 2015 at 14:02 UTC as 69th comment | 2 replies
In reply to:

Dimitris Servis: Hydrophobic

Not sure what you mean exactly, these are very precisely defined chemical properties, not to mention the language these terms originate from

"A hydrophilic molecule or portion of a molecule is one that has a tendency to interact with or be dissolved by water and other polar substances."

http://en.wikipedia.org/wiki/Hydrophile

So you mean the filter molecules, will in time dissolve in the rain?

Direct link | Posted on Mar 9, 2015 at 14:50 UTC

Hydrophobic

Direct link | Posted on Mar 4, 2015 at 07:51 UTC as 1st comment | 2 replies
On Nikon D750 flare investigated: Why we're not worried article (364 comments in total)

There will be a time when people will sell D600 with oil splash effects and D750 with flare issues as collectors' items.

Direct link | Posted on Jan 21, 2015 at 07:45 UTC as 84th comment | 1 reply
On Nikon D750 Review preview (1914 comments in total)
In reply to:

bensherman: Is Dpreview working for Nikon by any chance? To begin with they missed the whole flare issue,then denied it and now this so called investigation (primitive compared to other review sites) that had to bring Canon in make dpreview feel good about their argument....Plain silly!

@halfwaythere

"As a consolation: they don't make 'm like they used to."

Or you never found out without the web

Direct link | Posted on Jan 21, 2015 at 07:28 UTC

But that's only Nikon US?

Direct link | Posted on Jan 20, 2015 at 12:55 UTC as 25th comment
On Samyang launches 135mm f/2.0 lens for stills and video article (151 comments in total)
In reply to:

Roman Korcek: "The lenses [...] will be available in [...] MFT mounts initially, with the company promising [...] Micro Four Thirds at a later date."

I assume this is a typo or am I missing something?

Let's hope m43 will not be left out...

Direct link | Posted on Jan 13, 2015 at 13:55 UTC
On Samyang launches 135mm f/2.0 lens for stills and video article (151 comments in total)
In reply to:

Langusta: Nice lens but at least some basic electronics for aperture control and focus confirmation (like dandelion chip) should be imo included. Voigtlander could do that why not samyang? It's really no rocket science nowadays...

I think the Nikon mount is chipped

http://www.samyang-lens.co.uk/samyang-135mm-f20-ed-umc-lens.html

Direct link | Posted on Jan 13, 2015 at 13:51 UTC
On Nikon D750 Review preview (1914 comments in total)
In reply to:

HowaboutRAW: Mr Physics+Frank C:

According to Wikipedia the flash sync speed of the D70 is 1/300 sec.

With a smaller (APSC) focal plane shutter it is easier to build higher sync speeds.

The top shutter speed of the camera is indeed 1/8000 sec.

Speed might even be the same. Exposure time is different due to the sensor size...

Direct link | Posted on Dec 21, 2014 at 19:28 UTC
On Nikon D750 Review preview (1914 comments in total)
In reply to:

tecnoworld: A wonderful camera, its af performance makes me think of going back to dslr, after the poor performanve of even the best mirrorless around, but...I'll wait and see what the a9 can deliver.

I am not so unhappy with Olympus AF and certain lenses. Still, have to see how D750 does

Direct link | Posted on Dec 21, 2014 at 09:11 UTC
On Nikon D750 Review preview (1914 comments in total)
In reply to:

Frank C.: That dumbed down 1/4000 and 1/200 x-sync is hard to swallow nonetheless

It is hard to swallow... That's why I wonder if the ISO 50 could compensate a little for that...

On the other hand I think that would require a differentmaybe larger shutter and would make the camera the same size as the D800/810. It is the reason why I will buy the D750 but keep my D7000

Direct link | Posted on Dec 20, 2014 at 14:56 UTC
On Nikon D750 Review preview (1914 comments in total)
In reply to:

garyknrd: What a camera! Insane sensor. If Nikon had the lenses I like to shoot with. I would make a lateral move in a heart beat.

Yup, that's probably a niche not covered properly

Direct link | Posted on Dec 20, 2014 at 11:05 UTC
On Nikon D750 Review preview (1914 comments in total)
In reply to:

garyknrd: What a camera! Insane sensor. If Nikon had the lenses I like to shoot with. I would make a lateral move in a heart beat.

What do you miss?

Direct link | Posted on Dec 20, 2014 at 10:38 UTC
On Nikon D750 Review preview (1914 comments in total)

How does it work at iso 50?

Direct link | Posted on Dec 20, 2014 at 09:38 UTC as 426th comment | 4 replies
On Nikon Df Review preview (1624 comments in total)
In reply to:

Lassoni: I'm confused what you're supposed to do with this camera. To use older lenses? But there are sites online (not just dxomark) that show the older lenses are MUCH softer than any of the newer generation of lenses. Less chroma, less distortion, less fringe..

If someone with collection of older lenses buys this camera so he doesn't have to "upgrade" his/her lenses, why not just buy a different camera and newer lenses? I'm curious.

Using a number of Nikkor Ais lenses, I can tell you they are not soft at all on modern Dslrs, on the contrary. If there is one thing that you need to control is flare.

That said, I use these lenses not because I am looking for the quantified image quality you refer to (resolving power, aberrations and so on) but for qualities that lie exactly in their flaws and their special signatures when used properly. I am sure that if you used a 50mm 1.2 Ais for close subjects at 1.2 you would appreciate it beyond its apparent halos and flaws.

Direct link | Posted on Nov 28, 2014 at 10:31 UTC
Total: 151, showing: 1 – 20
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