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04-16-2011, 11:32 PM   #1
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Will K-X meter through a 1970's K lens?

I know that a lot of entry level Nikon bodies (e.g. D3100) will not meter through old AIS Nikkor lenses; you have to manually measure the light with a spot meter and calculate the aperture and shutter speed you want, then set the camera to that.

How about say a Pentax K-X with a late 1970's k series manual lens? Will it meter fine? What are the drawbacks of using an old manual lens on a K-X besides the crop factor?

I was going to get a Nikon D3100 because I can get the kit for $599 now.. but after comparing the two cameras on, it seems like the k-x is better in so many ways (besides movies which I dont' care about): image quality, dynamic range, color depth, AF motor inside, HDR, lens compatibility, etc.. btw teh d3100 seems to be better than all entry level Canon cameras too.. So the pentax really rocks and is less money! I just worry about Pentax DSLR business dying cause not many people buy them here (at least in the USA).. to me they seem like much better entry level slr's (compared to Nikon and Canon).. and so many lenses you can use with em. Nikon brags about lens availability yet you can't even meter through the lens of the AIS lenses (unless you get a pro body)

Last edited by geekette; 04-16-2011 at 11:38 PM.
04-17-2011, 12:06 AM   #2
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It should. My K20D and my brothers K-x works perfectly fine with any lens ( My M42 and his K mount MF lenses ). Although only Spot and Center Weighted are available.
04-17-2011, 12:39 AM   #3
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my most used lenses are 1970's K mount lenses and they meter as accurate as with any modern lens. The only practical way to use these lenses is on manual mode (or aperture priority mode but only wide open) so you might call that a draw back (I call it fun)

as Junyu said, no matrix metering mode
04-17-2011, 01:50 AM   #4
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I have an old 200mm M42 lens that meters just fine. I'm not sure on the year of the lens but it's probably around the 70s.

04-17-2011, 03:31 AM   #5

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Yes, many of us have used our K-x bodies with the original SMC K-mount lenses (1st generation K-mount) as well as the many the K-mount lenses since. Green button stop-down metering is easy.

The K-r is a good camera too - much like the K-x.
04-17-2011, 05:23 AM   #6
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Lens availability and Nikon low-end? What a joke. Even the D7000 is limited to 16 manual lenses. You can't even use all the AF lenses because the low-end bodies don't have a screw drive. When you take into account that Nikon has the longest lens registration distance of any of the major SLR makers, meaning you can't use M42 lenses, and you have even less lens availability.

The biggest danger using Pentax isn't that they will go out of business. The biggest danger is LBA. I spent $500 on my K-x, and since then I've spent almost $1,500 on lenses and film bodies for the included lenses. Browse the posts of RioRico to see someone with real LBA.
04-17-2011, 05:40 AM   #7
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boriscleto: giggle, at least you can sell all those lenses for what you paid for them, so essentially they are free They won't depreciate. I only worry about the depreciation of the DSLR bodies and potentially the DA lenses I might buy.. But I doubt I'll pay that much for em.
04-17-2011, 07:31 AM   #8
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I use the K-r a lot with M42 lenses.

Pressing the "green" button gives your the meter and then keeping it pushed, you can change the exposure time by turning the wheel. Works flawless and should be the same with your K-x.

04-17-2011, 07:37 AM   #9

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QuoteOriginally posted by geekette Quote
I just worry about Pentax DSLR business dying cause not many people buy them here
I refer you to this. flickr is full of US K-x users.
Flickr: Camera Finder: Pentax: K-x
I mean the K-x was even advertised on HSN quite a lot, so Pentax probably sold shiploads of K-x's in the US.
04-17-2011, 08:33 AM   #10
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QuoteOriginally posted by boriscleto Quote
Browse the posts of RioRico to see someone with real LBA.
Me, exemplifying LBA? Pshaw! Compared to some, I'm the most meagre of misers.
[/me fondles latest unusable arrival, yesterday's MATI TV-SYNCHRONEX 25/1.4]
I don't *suffer* from LBA; I enjoy every buck of it! (That Mati cost US$4 shipped.)
Now, if I get an NEX, *then* the LBA will likely kick in! All those possible lenses...

For those unaware of the optics: Cameras possess a property called REGISTER aka FLANGE FOCAL DISTANCE, the distance from the lens-mount to the frame (film or sensor). Longer register lenses can more-or-less-easily adapted to shorter register cameras. Shorter register lenses MAY work on longer register cameras, but will not be able to focus to infinity without either 1) major surgery, or 2) an optical adapter that degrades image quality (IQ). Some common registers, in millimeters:

46.5 -- Nikon
46.0 -- Olympus OM
45.5 -- Petri, Contax/Yashica
45.46 - Pentax PK, Praktica M42
44.7 -- Exakta
44.5 -- Minolta AF / Sony Alpha
44.0 -- Canon EOS/EF/EFS
43.7 -- Minolta MC/MD
42.0 -- Canon FD/FL/R
40.5 -- Konica AR/F
38.67 - 4/3 system
28.8 -- Leica L39/LTM
27.0 -- Pentax Auto-110
20.0 -- m4/3 system
18.0 -- Sony NEX / E-mount
17.526 -- CCTV C-mount

Lenses higher on this list can be fitted to cameras lower on the list with straight (non-optical) adapters. Some slightly-shorter-register lenses MIGHT be fitted to slightly-longer-register cameras with only minor surgery -- I have a trick for putting Exakta lenses on my Pentax PK cams. But generally, longer-register brands are donors and shorter-register brands are recipients aka leeches. Canonites leech our Pentax lenses. Sony NEX'ers leech just about everything. And when some CCTV and cine lenses around 10mm f/1.0 cost just ONE BUCK, you can maybe understand why optics junkies head for the NEX.

One reason for increasing prices of vintage lenses is that more Kx-Kr users (and Canonites, m4/3'ers and NEX'ers) find that they are very usable. Get them while they last!

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