Spotmatic F: non-Pentax lenses won't mount

BarneyL · 02-11-2018, 11:51 AM

Hello everyone,

Besides old-but-gold S-M-C Takumars, I have a few M42 lenses from other manufacturers. I wanted to try them on Spotmatic F, but it seems not every one of them would screw-in fully; some lenses just 'bounce off' something after few screw motions and the camera won't let them go further.

Preset/non-auto pin lenses work fine. Some of the auto-pin glass don't. I tried with Auto Mamiya/Sekor 135/2.8 - works fine, but Auto Mamiya/Sekor 55/1.4 will not mount (these are not SX-type, but older TL/DTL). Rollei 85/2.8 won't mount either.

Does anyone know if it is the case with all Spotmatic-Fs (and maybe other open-aperture metering bodies, like ES II), or do I have some sort of a defective model?

All the best

MarkJerling · 02-11-2018, 03:20 PM

Are you sure the lenses that won't mount are M42? They could be T-mount which is also a 42mm diameter, but a different thread.

**TomB_tx** · 02-11-2018, 03:40 PM

I just checked the Mamiya 55 1.4 on my F, and you are right. The rear element is too large and extends deep enough to interfere with the added linkage in the F that detects the aperture setting. That lens does work well on. The Spotmatic and Spotmatic II and is a very good lens.

Wasp · 02-12-2018, 05:53 AM

Originally posted by MarkJerling

Are you sure the lenses that won't mount are M42? They could be T-mount which is also a 42mm diameter, but a different thread.

Seems the most likely explanation to me.

timw4mail · 02-12-2018, 08:28 AM

Most likely, there's a rear-element that extends too far, or some other aspect of the lens that is larger than the M42-ES variant that the Spotmatic F uses.

Pentax sometimes had its own compatibility problems, as there were some pre-Spotmatic M42 bodies that couldn't mount the 50/1.4 lens. With the same model number, only the later variant of the body could use the 50/1.4 lens.

As great as the M42 mount is in terms of diversity, there are bound to be issues. If you want to mount any M42 lens, you're best off using a body that doesn't have the auto-aperture lever.

02-11-2018, 11:51 AM	#1
BarneyL Pentaxian Join Date: Feb 2017 Posts: 899	Spotmatic F: non-Pentax lenses won't mount Hello everyone, Besides old-but-gold S-M-C Takumars, I have a few M42 lenses from other manufacturers. I wanted to try them on Spotmatic F, but it seems not every one of them would screw-in fully; some lenses just 'bounce off' something after few screw motions and the camera won't let them go further. Preset/non-auto pin lenses work fine. Some of the auto-pin glass don't. I tried with Auto Mamiya/Sekor 135/2.8 - works fine, but Auto Mamiya/Sekor 55/1.4 will not mount (these are not SX-type, but older TL/DTL). Rollei 85/2.8 won't mount either. Does anyone know if it is the case with all Spotmatic-Fs (and maybe other open-aperture metering bodies, like ES II), or do I have some sort of a defective model? All the best

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
adapters for non-K-mount lenses to Pentax K-mount DSLRs: new dimensions for LBA	Douglas_of_Sweden	Pentax Camera and Field Accessories	154	07-10-2020 10:57 AM
Architecture I won, I won, I won	Culture	Post Your Photos!	12	11-13-2015 11:34 PM
DA-L and non * / non ltd lenses to be DC ?	formercanuck	Pentax SLR Lens Discussion	10	01-09-2015 06:56 PM
People Sigma 70-200mm (non DG, non macro, non HSM)	Just12hvFun	Post Your Photos!	7	04-17-2010 10:49 PM

02-11-2018, 03:20 PM	#2
MarkJerling Moderator Site Supporter Join Date: May 2012 Location: Wairarapa, New Zealand Photos: Gallery \| Albums Posts: 20,421	Are you sure the lenses that won't mount are M42? They could be T-mount which is also a 42mm diameter, but a different thread.

02-11-2018, 03:40 PM	#3
TomB_tx Loyal Site Supporter Join Date: Jun 2011 Location: Texas Photos: Gallery Posts: 1,446	I just checked the Mamiya 55 1.4 on my F, and you are right. The rear element is too large and extends deep enough to interfere with the added linkage in the F that detects the aperture setting. That lens does work well on. The Spotmatic and Spotmatic II and is a very good lens.

02-12-2018, 05:53 AM	#4
Wasp Pentaxian Join Date: Mar 2017 Location: Pretoria Photos: Gallery Posts: 4,661	Originally posted by MarkJerling Are you sure the lenses that won't mount are M42? They could be T-mount which is also a 42mm diameter, but a different thread. Seems the most likely explanation to me.

02-12-2018, 08:28 AM	#5
timw4mail Pentaxian Join Date: Apr 2017 Location: Driving a Mirage Photos: Gallery \| Albums Posts: 1,670	Most likely, there's a rear-element that extends too far, or some other aspect of the lens that is larger than the M42-ES variant that the Spotmatic F uses. Pentax sometimes had its own compatibility problems, as there were some pre-Spotmatic M42 bodies that couldn't mount the 50/1.4 lens. With the same model number, only the later variant of the body could use the 50/1.4 lens. As great as the M42 mount is in terms of diversity, there are bound to be issues. If you want to mount any M42 lens, you're best off using a body that doesn't have the auto-aperture lever.