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Forum: Photography Articles
10-31-2010, 10:10 AM
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This article contains a few pictures and clip art so it is posted as a series of 3 jpeg files below:
The above article was 'inspired':D by this forum and by a project called Single in September that took place in the Pentax Forums in September 2010. The objective was to take a single picture everyday in September using only a single lens as a therapy for LBA!!
One result of that challenge was a book:
Took a look at the preview of the book on blurb:
http://www.blurb.com/bookstore/detail/1682528 |
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Forum: Pentax Full Frame
06-14-2014, 06:12 PM
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Here's what places like dpreview should do more of:
There's ^^ an application of the dreaded equivalence (both equivalent FL *and* f-stop shown,) in a pretty graph.
Note that it's using the typical 135mm (FF) as the 'standard' reference anchor in this particular graph, but that's a choice that equivalence doesn't demand - there is no 'standard' with equivalence. So don't get mad about that and then attribute it to equivalence - that's just something that photographers and review sites do so we have a common way to compare how different FLs look on different formats. aps-c could be the standard anchor for FL, m43 could, it doesn't matter with regard to equivalence.
What's unusual is that dpreview, above, gives a nod to the physical realities and did a conversion with aperture too at the same time. Kudos.
Thoughts, foot-stompin'-angry or otherwise? (keep it civil or Parallax will shut it down! :) )
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Forum: Pentax Full Frame
06-14-2014, 08:09 PM
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Indeed. I should have perused the first pages of the reviews more carefully and given them credit where due.
Here's the section leading into that chart:
Total Light != exposure. Kudos again, dpr.
Or as I said to someone earlier who stated that caring about total light was 'silly' :
"...'total light' is important to any photographer who might like to get less image noise for a given exposure. You can't control total light for a given exposure in the same way you can control exposure itself - but you can make purchase decisions up front that will give you more total light for your typical shooting scenarios and available, affordable autofocus lenses - if that's what you're after. The majority of shooters who buy FF are after that. (As are the majority of aps-c shooters who choose that format over m43, or 1 inch sensors, etc.)
Has anyone reading his bought an aps-c DSLR system because you wanted (in part) better noise performance over a point n' shoot? Then you care about total light."
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Forum: Pentax Full Frame
06-13-2014, 09:09 PM
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You're not understanding what Joseph James was saying there, and a lot of people make this exact same mistake so I'm not picking on you - here's the quote for reference, then I'll explain:
"...In short, the advantage of a larger sensor system over a smaller sensor system is that the larger sensor system will generally have lenses that have wider aperture (entrance pupil) diameters for a AOV (diagonal angle of view) than smaller sensor systems, which allows for more shallow DOFs (as an option, not a requirement) and will put more light on the sensor for a given exposure, resulting in less noise..."
Note the 'wider aperture diameters for a AOV' - he's talking about the linear aperture, the entrance pupil, not the f-stop, for a given AOV.
Remember, the linear aperture (entrance pupil when you look down the front of the lens) is related to the F-stop with this formula:
FL / f-stop = entrance pupil diameter (linear aperture)
So, for a 50mm f/1.8 lens, wide-open we have:
50 / 1.8 == 27.8mm entrance pupil
Now, for the same AOV on, say, micro-4/3, we have to use a 25mm lens, so say we have a 25mm f/1.8 lens available:
25 / 1.8 == 13.9mm entrance pupil
So, for the same AOV & distance to subject, even though we're using the same F-stop and getting the same light density (exposure) allowing the same shutter speed, the larger sensor is getting more total light due to the wider aperture diameter (27mm vs 13mm.) This results in less DOF, and less photon shot noise** for the larger sensor in that comparison.
Make sense?
To bring it home, a basic equivalence quiz: looking at the formula above, what f-stop would be needed on a 25mm micro 4/3 lens to match the 50mm 1.8 on FF?
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** Note, photon shot noise - not total noise - total noise is determined by shot noise, read noise, and sensor efficiency. So for example, a given m43 sensor with much greater efficiency and much less read noise than a given FF sensor could show less total noise in the image, even though the FF sensor starts out with lower shot noise.
