JensR

JensR

Lives in United Kingdom Bath, United Kingdom
Works as a Mechanical Engineer
Has a website at http://www.jr-worldwi.de
Joined on Nov 23, 2003
About me:

Hi,

thanks for stopping by!
If you want to contact me, just visit my homepage.
http://www.jr-worldwi.de
I am happy about feedback and mails!

My 'plan':
a) Get a D7 to work in IR as well as my modded Olympus 2040IR :->
(This is partly done, but there's a new project going on...)
b) Talk Pentax into a digital Electro-Spotmatic!
(This still needs some work...)

I am currently shooting with:
Pentax *ist DS
Pentax *ist DSIR
Pentax MZ-5n
and a few lenses.
These cameras give me great possibilities.

Former cameras
Olympus 2040IR / Minolta D7IR(modded for IR work)
Revueflex 5005 (not as often)
And:
Olympus 4040 (not for long)
Minolta D7 (not for long)
Olympus 2020
-------------

Older Signatures:

'LBA knows no bounds, and seeks no justification...' (Jim King, 2005)
http://www.jr-worldwi.de/photo/index.html - Photography, Tech and Geek stuff :}

'Why is everyone answering rhetorical questions?' (Me, 2005)

'Well, 'Zooming with your feet' is usually a stupid thing as zoom rings are designed for hands.' (Me, 2006)

'I only trust those photos I have faked myself.' (Me, 2007)
http://www.jensroesner.de/

--=! Condemning proprietary batteries since 1976 !=--

'I don't want them to believe me, I just want them to think.'
Marshall McLuhan

Comments

Total: 66, showing: 1 – 20
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On Roger Cicala investigates accuracy of lens adapters article (48 comments in total)
In reply to:

PhotoKhan: I don't get this...

If the only purpose of an adapter (the "pure" ones, not something like Metabones) is to reinstate the original Flange Focal Distance a lens was built to work with, why are they optically-bench-testing them?

The only appropriate testings to be done are mechanical and physical-dimensional ones, ie, how dimensional-accurate (and consistently throughout production output) is a particular adapter.

(I guess that would mean getting some measuring equipment they DON'T have...)

You are right, Khan!
I share your assumption: They are lacking the necessary equipment to check the physical dimensions precisely.

Direct link | Posted on Oct 3, 2013 at 12:07 UTC
On Pentax Q7 Review preview (240 comments in total)
In reply to:

Marvol: I have no axe to grind in this Q review, but after reading the posters below I agree that comparing it to "entry-level ILC" cameras completely misses the point of this camera. Even I can see that the camera is not aimed to compete against other ILCs. It actually makes a big effort to be quite different from these cameras.

> I'd really like DPReview et al to be more flexible and compare the same way a potential buyer would compare, not an engineer.

As an engineer, I politely object to that. That's not how an engineer worth their salt should operate.

Direct link | Posted on Aug 9, 2013 at 13:16 UTC
In reply to:

Guy McLoughlin: Too many people are trying to equate Micro 4/3 and FF DOF, which is largely missing the point. Equivalent FOV is what it's all about. Same F-stop, same exposure.

Micro 4/3 lenses have a 2 stop disadvantage when it comes to shallow DOF, but most Full Frame shooters aren't shooting EVERY shot wide open because often the DOF is TOO shallow.

i.e. A head-shot where the subject's eyes are in focus but their nose is out of focus is NOT a flattering shot.

I shoot corporate video for a living with Panasonic Micro 4/3 cameras, and most of the time my aperture is between f/2.0 and f/4.0 in order to get usable DOF in my shots. With a FF system I would be shooting at f/4.0 to f/8.0 to get the same DOF.

Unless you have a burning need to shoot EVERY shot at full aperture with your FF camera, the Micro 4/3 DOF difference is generally not an issue.

Now Micro 4/3 shooters have a very fast 85mm FF FOV equivalent with built-in optical stabilization, something none of the FF camera systems have.

> Equivalent FOV is what it's all about. Same F-stop, same exposure.

Misleading. On FT 42.5mm/1.2 on ISO 200 gives same FOV, same DOF and same number of photons per image&time as 85mm/2.4 on ISO 800 on "FF". *That* "is what it's all about".

> have a very fast 85mm FF FOV equivalent

I would not call that "very fast", I'm rather sure I'll call it "very expensive", though.

Direct link | Posted on Aug 2, 2013 at 14:29 UTC
In reply to:

Pat Cullinan Jr: <quote>should provide the depth-of-field control and low-light image quality on an APS-C DSLR that you'd get using an F2.8 zoom on 35mm full-frame.</quote>

The aperture of a lens is quite independent of the format of the film or sensor. In other words, f/1.8 is f/1.8 whether the lens is placed before an APS-C sensor or a full-frame sensor. The intensity of the light striking the target is the same whether you have a small or a large target. The aperture is a function solely of the focal length and the entrance "pupil" (meaning the diameter of the circle of light you see when you look through the lens from the rear).

