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Forum: Monthly Photo Contests 10-26-2010, 01:25 PM  
Liquid metal
Posted By le_roi_ponpon
Replies: 0
Views: 2,154
Taken around 9:00 AM two years ago in Ouakam beach, Dakar, Senegal. :)
Forum: Digital Processing, Software, and Printing 04-29-2010, 03:24 AM  
Experiences with PaintShop Pro X2 and Pentax raw?
Posted By le_roi_ponpon
Replies: 15
Views: 7,620
I have tried both the X2 Ultimate and X3 but pentax RAW (PEF), altough supported, remain either noisy or washed out (cannot find a set of parameters to get it right). Pentax Lab or Lightroom 2.3 do a much better job at RAW processing. So I use PSP for processing jpeg or tiff, not RAW. (I have a K20D)
Forum: Digital Processing, Software, and Printing 04-06-2010, 12:34 AM  
How To: RAW/PEF thumbnails in Windows XP
Posted By le_roi_ponpon
Replies: 5
Views: 4,649
Works perfectly (XP Pro), thanks!!
Forum: Digital Processing, Software, and Printing 04-04-2010, 12:46 PM  
Corel PaintShop Photo Pro X3
Posted By le_roi_ponpon
Replies: 45
Views: 20,116
Well I ugraded to PSP X3 from X2 Ultimate in an impulsive move, and did some empirical tests today. After trial and error with PSP Raw editor, I am a bit disappointed with the quality of the RAW results. Some annoying chromatic noise remains in dark areas, luminance noise reduction way too strong (you have to leave it at 0 because at 1 it washes out everything)... Finally I got (as expected I guess): Pentax Photo Lab is the best, followed by Lightroom 2.3 (tweeking with sharpening/noise reduction) , then PSPX3 which is ok (default) as long as you do not pixel peep. Also I have weird behavior with some files (perhaps because that I had already read them with X2): photos are way too bright, histogram is flat with lots of highlights... PSP is also very slow compared to LR... So I believe PSP is a good and much cheaper alternative to Photoshop for retouching/effets, but I still prefer Lightroom for daily stuff because of its speed and raw processing quality. But perhaps I did something wrong with PSP raw editor, so I would love to read about other experiences.
Forum: Pentax News and Rumors 03-10-2010, 05:06 AM  
645D lost the competition
Posted By le_roi_ponpon
Replies: 77
Views: 15,621
No shake reduction? :confused: I am quite sure the competition doesn't have it but it would have been cool.
Forum: Pentax SLR Lens Discussion 03-07-2010, 08:45 AM  
Send DA17-70 for repair?
Posted By le_roi_ponpon
Replies: 5
Views: 2,803
You are the best!! I made the adjustments (I have a K20D) based on test charts (both MTF and moiré), and it happens that I had to adjust focus by +10 for that lens (backfocus, right?). So I tested all my lenses and they also needed some non-negligibile adjustements on the + side. Also it probably explains why my DFA100 macro was a bit softer than I wanted at f2.8-4. I never thought that the focus adjustment would be more than an cool option: in fact it is an obligation once you unpack a new camera or a new lens! I would have probably tried it if all my lenses were soft, it just happens that this one was more obvious than the others. Still, the sharper setting for my DA17-70 is still f11, and the DA55-300 is still super sharp (and now probably sharper at 300). Funny that Pentax reps never suggested I try that. :hmm:
So thank you very much folks, I am now a happy man (and richer)! :p
Grégoire
Forum: Pentax SLR Lens Discussion 03-04-2010, 04:32 PM  
Send DA17-70 for repair?
Posted By le_roi_ponpon
Replies: 5
Views: 2,803
Thanks for the insights and for the hint to a possible focus problem. I'll do some tests this wee-end and let you know! :)
Forum: Pentax SLR Lens Discussion 03-03-2010, 07:18 AM  
Send DA17-70 for repair?
Posted By le_roi_ponpon
Replies: 5
Views: 2,803
Hello, I have a DA17-70 that I have sent for repair in Canada almost a year ago, for SDM problems :( and also sharpness problems. It came back with SDM repaired :) , but still with the same sharpness problems. I live in Africa so I took the lens anyway because I needed it (I was on vacation in Canada when the lens came back). I have a few months left on the warranty, and I need your advise before I pay big bucks to send it for repair...
My feeling (confirmed by MTF tests) was that the lens was bad between f4 and F8 (inclusively, which is weird) for focal length > 50mm. I did a side by side comparison of DA17-70 and DA55-300, both @ 70mm (so I am comparing two "consumer grade" lenses). DA55-300 is much much better between f4 and f8. The DA17-70 starts to be good at f11 (what lens is not at f11??). I was wondering: is it suposed to be like that, i.e. do I risk to have Pentax repair say my DA17-70 is fine (and therefore loose money and time)? Note that at in the range 17~30mm the lens is very sharp at most apertures (a bit soft at f4 but still fine).
Thanks in advance for you help.
Grégoire.
PS Attached is a 100% center crop.
Forum: Pentax SLR Lens Discussion 01-17-2010, 10:13 AM  
DA* 16-50mm Serial Number Database.
Posted By le_roi_ponpon
Replies: 528
Views: 161,102
Hi everybody,

