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Forum: Pentax SLR Lens Discussion
09-02-2013, 07:32 PM
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I can't answer exactly, but it appears to me that my K5 with the older Sigma 17-50 with OS is not identified by the old version of Photoshop that I am using. The Pentax 12-24 is identified. I had tried out Lightroom last year, and I thought that Lightroom was able to identify the lens for corrections, but I can't verify that now.
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Forum: Pentax SLR Lens Discussion
06-20-2013, 07:58 PM
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I have the Sigma 17-50 f2.8. I think that it's a good lens. I bought the Pentax 16-50 2.8 at the same time for testing. I returned the Pentax, even though at that time the prices were essentially the same. The CA on the Pentax was much worse. I only have the Sigma lens for now, but I'm wondering about buying the Pentax 12-24.
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Forum: Pentax SLR Lens Discussion
10-07-2011, 11:02 PM
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In July, I bought both the Pentax and the Sigma. I don't make any claims to testing them properly, but I kept the Sigma and returned the Pentax. The chromatic aberration with the Pentax was terrible. I sent an image to Pentax, and they said that it was par for the course. Even in the center of the field (at 16mm, f2.8), there was considerable blue fringing. CA was reduced by stopping down, but I don't carry an f2.8 lens to use it at f5.6 and above. The fringing at the edges was not removed by the in-camera correction (JPEG only) and, for RAW images, could barely be removed with Photoshop Camera Raw (no certainty that I was using it correctly; I've never used it before). The Sigma is much better for CA. In my unsophisticated image sharpness tests, the Sigma was a little bit better, but I'm not sure that this would matter in real usage. The Sigma does have problems. In the identical situation (with the tripod and with indoor lighting), the Pentax K5 with the Sigma lens overexposes by about 2/3 of a stop. It seems to be this way every time. With the flash, the K5 has some exposure issues, and these are much worse with the Sigma lens (especially with the Pentax external flash). Sigma Tech Support says that they have a firmware update for the lens that will correct these problems, but I have not had a chance to send the lens in for them to update it.
Now I'll have to read the review here.
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Forum: Troubleshooting and Beginner Help
08-09-2011, 09:51 PM
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Update:
Pentax says that the chromatic aberration that I see is normal. They recommend using the in-camera CA correction. However, I tried it, and it doesn't help much.
Sigma says that there is a firmware update that will fix the exposure problems. They are willing to pay shipping both ways to apply this update.
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Forum: Troubleshooting and Beginner Help
08-09-2011, 07:51 AM
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Thanks for all the responses.
I did use the tripod, and I tried to set up exactly the same image. Posting images exceeds my digital knowledge, I am afraid.
I will be taking some actual photos this week. I wasn't planning to spend the first two weeks with my new camera testing lenses. I have to decide which lens today. The Sigma is sharper, but seems to have some problems, most of which I can deal with by changing settings, but this is inconvenient at best. The Pentax has CA issues that I don't know how to fix easily (I do not see that the in-camera correction is fixing the blues fringes). The Pentax costs somewhat more ($900 vs. $670) and interferes more with the built-in flash. I called both Sigma and Pentax, and sent images, but neither company is providing much help.
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Forum: Troubleshooting and Beginner Help
08-09-2011, 12:54 AM
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I am comparing a Sigma 17-50 f2.8 and a Pentax 16-50 f2.8. I got the Sigma first, and I thought that its exposures were OK, although a little bit high for my taste. Now I find that the Sigma and Pentax lenses show different exposures in the K5. The Sigma is about 2/3 of a stop over exposed. I think that the Pentax is correctly exposed (although I can't prove this). Has anyone else experienced this issue with the Sigma lens? Perhaps I have a defective copy (that yields very sharp images).
This slight overexposure is part of the explanation for the flash overexposure problems that I was having with my K5, but the external has problems even after this issue is taken into account. See https://www.pentaxforums.com/forums/pentax-beginners-corner-q/153865-flash-ov...re-new-k5.html |
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Forum: Troubleshooting and Beginner Help
08-05-2011, 03:01 PM
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Class A and asp1880:
The Sigma lens works correctly without flash. I don't see a difference in overall exposure going from f2.8 to f16 with intermediate values. I think that it's stopping down correctly in these cases. I will test the flash with different f stops. The flash overexposure is worse with the 540 than with the built-in flash.
The Pentax lens definitely has more CA, and some of the CA is in the middle of the field, not at the edges. The Sigma has CA as well, but there's less, and the CA is at the edges of the field.
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Forum: Troubleshooting and Beginner Help
08-04-2011, 12:43 AM
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I did some tests comparing the Sigma 17-50 2.8 and the Pentax 16-50 f2.8. In flash exposures, the Pentax lens is better. I tried with direct (not bounced) flash from the 540, and it comes out OK with the Pentax lens. With the Sigma lens, the photo is >1 stop overexposed. In another photo, both are overexposed, but the Pentax is a bit closer. The overexposure might be because there are 2 black objects in the field. In a fill flash photo, the Pentax also had a lower exposure and did not require as much compensation.
