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Forum: Troubleshooting and Beginner Help
08-28-2011, 08:27 PM
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diffraction limits lens resolution at smaller apertures - the camera sensor can be a high resolution, but it is the lens that puts a limit on the total system resolving power. Correct me if I'm wrong but at f/8 the diffraction limit for average visible light is around 120 line pairs per millimetre and as far as I know there aren't many digital sensors that can record detail at that level of resolution so it's safe to say you are worrying about nothing. That's not to say diffraction doesn't exist but it's effect isn't a hard limit as most people perceive it to be.
incidentally, I would advise you to not take anything Ken Rockwell puts on the internet seriously - there are more educated people who have put decades of time and effort into studying technical aspects of photography than that dilettante.
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Forum: Pentax DSLR Discussion
08-15-2011, 08:47 PM
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Are you still using firmware 1.0? Because a firmware upgrade was released to deal with memory card compatibility issues (which is what this sounds like to me).
I had identical symptoms under similar circumstances, and after repeated reformatting of the card didn't fix my problem, the firmware update did.
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Forum: Post Your Photos!
08-10-2011, 12:16 PM
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Spiders lurking in the last light of the evening.
(Click to view bigger)
(Click to view bigger)
(Click to view bigger)
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Forum: Pentax Q
07-18-2011, 05:21 PM
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Forum: Pentax SLR Lens Discussion
02-27-2011, 04:33 PM
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i guess some people just don't "get it". :cool:
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Forum: General Talk
05-18-2011, 08:11 PM
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Don't take this the wrong way, but I think you're sick my friend.
Get some help.
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Forum: Pentax DSLR Discussion
06-27-2011, 11:30 PM
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If you look at that auction, it's got FOUR DAYS LEFT, and already two bids. It's going to close at a thousand dollars or more. If you search ebay for "Canon 5d body" and check the "completed listings" box, you'll see that they actually sell for ~$1200. I'm looking at a list where a couple closed at less than a thousand, with the lowest price one sold for recently being $933 (except a parts-only that closed for $499); the MkII are in the $2100 range.
Ebay is an auction site; if it doesn't say "buy it now", you probably won't get it for the price you find there. You bid, other folks bid, the price goes up, until time runs out. Just so you know why that price doesn't mean anything, and no, we aren't looking at MkIIs. :D
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Forum: Pentax SLR Lens Discussion
06-11-2011, 11:47 AM
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What is a zoom lens? Are they any good? At what?
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Forum: General Talk
05-22-2011, 04:21 PM
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He just needs Cindy Shermans agent......:)
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Forum: General Talk
05-20-2011, 07:54 PM
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I'm playing softball with friends from our church in a Christian softball league. I'll be taking pictures of the game. If the rapture does happen during the game then somebody is going to find some top notch camera gear at the ball field. Anybody know what time? The Bible doesn't seem to say.
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Forum: Pentax SLR Lens Discussion
02-25-2011, 03:55 PM
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:lol: :lol: Have you read your posts vociferously defending your Sigma? Get a grip - their just lenses!
This is what I saw in my images when I compared the DA12-24 to the Sigma 10-20 f/3.5. Maybe my 12-24 is better than most, or my early production 10-20 was worse than most ( :p Sigma QC anyone?). What do you see in your photos with those same two lenses - a test chart? :lol:
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Forum: Lens Clubs
12-23-2010, 08:28 AM
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Hard to believe there have been 2000 posts in this thread you started two years ago now Jay. As I recall you showed me how to post an image in the forum in this thread. I was a bit intimidated by the "new technology" of my K10 at the time. It reminds me as well of how much I have learned from this forum and folks like yourself. Perhaps more importantly it has shown everyone how good the old M series glass can perform with a little time and effort. Thanks for starting this thread and so many others Jay.:D
Tom G
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Forum: Weekly Photo Challenges
11-17-2010, 08:42 AM
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I'm glad all seemed to appreciate the comments and judging. It was a tough challenge! But only one +rep. Sheesh! :lol:
Guess I'll just have to do some lens reviews. :D
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Forum: Pentax K-5 & K-5 II
10-21-2010, 12:10 PM
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'All' is quite a strong word to use. ;)
However... if the sample is bogus, then I don't see the sense in pursuing a walkthrough with this particular file(I could use another though).
Having said that, I am hopeful that we can replace this one with something that feels a little more legitimate in terms of exposure.
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Forum: Photographic Technique
10-13-2010, 07:57 PM
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So I guess that makes you a pundit. If you were in the position of being a voting judge you would know the full gamut of submissions and how they relate to approvals.
Well put. As a non-participant, you haven't got a clue. The other contributors to this thread have approved gallery entries. They also have had rejected entries. For me, the rejection rate is about 60%, so you can imagine how I feel when I see the substandard crap being displayed in the same virtual hall as my substandard crap. Yes, maybe it is all junk, though I don't know that I ever submitted my vacation shots of deer grazing in front of a parking lot.
