Another "Frankenlens"

Fenwoodian · 08-26-2016, 07:18 AM - **1 Like**

Last night I adapted a Topcor 58mm f/1.4 lens to the Pentax K mount. This makes over 20 lenses that I've adapted to the Pentax K mount.

I bought it last week on Ebay for $100 USD. Other than some mold on the inside it's in great shape.

This Topcor lens is the "father" of the highly regarded Voigtlander 58mm 1.4 Nocton lens. It has the same optics, but obviously the Voigtlander has more modern coatings. Some reviews I've read state that the older Topcor produces a slightly better images at f/1.4 to f/2.8 than the Voigtlander does.

Here's some photos I took this morning at f/1.4 and f/2.0. I'd say the sharpness of this lens is just "average" (compared to the Pentax 50/2.8 Macro), however I really like the colors and bokeh that it produces.

If you don't mind manual focusing, there are lots of great old lenses out there that can be adapted for use on Pentax K cameras.

Last edited by Fenwoodian; 11-14-2016 at 08:49 PM.

ChristianRock · 08-26-2016, 07:38 AM

I'd say the sharpness is good enough for what it is! Great colors and bokeh.
Congrats on that project. Do you even have time to shoot all these lenses that you have?

a5m · 08-26-2016, 07:52 AM

I agree it looks plenty sharp and the colors and bokeh are amazing. The first picture of the red flower has a 3D pop to my eyes.

Good work! Might have to look into this myself since I've gained an interest in manual lenses recently. I also like the idea of modifying lenses to adapt them to Pentax; Reminds me of car upgrades or modifications where factory parts of a different car are used.

stevebrot · 08-26-2016, 08:15 AM - **1 Like**

Originally posted by Fenwoodian

This Topcor lens is the "father" of the highly regarded Voigtlander 58mm 1.4 Nocton lens. It has the same optics, but obviously the Voigtlander has more modern coatings. Some reviews I've read state that the older Topcor produces a slightly better images at f/1.4 to f/2.8 than the Voigtlander does.

Beautiful lens and good work making it usable on a modern body! I was surprised to read here that Cosina/Voigtlander based the Nokton 58/1.4 on the Topcor. Steve Gandy wrote otherwise when the Nokton first debuted in Topcor trim on the Bessaflex TM (LINK). I did a little Google work and came up with conflicting accounts. I eventually found a lens diagram on a Japanese Topcon fan site. Both lenses are Planar-derived, but differ in the details:

RE Auto-Topcor 58/1.4 (7 elements in 5 groups)

Image found at TOPCON CLUB-Various Talk-Drawing of Topcor Lens Cut

Voigtlander Nokton 58/1.4 (7 elements in 6 groups, sold in three different trims)

Image courtesy of Steve Gandy's cameraquest Web site, Voigtlander SL II Lenses

I don't know which lens I would rather have. The old Topcor has a great reputation, but the Nokton is also a credible lens and has modern coatings.

Steve

Last edited by stevebrot; 08-27-2016 at 01:18 PM. Reason: Corrected spelling

Fenwoodian · 08-26-2016, 08:20 AM

Originally posted by a5m

I agree it looks plenty sharp and the colors and bokeh are amazing. The first picture of the red flower has a 3D pop to my eyes.

Good work! Might have to look into this myself since I've gained an interest in manual lenses recently. I also like the idea of modifying lenses to adapt them to Pentax; Reminds me of car upgrades or modifications where factory parts of a different car are used.

Yeah, modifying lenses is lots of fun. I've got bins of parts and it's a thrill when you find just the right part to use for a conversion.

On this Topcor, I added a Pentax K mount from a Samyang 85mm lens that broke. Worked good enough. Don't have infinity focus on this Topcor, but I don't care as I'll be using it close up for subject isolation and bokeh.

Ontarian50 · 08-26-2016, 08:24 AM

Might we assume that your adapted lens only works for closeups? How far away can you focus with the adapted Topcor?

That 1.4 Topcor was an interesting design. It came about because Topcon, in their infinite wisdom decided to base their pro-grade SLR body on the Exakta lens mount

The narrow throat on the Exakta/Topcon mount leaves only about 33mm for a rear element, compared to about 35mm for M42. The jumbo EOS mount has more than 38mm of room.

Fenwoodian · 08-26-2016, 08:35 AM

Originally posted by Ontarian50

Might we assume that your adapted lens only works for closeups? How far away can you focus with the adapted Topcor?

