Mounitng M42 lenses on K100D Super

scimitar12 · 01-15-2010, 01:35 PM

After several years using many Pentax film cameras I made the jump the other day and picked up a really nice K100D Super. I have a truck load of M42s, Kmounts, Ms, As, and auto focus lenses, mostly Pentax, but some from other manufacturers.

After going through the original owner's manual and the Magic Lantern manual I do not see any explanation how to mount and use an m42 screwmount lens to the camera. I know the limitations (I think), but I guess I need a structured list of what to do. I do have an orginal Pentac lens adapter, so I am good there. Sorry if this has been answered before.

**Rense** · 01-15-2010, 01:42 PM

Don't know if I understand your question right. I use many M42 lenses on my K20, and it has become a second habit to mount and use them.

Of course you have to mount the adapter and screw the lens on the body.
Make it possible to use the aperture, by selecting this in one of the menu items in your K100D (at least this has to be done in my K20, and also in the K10 and K-7)
Be aware the camera doesn't control the aperture, you have to do it by hand!
Put your camera on Av (that is how I use my M42 lenses always)
Set the aperture, focus, shoot.

It's quite easy, realy! But probably I misunderstood your question

scimitar12 · 01-15-2010, 05:14 PM

Mounting the lens is the easy part. What I don't understand how to set the cameras controls to acknowledge a screwmount is in place. I will take your advice and check the menu items along with re-visiting the manuals.

Damn Brit · 01-15-2010, 05:23 PM

Here are a couple of threads that might help you - https://www.pentaxforums.com/forums/pentax-beginners-corner-q/59272-shooting-...x-dslrs-f.html and https://www.pentaxforums.com/forums/pentax-beginners-corner-q/60081-usage-green-button.html

I'm also moving this thread to Beginners Corner where it will do more good.

noblepa · 01-15-2010, 08:56 PM

Originally posted by scimitar12

Mounting the lens is the easy part. What I don't understand how to set the cameras controls to acknowledge a screwmount is in place. I will take your advice and check the menu items along with re-visiting the manuals.

I'm not sure I would say that the camera "acknowledges" that a screwmount lens is mounted.

First, when you mount the lens, you must tell the camera the focal length, so it knows how much shake reduction to apply. As soon as you mount the lens and the camera detects no information from the lens, it will display a menu of focal lengths. Choose the one that is closest to the lens you are using.

You must enable the use of the aperture ring in your menus. I have a K10D, so my menus are a little different.

Since the camera has no way to operate the aperture stop-down pin on an M42 lens, you must switch the lens to manual mode. All Pentax M42 lenses that I am aware of had such a switch. If your lens lacks the auto/manual switch, you are limited to shooting wide open, unless you figure out some way to keep the lens stopped down. My recommendation in that case; use a different lens, with the switch.

I use my 50mm, f/1.4 Super-Takumar with the camera in Av mode, sometimes M mode.

I just use the lens the way I did on my Spotmatic: I focus wide open, half-press the shutter to activate the meter, stop the lens down to the desired aperture (watching the shutter speed and adjusting the aperture if the speed gets out of line), recompose and shoot. I should note that I almost always leave my meter in center spot mode. Thus the need to recompose after metering.

That's really all there is to it.

If SR is turned on, the camera will record the focal length in the EXIF data, but not the aperture, since it has no way of knowing that. Unfortunately, if you turn SR off for some reason, like a tripod shot, the camera will not record the focal length.

Non-pentax lenses that lack the auto/manual switch are problematic. I simply avoid them. If you have a particular favorite, then you will have to figure out a way to keep the lens stopped down. Some people have opened up their lenses and jimmied something inside. Others have used superglue on the pin. I can't recommend any of these approaches.

Laurentiu Cristofor · 01-15-2010, 11:01 PM

Originally posted by noblepa

Since the camera has no way to operate the aperture stop-down pin on an M42 lens, you must switch the lens to manual mode.

noblepa's information is spot on, but on the above point I'd add that you don't have to switch to manual mode - M42 lenses, unlike K and M lenses, can be operated very nicely in Av mode.

Also, a lot of older Russian lenses (and the German ones they're based on as well) have nice aperture controls that allow you to preset the aperture, focus wide open, then turn a second aperture ring to stop down just before you shoot - this allows you to avoid recomposing after stopping down and makes shooting much faster and convenient. These aperture controls gave way to the auto mode which is useless on modern bodies and requires either a manual switch to operate or the pin surgery that noblepa mentioned. I don't think the surgery is that challenging - I've disassembled a few lenses and if you're careful, it is fun to clean them up and put them back together.

scimitar12 · 01-16-2010, 11:15 AM

Thanks all. I mounted one of myA lenses and took some shots. Works great. Will try some M lenses later as well as some M42s. The links provided by Damn Brit were great.

noblepa · 01-16-2010, 10:47 PM

Originally posted by Laurentiu Cristofor

noblepa's information is spot on, but on the above point I'd add that you don't have to switch to manual mode - M42 lenses, unlike K and M lenses, can be operated very nicely in Av mode.

