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Forum: Pentax Q 12-01-2017, 03:59 PM  
Looking at a Pentax Q, but I have some questions
Posted By CFWhitman
Replies: 22
Views: 2,426
Just for information's sake, lenses of this type are usually referred to as retrofocus lenses, after the name of the earliest marketed such lens.
Forum: Pentax Q 11-29-2017, 03:33 PM  
Looking at a Pentax Q, but I have some questions
Posted By CFWhitman
Replies: 22
Views: 2,426
That's as good as you can get for a camera that takes the same lenses. The problem is that the registration distance of lenses doesn't change just because you use them on a mirrorless camera, so the K-01 is about as compact as you can make a camera that takes K mount lenses.

That's why there are two different 4/3 mounts. The original one, which was made for DSLRs and the Micro 4/3 for mirrorless cameras with a smaller registration difference. You can use a 4/3 lens on a Micro 4/3 camera, but you need an adapter to make up the registration difference. Incidentally, there are also two different versions of the old M39 screw mount lenses. The more common one was for Leica rangefinder cameras, and the other was for Zenit SLR cameras (a Russian brand). The registration distance was entirely different, with the Zenit one being much larger to accommodate the mirror box in an SLR.

So the bottom line is that you will never really be able to go more compact than the K-01 with K mount lenses. To go more compact, you have to look at different mounts.
Forum: Pentax Mirrorless Cameras 06-30-2016, 11:21 AM  
The next Q model sensor
Posted By CFWhitman
Replies: 43
Views: 9,931
Your post prompted me to look into this a bit further, and I found that there are actually several cell phone cameras that have a sensor the same size as the original Q, but very few that have one bigger than that, most of them Nokias, and only three that I found with as large or larger sensor than the Q7/Q-S1. Two of those you mentioned, the Nokia N8-00 (same size) and the Nokia PureView 808 (bigger as mentioned). The third is more a camera with a cell phone attached than a cell phone with a camera, and that is the Panasonic Lumix CM1, with a 1" sensor.
Forum: Pentax Q 06-24-2016, 09:18 AM  
Left handed Q
Posted By CFWhitman
Replies: 8
Views: 1,107
That's all correct except that it was Reese's Pieces which were featured in the movie rather than Skittles. Skittles and Reese's Pieces were introduced to the American market around the same time, both in 1979 (though Skittles were sold in the U.K. before that). Reese's Pieces exploded in popularity thanks to the movie. That was in 1982. Skittles biggest boost in popularity didn't come until the successful "Taste the Rainbow" ad campaign in 1994 (obviously they weren't an abject failure before that, or they would have been dropped).

Incidentally, Reese's Pieces are made by Hershey Corporation while M&Ms are made by Mars. Skittles are made by Wrigley in the US, which was its own company up until 2008 when it was acquired by Mars.
Forum: Pentax Mirrorless Cameras 06-15-2016, 06:43 AM  
The next Q model sensor
Posted By CFWhitman
Replies: 43
Views: 9,931
Incidentally, the 1/1.7" is significantly larger than any cell phone camera sensor I've ever heard of. The largest cell phone camera sensor I'm aware of was the one on the Nokia Lumia 1520, a 1/2.5" sensor, which is slightly smaller than the original Q sensor (1/2.3"), though it was 20 a megapixel sensor.
Forum: Pentax Q 08-26-2015, 12:57 PM  
The Future Q -- what's your take?
Posted By CFWhitman
Replies: 177
Views: 19,614
I don't think Nikon has given up on it. However, I've noticed that the regular stores that carry it have put Nikon 1 models on clearance and are not carrying new ones (and the clearance models do not sell out, though I'm sure they would if they marked them down more). I don't know that means the format is failing, but it's not a runaway success either. Of coure, M 4/3 cameras are not even sold at most of these stores.






QuoteQuote:

You may be right in terms of image quality, but aren't you forgetting that smaller sensors mean [more] DOF? (again, that doesn't bother me so much in case of the Q)



I agree that this will play an important factor as far as more serious photographers are concerned (especially for certain kinds of shots, for example, portraits). The people who are satisfied with small sensors will probably be more and more satisfied with cell phone cameras.

Of course, my Q7 still blows cell phone cameras away as far as picture quality is concerned even though some of the cell phone cameras have more megapixels. People who know what they're doing will always want bigger sensors for certain occasions where quality is more important, so I think price will always be a big factor. It's just as possible that the in-between models will end up being squeezed out by the cell phone cameras at the one end for ultimate portability and APS-C or full-frame cameras at the other end for ultimate image quality (including depth of field effects). It depends on what compromises people find appealing.