I took a couple of photos outside, and the Pentax has terrible chromatic aberration. I have not seen anything like this with the Sigma.
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Forum: Troubleshooting and Beginner Help
08-03-2011, 01:21 PM
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I now have the Pentax 16-50 2.8 for testing. I haven't tested carefully, but the first couple of flash pictures seem to be better with the Pentax than with the Sigma. Trouble is, a couple of the Sigma shots seemed to be better than they were when I took them a couple of days ago. I will have a further report tomorrow.
philbaum, the internal flash does overexpose less than the 540. The K5 is brand new. If it really doesn't work, Pentax should replace it with one that does. And, yes, this is a PITA.
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Forum: Troubleshooting and Beginner Help
08-03-2011, 11:50 AM
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boriscleto, I didn't realize that Aperture 3 ran in 10.5. I think that Aperture 3 can still be bought on CD, but it's 2x as expensive.
normhead, I don't understand the RAW formats. I thought that each type of RAW would be different and would require its own interpreter. That is, DNG files from a Nikon and a Pentax could have the same format but that their colors would require some sort of interpretation to create an image, and this interpretation would be specific for each camera.
For me, the other advantage of DNG is that I have PS CS4. CS4 opens the K5's DNGs but not its PEFs. What I don't understand is whether CS4 is correctly interpreting the information in the DNGs (since CS4 doesn't know what a K5 is).
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Forum: Troubleshooting and Beginner Help
08-03-2011, 10:46 AM
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Metering = matrix (default)
Minimum distance = 0.7 for built-in, and I'm taking test pictures between 1 and 4m
I think that the FEC is additive, although I didn't test it carefully, and there is a -3 adjustment on the 540. Auto works pretty well for the 540, but there is no auto on the built-in. Isn't there auto on the Metz 58? Also, Metz remembers previous settings when you turn it off; Pentax forgets (according to the reviews). So, every time I start up the flash I can set it to FEC -2. That's not ideal.
On my Pentax ME Super, Auto for the Sunpak flash also worked very well. The ME Super cost about $200 new (with a 50 f1.8 lens), and the Sunpak flash was $60 in 1981. For $2400 (camera + zoom + flash) and 30 years of technological advancement, this should work better.
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Forum: Troubleshooting and Beginner Help
08-03-2011, 09:27 AM
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I talked to Apple. It appears that updates to Digital Camera RAW beyond 3.4 require OS 10.6. iPhoto '11 (= iPhoto 9) requires 10.6. So, it appears that the information in the supported formats document at Apple is wrong. I guess that I can use DNG for the time being.
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Forum: Troubleshooting and Beginner Help
08-02-2011, 10:37 PM
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This is a very bad thing, if true. I spent months reading reviews of DSLRs before buying the K5, but either I did not see or did not properly appreciate this problem beforehand. If it is a systemic problem, it's hard to understand why Pentax would not be interested in fixing it.
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Forum: Troubleshooting and Beginner Help
08-02-2011, 10:24 PM
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Sorry to start so many threads while a newbie.
I tried to import PEF files from my new K5 into iPhoto, but it said that the format was unreadable. I have iPhoto '09 and run OS 10.5.8. I tried this on another computer running 10.6.7 and iPhoto '09, and PEFs were imported, apparently correctly. Another 10.5.8 Mac also failed. I am assuming that PEFs don't work under 10.5 for some reason. Can anyone confirm that PEF import requires 10.6?
If I set the camera to save as DNG, iPhoto under 10.5 can read them, but I don't understand whether iPhoto is actually interpreting them correctly. Are there different ways of saving DNG files that require different types of interpreters?
You might wonder why I'm running 10.5, now 2 generations behind. The reason is that Nikon never updated NikonScan to run after 10.4, but it mostly works under 10.5. If Nikon had demonstrated that they were more responsive to their Mac users, I might have bought a D7000 instead of a K5.
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Forum: Troubleshooting and Beginner Help
08-02-2011, 09:38 PM
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Ash, did you ever call Pentax to ask them about the flash exposure problems? When I called, they blamed the Sigma lens, but that couldn't be their answer to you.
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Forum: Troubleshooting and Beginner Help
08-02-2011, 03:12 PM
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Those are really nice. I won't have time for serious testing. I almost bought the Pentax to begin with. Maybe I'll decide to keep it instead of the Sigma, although the Sigma test pictures I took look sharp to me (based on 3 days of digital experience).
