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01-17-2007, 04:28 PM   #1
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how to use prime lens with K100D?

Bit of a milestone here today. UPS just delivered a lens that represents two firsts for me: my first used lens, and my first prime or fixed-focal-length lens. It's an smc Pentax-M 1:1.4 50mm lens. I purchased it from KEH.com for $115; condition is excellent.

Problem is, I'm having some difficulty figuring out how to use the darned thing.

When I turn the camera on, the LCD now shows me a Shake Reduction screen that I don't understand. It seems to be asking the focal length of the lens. I set it so that it says

<[40 50 55]>

which has to be right. It's a 50mm lens, after all.

I also went to Menu > Custom Setting > Using aperture ring, and set it to 2 ("Permitted"). The on-screen help says "Pictures can be taken even when aperture ring position is other than A." I do not understand this. I don't know what the aperture ring is, and I don't anywhere see an "A" setting. Nevertheless, this was originally on 1 ("Prohibited") and the camera didn't work with this new lens attached at all then. It worked when I changed this setting, so I assume that's the right thing to do.

The camera does not appear to know what the f-stop value is. Is that just the way it is? Kind of a bummer. It doesn't appear to be possible with this lens attached to set the exposure automatically at all since the camera has no idea what the aperture is. What am I missing?

And as far as I can tell, I [can't] use auto-focus while this lens is attached. The shutter simply won't depress at all.

Anybody have experience with this sort of thing? I have managed to take a few pictures so far. At the moment, to be honest, I'm either disappointed or frustrated; not sure which. Manual focusing is difficult - I can't quite tell if the picture is in focus or not. And depth of field seems pretty shallow as you might expect at f/1.4, so focus becomes critical. I'm getting the impression this may be a lens useful only for special kinds of shots.

Thanks in advance,

Will


Last edited by WMBP; 01-17-2007 at 07:36 PM. Reason: Added "can't" in antepenultimate paragraph before "use auto-focus..."
01-17-2007, 04:50 PM   #2
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Will, I haven't got an M lens to try out and my camera is the K10D, so things may be slightly different, but I can give you some early help, and others will no doubt fill in.

You were right to set the Anti shake to 50 for a 50mm lens. This is because the amount of movement in the sensor for shake reduction is different depending on the focal length of the lens, so when using a lens that the system can't detect you need to give it a bit of help.

Your M lens doesn't have an A setting on the aperture ring, so you are correct to set the camera to allow use of aperture ring. The A setting came in with the A lenses (surprise ;-) ). The aperture ring is the one with numbers such as 1.4, 1.7, 2, 4, 5.6... on it (sorry if I am insulting your level of knowledge here, but you said you didn't know what the aperture ring was). This sets the aperture you will be using.

Using an M lens it is likely that the camera won't know the aperture that is set. There have been various threads on what modes will and will not work with M and K series lenses (which are mechanically similar as far as I am aware).

The K10D manual has a section "Notes on [Using Aperture Ring]". I suspect your manual will too. In brief:

Av mode - aperture remains open regardless of aperture ring position. (Some people have said that you can activate the depth of field preview at the same time as pressing the shutter release to stop down to the selected aperture)

M mode - Pictures can be taken with the set aperture and shutter speed.

So the lens is probably going to be useful to you mainly in manual mode.

On my K10D I can set autofocus (AF-S) with a manual focus lens, but the camera will only let me fire the shutter if it thinks it is in focus (the focus found light is lit). If I set the camera to manual focus (MF) the focus check still works, but there is nothing preventing me from firing the shutter when it is not in focus (it took a while to work that one out).

I hope this helps.

Simon
01-17-2007, 04:51 PM   #3
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QuoteOriginally posted by WMBP Quote
Bit of a milestone here today. UPS just delivered a lens that represents two firsts for me: my first used lens, and my first prime or fixed-focal-length lens. It's an smc Pentax-M 1:1.4 50mm lens. I purchased it from KEH.com for $115; condition is excellent.

Problem is, I'm having some difficulty figuring out how to use the darned thing.

When I turn the camera on, the LCD now shows me a Shake Reduction screen that I don't understand. It seems to be asking the focal length of the lens. I set it so that it says

<[40 50 55]>

which has to be right. It's a 50mm lens, after all.

I also went to Menu > Custom Setting > Using aperture ring, and set it to 2 ("Permitted"). The on-screen help says "Pictures can be taken even when aperture ring position is other than A." I do not understand this. I don't know what the aperture ring is, and I don't anywhere see an "A" setting. Nevertheless, this was originally on 1 ("Prohibited") and the camera didn't work with this new lens attached at all then. It worked when I changed this setting, so I assume that's the right thing to do.