More Bayes nets with updated list of S/N (as of 17Jan2010): there is still a 65% random chance to get a good copy, and 90% if the fourth digit is 0, 1 or 2. The digit to check is the X as in 902X306. So if you have the possibility, you could improve your odds by asking for a fourth digit <= 2 ! :)

EDIT: actually, if 4th digit = 0, chance of a good copy is 90%, if it is =1, chance is 100% (!), if it is =2, chance is 77%.

Cheers,
Grégoire
PS: sorry for you mdsnexp, you had a 10% chance of getting a lemon...
Forum: Troubleshooting and Beginner Help 04-01-2009, 11:58 AM  
pentax k20d and lifeview ?
Posted By le_roi_ponpon
Replies: 9
Views: 2,838
Bueno no se de flash, pero si tomas fotos en raw puedes ajustar el balance de blanco en pentax Photo laboratory usando uno o varios puntos en una o mas zonas gris de la imagen (o un carton gris)... pero hay que hacerlo para cada photo... O hacer lo mismo en Ligtroom, y el te da la temperatura (sabiendo que no sera exactamente igal a la del K20D). Pero en LR puedes corregir una sola photo, y luego sincronizar todas las demas tomadas en las mismas condiciones. Sino lo unico que veo es prueba y error jugando con temperatura entre 5000 y 6000K, sabiendo que si corriges la exposicion (Ev) o el ISO al tomar la photo, deberas ajustar la temperatura de unos cientos de grados)... Asi puedes hacer tu propia tabla de temperaturas para cada exposicion (y ISO!).. me explico?? :confused: Pero no soy ningun experto! De pronto si haces la pregunta en ingles en otro thread alguien tendra la respuesta adecuada. Suerte!
Forum: Troubleshooting and Beginner Help 03-28-2009, 03:05 PM  
pentax k20d and lifeview ?
Posted By le_roi_ponpon
Replies: 9
Views: 2,838
fue un placer! Chau.
Forum: Troubleshooting and Beginner Help 03-28-2009, 08:27 AM  
pentax k20d and lifeview ?
Posted By le_roi_ponpon
Replies: 9
Views: 2,838
Bueno no se lo que has configurado, pero en mi K20D lo unico que tengo que hacer es girar el boton de "off/on" mas alla del "on", hacia donde esta la imagen del diafragmo, y aparece la imagen en el LCD... Quizas si nos dice exactamente lo que has configurado y probado podemos ayudar mas?
Forum: Pentax SLR Lens Discussion 03-07-2009, 01:47 AM  
DA* 16-50mm Serial Number Database.
Posted By le_roi_ponpon
Replies: 528
Views: 161,102
Attached is an excel file with SN and perceived quality as of March 6, 2009. I hope there are no typos (I did not check twice)... :confused: Cheers, Grégoire.
Forum: Pentax SLR Lens Discussion 02-14-2009, 06:14 AM  
DA* 16-50mm Serial Number Database.
Posted By le_roi_ponpon
Replies: 528
Views: 161,102
Hi everybody,

