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**gordon_l34** · 10-11-2014, 03:05 AM

Hi All,

I have the above lens and took it out today the first or time. The aperture ring is locked on f4.5. The rear ring moves very slightly and the blades do as well. What is the front aperture ring for which appears to be locked?
Hopefully it does not need a visit to my camera repairer.

Yours in anticipation.

**seventhdr** · 10-11-2014, 03:36 AM

This lens works like the SMC Pentax Shift 28mm f23.5 lens for K mount.

One aperture ring has click stops on it and actually stops down the lens.

The other aperture ring turns between the fully open aperture and the aperture set on the first aperture ring. This allows you to set the desired aperture on the first ring and quickly change from the open aperture to the set aperture by turning the second ring. the reason for this is that the aperture is not coupled to the lens mount, so there is no way for the camera to move the aperture to the set value when an exposure is take.

Regards

Chris

**gofour3** · 10-11-2014, 08:30 AM

Originally posted by gordon_l34

Hi All,

I have the above lens and took it out today the first or time. The aperture ring is locked on f4.5. The rear ring moves very slightly and the blades do as well. What is the front aperture ring for which appears to be locked?
Hopefully it does not need a visit to my camera repairer.

Yours in anticipation.

The 75/4.5 shift is a preset aperture lens

Here is a copy of the manual:

Pentax 67 75/4.5 Shift Manual pdf

Phil.

desertscape · 10-11-2014, 10:09 AM

So, this lens has a single diaphragm with two actuation rings?

**gordon_l34** · 10-11-2014, 05:38 PM

Hi All,

Thanks for the link gofour3. everything is alright on the lens now that I have read the instruction manual!

Regards.

**gofour3** · 10-13-2014, 09:12 PM

Originally posted by desertscape

So, this lens has a single diaphragm with two actuation rings?

Correct. The first preset ring you select the shooting aperture you want and set the actual aperture to f/4.5.

After focusing, you turn the aperture ring until it stops at the previously selected “preset” aperture.

Would have been easier/better to make this lens a straight manual diaphragm lens and remove the preset ring. The K28/3.5 Shift works the same way.

Phil.

desertscape · 10-14-2014, 05:57 PM

Thanks Phil; that is one of the few lenses that I have never owned.

10-11-2014, 03:05 AM	#1
gordon_l34 Loyal Site Supporter Join Date: Sep 2008 Location: Brisbane, Australia Photos: Gallery \| Albums Posts: 779	SMC Pentax 6x7 Shift 1:4.5 75mm Hi All, I have the above lens and took it out today the first or time. The aperture ring is locked on f4.5. The rear ring moves very slightly and the blades do as well. What is the front aperture ring for which appears to be locked? Hopefully it does not need a visit to my camera repairer. Yours in anticipation.

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10-11-2014, 03:36 AM	#2
seventhdr Site Supporter Join Date: Mar 2007 Location: Christchurch, New Zealand Photos: Gallery Posts: 1,453	This lens works like the SMC Pentax Shift 28mm f23.5 lens for K mount. One aperture ring has click stops on it and actually stops down the lens. The other aperture ring turns between the fully open aperture and the aperture set on the first aperture ring. This allows you to set the desired aperture on the first ring and quickly change from the open aperture to the set aperture by turning the second ring. the reason for this is that the aperture is not coupled to the lens mount, so there is no way for the camera to move the aperture to the set value when an exposure is take. Regards Chris

10-11-2014, 08:30 AM	#3
gofour3 Site Supporter Join Date: Oct 2008 Location: Vancouver, Canada Posts: 8,093	Originally posted by gordon_l34 Hi All, I have the above lens and took it out today the first or time. The aperture ring is locked on f4.5. The rear ring moves very slightly and the blades do as well. What is the front aperture ring for which appears to be locked? Hopefully it does not need a visit to my camera repairer. Yours in anticipation. The 75/4.5 shift is a preset aperture lens Here is a copy of the manual: Pentax 67 75/4.5 Shift Manual pdf Phil.

10-11-2014, 10:09 AM	#4
desertscape Pentaxian Join Date: Feb 2009 Location: Arizona Posts: 1,272	So, this lens has a single diaphragm with two actuation rings?

10-11-2014, 05:38 PM	#5
gordon_l34 Loyal Site Supporter Join Date: Sep 2008 Location: Brisbane, Australia Photos: Gallery \| Albums Posts: 779 Original Poster	Hi All, Thanks for the link gofour3. everything is alright on the lens now that I have read the instruction manual! Regards.

10-13-2014, 09:12 PM	#6
gofour3 Site Supporter Join Date: Oct 2008 Location: Vancouver, Canada Posts: 8,093	Originally posted by desertscape So, this lens has a single diaphragm with two actuation rings? Correct. The first preset ring you select the shooting aperture you want and set the actual aperture to f/4.5. After focusing, you turn the aperture ring until it stops at the previously selected “preset” aperture. Would have been easier/better to make this lens a straight manual diaphragm lens and remove the preset ring. The K28/3.5 Shift works the same way. Phil.

10-14-2014, 05:57 PM	#7
desertscape Pentaxian Join Date: Feb 2009 Location: Arizona Posts: 1,272	Thanks Phil; that is one of the few lenses that I have never owned.

SMC Pentax 6x7 Shift 1:4.5 75mm

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