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Forum: Pentax K-1 02-18-2016, 08:01 AM  
"Crippled" mount or not?
Posted By dlacouture
Replies: 32
Views: 2,765
Yep, no sign of the aperture link lever... So we are stuck with stopped-down metering...
Forum: Pentax Forums Giveaways 12-15-2014, 08:51 AM  
3 Million Post Giveaway: Confirm your entry!
Posted By dlacouture
Replies: 2,854
Views: 79,333
Still open?
Forum: Pentax K-5 12-10-2014, 08:15 AM  
Best screen ever for manual focus : Canon ee-S!!!
Posted By dlacouture
Replies: 769
Views: 152,043
One thing that I've learned while playing with the EE-S screen is that no matter what screen you're using, the stopped-down view is actually never a true rendering of the final depth of field...
Reason is simple : modern focus screens are not made of ground glass anymore, but use complex Fresnel lenses designs...
Okay, from f/2.8 on, the differences are small enough to go unnoticed... But if DoF is critical, then digital preview is the only sure way...
Forum: Pentax K-5 12-10-2014, 07:17 AM  
Best screen ever for manual focus : Canon ee-S!!!
Posted By dlacouture
Replies: 769
Views: 152,043
Seems like the flow have ebbed down...

No more manual focus aficionados out there? Everyone already switched to the EE-S?
Forum: Pentax DSLR Discussion 08-21-2014, 12:32 PM  
Histogram- using it. Any good reads?
Posted By dlacouture
Replies: 49
Views: 4,149
... which is perfect proof that the histogram of a RAW image is in fact taken from its JPG preview pic, I really don't see how you can be persuaded otherwise!

If the contrary was true (the JPG histogram being based on the RAW data), then it would mean that the histogram would be useless for JPG shooters (as it would be based on data from a format not even recorded)...
Forum: Pentax DSLR Discussion 08-09-2014, 12:49 AM  
Histogram- using it. Any good reads?
Posted By dlacouture
Replies: 49
Views: 4,149
You don't admit to defeat easily, huh?

Well, try this one : in manual mode, RAW, take two identical shots, only changing WB between the two (say, alternate between Shade and Tungsten)...

From your theory, histograms should be identical, no? I'll let you try and comment...

From memory, I think only Hasselblad (or was it Phase One?) does propose a true RAW histogram in their cameras...
Forum: Pentax DSLR Discussion 08-01-2014, 06:51 AM  
Histogram- using it. Any good reads?
Posted By dlacouture
Replies: 49
Views: 4,149
And again: yes, it's based on the jpg preview...

Proof again (and I checked this on my K5!):
- take a RAW photo in a given WB
- develop this photo in-camera using the same WB (you should get the same photo)
- compare the histograms

If what you say is true, the histograms should be different, as the JPG histogram is always different from RAW, no matter what WB you use.
At least on all Pentax cameras I had laid my hands upon (the last one being the K5, so maybe the K3 differs on this), this method gives identical histograms, proof that the displayed histogram of a RAW file is in fact the JPG preview histogram.

Again, the only way to have an accurate RAW histogram is to give UniWB a try, but you lose the RAW+JPG benefits
Forum: Pentax DSLR Discussion 07-24-2014, 08:23 AM  
Histogram- using it. Any good reads?
Posted By dlacouture
Replies: 49
Views: 4,149
Nope, it's based on the jpg... Easy way to check: develop the same file in-camera using different white balances or exposure settings...

There is only one way IMO to use ETTR in RAW : UniWB...
Is quite easy to set up :
* create a custom white balance using a completely overexposed image (pure white), the camera will then lose its marbles and apply a 1-1-1 conversion ratio on its RGB channels (resulting in a greenish image due to the RGBG Bayer filter).
* tweak contrast and luminosity settings so the histogram gets similar to what you can have using a software like Rawnalyze.

