M42 Lens Question

DILWORTH · 06-03-2008, 07:18 PM

ON the m42 pentax lenses their is a slide switch for auto or manual. Which do you set it to when using on a pentax adaptor on a digital camera thanks .....

KungPOW · 06-03-2008, 07:47 PM

Use it to stop the lens down before you take a photo.

The K mount does not has the mechanism to automatically stop the lens down when the photo is taken.

maxwell1295 · 06-03-2008, 07:56 PM

It should be set to Manual.

ryan s · 06-03-2008, 09:26 PM

Originally posted by maxwell1295

It should be set to Manual.

+1 for manual...

Big Dave · 06-03-2008, 10:56 PM

If you don't set it to manual, the lens will remain wide open, regardless of the f-stop setting.

Dave

**pentagor** · 06-03-2008, 11:05 PM

I set it to manual and use Av setting on the body. The focusing is somehow tough at small apertures, but it does work.
I'm not used to stole the topic, but the focus confirmation does not work with M42 lenses. Is this normal?

frank · 06-03-2008, 11:47 PM

You can set it to auto for focusing (the lens is wide open now, easier to focus), then move it to manual to take the shot (at your setting aperture). This works the best for small apertures and w/ a tripod

frank · 06-03-2008, 11:51 PM

Originally posted by pentagor

I set it to manual and use Av setting on the body. The focusing is somehow tough at small apertures, but it does work.
I'm not used to stole the topic, but the focus confirmation does not work with M42 lenses. Is this normal?

As I said above, you can set it to auto to focus first, then shift to manual to take the shot.

The focus confirmation should work w/ the original M42 to K adapter, as long as you got enough light (aperture is big enough).

Mechan1k · 06-04-2008, 01:19 AM

Frank ... I never thought of doing that .... I notice the VF go dark ... and focus confirmation was hard to get ... plus me squinting at the same time ... hee hee.

I might try that next time.

Zewrak · 06-04-2008, 01:39 AM

You got a k100d, I think there is a setting in the menus for focus confirmation to work. "something screwmount something". On the K10D it works out of the box. You on the other hand have Focus trapping on m42 out of the box, K10D don't unless its wide enough to short the contacts. Which is annoying.

**pentagor** · 06-04-2008, 01:45 AM

Originally posted by Zewrak

You got a k100d, I think there is a setting in the menus for focus confirmation to work. "something screwmount something". On the K10D it works out of the box. You on the other hand have Focus trapping on m42 out of the box, K10D don't unless its wide enough to short the contacts. Which is annoying.

Sorry for a dumb question: what is focus trapping?

Zewrak · 06-04-2008, 02:00 AM

Originally posted by pentagor

Sorry for a dumb question: what is focus trapping?

When you hold the shutter release pressed down fully and then focus. When something gains focus the shot is taken. It wont take a shot until your in focus. You need to have the camera set in Autofocus mode though.

It's great for flying birds etc just keep the button pressed down and everytime you get focus in on that bird, a shot is taken (given that you have rapid fire set).

Also very useful when you have long teles.

Transit · 06-04-2008, 02:02 AM

There are no dumb questions

Trap focus is when you stick the camera on autofocus (switch on front left of cam)
with a manual focus lens. Depress shutter release fully then slowly focus lens.
The shot will be taken when the camera is happy with focus

The cam will only release the shutter when it thinks focus is achieved.

I'm sure someone else can explain it better

cheers
Pete

**pentagor** · 06-04-2008, 02:06 AM

Oh, thanks. I know the functionality, but I didn't know what it is called.

Arjay Bee · 06-04-2008, 02:41 AM

Some M42 lenses prior to A/M switch incorporation have a very small lens barrel and the pin that actuates the aperture does not strike against any object on the dslr body. In order to close down the aperture to the ring value the pin needs to be held in somehow. I used a nylon tube drilled out to act as a sleeve, removed the back plate of the lens and cut the sleeve to sit between the plate and the heel of the pin. Problem solved and easily reversed.
There is now a constant tension on the aperture return springs - somust remember to store the lens at the widest aperture.

06-03-2008, 07:18 PM	#1
DILWORTH New Member Join Date: Feb 2007 Location: WINNIPEG Photos: Gallery Posts: 17	M42 Lens Question ON the m42 pentax lenses their is a slide switch for auto or manual. Which do you set it to when using on a pentax adaptor on a digital camera thanks .....

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06-03-2008, 07:47 PM	#2
KungPOW Veteran Member Join Date: Nov 2007 Location: Vancouver, Canada Photos: Gallery Posts: 1,699	Use it to stop the lens down before you take a photo. The K mount does not has the mechanism to automatically stop the lens down when the photo is taken.

06-03-2008, 07:56 PM	#3
maxwell1295 Veteran Member Join Date: Jan 2008 Location: Long Island, New York Photos: Gallery Posts: 2,703	It should be set to Manual.

