Zeiss Tessar Vorwahlspringblende

**Cerebum** · 06-30-2021, 01:12 PM - **1 Like**

Some people will probably already know this, also, the below may not be the same on every copy, but i am assuming it is.

I was using this old (1958) silver Tessar on my S1a and I discovered something

The Tessar has an aperture pin but no A/M switch. To set the aperture you push the ring back against the spring, turn it to the chosen aperture then release it. To open the aperture for focusing you turn the same ring as you would with a preset. Where this differs is that turning the ring locks the aperture open until the pin is depressed by the camera body, at which point it stops down.

This is great to use with an S1a but presumably a film camera with in built metering would require you to meter before fine focusing.

As for using it with a DSLR, you need an M42 adapter with an internal flange, otherwise you run the risk of being stuck wide open.

**othar** · 06-30-2021, 02:12 PM

Originally posted by Cerebum

Some people will probably already know this, also, the below may not be the same on every copy, but i am assuming it is.

I was using this old (1958) silver Tessar on my S1a and I discovered something

The Tessar has an aperture pin but no A/M switch. To set the aperture you push the ring back against the spring, turn it to the chosen aperture then release it. To open the aperture for focusing you turn the same ring as you would with a preset. Where this differs is that turning the ring locks the aperture open until the pin is depressed by the camera body, at which point it stops down.

This is great to use with an S1a but presumably a film camera with in built metering would require you to meter before fine focusing.

As for using it with a DSLR, you need an M42 adapter with an internal flange, otherwise you run the risk of being stuck wide open.

I have a 135mm lens with a similar aperture mechanism (I don't have it with me and can't remember the name at the moment). It has a threaded hole on the barrel next to the mount, I guess the lens can be stopped down with an old cable release when used with an adapter without internal flange

stevebrot · 06-30-2021, 03:11 PM

Originally posted by Cerebum

The Tessar has an aperture pin but no A/M switch. To set the aperture you push the ring back against the spring, turn it to the chosen aperture then release it. To open the aperture for focusing you turn the same ring as you would with a preset. Where this differs is that turning the ring locks the aperture open until the pin is depressed by the camera body, at which point it stops down.

What you described is sometimes called "semi-auto" aperture actuation and is similar to the mechanism used with Asahi Auto-Takumar lenses having the cocking lever. With a camera such as the Spotmatic, it is important to meter before cocking the lens. When adapted to K-mount or non-Pentax cameras, take care to operate as a full manual aperture lens (don't cock the lens).

Steve

**Cerebum** · 06-30-2021, 03:48 PM

Originally posted by stevebrot

What you described is sometimes called "semi-auto" aperture actuation and is similar to the mechanism used with Asahi Auto-Takumar lenses having the cocking lever. With a camera such as the Spotmatic, it is important to meter before cocking the lens. When adapted to K-mount or non-Pentax cameras, take care to operate as a full manual aperture lens (don't cock the lens).

Steve

I have an adapter, I think it’s a Kipon, with an internal flange, just for this lens. It was hard to find and is a very tight fit. I had to take a hair off the circumference so it would fit. It works though, and thankfully doesn’t jam. Using it means the tessar works like a preset

it is a lovely lens

In truth, I just wanted to get “vorwahlsprungblende” into the thread list

Last edited by Cerebum; 06-30-2021 at 03:56 PM.

06-30-2021, 01:12 PM - 1 Like	#1
Cerebum Site Supporter Join Date: Oct 2017 Location: Lancaster Photos: Gallery Posts: 3,829	Zeiss Tessar Vorwahlspringblende Some people will probably already know this, also, the below may not be the same on every copy, but i am assuming it is. I was using this old (1958) silver Tessar on my S1a and I discovered something The Tessar has an aperture pin but no A/M switch. To set the aperture you push the ring back against the spring, turn it to the chosen aperture then release it. To open the aperture for focusing you turn the same ring as you would with a preset. Where this differs is that turning the ring locks the aperture open until the pin is depressed by the camera body, at which point it stops down. This is great to use with an S1a but presumably a film camera with in built metering would require you to meter before fine focusing. As for using it with a DSLR, you need an M42 adapter with an internal flange, otherwise you run the risk of being stuck wide open.

06-30-2021, 03:11 PM	#3
stevebrot Otis Memorial Pentaxian Join Date: Mar 2007 Location: Vancouver (USA) Photos: Gallery \| Albums Posts: 42,007	Originally posted by Cerebum The Tessar has an aperture pin but no A/M switch. To set the aperture you push the ring back against the spring, turn it to the chosen aperture then release it. To open the aperture for focusing you turn the same ring as you would with a preset. Where this differs is that turning the ring locks the aperture open until the pin is depressed by the camera body, at which point it stops down. What you described is sometimes called "semi-auto" aperture actuation and is similar to the mechanism used with Asahi Auto-Takumar lenses having the cocking lever. With a camera such as the Spotmatic, it is important to meter before cocking the lens. When adapted to K-mount or non-Pentax cameras, take care to operate as a full manual aperture lens (don't cock the lens). Steve Last edited by stevebrot; 06-30-2021 at 03:16 PM.

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06-30-2021, 02:12 PM	#2
othar Site Supporter Join Date: May 2014 Location: Linz Photos: Albums Posts: 3,098	Originally posted by Cerebum Some people will probably already know this, also, the below may not be the same on every copy, but i am assuming it is. I was using this old (1958) silver Tessar on my S1a and I discovered something The Tessar has an aperture pin but no A/M switch. To set the aperture you push the ring back against the spring, turn it to the chosen aperture then release it. To open the aperture for focusing you turn the same ring as you would with a preset. Where this differs is that turning the ring locks the aperture open until the pin is depressed by the camera body, at which point it stops down. This is great to use with an S1a but presumably a film camera with in built metering would require you to meter before fine focusing. As for using it with a DSLR, you need an M42 adapter with an internal flange, otherwise you run the risk of being stuck wide open. I have a 135mm lens with a similar aperture mechanism (I don't have it with me and can't remember the name at the moment). It has a threaded hole on the barrel next to the mount, I guess the lens can be stopped down with an old cable release when used with an adapter without internal flange

06-30-2021, 03:48 PM	#4
Cerebum Site Supporter Join Date: Oct 2017 Location: Lancaster Photos: Gallery Posts: 3,829 Original Poster	Originally posted by stevebrot What you described is sometimes called "semi-auto" aperture actuation and is similar to the mechanism used with Asahi Auto-Takumar lenses having the cocking lever. With a camera such as the Spotmatic, it is important to meter before cocking the lens. When adapted to K-mount or non-Pentax cameras, take care to operate as a full manual aperture lens (don't cock the lens). Steve I have an adapter, I think it’s a Kipon, with an internal flange, just for this lens. It was hard to find and is a very tight fit. I had to take a hair off the circumference so it would fit. It works though, and thankfully doesn’t jam. Using it means the tessar works like a preset it is a lovely lens In truth, I just wanted to get “vorwahlsprungblende” into the thread list Last edited by Cerebum; 06-30-2021 at 03:56 PM.