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08-11-2010, 03:48 PM   #1
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Just got Nikkor 28mm F/2 for free

The manual says that it's AI-s, but nothing on the lens indicates it.

There are adapters available for it, but I have heard that if the lens can be mounted without one, there is no loss of light/clarity.

I am wondering if turning on the camera (assuming lens does mount) will not short any sensors on the body?
How do sensors work?
How safe are these operations?

Another question on adapters - are they all metal or there is some plastic in-between to prevent current from traveling from body mount to lens or shorting?

I have a K-7.
Thanks for any suggestions.

08-11-2010, 03:51 PM   #2
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I have no idea what you mean by sensors shorting. Do you mean the lens contacts? They won't short.

Some Nikon lenses can be mounted on Pentax cameras but they're not exactly tight fits. They also do not focus to infinity. No adapters are available currently. There might be an adapter with glass that will elongate the focal length and decrease max aperture. They will negatively affect image quality.
08-11-2010, 03:56 PM   #3
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QuoteOriginally posted by SergioFromSF Quote
The manual says that it's AI-s, but nothing on the lens indicates it.

There are adapters available for it, but I have heard that if the lens can be mounted without one, there is no loss of light/clarity.

I am wondering if turning on the camera (assuming lens does mount) will not short any sensors on the body?
How do sensors work?
How safe are these operations?

Another question on adapters - are they all metal or there is some plastic in-between to prevent current from traveling from body mount to lens or shorting?

I have a K-7.
Thanks for any suggestions.
Pentax cameras are designed to be able to shoot without any lens attached to it. Incidentally this is also how the all the M42s lenses work on digital pentaxes. I've on multiple occasions shorted the pins on purpose to enable correct metering for some takumar lenses on K100d, so putting anything on the K-7 should be fine as well, shorting and whatnot.
08-11-2010, 04:07 PM   #4
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hangu: Yes, I meant contacts. Thanks for replying!
Andi: Thanks. Did you say that I can turn on K7 without a lens attached it would take pictures?

08-11-2010, 04:21 PM   #5
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>> The manual says that it's AI-s, but nothing on the lens indicates it.

There is nothing on the lens that says "pre-AI", "AI", or "AI-s". The difference is in the metering coupling. For more details, read this article.

>> if the lens can be mounted without one [an adapter], there is no loss of light/clarity.

That is correct. Among Nikon lenses, pre-AI lenses are the easiest to mount on Pentax DSLR bodies. AI or AI-s lenses can be mounted but not very solid (the coupling ridge gets in the way). You have to be extra careful - the lens may fall off.

Do not attempt to mount Nikon lenses onto Pentax film camera bodies. You may damage the body, or the lens, or both.

If you can mount a Nikon lens onto a Pentax DSLR body, you can focus to infinity - no problem.

I played with Nikon lenses on Pentax DSLR bodies for a while, and collected quite a few Nikon lenses and film camera bodies. I however got tired after a while and sold most of them (still have 2 F2 bodies, an FE body, an 85mm f/2 and a 50mm F/1.8 listing on FleaBay any day now).

Note that there is no coupling between the Nikon lens and the Pentax body, so you have to stop down the lens yourself. Also, Nikon G lenses (without aperture ring) will always be at smallest aperture.

>> Did you say that I can turn on K7 without a lens attached it would take pictures?

He wrote "be able to shoot without any lens attached." He didn't say that it would take pictures. Yes, the shutter will trigger without a lens, but I wouldn't call what is recorded on the sensor a picture.

Last edited by SOldBear; 08-11-2010 at 04:26 PM.
08-11-2010, 05:32 PM   #6
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QuoteOriginally posted by SOldBear Quote
>> Did you say that I can turn on K7 without a lens attached it would take pictures?

He wrote "be able to shoot without any lens attached." He didn't say that it would take pictures. Yes, the shutter will trigger without a lens, but I wouldn't call what is recorded on the sensor a picture.
yep... that's what I mean already answered
08-11-2010, 05:42 PM   #7
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I have also read you need to be careful how far the Nikon lens protrudes into the camera body. Some are too deep and the mirror will hit it.
08-11-2010, 05:58 PM   #8
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Bear, I looked up the link/article - yes, I have the AI-s version of the lens.
Tried to fit it into K-7 gently, could not.
So for now I gave up in the idea.

08-11-2010, 06:10 PM   #9
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You can look for such adapter on flebay. I have got one that I can use it for AI lens - one with rabbit ears. I believe there are ones that allows focus to infinity and some don't.
08-12-2010, 06:43 AM   #10
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I'm not an expert in this, but I have used a couple old pre-AI Nikkor lenses on my K20D/K-7 with no issues. One was a 20cm (200mm) F4 and one was a 105mm F2.5. I sold the 20cm as I was unimpressed by the IQ but the 105mm is quite nice! It fits tightly in the lens mount; it's the friction that holds it in place. When mounted, there's not much danger of it falling off accidentally. The problem is now that I have too many 105s! (Nikkor, Lester Dine, 2x Super Tak...)

When using a lens like this, make sure that you've gone in the Custom menu and allowed the use of the aperture ring, otherwise it will refuse to shoot.
08-12-2010, 02:18 PM   #11
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QuoteOriginally posted by SergioFromSF Quote
...yes, I have the AI-s version of the lens.
Tried to fit it into K-7 gently, could not.
So for now I gave up in the idea.
I'll take it off your hands if you can't use it.
08-12-2010, 02:28 PM   #12
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I'd even give you a couple bucks for it!
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