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Forum: Post Your Photos!
03-01-2024, 06:55 PM
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Aperture Priority Mode with Multi-Segment Metering. F/L @157mm.
Muchas Gracias for viewing.
Tony :))
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Forum: Pentax Medium Format
10-25-2023, 09:27 AM
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Forum: Pentax DSLR Discussion
05-15-2023, 01:38 PM
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Medium format, e.g. Pentax 645z, is 4:3.
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Forum: Lens Clubs
01-18-2023, 05:26 AM
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Forum: Pentax Medium Format
12-20-2017, 01:46 PM
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I love that last one in particular.
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Forum: Lens Clubs
12-27-2016, 08:16 AM
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1.
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Forum: Lens Clubs
12-14-2016, 08:41 AM
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Forum: Pentax K-1 & K-1 II
11-30-2016, 02:53 PM
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K-1 and Pentax 24-70 f2.8 @70mm.
Pixel shift with 2 exposures merged. Lunenburg NS Canada.
WIshed I'd had the 70-200 to reach further over the seaweed in the foreground. Oh well. Pretty happy with IQ from the 24-70 with PS.
Maritime Adventures by Sky Matthews, on Flickr
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Forum: Travel, Events, and Groups
02-22-2014, 08:28 PM
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Everyone who likes this post may or may not win a free CORNDOG!
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Forum: Pentax SLR Lens Discussion
05-01-2013, 12:09 PM
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This makes it easy for someone like me who is waiting for Pentax FF to just sell everything and move to Nikon.. :)
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Forum: Photographic Technique
05-25-2012, 03:08 PM
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EDIT: Revised version here.
I'm sure this has been stated many times before but here it is once again anyway: APS-C does not increase focal length over FF, it decreases field of view.
Many people seem to confuse reduced field of view for increased focal length in their understanding of a cropped sensor (APS-C format: 23.7 x 15.7 mm) image vs. a full frame sensor (135 film format: 36 x 24 mm) image. The matter can be somewhat confusing so, there are many people who mistake less field of view for a longer focal length. This misunderstanding is perpetuated all over the internet and elsewhere. The perceived magnification from an APS-C sensor vs. a FF sensor only applies once the final image is viewed on a screen or when it is printed. It is not the case in the viewfinder of your camera, on the film negative, or when viewing the final image at 100% on a screen.
Contrary to what some incorrectly believe, you can't get any closer, i.e. have greater magnification, with an APS-C camera when doing sports photography, birding, or whatever other type telephoto work. This idea needs to stop being repeated as it is misleading. You won't be able to reach any farther with an APS-C camera than with a FF camera. Reduced field of view is what you're getting, not a longer focal length. If you want to reach farther, you need to get a longer lens not a smaller sensor.
I think that using the term EFL (equivalent focal length) is part of what helps perpetuate this misunderstanding. We may be better off using some term like EFOV (equivalent field of view) or EAOV (equivalent angle of view). EFL is a convenient shorthand for converting to the more widely known 35mm format FOV but it is also misleading to those who don't quite understand what is the real difference between the different sensor formats.
As it is stated in Wikipedia's Magnification factor section of their article on crop factor: "A given lens casts the same image no matter what camera it is attached to. The extra 'magnification' occurs when the image is enlarged more to produce output (print or screen) that matches a standard output size. That is, the magnification as usually defined, from subject to focal plane, is unchanged, but the system magnification from subject to final output is increased."
Similarly, in Wikipedia's macrophotography article it states that "when producing a 6×4 inch (15×10 cm) print using 135 format film or sensor, a life-size result is possible with a lens having only a 1:4 reproduction ratio." This goes to show that magnification, in addition to being a result of a given lens' focal length and minimum focusing distance, can simply result from the enlargement of the image on a screen or on paper. My point is, the magnification is not coming from the cropped sensor; it either comes from the lens or the reproduction when printed or displayed on screen.
Say you take two pictures of a beetle from the same distance with a 100mm macro lens (a true macro lens capable of 1:1 reproduction, to be specific). Imagine that the picture you take with the APS-C camera has the beetle filling the entire frame. Now imagine that you us a full frame camera using the same lens and from the same distance to get the same 1:1 magnification. The beetle on the full frame image will not fill the entire frame. You will still get the very same 100% magnification from both cameras. What you will get from the FF image though, that you will not get with the APS-C image, is more of the beetle's surroundings. View both those images at 100% and the beetle is going to be the same size on your screen, as long as the pixel count is roughly the same. You will not have any reduction in terms of magnification with the FF image. To have the beetle be the same size on your screen, when your viewing mode is set to fit the screen, then you would have to crop the FF image. But at a 100% viewing size, given that the images have the same number of pixels, the magnification will be identical.
Imagine that you are taking these two pictures of the beetle above, again from the same distance and using the focal length, on film instead of digital. One image would be taken with a full frame camera on 135 film. The other image would be taken on an APS camera on 24mm film in the APS-C 3:2 aspect ratio. Imagine taking the negatives from both films and then placing them on top of each other: the beetle is going to be the same size on both images when lined up. The difference will be that with the 135 film the negative is larger so there will be more picture content surrounding the beetle.
I often times read opinions that a cropped sensor is advantages for telephoto work; I don't agree with that for all the reasons already outlined. The example with the beetle and the macro lens above could just as easily be made with a bird and a 200mm telephoto lens. If shooting from the same distance and with the same focal length, the bird is going to be the same size on either sensor, it's just that the size of the frame (i.e. the FOV) of the picture will be bigger with the full frame than with the cropped sensor.
