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Forum: Pentax SLR Lens Discussion 08-02-2012, 12:22 AM  
A close-focusing, fast 28mm shootout: Sigma 28/1.8 vs Vivitar 28/2
Posted By Erik
Replies: 6
Views: 4,906
Yeah, of course, I don't know what I was thinking there. In some other pics I took with the Vivitar, the 6-blade aperture did make some pretty unpleasing highlights when stopped down to I think f/5.6 or f/8, that's why I was thinking of the blades when talking about the bokeh.
Forum: Pentax SLR Lens Discussion 08-01-2012, 08:56 AM  
A close-focusing, fast 28mm shootout: Sigma 28/1.8 vs Vivitar 28/2
Posted By Erik
Replies: 6
Views: 4,906
I just found this little Vivitar in a second-hand shop, picked it up, and immediately thought to compare it to my Sigma 28/1.8 which I use all the time. According to the bestiary, this is a Komine-made model. So yeah, let's see what we've got:

The contestants:



Vivitar 28mm 1:2.0 MC Close Focus Wide Angle
8 elements in 7 groups
Minimum focusing distance: 23 cm
Maximum magnification: 1:5
Aperture: 6 blades, f/2-f/16
Filter size: 49 mm
Weight: 280 g

Sigma 28mm 1:1.8 EX DG
10 elements in 9 groups
Minimum focusing distance: 20 cm
Maximum magnification: 1:2.9
Aperture: 9 blades, f/1.8-f/22
Filter size: 77 mm
Weight: 500 g

Now, obviously, the Sigma is a modern lens with "A" mode on the aperture ring as well as autofocus, and is therefore quite a bit more convenient to use on a modern camera. It also focuses closer. However, it is a lot bigger and heavier than the Vivitar! Not only that, but seeing as there are few (inexpensive) options for fast lenses in the 28 mm range, and given how useful this focal range is as a walk-around lens on an APS-C DSLR -- especially when the lens does close-focus -- the Vivitar could be potentially interesting for many Pentax DSLR owners.

All these pictures were shot on a K-5 on a tripod, manually focused in zoomed-in LV mode. RAW processed in Lightroom, default settings. No attempt made to correct exposure. The shutter speed was the same for a given aperture with both lenses.

Brick wall series (sharpness test):

Sigma:
f/1.8
f/2
f/2.8
f/4
f/5.6
f/8
f/11

Vivitar:
f/2
f/2.8
f/4
f/5.6
f/8
f/11

As uninteresting as brick walls are, here they allow us to note a couple of things right away:
  • While both lenses are nominally 28mm, the Sigma has a slightly wider field of view.

  • The Vivitar seems to let in slightly more light at the same shutter speed and aperture, i.e. exposes brighter.

  • The Sigma has slightly more contrast and seems to render colours a bit warmer, but beware that the differing exposures exaggerates this effect. Equalize the exposures and they're much closer.

  • The Vivitar is visibly sharper in the corners, right up to about f/8. In the center, I find they're pretty much equal.



Close-focus/bokeh test:
In this test, I focused the Vivitar to its absolute closest point and then adjusted the Sigma to match. The focus point looks to be a bit further back on the Sigma. Sorry about that. Remember that the Sigma CAN focus quite a bit closer than this, but I wanted to level the playing field.

Vivitar:
f/2
f/2.8
f/5.6

Sigma:
f/2
f/2.8
f/5.6
  • Again, we can see that the Vivitar lets in a little bit more light and has a different field of view -- the camera was not moved between the lens change.

  • The bokeh on the Vivitar is a little busy (check out the "KR-10" writing in the f/2 sample) owing to the mere 6 aperture blades. The Sigma is smoother with its 9 blades.

  • I much prefer the calmer rendering of the Sigma in the f/2 image. Already by f/2.8, I don't really have a clear preference.

  • Both lenses display a little CA/PF. It is not really a big deal and gone by f/5.6.


