Lives in Czech Republic Prague, Czech Republic
Has a website at http://jtra.cz/
Joined on Mar 6, 2008


Total: 10, showing: 1 – 10
In reply to:

ProfHankD: "The open nature of Sony's E-Mount standard" is that it is NOT open at all!

I formally applied for my research group (based in the University of Kentucky) to get the specifications and Sony eventually gave a two-part reply:

1. Basic means mechanical only -- no electronics communication protocol, etc.

2. They will only give basic info to a company making what they consider to be a worthwhile E-mount device; they considered the device I was working on (something much like what TechArt later put out as the LM-EA7) appropriate, but didn't consider a university research group manufacturing a device (with intent to spawn a company) to be a company. Thus, they refused to even disclose the mechanical specs.

Please stop congratulating Sony on their statement of open disclosure when it is really: "These BASIC SPECIFICATIONS will be disclosed to manufactures of lenses and mount adaptors following a predefined PROCESS OF APPROVAL and the signing a license agreement with Sony."

I have recently asked about it. See here:

Link | Posted on Jun 1, 2018 at 12:47 UTC

Lens designed for 50MP sensors.
Sample pictures here and on samyanglensglobal.com at 0.65MP.

Link | Posted on Feb 20, 2018 at 18:18 UTC as 20th comment
On article Sony FE 100mm F2.8 STF bokeh demystified (356 comments in total)
In reply to:

SimenO1: I cant make up my mind about what I like best. STF or not. Its very situation dependent. But I don't want to shell out for two very similar lenses ether, so how close to the SFT effect can I get with a similar radial graded ND filter? (I would like to literally screw on and off the STF effect)

See my drawings that show how position of apodization filter affects bokeh: http://jtra.cz/stuff/essays/bokeh/index.html#apodizationdiy

Link | Posted on Feb 17, 2017 at 22:15 UTC
On Article:2355927234 (36 comments in total)
In reply to:

Photato: DxO took 4 months to review the LG G4 despite being the most Photo friendly phone currently and almost a year for the Note 4 !
I bet all my photo gear that it will take them less than 14 days to show results for the new iPhone 6S.
Timing is an important factor for objectiveness not just the numbers.

--> Bias

They reviewed Moto X Style (Pure) on July 28, on the day it was announced. A month before it was available to consumers. Something fishy. Seeing the pictures from it, there is way too much NR or compression artifacts in midtones (I would expect them just in shadows), compared to other top phone cameras. I have considered it, but after seeing pictures, I got the G4.

Posted on Sep 25, 2015 at 08:29 UTC
In reply to:

watson076: I'm done with Adobe. I tried to cancel CC and they told me they were charging me for canceling. I honestly didn't know it was a contract, simply thought this was month to month plan (so I admit that's my fault for not reading the fine print). I argued with them that this isn't a good time financially and just wanted to cancel the service without any charges but they were unable to comply.

Somebody describes her cancelling experience here:

Link | Posted on Jun 16, 2015 at 16:22 UTC
On photo Towers and Churches behind Charles Bridge, Prague in the An image challenge (2 comments in total)

Link to the mentioned Tripod & ballhead & technique test (it also includes full 24MP version of this image):

Link | Posted on Apr 23, 2015 at 08:08 UTC as 2nd comment
In reply to:

ThePhilips: The “Gaussian Approximation” by Shea Hadstrom looks very interesting.

If we would ever get a decent programmable camera API, it'd be interesting to see what else can be achieved by changing the aperture during exposure. (Just imaging toying with the zoom effect!)

Yeah, too bad, most cameras are not programmable today.
I have had same idea, I wrote about it here:
but none of my cameras and lenses allow to do that (without freelensing).

Link | Posted on Dec 2, 2013 at 20:41 UTC
On Challenge:8946 (16 comments in total)
In reply to:

Henry Lozykowski: “bokeh” look at:

"Nine rounded diaphragm blades guarantee images with exceptional bokeh"
Wherever there are reports about a new camera lens, this sentence is often found. What characteristic of the image is actually meant by it? And what does the diaphragm have to do with it?
We would like to address these questions today. But because "bokeh" is closely related to "depth of field," I would like to first begin with those topics on the following pages. It is true that a great deal has already been written about them elsewhere, and many may think that the topics have already been exhausted. Nevertheless I am sure that you will not be bored. I will use a rather unusual method to show how to use a little geometry to very clearly understand the most important issues of ‘depth of field’.

Yeah, that article is great. I have written something about bokeh too:

Posted on Nov 9, 2013 at 21:41 UTC
In reply to:

Sanjay Mehta: It's quite obvious that this move in response to piracy concerns. I can't remember where I read it, but an Adobe manager was claiming recently that this move was driven by more by software development cost concerns than anything else.

Words to the effect that their new cloud strategy would make it cheaper for them to deploy software on the lines of Google's server side changes.

But when you look at the details, the software still downloads and installs on your machine and periodically goes back to Adobe servers for updates and license management. They also claim that it can run up to some 90 days without needing internet access.

If that is the case, it's really just the regular installation on your machine, with some internet access.

As an Aperture user who was considering Lightroom, I'm now planning to stick with Aperture. Apple's App Store model is much more convenient and reasonable.

"this move was driven more by software development cost concerns than anything else"

Problem for Adobe is that Photoshop and related products are too good. It is becoming harder and harder to sell you next version.
Some professionals may need it, but most could live with CS6 for a decade (though RAW support for new cameras may force them to upgrade).

In fact when Adobe gets most customers on to this rental model (they may lower the price for some time to do so), they may significantly reduce their software development.

As long as you are locked into file formats, you will have to pay to rent your access to your files (and also to apply your PS skills). They won't need to add new important features by then like they did have to do in past for each CS release.

I (non-pro) use a GIMP (on Linux), Geeqie (sorting images) and some RAW converters - all free. I have considered LR and PS, but with this kind of software rental I don't like it. LR is not tied to CC, but it may be in future.

Link | Posted on May 9, 2013 at 08:18 UTC
On photo Moonrise in the Your best 2009 challenge (6 comments in total)

The 17mm full-frame cannot capture the moon that big.

This page compares how much the moon fills the picture for several focal lengths (full-frame film): http://home.hiwaay.net/~krcool/Astro/moon/howtophoto/

This is composite or a single picture where moon part is very enlarged in post processing. The result looks great, but author should have told us.

Link | Posted on Jan 23, 2010 at 07:15 UTC as 4th comment
Total: 10, showing: 1 – 10