I hope everybody understands this, because otherwise you'll be making disadvantageous decisions or doing things wrong.

> The aperture is a function solely of the focal length and the entrance "pupil" (meaning the diameter of the circle of light you see when you look through the lens from the rear).

You mean f-stop. Aperture in optical physics is measured in mm. Sadly in popular photography, the terms have become mangled, so I usually say "aperture diameter" to make it clear that I am not talking about the dimensionless f#.

Direct link | Posted on Jun 7, 2013 at 13:27 UTC
In reply to:

SunnyFlorida: The Nikkor 35mm F/1.8 sells for $180, the 35mm F/2.0d sells for $270 and can be used in 2 formats, Oly is asking $500 for this???

> The Oly is likely to compare quite well, even vs. FF (could even beat that old 35, at least wide open).

But the 35/2 on "FF" would be stopped down to 3.5 for a fair comparison. (Fair= same angle, same DOF, same number of photons captured per time)

Direct link | Posted on Nov 15, 2012 at 12:44 UTC
On Just Posted: Pentax K-30 full review article (272 comments in total)
In reply to:

OneGuy: It seems Pentax is applying the age old method of subsidizing the body (hamburger) to make some money off the lenses (french fries).

Being new to the various lens mounts, I'd appreciate a primer (or a reference to one) explaining the various acronyms the dpr readers here are sooo capable of tossing about.

DA are the APS-C lenses that support full metering and AF. You can mount any of the older K-mount (Pentax bayonet) lenses directly, with more or less limited functionality (K, M, A, KAF, DFA, FA, FAJ). You can also attach M42 lenses (with an adapter).
Edit: Forgot the Limited and DA* and possibly others ;)

Direct link | Posted on Nov 1, 2012 at 01:52 UTC
In reply to:

Rupert Bottomsworth: Why would anyone buy this over a Sony RX100?

Elaka, noise at same output size is almost independent from sensor resolution. If you look at it at 100%, the pic with more MP will be also larger, so the noise appears worse (per pixel noise vs. per image noise).

Direct link | Posted on Oct 24, 2012 at 09:21 UTC
In reply to:

roy5051: UGLY, UGLY, UGLY! Why on Earth have that bl**dy great lump on the top? Surely it is not beyond the bounds of the designers to build the viewfinder and flash into the body? Looks like it was designed by a committee!!!!!

I think you mean abomination, not abortion.

Direct link | Posted on Oct 24, 2012 at 09:17 UTC

I hope the rating algorithm will be smart enough to detect mob behaviour and people voting multiple times through different accounts and punish those accordingly.
Also, there are cases where a post was criticised (or praised) a lot and then it turns out that the post was actually correct (or wrong) - would a voting be reversed in such a case? I don't see how it would be done.

Direct link | Posted on Oct 1, 2012 at 13:38 UTC as 68th comment
On Photokina 2012: Hasselblad Stand Report article (47 comments in total)

So Sony themselves are switching to a normal hot shoe and Hasselblad "inherits" a hot shoe that does not match any of their previous cameras?!
They have enough money to design a crocodile hand grip, but fail to make the flash system compatible with their system?!
Oh boy...

Direct link | Posted on Sep 20, 2012 at 14:30 UTC as 23rd comment

Right now someone at Sony is seriously mad that they didn't go for the NEX fullframe and instead did the RX1. Ah well, there's always next year.

Direct link | Posted on Sep 17, 2012 at 19:26 UTC as 116th comment | 1 reply
In reply to:

increments: Given the quality of some of the existing AF wide angle zooms, this is either going to have to be stellar in terms of IQ, or be very affordable...

Is it greedy to want both? ;)

> Sigma 10-20mm £326, Tokina 11-16mm £500, Canon 10-22mm £540, Tamron 10-24mm £350.
> Samyang 14mm £330

The Samyan g is a FF lens. While this is maybe of no relevance to an APS-C user, it does explain some of the price. (Pentax's APS-C 14/2.8 is also more expensive.)

Direct link | Posted on Sep 14, 2012 at 19:30 UTC
In reply to:

Jan Kritzinger: I can't believe there are people on this forum who say no to f/2.8.
You will always run into situations where you don't have enough light. ALWAYS.

It's nice, but being able to mount a filter and size are also important. I can understand people preferring one over the other.

Direct link | Posted on Sep 14, 2012 at 14:41 UTC
In reply to:

toughluck: In terms of DOF, it's a 50/9 equivalent, so good luck trying to get meaningful defocusing. It should have been f/1.2 or f/0.9 for the size -- while it would still have poor defocusing control, it would have been much better.