For the moment, my Q is an interesting compromise, and I bring it with me sometimes when I would have left my APS-C cameras at home.
Forum: Pentax SLR Lens Discussion 08-11-2015, 01:34 PM  
Just what is a "stack of primes"? (Philosophical discussion)
Posted By CFWhitman
Replies: 83
Views: 7,178
Well, I think it's hard to quantify the phrase "stack of primes," since it seems to be an impression that someone gets rather than anything technical about the lenses. One thing I would say is that it implies the lens is very sharp and has no weak focal lengths, i.e., it's not significantly softer toward one end like many zooms seem to be.
Forum: Pentax Q 08-05-2015, 01:24 PM  
The Future Q -- what's your take?
Posted By CFWhitman
Replies: 177
Views: 19,614
I can appreciate the desire for such a system, but that wouldn't be a Q system anymore. It would be something entirely new (though I suppose you could create such a system to use Q lenses in a crop mode, as certain lenses already are cropped on the Q7 and later).
Forum: Pentax SLR Lens Discussion 08-04-2015, 10:59 AM  
Search for a FF normal prime and wishlist
Posted By CFWhitman
Replies: 90
Views: 6,805
Let's see -- you want fast, sharp, light, cheap, durable, and weather resistant with autofocus, good resistance to vignetting and color aberrations, and just the right focal length. Don't we all? :)

If you leave cheap out, then I can see that perhaps none of the lenses are exactly the right combination of high end features and focal length (mostly WR and focal length), but some of the criticism of some really good glass seems a bit nitpicky to me.
Forum: Pentax SLR Lens Discussion 07-30-2015, 07:10 AM  
What lens was used for this ?
Posted By CFWhitman
Replies: 20
Views: 1,610
You definitely want it available, but it could be available with another lens or without the tele-adapter, and this combination could still be nice to have.
Forum: Pentax SLR Lens Discussion 07-30-2015, 07:07 AM  
Wedding photo shoot
Posted By CFWhitman
Replies: 47
Views: 2,950
People also fall into the trap of thinking that it's all about the gear. 'Oh, he/she can shoot great pics at my wedding because he/she has a good camera,' is what they're thinking, consciously or not. While it's true that good gear makes better pictures more possible, it in no way guarantees the quality of the pics. (Although I admit that certain lenses have made me look very good at times :) )
Forum: Pentax SLR Lens Discussion 07-30-2015, 05:52 AM  
50 mm crop factor
Posted By CFWhitman
Replies: 27
Views: 2,032
That's true on a Canon APS-C, but Nikon and Pentax have a slightly larger sensor making the crop factor 1.5x.
Forum: Pentax SLR Lens Discussion 07-29-2015, 07:02 PM  
wanted: DA 15 perspective distortion examples
Posted By CFWhitman
Replies: 23
Views: 1,545
Well, perspective distortion is an intrinsic property of the angle of view, so it is related to the lens/camera combination (assuming you don't crop the photo), but one 15mm should be pretty much like any other for this purpose.
Forum: Pentax SLR Lens Discussion 07-29-2015, 12:31 PM  
What is the sharpest lens for a K3, 17-70 or similar?
Posted By CFWhitman
Replies: 48
Views: 5,675
My results:

Raw developers:
RawTherapee 4.0.12.0 opens this file with no problems.
Darktable 1.6.7 opens it with no problems (only works on Unix-like operating systems, like Mac OS X or Linux).
Lightzone 4.1.2 opens the file with no problems.

Image editors:
Gimp 2.8.10 opens the file with no problems.
Krita 2.8.1 opens the file with no problems.

Image Previewers:
Ristretto 0.6.3 will not preview the file (it just ignores it).
Geeqie 1.1 previews the file with what seems to be a negative preview.
Shotwell 0.18.0 previews the file with no problems.

ImageMagick 6.7.7 (display) opened the file with no problems (ImageMagick is a set of image processing utilities).

I did notice that RawTherapee and Darktable both displayed the image with more vivid colors (particularly the clay pot), and I'm guessing that this is the over-saturation that you were talking about in IRfanview. All the other programs that opened it correctly seemed to open it with what I'm guessing are more accurate colors. As you may have guessed, I'm generally on Linux and so don't have that much use for programs that won't run on Linux. However, several of these programs are available for Windows and/or OS X as well. So at least you have some more options.
Forum: Pentax SLR Lens Discussion 07-28-2015, 08:57 AM  
Pentax q7 focal reducer
Posted By CFWhitman
Replies: 9
Views: 1,269
You could theoretically adapt nearly any ILC lens to a Q because the registration distance for the Q is the shortest around. However, most ILC cameras have (or had) a much larger sensor or film size than the Q. This makes it so that lenses for most systems will only be helpful for 'telephoto' type applications. There are a few exceptions.