So, a conclusion from this very unscientific test? Well, draw your own, if you want. The Sigma has better bokeh and focuses quite a bit closer, but the Vivitar is actually slightly sharper overall. If I had to sell one of these I would keep the Sigma, but the Vivitar seems to be a great lens for its size and price. I got it for $65 with a Ricoh KR-10, a Rikenon 50/2, Soligor C/D 80-200, bag and flash. :lol:

EDIT: Oh yeah. The Sigma had a Hoya UV filter on, the Vivitar nothing. So keep that in mind. It didn't even occur to me until right now.
Forum: Pentax News and Rumors 05-16-2012, 07:22 AM  
K-r successor: K30
Posted By Erik
Replies: 653
Views: 104,632
Oh, that earlier post of mine went through – I didn't think it did :)

Almost certainly pentamirror, yes. Whether the shutter is quiet remains to be seen, but hopefully it is a bit quieter than the K-r, which was surprisingly loud. Not a big deal for me personally, but I realize why that matters to some folks.
Forum: Pentax News and Rumors 05-16-2012, 07:02 AM  
K-r successor: K30
Posted By Erik
Replies: 653
Views: 104,632
But it also goes on to say that it "enables the photographer to shoot/film for twice as long in severe conditions" which would be downright misleading if it was just like the K-r design. I read it like "in really crappy conditions you probably don't want to futz around with changing batteries, so here's a camera that will enable you to stick some AA's in there as a backup".

Again, reservations for my terrible French :) and I don't doubt for a second that this could just as well be a misunderstanding or miscommunication. I just thought it was an interesting thing to point out.
Forum: Pentax News and Rumors 05-16-2012, 06:51 AM  
K-r successor: K30
Posted By Erik
Replies: 653
Views: 104,632
Two things –

Firstly, I don't really know French but I'm pretty sure "batterie et/ou piles AA" means it can be powered by "[regular] battery and/or AA batteries". That is, not AA batteries OR the lithium battery like the K-r, but both at the same time. That sounds pretty cool, but it could just be poorly worded in the ad.

Secondly, with the K-5 sensor, the double e-dials, weather sealing and K-5 style AF-S/AF-C/MF switch, this is going to cannibalize K-5 sales like crazy. Which, to me, must mean that the K-5 replacement is also imminent.
Forum: Pentax News and Rumors 05-16-2012, 06:45 AM  
K-r successor: K30
Posted By Erik
Replies: 653
Views: 104,632
Okay, check this out --
  • Same sensor as K-5

  • Two dials

  • The same AF-S/AF-C/M focus switch

  • Focus assist light beam

  • Weather sealing


This is going to cannibalize K-5 sales like crazy, because it basically is a K-5, excepting details like the top LCD and expansion to ISO 51200, both of which don't really matter to most people. What that means is probably not that Pentax/Ricoh is stupid, but that the K-5 replacement is also imminent.
Forum: Non-Pentax Cameras: Canon, Nikon, etc. 02-28-2012, 08:08 AM  
41 Megapixel Nokia 808 smartphone camera
Posted By Erik
Replies: 375
Views: 72,772
Not talking about that kind of equivalence, I am talking about "equivalent focal length" and this term's lack of suitability when talking about this camera. :) Nokia realizes this, as in the white paper they never state any other focal lengths than 8 mm. It is an 8 mm (26 mm-e in 16:9 mode and 28 mm-e in 4:3 mode) prime lens and this camera + lens combo is not capable of taking photos with any other focal lengths, "equivalent" or otherwise.

That is the entire point, and I think I've made myself abundantly clear, so I'll now leave this thread to more constructive discussion.
Forum: Non-Pentax Cameras: Canon, Nikon, etc. 02-28-2012, 07:28 AM  
41 Megapixel Nokia 808 smartphone camera
Posted By Erik
Replies: 375
Views: 72,772
OK. I understand this is technically true, but I cannot agree that it is a useful way to think. If I have a photo taken at f/2.8 and crop it severely, it would still be wrong to me to say "this is picture with the depth of field of a f/0.1 lens". It's just a crop. I will concede that I was technically wrong to say depth of field does not change, though.


I understand that, but this still means that if this sensor was cropped to what you might call "100 mm-e", you still often cannot get pictures with the same perspective as you could with an actual 100 mm-e lens -- so talking about a camera that functions by cropping in terms of "equivalent focal lengths" is misleading.

