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25

Yes, all Pentax DSLRs accept all K-mount lenses. This includes autofocusing (if applicable), focus confirmation, metering, IS, etc. The oldest two series, K and M series (database), do not have aperture contacts, and thus do not work with Av and Tv mode. Instead, you'll have to use M mode, but you will get meter readings. It can also suggest a shutter ...


22

Your friend is right that it is actually always a 24mm lens — that is a property of the optics and never changes. But, he's wrong in saying that the crop factor does not apply. That's a property of the sensor size of the camera. From a practical point of view, zoom — changing focal length — and cropping are interchangeable. So, using a camera with a smaller ...


15

In talking with a number of working pros, the general attitude tends to be that you buy lenses to keep and you buy bodies to upgrade. My personal planning mirrors this; I've tried to invest in higher quality lenses that i expect to own for a while (10-15 years) while given how body technology is changing, upgrading a body every 2-3 years doesn't surprise me. ...


15

I think this question boils down to a balance between backwards compatibility and technological progress. You can strive to maintain the ultimate in backwards compatibility, and never change a lens mount. Some camera manufacturers have succeeded in that, such as Nikon and Pentax, to a large degree. However, what is the long term cost of progress there? ...


12

You have already chosen your answer but I'd thought I would elaborate a little. Focal Length: Yes, it stays the same! The age of the lens doesn't matter regarding focal length. As long as there is some way of fitting any lens onto a body (generally a bigger format lens on a smaller format body), whether by an adaptor or by physically changing the mount, ...


11

The article in rfusca's answer includes some references: The Aero-Ektars, by NASA scientist Michael Briggs; Radioactive Materials in Camera Lenses, from the Health Physics Society (an organization focused on radiation safety); and Thoriated Camera Lens (ca. 1970s), from Oak Ridge Associated Universities's professional training on radiation safety. From the ...


11

Yes, there are. Most DSLRs are backwards compatible with lenses of film DSLR from the same brand. The main exceptions are Olympus, Panasonic and Sony. Canon changed its mount completely when they introduced autofocus, so you will have less luck there. Nikon manual focus lenses are compatible with higher-end bodies (D90, D300S, D7000, D3S, D3X, etc). ...


10

Sadly for Nikon users, the F mount has one of the longest registers ever. (Mechanically) adapting a lens designed for a certain system to one with a shorter register is easy: just manufacture an extension tube of the correct length. The ability of controlling the lens will be mostly lost but this is less of an issue with lenses with mechanical aperture ...


9

That statement about lenses actually being designed, on purpose, to focus colours in separate planes sounds dubious. Even in film days, "APO" was a selling point for lenses - "Apochromatic"; APO meaning that all three colours are actually focused in one and the same plane. We can infer from this that achieving this was no mean feat and that it was a ...


9

As stated here ( and guessed by Dreamager) it is aligned with the lens release button of older Pentax cameras. It's much easier to change the lens in the dark. ( I don't really understand the advantage of the newer orange dots. ) From K-1000 user's manual: In the dark, when red dots are difficult to see, align the white plastic bump on the lens ...


9

Have a look at the Lensbaby Composer: It has an unique feel to it, has been used very effectively by wedding and portrait professionals for a long time. At $200 for the Canon EOS mount version, it isn't cheap for a lens that isn't really general purpose at all, but for sheer creative possibilities, it is unmatched. At a much lower price point, some very ...


9

When you shoot with a manual lens, with no lens attached or a lens that can't communicate with the camera (tested on the 550D/X2i, I believe this applies to all Canon DSLRs) you have 2 options: Shoot in M mode - you need to set everything yourself but the exposure indicators works and is about as accurate as it is with a Canon lens. Shoot in Av mode - the ...


8

Ah, I think what you may be missing is that you're putting two things together that aren't intended to be: A lens that is soft isn't necessarily bad for portraits because people often soften portrait shots anyways and so the lens isn't really a problem. Prefering a soft lens because the softness is a desirable feature. They seem the same, but they ...