The camera does not appear to know what the f-stop value is. Is that just the way it is? Kind of a bummer. It doesn't appear to be possible with this lens attached to set the exposure automatically at all since the camera has no idea what the aperture is. What am I missing?

And as far as I can tell, I use auto-focus while this lens is attached. The shutter simply won't depress at all.



Anybody have experience with this sort of thing? I have managed to take a few pictures so far. At the moment, to be honest, I'm either disappointed or frustrated; not sure which. Manual focusing is difficult - I can't quite tell if the picture is in focus or not. And depth of field seems pretty shallow as you might expect at f/1.4, so focus becomes critical. I'm getting the impression this may be a lens useful only for special kinds of shots.

Thanks in advance,

Will
Put the wheel at "M". Set the switch to "MF". Set the lens to the apeture you want. Half depress the shutter button so display in view finder lights up. Rotate the focus ring until you hear the beep or see the red square.
Yare now focused. Press the green button and it will set the shutter speed. Take the photo. Look at histgram to check shutter speed.

Once you can do all that move on to "AF". Put the switch in "AF". Do everything the same way you did before. Move the camera to an area that will not be in focus and press the shutter button and hold it down. It won't take the photo. With the shutter button still depressed move the camera back to the in focus area. When you cross it the camera will take the photo.
Regards,

Last edited by regken; 01-17-2007 at 05:17 PM. Reason: Added info
01-17-2007, 05:11 PM   #4
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QuoteOriginally posted by WMBP Quote
smc Pentax-M 1:1.4 50mm lens.
Envy, envy - I have the f2 version that everyone looks down on. Apparently that f1.4 is niiiice.

QuoteQuote:
When I turn the camera on, the LCD now shows me a Shake Reduction screen that I don't understand. It seems to be asking the focal length of the lens. I set it so that it says

<[40 50 55]>

which has to be right. It's a 50mm lens, after all.
That's all correct. And only relevant if you're going to turn SR on, but I assume you got the lens for low light, so you will.

QuoteQuote:
I also went to Menu > Custom Setting > Using aperture ring, and set it to 2 ("Permitted"). The on-screen help says "Pictures can be taken even when aperture ring position is other than A." I do not understand this. I don't know what the aperture ring is, and I don't anywhere see an "A" setting. Nevertheless, this was originally on 1 ("Prohibited") and the camera didn't work with this new lens attached at all then. It worked when I changed this setting, so I assume that's the right thing to do.
Yes, you need it set to 2. The aperture ring is the narrow ring with all the little numbers on it. It's an "M" lens, so it has no "A" position. You set the aperture by turning the ring, rather than using the thumb wheel on the camera.

QuoteQuote:
The camera does not appear to know what the f-stop value is. Is that just the way it is? Kind of a bummer. It doesn't appear to be possible with this lens attached to set the exposure automatically at all since the camera has no idea what the aperture is.
The lens doesn't have the necessary contacts to talk to the camera - that technology didn't exist when it was built. And no, none of the automatic functions will work. You have to set the camera to M (manual). Then you can either press the AE-L button, or use the DOF preview (the little lever on the shutter button). Pressing AE-L stops the lens down momentarily, allowing the camera to meter the incoming light, and it then sets the appropriate shutter speed. You may need to set a menu option: custom settings, AE-L button on M expsr, set to 2: Tv shift. Using DOF preview will show you over- or under-exposure in the lower right of the viewfinder (e.g. -1.5) and you can change the shutter speed or aperture until it's 0.0 (or something else if you're getting fancy).

QuoteQuote:
And as far as I can tell, I use auto-focus while this lens is attached. The shutter simply won't depress at all.
I don't quite follow you here, but this is a manual lens, so you'll want to put the camera to MF and focus manually.

QuoteQuote:
Manual focusing is difficult - I can't quite tell if the picture is in focus or not. And depth of field seems pretty shallow as you might expect at f/1.4, so focus becomes critical. I'm getting the impression this may be a lens useful only for special kinds of shots.
Practice, practice, practice. You might want to consider an eyepiece magnifier or a Katzeye screen, I have neither but have heard good things about both - do a search and I'm sure you'll find more info than you need.

Once you get used to the slightly clunky metering, these manual lenses are a joy to use, in my opinion. I love the nice firm manual focus, and having cut my teeth on a fully manual camera, I also enjoy the clicky aperture ring. Don't give up on it, you'll adjust and I hope enjoy the lens. If not, you can always send it to me!

Julie

01-17-2007, 05:43 PM   #5
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