That 1.4 Topcor was an interesting design. It came about because Topcon, in their infinite wisdom decided to base their pro-grade SLR body on the Exakta lens mount

The narrow throat on the Exakta/Topcon mount leaves only about 33mm for a rear element, compared to about 35mm for M42. The jumbo EOS mount has more than 38mm of room.

How far away from a subject will it focus? Let me put it this way, If I were shooting an adult, I could back up enough to get your upper body in focus.

If I had put in more time could I have made it focus at infinity? Don't know, but I doubt it. If I did further modifications to the mount, the rear of the Topcor lens just might interfer with the mirror.

Last edited by Fenwoodian; 08-26-2016 at 08:50 AM.

Ontarian50 · 08-26-2016, 10:30 AM

Yes, mirror clearance could become an issue.

So how did you move the Topcor's optics backwards. There's not usually all that much focus calibration adjustment in most lenses. I remember trying a similar stunt by adapting a 200mm Konica onto a Nikon. I replaced the Konica mount with a Nikon one taken from a teleconverter. It ended up fitting beautifully, but I found I wasn't able to move the optics back enough to work. The couple of mm's available in the Konica's factory focus calibration wasn't enough to get to infinity.

Many years ago I saw one of the conversions done to a Rollei 135mm Tessar that had been adapted to Nikon. Some guys apparently found it worthwhile enough to shave the lens bodies down to accommodate a Nikon mount - they even got the auto aperture to work, sort of. It wasn't reliable. Impressive though. Hard to justify at North American labour rates.

Fenwoodian · 08-26-2016, 12:42 PM

I like how this Topcor lens does black and white too.

**goatsNdonkey** · 08-26-2016, 05:08 PM

I can almost taste those tomatoes!

Of the black-and-white photo, it is interesting how the OOF bokeh areas have an X-ray quality, as if certain structures are seen through others.

08-26-2016, 07:18 AM - 1 Like	#1
Fenwoodian Pentaxian Join Date: Apr 2015 Location: USA Photos: Gallery \| Albums Posts: 2,875	Another "Frankenlens" Last night I adapted a Topcor 58mm f/1.4 lens to the Pentax K mount. This makes over 20 lenses that I've adapted to the Pentax K mount. I bought it last week on Ebay for $100 USD. Other than some mold on the inside it's in great shape. This Topcor lens is the "father" of the highly regarded Voigtlander 58mm 1.4 Nocton lens. It has the same optics, but obviously the Voigtlander has more modern coatings. Some reviews I've read state that the older Topcor produces a slightly better images at f/1.4 to f/2.8 than the Voigtlander does. Here's some photos I took this morning at f/1.4 and f/2.0. I'd say the sharpness of this lens is just "average" (compared to the Pentax 50/2.8 Macro), however I really like the colors and bokeh that it produces. If you don't mind manual focusing, there are lots of great old lenses out there that can be adapted for use on Pentax K cameras. Last edited by Fenwoodian; 11-14-2016 at 08:49 PM.

08-26-2016, 07:52 AM	#3
a5m Veteran Member Join Date: Oct 2015 Photos: Gallery \| Albums Posts: 576	I agree it looks plenty sharp and the colors and bokeh are amazing. The first picture of the red flower has a 3D pop to my eyes. Good work! Might have to look into this myself since I've gained an interest in manual lenses recently. I also like the idea of modifying lenses to adapt them to Pentax; Reminds me of car upgrades or modifications where factory parts of a different car are used. Last edited by a5m; 08-26-2016 at 08:05 AM.

08-26-2016, 12:42 PM	#9
Fenwoodian Pentaxian Join Date: Apr 2015 Location: USA Photos: Gallery \| Albums Posts: 2,875 Original Poster	I like how this Topcor lens does black and white too. Last edited by Fenwoodian; 11-14-2016 at 08:49 PM.

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08-26-2016, 07:38 AM	#2
ChristianRock Pentaxian Join Date: Jul 2013 Location: People's Republic of America Photos: Gallery \| Albums Posts: 9,912	I'd say the sharpness is good enough for what it is! Great colors and bokeh. Congrats on that project. Do you even have time to shoot all these lenses that you have?