8

Breaking down your question: Is it worth the effort? If you already own lenses and don't want to spend money on digital lenses, you could say it is worth it. If you don't want to fiddle with the manual focus, it's not worth it. If you have to use this in an environment where fast focusing is critical, then no, it's not worth it. This is a bit subjective. ...


8

Although jrista answers the question in a basic way, he does not explain WHY a lens may be optimised for colour. As far as I'm aware any given lens will produce an 'adequate' image on both colour and B&W film, as its the same focusing plane and film area, however chromatic aberration is far more prominent in colour (its very hard to spot in B&W, ...


7

I would suggest trying it yourself, especially if you are mechanically minded and have had success at other small part disassemble/reassemble jobs. If you do decide to give it a go, I am an electronic engineer by trade and here are some suggestions that I use when I have to repair small electronic devices ... Have a LARGE clean, clear, flat and preferably ...


7

It should also be noted that the conversion rate between Rems and Seiverts is 1 mR = 10 µSv. So if a chest x-ray is 10mR (according to the article @rfusca linked), thats about 100µSv. According to the chart, that is equivalent to the approximate total dose received at Fukishima Town Hall over a full two weeks, and just shy of half what those two Fukishima ...


7

I have a feeling that the "Color" portion of the name is simply marketing, as the lenses in question were released at a time when color film was not as common. If there were any technical differences, they would probably be focused on reducing chromatic aberration (CA). Reducing CA is done by modifying the lens design and/or materials so that different ...


7

That's the metering fork, that was used to send information about the aperture setting from the lens to the camera on older camera models. The camera would have a pin that fits in the fork, so that turning the aperture ring moves the pin. You can see some images of that here: Lens type overview Lens compatibility


7

Focus confirmation does indeed work. I have a D7000 (which is ergonomically very similar to a D600 - think of a D600 as a D7000 with an upgraded sensor) and have been using a Nikon 80-200mm f/4.5 AI on it perfectly fine. I just rotate the focus dial until the green confirmation dot shows up on the screen. An important concept to realize about a camera's ...


6

The question asks for photo examples, and having recently gone through this exercise first-hand, I'll share my results. I bought a Helios 44-2 58mm F/2.0 (M42 mount) on ebay for very cheap. To use the lens with my Nikon D7000 body, I bought a Fotodiox Lens Mount Adapter which includes a removable infinity focus correction lens. Shooting with the infinity ...


6

M42 prime lenses are single focal length lenses that fit the M42 mount, also known as screwmount. There are many M42 bodies other than the Zeiss Contax, but no digital M42 bodies. Beware that Contax mount lenses are typically not M42 mount, but it's replacement, the C/Y mount or even N-mount. The reason why primes are recommended is because when these ...


6

There is a great summary of K-mount features at Bojidar Dimitor's page. You should look for the "crippled" KAF2 body.


6

Typical lens radiation was apparently approaching 1 mR/hr at the surface of the lens and tapers off rapidly with distance. I'm not sure exactly where it lands in your chart, but the same source states that a chest xray is about 10 mR.


6

Consider getting a lens reversal ring. Screw it on the filter end and then you can mount the lenses on your D7000 in reverse for some macro shots!


6

Could it be slower or less accurate (auto-focus)? Well, it won't autofocus on a D3100. Because it doesn't have a built-in focus motor ("AF-S" for Nikon, "HSM" for Sigma) it's manual focus only. This lens will autofocus with bodies that have an AF motor, such as the D7000 and D300S. The 3100 body does not have an AF motor built in, and so only autofocus ...


6

The word "Color" in the name does indeed refer to color film. In the case of Yashinon, it does not necessarily mean it is "optimized" for color film, simply that it is capable of being used with color film. The lens is also fully capable of producing black and white photographs as well. At the time, in the 1960's and early 1970's, Yashica cameras were more ...



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