And voilą! a near-perfect RAW histogram... Only downside : all your pics are now green, so RAW+ is out of question...
Forum: Pentax K-5 07-24-2014, 08:04 AM  
K-5 Freezez up
Posted By dlacouture
Replies: 15
Views: 1,752
Mine does that occasionally, usually when exiting LiveView or Movie mode...
Forum: Pentax K-5 07-18-2014, 06:07 AM  
Best screen ever for manual focus : Canon ee-S!!!
Posted By dlacouture
Replies: 769
Views: 152,043
Whoah, that was some heated discussion!

Reminds me FF vs APS-C debates... :chuckle:
Forum: Pentax K-5 03-10-2014, 02:01 AM  
Best screen ever for manual focus : Canon ee-S!!!
Posted By dlacouture
Replies: 769
Views: 152,043
Guys, I'm glad to see that this thread is still living! Ranked as 6th thread (in posts or views!) of the K5 forum, never had so much success for my other posts!

Sorry for not chiming in recently to give answers to those having questions, but 2013 was a lousy photographic year for me (I think I barely made 500 clicks during the whole year!).

To all of you Fast Lenses Lovers, regards from the South of France!

Dominique.
Forum: Pentax K-5 02-13-2013, 08:49 AM  
Firmware Update K-5 V1.14
Posted By dlacouture
Replies: 109
Views: 23,665
While I was testing the AF with my lenses, I noticed something strange...

I was testing AF-C, using a Tamron 70-200/2.8 @ 200mm, and I was quite blown away by the speed and frequency of the AF. The camera was constantly on the move, the AF motor always whirring and quite nailing the focus, without hardly a heartbeat between focus updates... Felt like a machine gun!
But when I tried with shorter focal lengths (@70mm and with a FA50/1.4 and a sigma 30/1.4), AF-C became very reluctant to move, doing updates every half seconds at best...

Don't know if it was that way before 1.14 (never really tried), but I don't understand why there is such a difference... I'll try some more tonight...
Forum: Pentax K-5 02-13-2013, 01:41 AM  
K-5II P-TTL overexposure with tilted flash - test and analysis
Posted By dlacouture
Replies: 116
Views: 19,049
Hello...

Just to throw some more oil unto the fire, I've made my own set of tests...
I wanted to see if the lens aperture had an effect. After all, metering is done with the lens wide open, and that would also explain the different behaviors we see depending on the user : each of us has its own set of lenses so they surely have an impact...

OK, so here is what I've done : I've used only one lens (a PK-m Porst 135/1.8), but with the aluminum foil and halfway mount tricks to fool the camera so it thinks it always has a PK-A f/1.2 lens used at f/1.2, whereas the actual aperture varies (so I can actually choose what is the "wide open" aperture).

These tests were made using a EE-S screen.

First, straight flash: results are perfect from f/1.8 down to f/16 (with a slight variation, but you really have to look for it, I'd say maybe half a stop)... So, using an EE-S and any lens, you'll always get the same direct flash exposure (I'd suspect that using the stock screen would result in a -1 Ev variation with fast lenses, just like with stop-down metering).

Now, with bounce flash, results are really strange...
First, in my test conditions, between f/1.8 and f/2.8, exposure is good, with no visible variation...
Then, at f/4, a major overexposure occurs, followed by a seemingly constant flash power from f/4 down to f/16 (each pic being gradually darker than the previous one thanks to the decreasing aperture)... What is crazy is that the camera has no way to know that it reached f/4!!! So why the sudden overexposure? We already determined from the straight flash test that the focus screen gives accurate readings on the whole aperture range!

I'll go on with my tests, but it seems to me that in bounce mode, below a certain pre-flash metering reading, the camera loses its mind and fires the flash at a fixed output...

That would explain why some persons experience the problem, and others do not... For instance, I often use fast lenses only (between f/1.4 and f/2.8) at moderate distances, and so the pre-flash metering certainly stays above this threshold, and P-TTL works for me... But take someone using slower lenses, on longer distances, right at the edge of this threshold value... One moment the picture would be fine, then it would overexpose (or underexpose) for no reason, the flash being fired at this fixed level...