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Forum: Pentax Full Frame
06-10-2014, 07:00 PM
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Anybody have pics at -4EV? Personally I rarely take pictures outside at night, just wanted to see some.
I would like to take pics of aurora borealis but I don't need to focus for that!
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Forum: Pentax Full Frame
06-05-2014, 03:15 AM
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If Ricoh makes a new full frame camera, it will be as much to sell new K mount lenses as it would be to sell camera bodies. Obviously that means a new line up -- at least from a zoom standpoint. I just don't see them interested in pulling a Sony, where you make a camera primarily so people can mount old glass (or other mount's glass) on the camera body.
If you own old k mount lenses, you'll be able to use them without problem, but newer glass will (hopefully) have better contrast, better flare control, better borders and less purple fringing (a big problem, even with the FA limiteds).
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Forum: Pentax Full Frame
06-04-2014, 12:51 AM
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Except they can't start a system with a low volume "full frame". As I keep explaining, IMO the only realistic choice is: first make sure you have a large enough APS-C user base, then add a "full frame" option to the system. Like Sony did.
Making the camera is the easiest part, but we're not talking about standalone products but systems.
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Forum: Pentax News and Rumors
05-23-2014, 05:53 PM
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I'm not the one who claimed they are pancake lenses. The only Ltd lens thinner than the DA 21 is the DA 40 which few have much love for anyway due to its awkward focal length. The DA 70 is not smaller than the DA 21 nor is it retrofocus. They are all generally fine lenses but I just don't see the overwhelming argument that the only reason they are small is lack of focus motors.
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Forum: Pentax News and Rumors
01-24-2014, 04:58 PM
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Do they now? I just went out on my balcony and shot with the 18-55 WR kit lens and the FA 31 Limited. Can you tell which one is which? Both shot on the K-3 at f/8, focused at infinity (so no DOF/bokeh clues), and developed to JPEG in camera. Resized in Photoshop.
Lens A:
Lens B:
It's pretty blatantly obvious which one is the better lens at 100%, but can you tell at this resolution? You can download them bigger if you want, but I limited them to 1080 lines of vertical resolution, so no "cheating" by blowing them up bigger. Don't want to "unfairly" judge these lenses at huge magnification right?
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Forum: Product Suggestions and Feedback
01-21-2014, 10:20 PM
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Can you release as 24mm (35mm efl) f2.0 lens just like the fuji's x100/s?
The last 24mm released was to big (designed for FF) and the new lens 20-40 was not fast.
Thank you.
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Forum: Pentax News and Rumors
01-21-2014, 10:02 AM
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Seems like Good Things are coming to people that like photography.
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Forum: Pentax News and Rumors
01-21-2014, 09:58 AM
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Done it for years with Film Cameras, I certainly do not have to take my eye off the finder to change settings on my Nikon FE......
Nikon FE by Eric Auer, on Flickr
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Forum: Pentax News and Rumors
01-21-2014, 08:33 AM
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So...lets not give the people what they want?
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Forum: Pentax News and Rumors
11-22-2013, 04:22 PM
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I don't know. I have both the 17-70 and the 16-50, and I have been wondering that maybe, just maybe these subjective quality differences have more to do with how DA* or Limited lenses are perceived than with actual lens performance.
It is actually quite similar in the world of high-end audio. Expensive cd-players, for example, often have extremely solid build quality etc. But will you really be able to tell the difference between a $50 cd-player and a $5000 cd-player? I doubt it. And in the end, that's all that matters, right?
I can only speak for myself, but I would never consider 20-40mm a landscape range. The 12-24, sure. And I shot some landscapes with the 16-50 too, so that also fits the bill to me.
Now you're turning things around. If you like it, go buy it. I don't care. I don't like it, and I've explained why. If you don't agree with me, fine. Make your own choices, and so will I, and everybody's happy.
But if you can write why you like it so much, why can't I write what my thoughts are? They are just my thoughts, no reason to feel offended or anything.