06-03-2008, 09:26 PM	#4
ryan s Veteran Member Join Date: Jan 2008 Location: Madison, WI Photos: Gallery Posts: 2,383	Originally posted by maxwell1295 It should be set to Manual. +1 for manual...

06-03-2008, 10:56 PM	#5
Big Dave Veteran Member Join Date: Jan 2008 Location: San Antonio, Texas Photos: Gallery Posts: 547	If you don't set it to manual, the lens will remain wide open, regardless of the f-stop setting. Dave

06-03-2008, 11:05 PM	#6
pentagor Site Supporter Join Date: Dec 2007 Location: Ljubljana, Slovenia Posts: 495	I set it to manual and use Av setting on the body. The focusing is somehow tough at small apertures, but it does work. I'm not used to stole the topic, but the focus confirmation does not work with M42 lenses. Is this normal?

06-03-2008, 11:47 PM	#7
frank Veteran Member Join Date: Nov 2006 Location: Singapore Photos: Gallery Posts: 3,202	You can set it to auto for focusing (the lens is wide open now, easier to focus), then move it to manual to take the shot (at your setting aperture). This works the best for small apertures and w/ a tripod

06-03-2008, 11:51 PM	#8
frank Veteran Member Join Date: Nov 2006 Location: Singapore Photos: Gallery Posts: 3,202	Originally posted by pentagor I set it to manual and use Av setting on the body. The focusing is somehow tough at small apertures, but it does work. I'm not used to stole the topic, but the focus confirmation does not work with M42 lenses. Is this normal? As I said above, you can set it to auto to focus first, then shift to manual to take the shot. The focus confirmation should work w/ the original M42 to K adapter, as long as you got enough light (aperture is big enough).

06-04-2008, 01:19 AM	#9
Mechan1k Veteran Member Join Date: Jun 2007 Location: Sydney, Australia Posts: 2,891	Frank ... I never thought of doing that .... I notice the VF go dark ... and focus confirmation was hard to get ... plus me squinting at the same time ... hee hee. I might try that next time.

06-04-2008, 01:39 AM	#10
Zewrak Veteran Member Join Date: Mar 2008 Location: Nowhere, Sweden Photos: Gallery Posts: 654	You got a k100d, I think there is a setting in the menus for focus confirmation to work. "something screwmount something". On the K10D it works out of the box. You on the other hand have Focus trapping on m42 out of the box, K10D don't unless its wide enough to short the contacts. Which is annoying.

06-04-2008, 01:45 AM	#11
pentagor Site Supporter Join Date: Dec 2007 Location: Ljubljana, Slovenia Posts: 495	Originally posted by Zewrak You got a k100d, I think there is a setting in the menus for focus confirmation to work. "something screwmount something". On the K10D it works out of the box. You on the other hand have Focus trapping on m42 out of the box, K10D don't unless its wide enough to short the contacts. Which is annoying. Sorry for a dumb question: what is focus trapping?

06-04-2008, 02:00 AM	#12
Zewrak Veteran Member Join Date: Mar 2008 Location: Nowhere, Sweden Photos: Gallery Posts: 654	Originally posted by pentagor Sorry for a dumb question: what is focus trapping? When you hold the shutter release pressed down fully and then focus. When something gains focus the shot is taken. It wont take a shot until your in focus. You need to have the camera set in Autofocus mode though. It's great for flying birds etc just keep the button pressed down and everytime you get focus in on that bird, a shot is taken (given that you have rapid fire set). Also very useful when you have long teles.

06-04-2008, 02:02 AM	#13
Transit Pentaxian Join Date: Aug 2007 Location: Whanganui NZ Photos: Gallery \| Albums Posts: 4,624	There are no dumb questions Trap focus is when you stick the camera on autofocus (switch on front left of cam) with a manual focus lens. Depress shutter release fully then slowly focus lens. The shot will be taken when the camera is happy with focus The cam will only release the shutter when it thinks focus is achieved. I'm sure someone else can explain it better cheers Pete

06-04-2008, 02:06 AM	#14
pentagor Site Supporter Join Date: Dec 2007 Location: Ljubljana, Slovenia Posts: 495	Oh, thanks. I know the functionality, but I didn't know what it is called.

06-04-2008, 02:41 AM	#15
Arjay Bee Pentaxian Join Date: Sep 2006 Location: Horn Island, Torres Straits, Q Photos: Gallery Posts: 4,715	Some M42 lenses prior to A/M switch incorporation have a very small lens barrel and the pin that actuates the aperture does not strike against any object on the dslr body. In order to close down the aperture to the ring value the pin needs to be held in somehow. I used a nylon tube drilled out to act as a sleeve, removed the back plate of the lens and cut the sleeve to sit between the plate and the heel of the pin. Problem solved and easily reversed. There is now a constant tension on the aperture return springs - somust remember to store the lens at the widest aperture.