Now, the only time where I had trouble with bounced P-TTL and had to switch to manual was while snapping candid pics from afar in a dark venue, bouncing against the ceiling. Thinking back to this moment, I recall that I was baffled by the P-TTL behavior: it felt like it was indeed firing at a fixed power, as changing the iso was having a direct effect on flash exposure, even while I was far from the flash' maximum power and flash exposure compensation was useless (and switching to manual flash solved the problem anyway, so P-TTL should have handled it).
Forum: Pentax DSLR Discussion 01-23-2013, 01:42 AM  
Why a higher Max Sync Speed matters! Please address it Pentax!
Posted By dlacouture
Replies: 74
Views: 7,743
I never really understood this 1/250 fad... The only practical case I see is when you really have to balance a high ambient at base ISO, without closing your aperture further, and without using HSS.

And in this case, it means you work in plenty of light, so using a ND filter is possible... A simple ND2 will lead you into 1/360 territory (but, granted, it will cost you some flash power).

So, faced with this choice, well, I think I would rather spend some more dollars on a 2nd light source to compensate for the light loss, rather than wait for a higher sync speed...

EDIT: one thing that would sell like hot cakes : LCD filters!
Imagine a ND-like filter with a programmable "shutter" duration...
Wired to the flash hot-shoe, you enter the desired duration, it darkens at the end of the P-TTL communication and lighten on the flash signal, for the desired amount of time only...
Ta-daaaa, instant 1/1000 (or whatever!) shutter speed, compatible with any lens/body combo, and cheap!!!
Anyone for a kickstarter campaign?
Forum: Troubleshooting and Beginner Help 01-21-2013, 02:34 AM  
Manual Lens focusing issues (focusing screen)
Posted By dlacouture
Replies: 15
Views: 2,970
And the EE-S is simply the best "stop-downer" out there : it gives a near perfect linear metering with those old M or m42 lenses, regardless of the aperture used... No more wild roller-coaster rides depending on the aperture you use, it's a treat!
Forum: Pentax DSLR Discussion 01-18-2013, 12:51 AM  
pentax advantages, pentax vs nikon backwards compatibility, pentax future...
Posted By dlacouture
Replies: 13
Views: 4,758
Here are my Pros for both systems (cons are just down to personal subjective points nowadays, anyway):
Pentax:
- SR on all existing lenses, but you can also enjoy those 3rd party OS lenses if you want (great for tele!)...
- build quality: take a D7000 and squeeze it, now do the same with a K5 (just try not to hurt yourself!)...
- Auto-iso based on focal length.
- AF calibration possible on nearly all models.
Nikon:
- cheap fast glasses available for beginners.
- great flash system! The ability to set each of your flashes in manual or TTL mode right from the camera is great!
- better AF-C.
Forum: Pentax DSLR Discussion 01-17-2013, 01:46 AM  
Tenpa Vs KPS vs O-ME53 Eyepieces
Posted By dlacouture
Replies: 4
Views: 1,432
I have both the O-ME53 and the Tenpa...
I went back to the O-ME53, as the Tenpa cuts too much of the viewfinder (and I don't even have glasses!) and suffers from lateral chromatic aberrations (corners are slightly blurry, with distinctive blue-yellow separation)...
With the O-ME-53, I can see either the whole picture, or move slightly to include the Led display at the bottom...
Forum: Pentax Film SLR Discussion 01-15-2013, 06:44 AM  
Film full frame advantage
Posted By dlacouture
Replies: 15
Views: 1,833
Exactly...

And shooting digital just learned me to snap two slightly different pics (if I can) of my subject when using film... A bad pic is always cheaper than a missed opportunity, IMO...
Forum: Pentax Film SLR Discussion 01-14-2013, 06:04 AM  
Film full frame advantage
Posted By dlacouture
Replies: 15
Views: 1,833
For me, shooting film was all about DoF control and dynamic range, but since I got a K5 (right from its debuts) and experienced its very good DR, I shot maybe 2 rolls of film (and even that was because I had them lying around!).