The adaptors for the Q that are easy to come by for more normal focal length applications are for C mount, D mount, and Pentax 110 mount (and even the 110 mount tend a bit toward 'telephoto' lengths).

The adaptors that are easy to come by for 'telephoto' applications include those for K mount, EOS mount, F mount and M42 mount.

(Telephoto technically just means a lens that has a focal length longer than its physical length, but is often used it to mean lenses with a length longer than the normal focal length for the system.)
Forum: Pentax K-3 07-27-2015, 12:40 PM  
K-3 II + Manual Lens + Live View + Green Button = ???
Posted By CFWhitman
Replies: 43
Views: 6,057
This is clearly a case of the people reading the mail not bothering to figure out what you are really talking about. I got a similar answer regarding a malfunction in a printer at my workplace recently (fortunately, that issue can be worked around, at least for the time being). They're giving you the brush off. They assume you don't know what you're doing, and treat your email accordingly. They can't seem to imagine that you might be referring to an actual bug, issue, or equipment malfunction. When they get enough reports, they will eventually figure it out, but even with persistence, they won't pay that much attention to one complaint, unless or until just the right person sees it and actually tests it out.

Sometimes you can get better results for this sort of thing by reporting it as a firmware bug rather than asking questions about it, but not necessarily.
Forum: Pentax SLR Lens Discussion 07-17-2015, 12:16 PM  
Sigma 17 - 50 "unknown lens" on my K3
Posted By CFWhitman
Replies: 17
Views: 1,657
For Linux there is pyExifToolGUI (it's available for Windows and Mac as well). I'm not sure if it has the functionality to manipulate the exif fields involved though. It doesn't support everything that ExifToolGUI does (though it does have some functionality that ExifToolGUI lacks as well). It's a front end for exiftool written in Python using Qt 4.
Forum: Pentax SLR Lens Discussion 07-17-2015, 06:19 AM  
Equivalent focal length with crop factor
Posted By CFWhitman
Replies: 286
Views: 15,375
You're right that this is basically an argument over semantics. However, the problem with calling it "additional light" is that it's not the amount of light that makes the difference; it's where the light travels. You can have less light because of environmental changes in a picture at f/1.4 and ISO 400 than you do at f/2 and ISO 200, and the picture with less light will still have a shallower depth of field because the light that you do have is distributed a different way.
Forum: Pentax SLR Lens Discussion 07-17-2015, 05:48 AM  
Equivalent focal length with crop factor
Posted By CFWhitman
Replies: 286
Views: 15,375
Yes, I understood your thinking, which is why I was explaining that this was a miscommunication/misunderstanding. I was just stating what was meant by dtmateojr in his original post. There was no point in arguing back and forth about the physics when the actual issue was just one of semantics.
Forum: Pentax SLR Lens Discussion 07-16-2015, 06:55 PM  
Mitakon views
Posted By CFWhitman
Replies: 10
Views: 887
Well, there was an EOS mount f/0.95 lens, but I believe it is impossible on the K mount.
Forum: Pentax SLR Lens Discussion 07-16-2015, 02:05 PM  
Equivalent focal length with crop factor
Posted By CFWhitman
Replies: 286
Views: 15,375
That's not what the original statement was about. It was about what I said in my previous post. That's why I said that perhaps you misunderstood dtmateojr when he first used the term, "projected image size." I'm guessing that Fogel70 misunderstood as well. Incidentally, just in case there is any question, it doesn't matter what system a lens was made for, at the same focal length, the projected image size will be the same (at least as long as it's mounted at the correct registration distance for the lens of course).
Forum: Pentax SLR Lens Discussion 07-16-2015, 01:31 PM  
Equivalent focal length with crop factor
Posted By CFWhitman
Replies: 286
Views: 15,375
That doesn't matter. Focal length is the only thing that affects projected image size (that is, the only thing related to optics; changing distance to subject will of course change the projected image size of the subject). Perhaps you misunderstand what he meant when he said "projected image size." The projected image size is the absolute size of the image when it hits the sensor regardless of the sensor size, so smaller or larger sensors will capture a smaller or larger part of that image, not a smaller or larger version of the image. If the image circle of the lens is smaller or larger it will project a smaller or larger part of the image, not a smaller or larger image.
Forum: Pentax SLR Lens Discussion 07-15-2015, 11:28 AM  
A Gentle Reminder: Keep those reviews on point
Posted By CFWhitman
Replies: 47
Views: 3,742
This kind of depends on whether you think the Pros and Cons are points upon which you are rating the lens or if they are just a list of advantages and disadvantages when using the lens. If you are rating the lens based on the Pros and Cons, then you shouldn't fault a lens for being exactly what it states it is whether that be f/2, manual focus, or a prime lens. On the other hand, if you think the Pros and Cons are just advantages and disadvantages, then compared to other lenses these things might be relevant. It looks as though the Pros and Cons aren't being used as a basis for the number ratings, so I'm guessing that most of the reviewers are viewing them as the advantages and disadvantages of that particular lens.