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Forum: Pentax News and Rumors
11-11-2013, 06:12 AM
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The "bad bokeh" in the picture you are presenting results from the combination of:
- Longitudinal chromatic aberrations (non-coinciding focal planes of the various colours), leading to magenta (red + blue) outlining in front of the focus point and green beyond;
- Coma (aka comatic aberration: off-axis point sources appearing distorted, sort of having a tail like a comet); and
- Mechanical vignetting (specular highlights in the background taking the form of "cat's eyes" in the corners).
Truly apochromatic lenses don't show longitudinal chromatic aberrations but can still suffer from coma (aplanatic lenses don't) and mechanical vignetting.
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Forum: Pentax News and Rumors
11-10-2013, 08:16 PM
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Actually, pretty much any lens can produce that kind of bokeh. At a close focus distance, at wide apertures, under harsh Australian sunlight, with bright specular highlights in the background - Images like that nearly always produce horrible results.The only exceptions to that rule are apochromatic lenses, which due to their superior optical correction are largely immune to producing bokeh like that.
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Forum: Pentax News and Rumors
11-09-2013, 04:53 AM
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I don't think the HD coating makes much practical difference in the field.
Here's a comparison of the smc and HD 15/4 limiteds. (The smc DA in fact looks better because its starbursts aren't stunted by rounded blades like the HD version).
HD version
smc version
Original images and thread link (thanks mooeep).
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Forum: Pentax News and Rumors
11-08-2013, 12:30 PM
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Alex, there was no ad hominem there.
I have read your authoritative posts for several years on DPR, now here, not having seen a single picture from you, ever. So it would be interesting to see if you are just a gadget junkie making posts purely from a spec-sheet comparison, or if you're actually a photographer and what you produce with it. When you're giving such authoritative information, it often helps to see what the person does, where they are coming from, and what they are able to produce.
Your recommendations and authoritative arguments for would be validated by such a thing. This is not turning the topic into one about you. We'd just like to see what you shoot, since you're very big on this item that you have never shot with.
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Forum: Pentax News and Rumors
11-06-2013, 05:21 PM
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I dunno what Ricoh are smoking, maybe they're watching too much "breaking bad" on Netflix :eek:
Honestly, I don't see the point the range is odd for APS-C, it's a small range..worse it's not even constant f2.8
Buy a Tamron 17-50mm f2.8, pocket the change and you can pay for most of a brand new K5II! Or buy another lens or 2
£849 is a crazy crazy price for a zoom like that. What is it gold plated?
This is why I don't think Ricoh are very smart, nobody really wants this lens so why bother making it?
I'm sure forum members can think of 3/4 much more useful lenses than this.
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Forum: Pentax News and Rumors
11-06-2013, 06:21 AM
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The first two are not easily available worldwide, particularly in Europe. The former is impossible and horrifically expensive. The latter is typically only available from Japan, used, and very expensive. And, as mentioned by several to many here, it doesn't perform as well as one would expect on a K5. Check the search for examples.
So no, they aren't really available and, for the most part, don't even exist outside of sourcing from around the world as used for horrific prices (same is the case for the FA35 in Europe right now, as I've also posted examples previously of its price going above that of the FA31 and 700EUR used being now a norm).
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Forum: Pentax News and Rumors
10-31-2013, 04:09 PM
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Stupid range for APS-C IMO....hopefully this is FF compatible and signs to come that FF is coming.
I think if Pentax wants to be taken seriously as a pro APS-C gear (which they are trying to do with K-3) they need to update 16-50/50-135 ASAP which are the bread and butter lens for any system
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Forum: Pentax News and Rumors
05-05-2013, 07:25 PM
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Not if the Zoom lens is sharper in the corners when compared to a prime: as is the case when I compared the Sigma 8-16mm f/4.5-5.6 to the DA15mm f/4:
Sigma 8-16mm f/4.5-5.6 ASPH @ 15mm f/8 - DA 15mm f/4 ASPH Limited @f/8 - unsharpened, uncorrected 100% crops from the extreme left corner: it is clear which lens is superior. |
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Forum: Pentax News and Rumors
04-01-2013, 08:27 PM
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You just made me choke on my food.:fedup:
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