Also: Why is the lens and the bodies so huge? Sony just released RX1 which, lens included, is thinner than this lens is long. Not to mention huge N1 bodies.

> So 50mm F/4.5 in terms of angle of view and depth of field. BUT NO that does not mean light transmission changes, it's still the same intensity of light regardless of crop.

Intensity of light doesn't really matter, because it ignores the area over which this intensity is applied.
Better way to look at it:
This lens lets through to the sensor as many photons per unit of time as a 50/4.5 would on 24x36. These lenses would be equivalent and their images would be indistinguishable.

Direct link | Posted on Sep 13, 2012 at 14:19 UTC
In reply to:

jaycob: First off let me just say that I am no expert in photography so please excuse my lack of knowledge on the subject.
My question about this camera is; Why would Sony develop such an great camera at a premium price yet slap a fixed lens on it? You would think that if they were to put a full frame sensor in any kind of camera they would want to open the doors to additional lenses.
Am I missing something? Please educate me.

I think it's testing the water for a future FF "NEX deluxe" (I call dibs on the name NEXluxe :D )

Direct link | Posted on Sep 12, 2012 at 20:57 UTC
In reply to:

liquidsquid: Sheesh, if you separated the body from the glass, and made separate purchases, many of you who don't want to shell out $2800 would be singing a different tune.

How much good glass out there goes for over $1K? How many FF bodies go over $1K?

Not that I am going to get one any time soon.

You are right. If this was a camera with interchangeable lenses, many here would be prepared to pay more than 2800USD. But it's not. And I think that's why several people are a bit unhappy.

Direct link | Posted on Sep 12, 2012 at 20:55 UTC
In reply to:

nicolaiecostel: So Pentax finally dropped the ball and introduced in-lens stabilisation. Oh dear, I can still hear fanboys explaining how much better it is to have sensor IS vs. lens IS.

I'm sure my sarcasm meter must be broken, but just in case you are serious:
1) Pentax has had IBIS in their APS-C cameras for years
2) This SR lens is for their medium format camera
I think there is not a single other stabilised MF system and if there is, it's not from Sony.

Direct link | Posted on Sep 11, 2012 at 15:42 UTC
On Lightroom Photo Import article (117 comments in total)
In reply to:

Gregm61: Last thing I'm gonna waste my time doing is importing all my photos "into" Lightroom so it can see them. If a program can't just "see" the dang photo where I have it in my computer (like Photoshop can), I have no use for it as a catalog system.

I tried Lightroom 4 while waiting for the CS6 update. Since getting CS6, Lightroom has just sat on my desktop, and I doubt it gets used again.

Hi LJ
First: LR uses a cache for the previews as well. So I am not sure where you are going with this.

Second: I don't want my RAW processor to keep track of my images. With RSE I could simply move or rename the folders and it would always have the settings to the files. I have never run into this "choosing" problem. Third: I don't want my RAW converter to be a file utility. I am disappointed at how bad a file utility LR is. It's gotten better, admittedly, and maybe 4 is decent, but I cannot run it (yet?).

Fourth: That is the one advantage to LR's catalogue system that _I_ like. It would be difficult to shoehorn a browser architecture like RSE's into allowing this.

Fifth: I want to be able to right-click a RAW file and edit it in my then-opening converter.

The benefits LR brings to the rest of my workflow outweigh my catalogue criticism, but it's obvious that the we have different ideas of how we want to manage our files. I'm sure yours is right for you and I am happy with mine.

Direct link | Posted on Aug 24, 2012 at 21:26 UTC
On Lightroom Photo Import article (117 comments in total)
In reply to:

Gregm61: Last thing I'm gonna waste my time doing is importing all my photos "into" Lightroom so it can see them. If a program can't just "see" the dang photo where I have it in my computer (like Photoshop can), I have no use for it as a catalog system.

I tried Lightroom 4 while waiting for the CS6 update. Since getting CS6, Lightroom has just sat on my desktop, and I doubt it gets used again.

Absolutely. I find that extremely annoying. I much preferred RawShooter's approach - sad that they did not carry that over when Adobe bought and killed it.

Direct link | Posted on Aug 24, 2012 at 16:01 UTC
In reply to:

MrTaikitso: Actually, running a top end DSLR or mirrorless on Android would make a lot more sense. Huge potential for customisation by the open source community, and potentially, an end to interfaces that some don't like. IE, user could customise the interface using Android 'skins'. Low end phones like this don't need this, but pros love to customise their toys.

I completely agree with you (toys and tools, I would say ;) ) - but at the same time, I think it's not realistic: I just don't think manufacturers are ready to embrace open-source user-interfaces, let alone open-source functions.

Direct link | Posted on Aug 22, 2012 at 17:49 UTC
Total: 66, showing: 1 – 20
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