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Forum: Troubleshooting and Beginner Help
08-02-2011, 02:54 PM
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I'm not going to keep both the Sigma 17-50 2.8 and the Pentax 16-50 2.8. I will be testing briefly and sending the loser back. It's an expensive and inconvenient way to troubleshoot. I had decided originally on the Sigma lens because its optics were highly reviewed and the Pentax optics are not supposed to be so great. We'll see. I'll post again with the results of the flash comparison. I forecast no difference, but then I'm not sure what that says about the camera.
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Forum: Troubleshooting and Beginner Help
08-02-2011, 12:49 PM
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Are you setting the FEC in the camera or on the flash? Are you using a Pentax lens? Pentax suggested that my Sigma lens is to blame. To test this, I ordered a Pentax lens for comparison, probably wasting time and money.
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Forum: Troubleshooting and Beginner Help
08-02-2011, 02:07 AM
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Maybe I have unrealistic expectations about the camera getting this right and about the quality of images with the built-in flash. My major concern at the moment is whether my Sigma 17-50 lens is failing to communicate properly with the camera (and hence should be replaced with the Pentax 16-50). What all these other threads seem to say is no.
Consistent with your experience the AF540 is much worse than the built-in. I can't say that this is a good thing.
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Forum: Troubleshooting and Beginner Help
08-02-2011, 12:03 AM
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I applied the firmware update. No effect, I am sorry to report.
I also transferred the photos to my computer. On the computer the look a bit less overexposed, but they're still not right. The AF540 shots still look awful; for comparison with the built-in flash, I took these with the flash pointed straight at the scene, and the photos seem to me two or three stops overexposed.
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Forum: Troubleshooting and Beginner Help
08-01-2011, 12:02 PM
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I tried taking flash picture at different apertures including wide open, and they're all overexposed. I don't know if this addresses this issue. I still haven't updated the firmware.
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Forum: Troubleshooting and Beginner Help
08-01-2011, 10:27 AM
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I tried using the 540 on Auto instead of PTTL, and it works perfectly. I called Pentax, and they say that maybe the Sigma lens is the problem. I have no idea if that's possible. The lens does seem to send information to the camera and the flash about zoom length and exposures without flash seem to be accurate. Does anyone know? Thanks.
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Forum: Troubleshooting and Beginner Help
07-31-2011, 09:09 PM
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Thanks to all for your answers. On my old camera, flash exposure was reasonably reliable, but I had to set the flash and the aperture manually. I thought that my new camera could do that without my manual intervention.
I believe that everything is set to default. The metering is zone. I am not sure what a high key is. AF point selection is set to auto, but I don't think that AF and AE are linked?
I bought the camera on Tuesday from B&H, and I am surprised to see that it's firmware version is 1.01. One of the reasons that I had waited to buy the camera was to wait for any new production issues to be resolved. I am going to try to update the FW...
OK, I won't try the old flash.
Even at ISO 100, the camera was able to get enough light at f2.8.
I can get the flash photos to look OK by using FEC of -1.0. I'm not really eager to have to adjust anything in manual for flash pictures. I don't understand why the manual method that you're suggesting is different from setting the EC to -1 to -3 and shooting in an automatic mode.
I also tried to take a flash fill picture outside. I needed to adjust the FEC to -2.0. This is certainly a problem because some fill pictures would need less fill than the one that I took.
I am going to work on the firmware update. I did try X mode and still got overexposed pictures. I will try some more pictures tonight.
Thanks.
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Forum: Troubleshooting and Beginner Help
07-31-2011, 12:11 PM
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Thank your for your response. In auto, it does select high ISOs (1600 and 3200), but I reset it to 100. Maybe the 100's are better, but they're not right. I think that the room I took these in is reasonably illuminated, and I'm not sure that it's low light. I also tried X mode, but I still am not getting good results. I am going to figure out if my 540 has Auto, or I'll try my old Sunpak flash on Auto, just for comparison.
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Forum: Troubleshooting and Beginner Help
07-31-2011, 10:10 AM
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I just bought a K5 with a Sigma 17-50 f2.8 lens. Flash pictures seem to me to be overexposed, both with the built-in flash and with the 540 that I bought. The mode (Av, P, auto) doesn't seem to affect this problem. The problem can be fixed by adjusting the flash compensation to -1.0 either on the camera or on the 540 (I haven't read its manual yet, so who knows what I really did). I really don't like this as a solution because it limits how far down flash illumination can be used for fill since there's only one more compensation stop. I don't have any other lenses to test (I think that Pentax M lenses can't be used), and the Sigma seems to be communicating correctly with the camera.
I should say that I know nothing about digital photography. The K5 is replacing my ME Super. I haven't read far enough in the manual to learn how to transfer pictures to my computer, and I am judging on the camera monitor. Other photos appear more or less correctly exposed, I think, although I prefer the underexposed versions of some photos that I took outdoors.
Am I doing something wrong with the flash? Is this normal behavior? Thanks for any help.
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