That the focal length never changes here is fact, so why muddy the waters with "equivalents", since it in no way acts like an actual zoom lens?
Forum: Non-Pentax Cameras: Canon, Nikon, etc. 02-28-2012, 06:35 AM  
41 Megapixel Nokia 808 smartphone camera
Posted By Erik
Replies: 375
Views: 72,772
For those who are still curious, though, it is trivial to demonstrate that any attempt to put this "zoom by cropping" technology into terms of focal length is not useful or correct:



Assuming the camera is at the same distance from the subject in all three pictures, the facts are: the focal length never changes, the perspective never changes, and the depth of field never changes. The last two are defining properties of a given focal length. Therefore, it is deceptive to talk about "equivalent focal length" ever differing, regardless of "zoom level", in this design. It simply does not. The sensor always sees the exact same image, you are just selecting which portion you want to crop.
Forum: Non-Pentax Cameras: Canon, Nikon, etc. 02-28-2012, 06:18 AM  
41 Megapixel Nokia 808 smartphone camera
Posted By Erik
Replies: 375
Views: 72,772
Since you will not discuss this further, I will end with this then: false, and your link is not relevant to what I am saying.
Forum: Non-Pentax Cameras: Canon, Nikon, etc. 02-28-2012, 04:47 AM  
41 Megapixel Nokia 808 smartphone camera
Posted By Erik
Replies: 375
Views: 72,772
And also, just to set the record straight -- if I sound a bit negative in this thread, it's only because I'm allergic to marketing-speak and wish to demystify some things about the technology involved. The camera module still looks pretty profoundly awesome compared to every compact digital camera and cameraphone ever. Let it be known that if I ever buy a smartphone, this is a very likely contender. I would LOVE to have decent imaging capabilities always in my pocket.

Right now, Nikon's CX system is looking pretty stupid.

Check out this 5MP ISO 800 picture. That is some amazing, amazing performance. I hate to drag out the old "the noise profile looks like film grain!!!" thing, but... the noise profile looks like film grain!!!
Forum: Non-Pentax Cameras: Canon, Nikon, etc. 02-28-2012, 04:25 AM  
41 Megapixel Nokia 808 smartphone camera
Posted By Erik
Replies: 375
Views: 72,772
OK -- but in that case, where's the cutoff point? As you "zoom in" on this camera, you go from binning, say, 16 pixels (actually, 16 groups of 4 monochrome photosites) to 1 to eventually 4 to 1, and at last, 1 to 1.* Where exactly do the "true RGB" pixels end? I'm just advocating calling a spade a spade, because to me, at no point are those actually "true RGB" pixels. They're a close approximation at best. So yes, it's a lie, because it's not actually true.


* These numbers are grabbed out of thin air just to demonstrate the point; I don't feel like actually doing the math :)



It would probably be done before demosaicing, I'd hope! So with that said, my previous assertion that downsampling in Photoshop is pretty much the same thing was a bit over-simplified.
Forum: Non-Pentax Cameras: Canon, Nikon, etc. 02-28-2012, 03:37 AM  
41 Megapixel Nokia 808 smartphone camera
Posted By Erik
Replies: 375
Views: 72,772
Yes, well, they're cropping and then averaging a cluster of pixels -- which is exactly the same thing as downsampling, whether it is done in firmware or in Photoshop isn't really relevant. Granted, if they're doing the averaging in the analog domain before the ADC conversion takes place then it is likely to produce slightly better results, but it's still basically the same thing. It IS marketing-speak when they dream up special ™ words for this process. It makes a lot of sense to do it this way in a camera phone, but there's nothing new or unique about it. The news is they're using a sensor with an insane amount of pixels per square millimeter, so the process is likely to be far more effective than previous attempts to do pixel-binning and/or cropping in-camera.

It is ALSO a marketing lie when they claim that the pixel binning process somehow turns individial pixels in the resampled output picture into "true RGB pixels". Nope, sorry. A downsampled cluster of Bayer-filtered pixels is just that, a downsampled cluster of Bayer-filtered pixels. Sure, resolution and colour fidelity is better, but this is not a Foveon sensor or anything like it.



But the fact is that the "equivalent" focal length never ever changes. A picture taken at 35 mm-e is still 35 mm-e no matter how hard you crop it. As you know, focal length does not only determine field of view, but also depth of field and perspective, among other things, so it is completely useless to talk about the focal length changing in this case, because it does not. It's 8 mm (35 mm-e) no matter how you slice it.

