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Forum: Pentax DSLR Discussion
01-22-2009, 03:54 PM
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dlacouture, aren't all contacts except A automatically shorted? How do you short contacts? Can you summarize to which lenses the trick work? Can you take advantage of P-TTL by lenses in M mode i.e. mode in which aperture is always dimmed to the setting of aperture ring?
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Forum: Digital Processing, Software, and Printing
03-08-2008, 08:50 AM
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NaClH2O, try to shoot 2GB card full of PEFs and another time full of DNGs. I predict bigger difference in the number of images stored.
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Forum: Digital Processing, Software, and Printing
02-20-2008, 02:46 PM
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I just learned that I can compress DNG files generated by K10D in Adobe DNG converter (Adobe - Digital Negative (DNG)). That saves about one third disk space. The Windows version of the software can be used by Wine under Linux.
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Forum: Digital Processing, Software, and Printing
02-20-2008, 08:20 AM
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I am using DNG from K10D. But I have thought about using PEF for the one third storage space savings. I am using Linux operating system on my PC. Both DNG and PEF are currently supported, but DNG somewhat better, in my experience (when it comes to thumbnails). I which I could compress DNG files losslessly in Linux. Actually, I which Pentax would release firmware update to give option to store losslessly compressed DNGs in K10D. But they have not done anything since firmware version 1.30, as far as I know, even if there have been many requests from customers.
Colin, it was new thing to me that you can store metadata and change preview image in DNGs. I which I knew how I do it in Linux. Can some software search images based on keywords stored inside DNGs?
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Forum: Flashes, Lighting, and Studio
01-22-2008, 04:31 PM
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Also flash durations for Metz 58AF-1 are listed in its manual in page 180.
Less light for lower part of image may be an advantage some time, if you have some ground in the picture much nearer to the camera than the main subject, but usually it is just disadvantage. It is less disadvantage, when using indirect flash. Well, AF540FGZ has its own problems, like zoom or getting stuck or the flashgun getting stuck in the hot shue in some cases. I guess there are no better options than these two flashguns with Pentax D-SLRs.
Is there some option to prevent K10D from choosing exposure time shorter than 1/60 s automatically? In my experience in A and P modes, it sets exposure time according to focal length (in dim light), if it can read the focal length from the lens, but I uses 1/180 s, if it can not read the focal length from the lens (even if the focal length was manually told by the shake reduction setting).
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Forum: Flashes, Lighting, and Studio
01-17-2008, 04:10 AM
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I got this information from Lutz Goeschel/Metz: "now we had checked a K10D with a Penax A lens and another M lens and found exactly the same behavior with both a 58 AF-1P and a Pentax flash unit. When using an A lens, the flash unit take over the f-stop from the lens. When using a M lens, the aperture on the flash unit has to be set manually."
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Forum: Flashes, Lighting, and Studio
01-10-2008, 10:38 AM
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By the way, do the flashes cut firing in P-TTL mode, when shutter starts to close, even if the flash does not have enough light to give proper exposure? I doubt they do in Auto mode.
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Forum: Flashes, Lighting, and Studio
01-09-2008, 02:08 PM
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Lowell, Goudge, thanks for testing. If I understood right, you get full input of flashlight, if you use shutter speed 150 or slower with the Pentax AF540FGZ, whereas you would have to use shutter speed 60 or slower with the Metz mecablitz 58 AF-1 to get full input.
Intensity of flashlight lowers towards the end of firing (after the peak), but the intensity of ambient light remains about constant. I wonder what shutter speed would be optimal for the flashguns when shooting daylight fill flash shots?
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Forum: Flashes, Lighting, and Studio
01-07-2008, 04:01 AM
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But was the low part in images exposed 1/180 s darker than the low part in images exposed 1/60 s (and was the difference between the images there bigger than in upper part of the images)?
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Forum: Flashes, Lighting, and Studio
01-07-2008, 03:55 AM
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Lowell Goudge, it it true that a frame is not exposed by flashlight before a shutter is fully open (if high speed syncronization is not used), but closing shutter does not stop flash firing in manual mode, if the flash needs so much time to discharge.