Also, a lot of older Russian lenses (and the German ones they're based on as well) have nice aperture controls that allow you to preset the aperture, focus wide open, then turn a second aperture ring to stop down just before you shoot - this allows you to avoid recomposing after stopping down and makes shooting much faster and convenient. These aperture controls gave way to the auto mode which is useless on modern bodies and requires either a manual switch to operate or the pin surgery that noblepa mentioned. I don't think the surgery is that challenging - I've disassembled a few lenses and if you're careful, it is fun to clean them up and put them back together.

I did mention that I use my K10D in Av mode with my Super Takumar 50mm lens. I was really talking about putting the LENS into M mode. In Auto mode, an M42 lens remains open until the camera pushes the pin to stop it down. A dslr will never push that pin, so the lens can only be used wide open.

Putting the LENS (not necessarity the camera) into M mode fixes this, but always stopping the lens down to the opening indicated on the aperture ring.

scimitar12 · 01-17-2010, 09:50 AM

I think I got the hang of it. I mounted both A and M lenses and they work great. I will try the M42 later but I don't think it will be much different than mounting an M lens. And, I found this site which I believe was posted some time ago on this forum more than helpful; it uses the K100D Super as the example. The other suggestions were fine but they kept alluding to the green button. The K100 D Super does not have the green button and that kept throwing me off. The AE-L button does the same thing as the green button (at least in stopping down the lens).
K100D (Super) Pictorial guide to using manual lenses [imgs] [Page 1]: Pentax SLR Talk Forum: Digital Photography Review

Laurentiu Cristofor · 01-17-2010, 01:52 PM

Originally posted by noblepa

I was really talking about putting the LENS into M mode.

You're right - I read your statement too fast and I thought you mentioned manual mode of the camera, not of the lens. Sorry about that.

01-15-2010, 01:35 PM	#1
scimitar12 Forum Member Join Date: Apr 2009 Location: Sterling, VA Photos: Gallery Posts: 70	Mounitng M42 lenses on K100D Super After several years using many Pentax film cameras I made the jump the other day and picked up a really nice K100D Super. I have a truck load of M42s, Kmounts, Ms, As, and auto focus lenses, mostly Pentax, but some from other manufacturers. After going through the original owner's manual and the Magic Lantern manual I do not see any explanation how to mount and use an m42 screwmount lens to the camera. I know the limitations (I think), but I guess I need a structured list of what to do. I do have an orginal Pentac lens adapter, so I am good there. Sorry if this has been answered before.

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01-15-2010, 01:42 PM	#2
Rense Site Supporter Join Date: Dec 2008 Location: Zetten - The Netherlands Photos: Gallery \| Albums Posts: 9,050	Don't know if I understand your question right. I use many M42 lenses on my K20, and it has become a second habit to mount and use them. Of course you have to mount the adapter and screw the lens on the body. Make it possible to use the aperture, by selecting this in one of the menu items in your K100D (at least this has to be done in my K20, and also in the K10 and K-7) Be aware the camera doesn't control the aperture, you have to do it by hand! Put your camera on Av (that is how I use my M42 lenses always) Set the aperture, focus, shoot. It's quite easy, realy! But probably I misunderstood your question

01-15-2010, 05:14 PM	#3
scimitar12 Forum Member Join Date: Apr 2009 Location: Sterling, VA Photos: Gallery Posts: 70 Original Poster	Mounting the lens is the easy part. What I don't understand how to set the cameras controls to acknowledge a screwmount is in place. I will take your advice and check the menu items along with re-visiting the manuals.

01-15-2010, 05:23 PM	#4
Damn Brit Guest	Here are a couple of threads that might help you - https://www.pentaxforums.com/forums/pentax-beginners-corner-q/59272-shooting-...x-dslrs-f.html and https://www.pentaxforums.com/forums/pentax-beginners-corner-q/60081-usage-green-button.html I'm also moving this thread to Beginners Corner where it will do more good.