I tried to find (with Bayes nets) some correlation between the SN and the probability of having a good copy of the DA*16-50, and the only valid explanation seem to be linked to the fourth digit. :hmm:

Based on all the samples, there 65% random chance to get a good copy. But if the fourth digit is 0, 1 or 2 then the probability increases to 89%. The digit to check is the X as in 902X306. (of the 147 SN I checked, 37 have X <=2). I cannot find any correlation with the other digits.

I am not sure how statistically valid it is but I guess that if I had to buy this lens I would give it a try! Who knows why... perhaps this correspond to a plant, or workgroup, or an individual... or it is pure coincidence.

Cheers,
Grégoire
Forum: Photographic Technique 01-18-2009, 03:34 AM  
HDR Photography
Posted By le_roi_ponpon
Replies: 12
Views: 3,634
Hannican, the multiple exposure is not what you want to use. You use the Exposure bracket button (p129 of the K20D manual), to take (I strongly recommend a tripod) a number of separate pictures (preferably RAW) at various exposure compensation (e.g. 0 and +/- 2Ev), then you combine the shots in an HDR and "tonemap" it with dedicated software (I use qtpfsgui1.9). The tonemap is to compress the huge (16 or 32 bit/color) HDR in a into a 8bit/color image. Here is my first test done last week (3 photos at 0,+/2Ev) with two tonemapping parameters (one for a natural look, the other more drawing like). Hope this helps. Grégoire.
Forum: Pentax SLR Lens Discussion 11-21-2008, 01:29 AM  
SDM focus question
Posted By le_roi_ponpon
Replies: 3
Views: 2,269
Hi Kees, I have found some hunting in contrasty situations even in natural light, or for macro at 70mm, I am not sure if there is a pattern. I think it happens towards the longer focal lengths but I have not done systematic tests. Perhaps it is due to the softness of the lens at f4. But no clicks or ticks, just plain sdm "short" hunting ("brr-brr-brr").
Grégoire
ps I would like to know if you have the same pattern for center sharpness as me (see my post in https://www.pentaxforums.com/forums/pentax-slr-lens-discussion/41158-pentax-17-70-f4.html). If you have a chance to do some tests... :)
Forum: Pentax SLR Lens Discussion 11-07-2008, 07:49 AM  
Pentax 17-70 f4?????
Posted By le_roi_ponpon
Replies: 24
Views: 7,886
I have this lens since June and am learning about its strenghts and limitations. It has some strange characteristics which I am starting to understand. I'll post some test shots when I have some spare time (year end is tough jobwise)...

It has a great snappy contrast, colors are great, weight and look are perfect, autofocus is smooth and fast and silent. I don't see centering defects in my copy.

Optically it has some inverse behavior at shorter and at longer focal lenghts, which is perhaps intentionnal by design.

Longer focal lengths (>35mm): a bit sharper than my DFA 100mm macro at f11-f16; but very soft up to f11 (there is a jump in sharpness past f8) and at f22. Sharpness at f8 about the same as at f4! Sweet spot is f11 where it shines.

17mm focal length: very soft at f4 but a bit sharper than DFA100mm stopped down (even at f5.6 which is the sweet spot) up to f22. It produces stunning landscapes stopped down 1 stop or more.

So knowing that I have been able to get very sharp and snappy pictures. But it is not what the tests in CI showed... so I believe there is some variability from lens to lens.

I have started to notice some problems locking focus af 70mm even in good light and contrast, perhaps it is due to the softness at f4? (advises welcome.) But I may send it to Pentax repair because 1) it is very annoying when you press the shutter and cannot take the shot; 2) it is not normal, I think, that it is so soft at f8 for longer focal length.
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