Please read above about the information I got from Metz concerning results of flash duration test done using T10 method for the Metz flashgun. Also I don't think the test results made above can be explained by ambient light; kurt reported he saw the same effect when shooting in no ambient light.
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Forum: Winners' Showcase
01-05-2008, 01:20 PM
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Applying some Unsharp Mask filter in Gimp with zero threshold and small radius would give some sharpness to the image, if you like.
Funny photo by the way. It looks like the owl is playing with you: It sees only one big eye - namely your lens - and shows you one as well.
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Forum: Flashes, Lighting, and Studio
01-05-2008, 12:02 PM
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Frame is exposed also during the opening and closing of shutter. It seems that at least with the Metz flashgun flash duration can be longer than the time shutter is fully open even if using camera's flash sync speed as shutter speed. If the flash is emiting light even after shutter begins to close, you may get uneven exposure. Camera does not know how long it takes to get full flash output and I am not aware of any standard about such maximum time.
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Forum: Flashes, Lighting, and Studio
01-05-2008, 08:05 AM
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Good for you. I have no information about any other flash with as high guide number that has faster flash duration. Can anybody do similar test for PENTAX AF-540 FGZ?
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Forum: Pentax SLR Lens Discussion
12-29-2007, 09:34 AM
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Is it a screw mount lens? I have one. I think the coating is not the best possible; proper lens hood would be needed to help to eliminate reflections.
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Forum: Flashes, Lighting, and Studio
12-26-2007, 01:19 PM
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Thanks for making sure.
I have not, but I would expect to see similar effect with other cameras since I doubt the flash models differ in manual mode. Furthermore, some Canon and Nikon cameras have X-sync time 1/250 s where the effect is more dramatical.
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Forum: Flashes, Lighting, and Studio
12-26-2007, 12:52 PM
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That is too bad. The Metz is then less usable than non-dedicated auto flashes with such lenses, as those flashes usually have at least couple of settings in auto mode. I wonder what aperture setting the Metz flash uses in auto mode with such lenses then, if you can not change the setting. (Camera does not know the F-number set in such a lens.)
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Forum: Flashes, Lighting, and Studio
12-24-2007, 07:55 AM
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rogerstg, there would not be obvious shadow line, if flash light brightness dims slowly enough while shutter curtain is closing. I have also been sceptical about such a long firing time, but I have been told by Goeschel Lutz / Metz that "with a full power flash, a 58 AF-1 has a flash duration of 1/125s measured according T10 metod" and "in T10 metod, the measurement starts at that moment when the light curve is triggered plus 10% (of its maximum) and stops after reaching the maximum when the light is fall down on 10%". Flash is triggered by X-sync exactly when the shutter curtain is fully open, but the opening period is part of exposure time so you need to choose at least shutter opening duration plus flash firing duration as exposure time to get full flash input.
If the difference is caused by ambient light, how do you explain that there is significantly more difference between the images shot by 1/180 s and 1/125 s than between the images shot by 1/60 s and 1/30 s in the lower part? (Ambient light should give half stop difference to the former couple and one stop difference to the latter couple.)
Maybe Kurt can tell, if the difference is visible in the areas where the ambient light does not come directly to.
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Forum: Flashes, Lighting, and Studio
12-23-2007, 02:39 PM
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Tell me if I am wrong, but taking into account K10D's normal contrast tone curve the above numbers mean that by using exposure time 1/180 s you loose roughly one stop light in lower part of image and one sixth of stop in upper part of image.
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Forum: Flashes, Lighting, and Studio
12-23-2007, 02:03 PM
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I suppose you post-processed the images equally.
Brightness varies more between the lower part of the images. Logical explanation would be that shutter curtain starts to cover that part of the image first when there is still some flashlight firing.
I opened the images at Gimp and took the HSV brightness values at certain points of each image; values calculated from "sample merged":
Coordinates 180 125 60 30
20,20 (upper left part) 77% 78% 81% 80%
700,10 (upper right part) 73% 73% 76% 76%
10,494 (lower left part) 52% 64% 71% 71%
720,450 (lower right part) 35% 42% 44% 46%
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Forum: Pentax DSLR Discussion
12-23-2007, 07:22 AM
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RiceHigh, as I mentioned the door is white, but exposure compensation was set to maximum i.e. +1 EV. Actually +2 EV would be better when you measure from white object. I wonder why Pentax has limited it to +1 EV. Thanks for the link to your test.