BTW, the other contributors to this thread also frequently post their work here on PF, mostly just to share, but often enough for critique. So I would suggest before you start bitching about these people's attitude, you might do well to share and participate yourself. It called paying your dues.
Steve
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Forum: Photographic Technique
09-27-2010, 05:14 PM
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Forum: Troubleshooting and Beginner Help
09-10-2010, 10:02 AM
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I use to think the same thing. No aperture ring, leave it on the shelf and keep my money in my pocket. However (and this may be different when using a K200), with 2 e-dials, one for changing aperture, and one for changing shutter speed, I rarely Use the aperture ring. That is, except on lenses that aren't auto aperture capable (M and K). Electronically changing it offers more than just a method of change. It shows me in the viewfinder what the aperture is, and it saves the information. A minor convenience perhaps but one I do welcome.
The bottom line is this.. I've yet to use a dedicated macro lens, both from pentax and third party, that I did Not think a great lens and wouldn't readily recommend. All have been silly sharp and a great performers. The real questions become, how much do you want to spend, how far away do you want to be from your subject, how are you going to light your subjects, etc.
:cool:
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Forum: Pentax SLR Lens Discussion
08-30-2010, 11:21 AM
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Hi, during the summer I (again) had the chance to borrow my friends K20D to do some testing. Some of you might remember that I did a similar comparison last year, but screwed up the focus on one of the lenses. So now I'm back with a more extensive and better executed test.
I will update with more pictures and results in time. But for now I'll post the first part of the comparison, centre sharpness at different apertures.
The lenses that take part in this test are:
From left to right, Pentax DA AL II 18-55/3.5-5.6, Pentax 50/1.2, Pentax 55/1.8, Pentax 50/1.4, Pentax M 50/1.7, Super-Takumar 55/1.8 and Takumar 55/2.2
I chose to include the DA 18-55 because it's such a common lens and many people can relate to it, also the M50/1.7 and K55/1.8 are common lenses so I think most people should be able to relate to the results.
100% crop from centre of image
My Conclusions:
My first thought when putting together the chart was that the M50/1.7 is amazingly sharp at f/2, with the two 55/1.8s not far behind. The M50/1.7 reaches it's peak quickly and stays there up until f/8 where it starts to fall of. Very impressive.
The two 55/1.8s show a similar development, peaking at f/4-5.6, and holding out until about f/8. The SMC version has a little edge over the Super-Takumar, this might be the result of the better contrast it has probably thanks to the SMC coating.
The oddball Takumar 55/2.2 that came with my 1958 Pentax S is quite soft wide open but definitely up there with the two 55/1.8s at f/4-5.6, after that it gets soft again. However, being comparable to the SMC K55/1.8 is not at all a bad score for any lens.
The DA compared to the rest at f/5.6 is of course terrible, but that is to be expected when comparing a stopped down prime to a wide open zoom fully zoomed in. But stop it down to 8 or 11 and the results are already much better. I'd say it's about as good as the Takumar 55, and better when getting to f/16-22. But it not as sharp as the other primes, for example it doesn't ever reach the level of the M50/1.7 at f/2.
Now the K50/1.2 and K50/1.4, the two I personally am most interested in. Is the 1.2 only a extreme lens for bragging and the 1.4 a much more sensible choice? Or is there any real sense in getting the 1.2? Wide open they are quite close in my opinion, I have a hard time deciding which I think is the sharper. They are both quite foggy but in pure sharpness terms it isn't all that bad, even at 1.2! But most critically, and this was what I originally wanted to find out when I started my tests last year, the 1.2 stopped down half a stop IS noticeably better than the wide open 1.4, and that in itself gives me enough of a reason to own the 1.2. It is in fact very near the 1.4 stopped down to f/2. From f/2.8 up to f/11 the 1.2 seems fairly consistent, equal or better than the M50/1.7. I don't know if this has reached the limits of what the K20Ds sensor can produce or if they are indeed that equal and similar. The 1.4 doesn't do a bad job either, it seems to reach it's top at about f/4 and stay there until I screwed up the exposure at f/11-16 (don't know how this happened...).
In this part of the test I would have to say that the k50/1.2 comes out on top. Because of the picture quality stopped down half a stop to match some of the others wide open. Also it is among the sharpest when stopped down to optimum aperture. But the M50/1.7 and the two 55/1.8s are really impressive stopped down to f/2, simply very good sharpness at that aperture.
More to come later. All questions, opinions and comments are welcome. |
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Forum: Pentax SLR Lens Discussion
08-30-2010, 12:29 PM
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I don't have time to look at the results right now, but I wondered if you are using a lens shade for these tests? It's been proven that the FA 50mm 1.4 for example loses contrast if not used with a hood because of its prominent front element.
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Forum: Pentax SLR Lens Discussion
08-31-2010, 05:36 PM
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"In this part of the test I would have to say that the k50/1.2 comes out on top."