And now with news of upcoming FF-to-Mirrorless "true" adapters that supposedly condensate a FF image onto an APS-C sensor, DoF control will not be a problem anymore...
Forum: Pentax SLR Lens Discussion 01-13-2013, 03:48 PM  
M Lenses - Purple Fringe Masters
Posted By dlacouture
Replies: 39
Views: 3,349
I'm still curious about the possible cause of PF myself, but one thing I noticed: off all the Pentax DSLRs I've ever owned (K10, K20, K7, Kx and K5), the K5 seems to be really prone to PF, to the point where I seriously considered returning it...
And all where used with pretty much the same lenses collection, so...

But the effect is way too much "optical-like" for it to be a sensor-only blooming or whatever, IMO... Anyway, I thought that blooming was actually a thing of the past (and concerning CCD only!)..
Or maybe PF is some kind of heat propagation, just like we can sometime see on the borders of high-iso pics...
Forum: Welcomes and Introductions 01-10-2013, 03:24 PM  
Manual glass.. for now
Posted By dlacouture
Replies: 5
Views: 456
If you want to go light and dig the 30mm focal length, then have a look at a samsung NX with the 30/2 pancake... It's APS-C, sharp as hell, and it can be found cheap as 2nd hand!
I have the NX200, and it's small enough to go into my coat pocket or my wife's purse...
Forum: Troubleshooting and Beginner Help 01-10-2013, 03:17 PM  
Will a ground glass/split focusing screen affect autofocus on a K-5?
Posted By dlacouture
Replies: 18
Views: 4,576
JBennett, if you are truly doing a lot of manual focus using old lenses, you should really get an EE-S screen... It shows true DoF right down to f/1.6, and it's so nearly perfectly linear wrt stop-down metering that it's pure joy for legacy lenses!
We had a pretty lengthy thread going on about it in the K5 section...
Forum: Pentax K-5 12-21-2012, 06:12 AM  
Best screen ever for manual focus : Canon ee-S!!!
Posted By dlacouture
Replies: 769
Views: 152,043
The EE-S screen is good for fast lenses (f/1.4-f/2) only... From f/2.8 on, there is no real benefit to it, except that it gets less grainy in low-light (but it's slightly darker with f/3.5-5.6 lenses, so...).

Taking into account that you have no fast lenses:
- If you are more into architectural subjects, then a split would be better.
- If you are into portraits, well, a split is not that easy to use on facial features anyway, so I'd say that it's a tie between a split, an EE-S and the stock screen...
Forum: Flashes, Lighting, and Studio 12-05-2012, 01:45 AM  
Wireless PTTL and HSS
Posted By dlacouture
Replies: 2
Views: 1,189
The easiest way to do off-camera HSS is to get a F5P sync cord...
2nd solution is to get another (cheap) HSS-capable flash and use it as controller...

Now, HSS has its uses in nearly only two case, IMO :
- for the wedding photog, under rapidly changing conditions...
- to freeze motion in a brightly lit environment.

For slow-moving subject, with HSS, you're basically trying to balance a high ambient light with your flash, at base ISO. But if you do the math, you'll see that going back to X sync by closing your lens a little bit (or using a good ND filter!) will actually save power and get you there faster...

Also, if you're trying to freeze motion in a low-light situation, HSS is not the solution. Using the standard flash burst is much more efficient for this.
Forum: Pentax K-01 11-27-2012, 06:30 AM  
Strange AF behavior with Tamron 70-200 f2.8
Posted By dlacouture
Replies: 9
Views: 3,929
Yep, got the same behavior on my K5-Tamron 70-200 combo...

To be precise, it looks like the camera overshoots and ends up slightly further than what it tried to achieve...
Indeed, you get front-focus if the lens was focused farther than your target when it started moving, and back-focus in the other case...
Maybe it's a inertia thing, with those heavy lenses...
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