It's not zoom in any sense that the word has ever been used thus far in photography; it's exactly like the common practice of taking a bird picture with a 300 mm lens and cropping it to a 600 mm-e field of view (because you have pixels to spare on your shiny new K-5.) Yeah, it now looks like the bird is closer, but it's still a picture taken with a 300 mm lens, and now you have less resolution per inch when printing. Cropping can not ever change the focal length, which is a physical property of the lens.
Forum: Non-Pentax Cameras: Canon, Nikon, etc. 02-27-2012, 10:54 AM  
41 Megapixel Nokia 808 smartphone camera
Posted By Erik
Replies: 375
Views: 72,772
There's no "technology" there, PureView is just a made-up marketing word. If you take your K-5's 16MP images and crop them to your desired field-of-view in Photoshop, and then resize the resulting picture to 5 megapixels -- boom! You just implemented PureView on your Pentax!

The sensor itself is pretty amazing, with 41 megapixels in such a small area, but that has nothing to do with what they call "PureView technology".
Forum: Non-Pentax Cameras: Canon, Nikon, etc. 02-27-2012, 07:26 AM  
41 Megapixel Nokia 808 smartphone camera
Posted By Erik
Replies: 375
Views: 72,772
Wait, what? The aperture and focal length never change. The "zoom" they're talking about is literally just cropping from the sensor and then scaling down. If it's f/2.4, it's f/2.4 throughout the entire "zoom range", though it is literally meaningless to use that term as the focal length never changes. It's always 8 mm, it's always f/2.4, it just has a chip that is able to make variable crops from the sensor. You're "zooming" from 41MP to 5MP.

So no, it IS a marketing lie. They're claiming "lossless zoom" which is simply not true. The pixel level quality decreases as you zoom in. It's only "lossless" in the sense that it's always at least as good as a 5MP sensor with the same pixel pitch. It's "lossless" compared to that, but that is not what a consumer thinks he's going to get when he buys something advertised as 41MP with "lossless zoom".
Forum: Non-Pentax Cameras: Canon, Nikon, etc. 02-27-2012, 07:14 AM  
41 Megapixel Nokia 808 smartphone camera
Posted By Erik
Replies: 375
Views: 72,772
How the what-now can they get this kind of shallow depth of field with an 8 mm lens?


Well, I guess they steal amazing technology from the future seeing as they obviously have a time machine :eek:

Forum: Non-Pentax Cameras: Canon, Nikon, etc. 02-27-2012, 07:11 AM  
41 Megapixel Nokia 808 smartphone camera
Posted By Erik
Replies: 375
Views: 72,772
It sure is good. Really, really good for a camera phone, easily the best on the market... But these are ideal conditions and ISO ~50 -- let's see it zoomed in to 5MP at ISO 400+ in a dark indoor setting, and I think it will become abundantly clear that not even the best technology can escape the laws of physics :)
Forum: Non-Pentax Cameras: Canon, Nikon, etc. 02-27-2012, 07:01 AM  
41 Megapixel Nokia 808 smartphone camera
Posted By Erik
Replies: 375
Views: 72,772
It's not digital zoom, it's kind of the opposite of digital zoom -- when you're fully "zoomed out", you're using the full 41 MP of resolution, which is then downsampled to (for instance) 5MP. As you zoom further in, eventually you end up with just 5 megapixels, straight up, without downsampling. At this point, it follows that the quality will be significantly worse on a pixel level. So in that sense, their claim of "lossless zoom" is a marketing lie.
Forum: Pentax News and Rumors 02-11-2012, 10:29 AM  
New K-01 mirrorless camera coming
Posted By Erik
Replies: 2,067
Views: 267,508
Remember when the K-7 came out, they also said it had a "newly developed sensor" but it turned out to be just the K20D sensor with some slight modifications to allow for video output or something like that... I'm thinking the K-01 will be 95% identical to the K-5 in terms of image quality (which is still great!)
Forum: Pentax K-01 02-10-2012, 06:05 AM  
Deuglifying the K-01: it's pretty easy
Posted By Erik
Replies: 16
Views: 2,763
Yeah, I acknowledge that this stuff doesn't matter to a lot of people. :) I personally am very interested in typefaces, graphic design and such, and it is really irritating to me how Pentax chooses to squander the good material they have and frequently emphasise the bad.