AGAIN. I can't help but smile when testing like this, inclusive of bokeh rendition put the SMCP-K 50mm f/1.2 at the top of the class. And people scoff at us who own them and say that such speed is unnecessary. It's nice to be vindicated.
Also, did you notice that the 50mm f/1.7 is slightly longer than the other lenses?...I actually think it is more of a 53~54mm lens. The actual focal length of the SMCP-K 50mm f/1,2 is 51.8mm
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Forum: Pentax DSLR Discussion
08-13-2010, 11:51 AM
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A couple of observations:
- The main purpose of an AA filter is to reduce moire. So if the AA filter is the reason the K-7 appears to be giving softer images, that's probably the *reason* it was designed that way.
- Just because both cameras had their options set to the same place doens't really mean that literally the same processing was applied to each. They are different cameras with different sensors, and it's quite possible that while an effort was made to produce "similar" results with similar settings, pixel peeping might well expose differences. I could see this being true especially with respect to sharpening, since the resolutions differ. Even with UFRAW, it would still be the case that processing would be different for the different cameras (although not to the same extent), so again, even with settings the same, that doesn't mean the images should be expected to come out exactly the same.
- Color differences don't tend to impress me, as that's also largely just an image processing difference.
- The K200D and K10D are similar but different. Same sensor, but not sure about the AA filter, and the A/D hardware and image processing are *definitely* different. K200D definitely performs quite a bit better at high ISO due to the A/D and image processing differences. Not sure about the AA filter, but since the K200D already pleases you, I wouldn't be in too big a hurry to get a K10D and potentially find it no better in sharpness but definitely a step back in noise. If you're really wanting the better viewfinder and control system, I'd consider the K20D first.
- There's basically no way one can generalize to say CMOS produces better color, WB, or especially exposure. Exposure, after all, is a function of the meter, not the sensor, and to the extent one might really be talking about the way the dynamic range maps, that's really a function of the pre-processing curves applied during demosaicing. Similar story for WB. Color overall is subjective, but hard to consider independently from whatever the camera does with demosaicing and WB.
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Forum: Pentax SLR Lens Discussion
08-12-2010, 10:46 AM
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Why not the M 85mm F2 ? I think you can get it for approx $200 USD.
Look for pics in the M-club thread to see what this lens is capable of. I love mine.
Kind regards
.lars
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Forum: Pentax DSLR Discussion
07-13-2010, 07:25 AM
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With all your negativism on all things Pentax related, I don't think anyone seriously gives a hoot if you buy Pentax or not.
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Forum: Pentax SLR Lens Discussion
07-07-2010, 11:31 PM
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I'd rather read a real-world-use review of a lens than stare at charts all day. In the end the charts don't matter. If that's your thing chances are you probably spend more time talking about your gear than taking pictures anyways.
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Forum: Pentax DSLR Discussion
07-03-2010, 11:09 AM
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I don't think it's about what amateurs can get by with. It's about what they want. The FF side of things is less popular than smaller formats, but only because of the price. The price is coming down, and there is less now that Pentax could put in an APS-C body and sell for what their high end bodies typically go for.
Staying committed to APS-C alone, or at least appearing to stay committed, will be a bad idea, even if for only another year. In my opinion, this is the year that it will be crucial to at least announce a FF if they will ever do so. They're gonna lose those at the top that want to know they have somewhere to go, whether they need it or not. The close to $10000 645D isn't an option for most.
A FF Pentax wouldn't have to compete with Canon, Nikon, or Sony FFs. It would undoubtedly be targeted primarily at those using Pentax already, and those that are used to, and expect Pentax's pros and cons.
My prediction is also based on the nature of Pentax lately. The most recent DSLR release was in September, a year before the upcoming Photokina, but it's still selling well so they probably won't replace it. The most recent APS-C lens release was what, the WR kit lenses? That was a year ago and they were only upgrades. The last lens released was a FF lens. The last lens roadmap removed any mention of new APS-C only lenses(DA* 30mm).
They surely wouldn't release a new from the ground up high-end APS-C DSLR this year(the K-7 is only a year old). They don't do that, so if all we can expect is a K-7 super and then maybe a marginal upgrade to the Kx I think most will be disappointed. Would they put in a new sensor for the K-7 upgrade? If so, what sensor, from who? If they kept the same sensor, how would they significantly improve output? What else would they do to upgrade it? New AF, new video?
They can do FF and make a profit. They have decades of FF experience with all the mechanical bits. R&D would be minimal. Trying to get all they can out of APS-C, while putting FF off for the future would not work out well, I imagine. They need to go FF. They could introduce FF lenses to fill the gaps in the APS-C line-up.
The Pentax strategy of the past marginalized them. They seem to be on the way up, and should ride that wave.
That's my rant. It's not meant to be doom and gloom at all, but sooner or later Pentax is going to have to go FF, and the sooner the better, IMO.
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