Roscot, thanks for the hint about Wein Safe Sync adapter. It is true, that light reflects brightly at certain small area of the white painted door in the test, and small change of angle of view could have big effect on the brightest area; I was not using a tripod. Another example is to shoot yourself in mirror using flash; your flash reflector will be about the only thing visible in the photo. I think there should be an option to let camera determine the exposure not by the lightest area of the preflashed view, but so that most of the image area has proper tones, as there may be highly reflective small areas in a random scene. That would not work well, if you shoot relatively small (angle of view) object in dark when there is nothing near behind the object.
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Forum: Pentax DSLR Discussion
12-23-2007, 04:36 AM
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I took some test shots using same settings except some shots were made in AF-S focus mode and other in MF: ISO 200, multi-segment metering, +1.0 flash exposure compensation, 1/180 s exposure time, F5.6. I got different kind of results. Some of them (that were shot using AF-S), were significantly lighter than most of the others. The object is a white door. Sample images are in the web temporarily:
I hope the inconsistency is not due I used Starblitz 3600BTZ TWIN flash with the camera few times. I later measured its trigger voltage 53V (and temporarily significantly higher). I wish I had been warned about the possible too high voltage beforehand. On the other hand, I have not heard anybody had broken his/her DSLR by too high flash trigger voltage. Can anybody else make similar test shots by K10D?
I hope external flashes give more consistent results in P-TTL mode.
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Forum: Pentax DSLR Discussion
12-18-2007, 04:22 AM
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See here for the new thread.
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Forum: Flashes, Lighting, and Studio
12-18-2007, 04:20 AM
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Please test, if your flash gives maximum output at shutter speed 180 by doing some test shots. Insturctions are at the end of this message. I am especially interested in test results of Metz mecablitz 58 AF-1 digital Pentax/Samsung, since I have read about rumors that tell you couldn't get full flash output in the flash X-sync speed of K10D. Of course, it is also interesting, if Pentax brand's own flashes perform any better with the camera. The feature is important when you do daylight fill flash shots.
Choose an object that is in dim light or in complete darkness. Put your camera on a tripod few meters away from the object and attach the flash. Select the manual mode in camera and flash. Set flash to full power. Choose ISO 100 and aperture so that it is the guide number of the flash divided by the distance between the flash and object in meters (or do test shots to determine usable aperture setting). Please note that the guide number depends on the flash zoom position. Then do some test shots changing only shutter speeds: 180, 125 and 60 (available when you select 1/2 stop EV steps). From these photos you should be able to see, if there is difference. Please post you test shots here.
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Forum: Flashes, Lighting, and Studio
12-16-2007, 10:06 AM
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Hi Kurt.
Thanks for the information.
Your Canon film camera works with different kind of TTL. Digital cameras usually work with Preview TTL that uses preflash. I though you had some experiences of P-TTL from other brands. I wonder why the latter type flashes seem to be worse.
I think you can test, if the Metz let you change aperture setting in Auto mode with lenses that have manual aperture ring, if you remove any lens from the K10D body. You may have to have setting "Using aperture ring" permitted in Custom Setting menu. Do you then have an option to change aperture setting in the flash?
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Forum: Flashes, Lighting, and Studio
12-15-2007, 04:01 PM
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Which brands do you refer to? Do you mean some other flash gives better results in P-TTL mode with Pentax K10D? Maybe P-TTL is not as predictable in general that TTL is for film cameras.
I got impression from Pentax AF-540FGZ's manual that you have to set zoom position and ISO setting manually in the flash in Auto Flash mode. If it is true, the Metz is better in this aspect. On the other hand, in Metz's manual it is not told a way to change aperture setting and ISO setting manually in Auto mode and that is why I am asking:
Have you tried the flash in Auto mode with K10D & a lens that has aperture ring (set not to A position) and have you tried it with a camera that has only X-sync connector in hot shue?
Isn't it -5 ... +4 as K10D has flash compenstion range -2 ... +1 ?
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