08-26-2016, 08:15 AM - 1 Like	#4
stevebrot Otis Memorial Pentaxian Join Date: Mar 2007 Location: Vancouver (USA) Photos: Gallery \| Albums Posts: 42,007	Originally posted by Fenwoodian This Topcor lens is the "father" of the highly regarded Voigtlander 58mm 1.4 Nocton lens. It has the same optics, but obviously the Voigtlander has more modern coatings. Some reviews I've read state that the older Topcor produces a slightly better images at f/1.4 to f/2.8 than the Voigtlander does. Beautiful lens and good work making it usable on a modern body! I was surprised to read here that Cosina/Voigtlander based the Nokton 58/1.4 on the Topcor. Steve Gandy wrote otherwise when the Nokton first debuted in Topcor trim on the Bessaflex TM (LINK). I did a little Google work and came up with conflicting accounts. I eventually found a lens diagram on a Japanese Topcon fan site. Both lenses are Planar-derived, but differ in the details: RE Auto-Topcor 58/1.4 (7 elements in 5 groups) Image found at TOPCON CLUB-Various Talk-Drawing of Topcor Lens Cut Voigtlander Nokton 58/1.4 (7 elements in 6 groups, sold in three different trims) Image courtesy of Steve Gandy's cameraquest Web site, Voigtlander SL II Lenses I don't know which lens I would rather have. The old Topcor has a great reputation, but the Nokton is also a credible lens and has modern coatings. Steve Last edited by stevebrot; 08-27-2016 at 01:18 PM. Reason: Corrected spelling

08-26-2016, 08:20 AM	#5
Fenwoodian Pentaxian Join Date: Apr 2015 Location: USA Photos: Gallery \| Albums Posts: 2,875 Original Poster	Originally posted by a5m I agree it looks plenty sharp and the colors and bokeh are amazing. The first picture of the red flower has a 3D pop to my eyes. Good work! Might have to look into this myself since I've gained an interest in manual lenses recently. I also like the idea of modifying lenses to adapt them to Pentax; Reminds me of car upgrades or modifications where factory parts of a different car are used. Yeah, modifying lenses is lots of fun. I've got bins of parts and it's a thrill when you find just the right part to use for a conversion. On this Topcor, I added a Pentax K mount from a Samyang 85mm lens that broke. Worked good enough. Don't have infinity focus on this Topcor, but I don't care as I'll be using it close up for subject isolation and bokeh.

08-26-2016, 08:24 AM	#6
Ontarian50 Veteran Member Join Date: Mar 2015 Posts: 530	Might we assume that your adapted lens only works for closeups? How far away can you focus with the adapted Topcor? That 1.4 Topcor was an interesting design. It came about because Topcon, in their infinite wisdom decided to base their pro-grade SLR body on the Exakta lens mount The narrow throat on the Exakta/Topcon mount leaves only about 33mm for a rear element, compared to about 35mm for M42. The jumbo EOS mount has more than 38mm of room.

08-26-2016, 08:35 AM	#7
Fenwoodian Pentaxian Join Date: Apr 2015 Location: USA Photos: Gallery \| Albums Posts: 2,875 Original Poster	Originally posted by Ontarian50 Might we assume that your adapted lens only works for closeups? How far away can you focus with the adapted Topcor? That 1.4 Topcor was an interesting design. It came about because Topcon, in their infinite wisdom decided to base their pro-grade SLR body on the Exakta lens mount The narrow throat on the Exakta/Topcon mount leaves only about 33mm for a rear element, compared to about 35mm for M42. The jumbo EOS mount has more than 38mm of room. How far away from a subject will it focus? Let me put it this way, If I were shooting an adult, I could back up enough to get your upper body in focus. If I had put in more time could I have made it focus at infinity? Don't know, but I doubt it. If I did further modifications to the mount, the rear of the Topcor lens just might interfer with the mirror. Last edited by Fenwoodian; 08-26-2016 at 08:50 AM.

08-26-2016, 10:30 AM	#8
Ontarian50 Veteran Member Join Date: Mar 2015 Posts: 530	Yes, mirror clearance could become an issue. So how did you move the Topcor's optics backwards. There's not usually all that much focus calibration adjustment in most lenses. I remember trying a similar stunt by adapting a 200mm Konica onto a Nikon. I replaced the Konica mount with a Nikon one taken from a teleconverter. It ended up fitting beautifully, but I found I wasn't able to move the optics back enough to work. The couple of mm's available in the Konica's factory focus calibration wasn't enough to get to infinity. Many years ago I saw one of the conversions done to a Rollei 135mm Tessar that had been adapted to Nikon. Some guys apparently found it worthwhile enough to shave the lens bodies down to accommodate a Nikon mount - they even got the auto aperture to work, sort of. It wasn't reliable. Impressive though. Hard to justify at North American labour rates.

08-26-2016, 05:08 PM	#10
goatsNdonkey Site Supporter Join Date: Jan 2016 Location: Fulton County, Illinois Posts: 3,736	I can almost taste those tomatoes! Of the black-and-white photo, it is interesting how the OOF bokeh areas have an X-ray quality, as if certain structures are seen through others.