In a way, the perceived magnification effect of using a cropped sensor is more akin to digital zoom than it is to a teleconverter. A cropped sensor gives you the "magnified" crop ahead of time, whereas cropping an image from a full frame photo accomplishes the same "magnification" but after the fact.
One of the main reasons I hope to be able to upgrade to a full frame system eventually is to have the advantage of greater magnification in the viewfinder relative to FOV. For example, when using a normal 50mm lens on FF I would get the approximate field of view of my 31mm lens on my K-5 but with the actual magnification in the viewfinder of a 50mm lens. That will make a big difference with manual focusing. Of course, in addition to field of view, the difference in sensor size between FF and APS-C affects depth of field, low light performance, and dynamic range.
Anyway, there's my long winded rant about what could admittedly just be described as a matter of semantics. I'd propose becoming more familiar with the different fields of view by focal length and sensor format, though that would be a bit more complex.
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Forum: Lens Clubs
02-29-2012, 11:32 AM
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Really nice pano Mike, i should try to do it some day...need some advice/trick too !
and nice portrait Nicole, really like the 2nd one.
This one was took last year just after christmas, with the FA 43, it was so cold here that i got lucky to have nobody out there :D
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Forum: Ask B&H Photo!
05-27-2010, 11:59 AM
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If given the choice, it's always best to use a lens with the focal length you need as opposed to using a teleconverter. Results will vary depending on the lens and converter model you use. If you paired Sigma's 70-200 with their converters, you would get excellent results. Using a brand A lens with a brand B converter you may notice a drop in contrast and sharpness.
This Sigma 150-500mm f/5-6.3 DG HSM APO Lens is an ultra telephoto zoom lens ideal for nature, wildlife, or sports photography. This zoom range translates into an equivalent range of 225-750mm when used with a Pentax digital SLR camera.
Sigma | 150-500mm f/5-6.3 DG HSM APO Autofocus Lens | 737109
The Bower SX7PK 2x Telextender (also known as a tele-extender) will multiply the focal length of your existing lens by 2x, and will cut back the amount of light by 2 f/stops while maintaining full autofocus coupling.
Bower | SX7PK 2x Telextender | SX7PK | B&H Photo Video
C h u c k C a p r i o l a
Live Chat and E-Mail Sales Manager B&H Photo-Video
Thank you, we appreciate your business.
*** Peace on Earth ***
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Forum: Troubleshooting and Beginner Help
07-17-2010, 11:13 AM
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Start with P mode, but turn auto ISO off.
Now, select 200 ISO and go outside for one shot, and note the shutter speed and aperture the camera is selecting for you. Now, change to ISO 400, and notice how the doubled sensitivity affects your shutter speed and aperture, how the three elements are always related. Do this a bunch of times.
Now, switch to Av, aperture priority mode, and manually change your aperture, and notice how the shutter speed now changes with different apertures.
And do the same thing in Tv mode, manually changing the shutter speed to see how the camera now automatically changes the f stop.
I suggest manual ISO for all of this because it makes the exercise a little bit easier to understand.
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Forum: Pentax SLR Lens Discussion
05-14-2010, 09:02 PM
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There have been other earlier threads on the topic and you received already solid suggestions.
Many see the 50mm focal length with large aperture (small f) atypical of a portrait lens. The large aperture allows you to work indoor and outdoor including in lw light conditions. In that categrory, there are a range of interesting length including:
- the older Pentax 50mm f1.7,
- the FA 50mm f1.4 {Pentax SMC-FA 50mm f/1.4 - Review / Lab Test Report},
- the Voigtlander Nokton 50mm f1.4 {Voigtlander Nokton 58mm f/1.4 SL II - Review / Test Report}
- the Carl Zeiss 50mm f1.4 {Zeiss Planar ZF T* 50mm f/1.4 - Review / Lab Test Report}.
The list is not exhaustive. The above lenses are some well-respected lenses in their own category and price range, and they are available in Pentax K-mount. I added the URL of the independent review by Photozpone.de beside.
The Carl Zeiss is the basic reference: i.e., a 'Rolls Royce', but expensive. The Nokton 58mm is very well respected, excellent image quality, and within your price range. For the same price as the Nokton, the FA50mm has AF, but the image quality is s par below. The older Pentax lenses are still good values, but can only be found 2nd hand.
Since you already have 2 kit lenses, both AF, I would encourage your to expand your photographic techniques by selecting a MF fast prime lens, like the Voigtlander Nokton 50mm f1.4 (or the Carl Zeiss if you can afford).
I add that I bought the Nokton for outdoor low light shooting. The lens si very rugged and well-suited ofor outdoor. But I love the lens and it found to use it much more than initially thought.
Hope that the comment help...:rolleyes:
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Forum: Pentax SLR Lens Discussion
05-15-2010, 03:11 PM
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Before you go shopping, put the 55-300 on the KX and set it for a given focal length (55, 70, 85, 100). Shoot. See what focal length you tend to use, and which you feel are limiting.
The 55-300 isn't really a 'portrait' lens, but I find that results are quite decent even wide open, and you can shoot at F4 thru right about 100mm.
I used this method when I acquired my 10-20, by noting that I almost always shot my 18-55 at 18, or 55. Now I just leave it at home. :D
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