But I do think that this camera is ugly, and I'm not alone in thinking that. I'm almost certain the changes in the first post, if made, would have elicited fewer "OH MY GOD THAT IS HIDEOUS" responses from "clueless consumers" as well as Pentax fans... instead, a lot more lukewarm "mehs." Not sure which is better, honestly ;)


EDIT: ...and to clarify, the thread was basically just made to show off something I threw together in Photoshop, which looks infinitely better to me. Not a big deal, just a picture. :) Maybe others would agree, and realize as I did, that the biggest problem is not really the shape of the camera, but the colours and logos.
Forum: Pentax K-01 02-10-2012, 05:34 AM  
Deuglifying the K-01: it's pretty easy
Posted By Erik
Replies: 16
Views: 2,763
I know they're reusing an old logo, but they're doing it for no good reason -- if this new camera was a retro-style body, the equivalent of a digital MX, sure! I could maybe* see them bringing back the old logo. But it isn't -- it's something else entirely. The fairly contemporary DIN typeface on letters "01" and the body (which is kind of reminiscient of Leica and such due to the German heritage) clashes spectacularly with both the old-style "K" and the old Pentax logo. That logo, like the Fujica logo below, looks severely dated today and is very much a product of a 70's design zeitgeist. It has no place on a supposedly contemporary camera, supposedly a member of a family of modern system cameras. All it does is make the design a bad in-joke that no one gets.

Without almost a single doubt, the next K-mirrorless camera (not designed by Newson) will go back to using the regular Pentax logo that they use in all other corporate and product branding. So why is this there? I'd like to see a rationale because to me it's easily the most offensive part of the design. It is very clear Marc Newson is a product designer, not a graphic designer.


* Maybe -- Fuji is making a big splash with retro-cool design yet you don't see them dragging out this abomination of a logo. Some things are best left where they belong; firmly in the past...
Forum: Pentax K-01 02-10-2012, 05:09 AM  
Deuglifying the K-01: it's pretty easy
Posted By Erik
Replies: 16
Views: 2,763
It is what it is, but it at least makes the look consistent with all their other cameras, which is undoubtedly a marketing advantage. There is a very good reason other camera/electronics companies don't futz about with putting different logos and typefaces on different devices.
Forum: Pentax K-01 02-10-2012, 04:11 AM  
Deuglifying the K-01: it's pretty easy
Posted By Erik
Replies: 16
Views: 2,763



See, I don't know about you guys, but personally I think this is a real improvement right here, and nothing has changed except it's all black and the ugly 70's logos are gone (is there ANY good reason to bring back the awful, old Pentax logo? This is not a retro camera, so what are you really trying to communicate here?) Stick some leatherette instead of the ribbed rubber on there, and you're pretty much done. Camera's ugliness would have been a non-issue in the marketplace.

Pentax has a real problem these days with coming up with a solid foundation of a design language, and sticking to it coherently. The early DA lenses looked great, but now there's the new, stretched-Helvetica lenses like the 18-55 WR, DA35 and new DA50 which just look cheap and bad. Why is this?

The K10D had one Pentax logo, the K20D had another, and now the K-01 has a third. Why three logos? Pick a style! Stick to it!

Sorry, I'm ranting, at the end of the day it doesn't matter what a camera or lens looks like, but the design nerd in me gets really upset that Pentax so often comes up with good ideas (the styling of the Limited lenses and the DA 17-70 were awesome, for instance) just to abandon them for a remarkably more terrible one the next week. :hmm:
Forum: Pentax News and Rumors 02-10-2012, 03:04 AM  
More photos from CP+
Posted By Erik
Replies: 174
Views: 30,002
A potential DA* 15-85/2.8 DC [IF] sounds like one hell of a useful lens.
Forum: Pentax News and Rumors 02-09-2012, 02:48 PM  
More photos from CP+
Posted By Erik
Replies: 174
Views: 30,002
Q with the K adapter + a Zeiss lens:



Hmm.
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