01-15-2010, 08:56 PM	#5
noblepa Veteran Member Join Date: Sep 2007 Location: Bay Village, Ohio USA Posts: 1,142	Originally posted by scimitar12 Mounting the lens is the easy part. What I don't understand how to set the cameras controls to acknowledge a screwmount is in place. I will take your advice and check the menu items along with re-visiting the manuals. I'm not sure I would say that the camera "acknowledges" that a screwmount lens is mounted. First, when you mount the lens, you must tell the camera the focal length, so it knows how much shake reduction to apply. As soon as you mount the lens and the camera detects no information from the lens, it will display a menu of focal lengths. Choose the one that is closest to the lens you are using. You must enable the use of the aperture ring in your menus. I have a K10D, so my menus are a little different. Since the camera has no way to operate the aperture stop-down pin on an M42 lens, you must switch the lens to manual mode. All Pentax M42 lenses that I am aware of had such a switch. If your lens lacks the auto/manual switch, you are limited to shooting wide open, unless you figure out some way to keep the lens stopped down. My recommendation in that case; use a different lens, with the switch. I use my 50mm, f/1.4 Super-Takumar with the camera in Av mode, sometimes M mode. I just use the lens the way I did on my Spotmatic: I focus wide open, half-press the shutter to activate the meter, stop the lens down to the desired aperture (watching the shutter speed and adjusting the aperture if the speed gets out of line), recompose and shoot. I should note that I almost always leave my meter in center spot mode. Thus the need to recompose after metering. That's really all there is to it. If SR is turned on, the camera will record the focal length in the EXIF data, but not the aperture, since it has no way of knowing that. Unfortunately, if you turn SR off for some reason, like a tripod shot, the camera will not record the focal length. Non-pentax lenses that lack the auto/manual switch are problematic. I simply avoid them. If you have a particular favorite, then you will have to figure out a way to keep the lens stopped down. Some people have opened up their lenses and jimmied something inside. Others have used superglue on the pin. I can't recommend any of these approaches.

01-15-2010, 11:01 PM	#6
Laurentiu Cristofor Banned Join Date: Nov 2009 Location: WA Photos: Albums Posts: 3,055	Originally posted by noblepa Since the camera has no way to operate the aperture stop-down pin on an M42 lens, you must switch the lens to manual mode. noblepa's information is spot on, but on the above point I'd add that you don't have to switch to manual mode - M42 lenses, unlike K and M lenses, can be operated very nicely in Av mode. Also, a lot of older Russian lenses (and the German ones they're based on as well) have nice aperture controls that allow you to preset the aperture, focus wide open, then turn a second aperture ring to stop down just before you shoot - this allows you to avoid recomposing after stopping down and makes shooting much faster and convenient. These aperture controls gave way to the auto mode which is useless on modern bodies and requires either a manual switch to operate or the pin surgery that noblepa mentioned. I don't think the surgery is that challenging - I've disassembled a few lenses and if you're careful, it is fun to clean them up and put them back together.

01-16-2010, 11:15 AM	#7
scimitar12 Forum Member Join Date: Apr 2009 Location: Sterling, VA Photos: Gallery Posts: 70 Original Poster	Thanks all. I mounted one of myA lenses and took some shots. Works great. Will try some M lenses later as well as some M42s. The links provided by Damn Brit were great.

01-16-2010, 10:47 PM	#8
noblepa Veteran Member Join Date: Sep 2007 Location: Bay Village, Ohio USA Posts: 1,142	Originally posted by Laurentiu Cristofor noblepa's information is spot on, but on the above point I'd add that you don't have to switch to manual mode - M42 lenses, unlike K and M lenses, can be operated very nicely in Av mode. Also, a lot of older Russian lenses (and the German ones they're based on as well) have nice aperture controls that allow you to preset the aperture, focus wide open, then turn a second aperture ring to stop down just before you shoot - this allows you to avoid recomposing after stopping down and makes shooting much faster and convenient. These aperture controls gave way to the auto mode which is useless on modern bodies and requires either a manual switch to operate or the pin surgery that noblepa mentioned. I don't think the surgery is that challenging - I've disassembled a few lenses and if you're careful, it is fun to clean them up and put them back together. I did mention that I use my K10D in Av mode with my Super Takumar 50mm lens. I was really talking about putting the LENS into M mode. In Auto mode, an M42 lens remains open until the camera pushes the pin to stop it down. A dslr will never push that pin, so the lens can only be used wide open. Putting the LENS (not necessarity the camera) into M mode fixes this, but always stopping the lens down to the opening indicated on the aperture ring.

01-17-2010, 09:50 AM	#9
scimitar12 Forum Member Join Date: Apr 2009 Location: Sterling, VA Photos: Gallery Posts: 70 Original Poster	I think I got the hang of it. I mounted both A and M lenses and they work great. I will try the M42 later but I don't think it will be much different than mounting an M lens. And, I found this site which I believe was posted some time ago on this forum more than helpful; it uses the K100D Super as the example. The other suggestions were fine but they kept alluding to the green button. The K100 D Super does not have the green button and that kept throwing me off. The AE-L button does the same thing as the green button (at least in stopping down the lens). K100D (Super) Pictorial guide to using manual lenses [imgs] [Page 1]: Pentax SLR Talk Forum: Digital Photography Review

01-17-2010, 01:52 PM	#10
Laurentiu Cristofor Banned Join Date: Nov 2009 Location: WA Photos: Albums Posts: 3,055	Originally posted by noblepa I was really talking about putting the LENS into M mode. You're right - I read your statement too fast and I thought you mentioned manual mode of the camera, not of the lens. Sorry about that.