Perhaps if you wanted to clarify these points you could have separate sections for points related to the score and points related to comparing it with other lenses. However, I think this could end up just adding confusion.
Forum: Pentax SLR Lens Discussion 07-15-2015, 08:00 AM  
Equivalent focal length with crop factor
Posted By CFWhitman
Replies: 286
Views: 15,375
Some of what I said may have been a bit simplified, but it was not wrong. Your statements don't even really mean anything when it comes to light gathering. You're trying to illustrate equivalence, which has its uses as far as comparisons go, but is very misleading when you try to talk about it in terms of absolutes. To state that the Pentax Q 01 lens gives you the same noise levels as a full frame lens at f10.64 as though that is an absolute is entirely misleading. The noise levels depend very much on the sensor used as well as other factors.

If you were theoretically to have a sensor of the same technology with the same pixel density on full frame as the Q, and used the same focal length (8.5mm), and the same f-stop, then the noise levels would be the same in any given area of the sensor (there is no camera and lens combination that meets these criteria of course). Of course the picture from such a camera would cover a much greater angle of view and contain a much greater number of pixels, and if printed at the same dimensions would have the noise reduced in size along with everything else, but if cropped to the same angle of view as the Q, would have the same amount of noise. It's not switching to a full frame sensor that causes the difference, but the other changes you make to get a similar picture (changing the size of the pixels, changing the focal length, etc.). However, you will never find an exact equivalent. There are combinations that may be compared and relevant in certain situations, but they are not absolutes (that is, they may apply quite well under certain conditions, but changing conditions will make them not apply).

Your final statement may be generally useful as a comparison, but again, it is not absolute.
Forum: Pentax SLR Lens Discussion 07-14-2015, 02:48 PM  
Equivalent focal length with crop factor
Posted By CFWhitman
Replies: 286
Views: 15,375
My take on this is that "equivalency" is never perfect. There are too many variables involved, and thus not really any such thing as equivalency. I tend to agree with Lowell. It's about learning to use your equipment to get what you want, and learning when you need to add another piece of equipment because what you have won't quite give you what you want.

This is not to say that comparisons can't be useful (notice how I said "comparisons" rather than "equivalency" ;) ). If the original poster is still paying any attention, then I would explain it a bit differently:



When you use the Tamron 17-50mm 2.8 on your K-5 your angle of view will be similar to 25 - 75 mm on a 35mm sized sensor.

Your aperture as far as light gathering ability goes will (theoretically, because some lenses have truer aperture ratings than others) be similar at f2.8 as any other lens that is f2.8. That is, the same ISO to f-stop ratio will get the proper exposure.

Your aperture as far as depth of field goes will be different because depth of field varies with focal length as well as aperture and you are shooting at a different focal length. Wider aperture gives less depth of field, and longer focal length gives less depth of field. So when you shoot at a shorter focal length as with APS-C, then you would need a wider aperture to get the same depth of field.

ISO/noise ratio is governed by pixel size. There are two types of noise involved with digital cameras: shot noise and read noise. Shot noise is almost completely dependent on area. Read noise is dependent on the number of pixels (more pixels mean more read noise). When signal is low (high ISO settings) then the fact that you get more read noise per pixel is the deciding factor and larger pixels give you less noise overall. When signal is high (low ISO settings) then the greater signal more than compensates for increased read noise and you actually get less noise with more pixels (because you have plenty of light to go around). Of course, you'll generally notice noise more when there is less signal, at high ISO settings, so for practical purposes you get less noise with larger pixels.
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