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6x7 Rear Converter 1.4x

Reviews Views Date of last review
3 12,581 Sun May 18, 2014
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Recommended By Average Price Average User Rating
100% of reviewers $207.33 9.33
6x7 Rear Converter 1.4x
supersize


Description:

This converter multiplies the focal length by 1.4. The light loss is one stop. The converter is more recent than the T5 version and is compatible with all 6x7 lenses except for the leaf shutter lenses. Refer the notes in the table below for caveats regarding lens compatibility.

It supports inner bayonet as well as outer bayonet lenses.


6x7 Rear Converter 1.4X
Image Format
6x7
Lens Mount
Pentax 6x7
Light Loss
1 stop
Magnification
1.4x
Optics
5 elements, 3 groups
Mount Variant (Rear)
Inner Bayonet
Mount Variant (Front)
Inner/Outer Bayonet
Focusing
Manual
Coating
SMC
Weather Sealing
No
Case
Diam x Length
91 x 39.5 mm
Weight
520 g
Production Years
N/A
Notes
Engraved name: REAR CONVERTER 1.4X
Grey finish.
Designed for lenses 165 mm to 400 mm, but is compatible with all 6x7 lenses except for the leaf shutter lenses.
Causes vignetting with the Shift 75 mm lens and lenses 500 mm and longer.
The converter supports lenses with inner as well as outer bayonets.
Features:
Medium-Format Support
Price History:



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Site Supporter

Registered: October, 2008
Location: Vancouver, Canada
Posts: 5,382

1 user found this helpful
Lens Review Date: May 18, 2014 I can recommend this lens: Yes | Price: $235.00 | Rating: 9 

 
Pros: Excellent optics, small.
Cons: Only usable on a small number of lenses.

The 67 1.4X Rear Converter is the only “non dedicated” one Pentax made for the 6x7 system. (The M*800/6.7ED lens has it’s own dedicated T5-1.4X Rear Converter.)

Usage:
I bought the 67 1.4X converter to use with my 67 120/3.5 Soft & 6x7 Takumar 400/4 lenses. The 1.4X converter allows me to use my 120/3.5 Soft lens at a traditional portrait focal length of 168mm, or extend my 400/4 to a 560mm telephoto. This converter works with inner or outer bayonet lenses (see the usable lens list below) and is quite sharp, with only a one stop light loss penalty. The converter is also very small, so it does not take up a lot of room in your camera bag.

The only issue with this 1.4X converter is that it only works with a limited number of lenses. After doing some online research and using the Pentax instruction booklets, here is a list of Pentax 6x7 system lenses that it will work with. Using the 1.4X converter with lenses not listed may cause damage.

Pentax 120/3.5 Soft
Pentax 165/2.8
Takumar & Pentax 200/4
Takumar & Pentax 300/4
Pentax M*300/4 ED
Takumar 400/4
Pentax M*400/4 ED
Takumar 600/4
Takumar 800/4

CASE: The 67 1.4X Rear Converter comes with the S90-100 soft case.

Summary:
The 67 1.4X Rear Converter is a great Pentax 6x7 lens accessory and allows you to get more distance with specific lenses at a reasonable price, with minimal deterioration in picture quality.

Price: I found my 67 1.4X Rear Converter at KEH and it cost $235.00USD. It was EXC+ condition and came with both caps, I purchased the case separately.

Sample shots taken with the 67 1.4 X & 2X Rear Converters are in my review of the SMC 6x7 Takumar 400/4.

SMC-Pentax-Takumar-6x7-400mm-F4-Lens Review
   
Pentaxian

Registered: February, 2009
Location: Arizona
Posts: 916

2 users found this helpful
Lens Review Date: April 2, 2012 I can recommend this lens: Yes | Price: $212.00 | Rating: 9 

 
Pros: Incredibly well corrected- Wide open metering
Cons: Limited fit on 6x7 lenses

This gray converter is the latest design by Pentax. Their older ones were black. This converter is made like a lens; rubber grip surface, SMC glass, lens release slider and diaphragm connection for wide open metering. The automatic diaphragm function of the lens is retained when using the 1.4x converter. To my surprise, it even has outer bay tabs for mounting the outer bay lenses. You lose 1 stop of speed with the converter because you are extending the focal length. This changes the focal ratio since the diaphragm remains unchanged. Since the focal length has changed, the DOF scale on the lens you are using will not be accurate. One solution is to put hyperfocal marks on the lenses you plan to use with the 1.4x, that represent the longer focal length.
Optics-
The optical construction is 5 elements in 3 groups. It consists of a positive achromat upfront, followed by a negative achromat, then a single positive element. This lens is afocal. It will not form an image by itself. It needs the converging rays from another lens to do that. With 3 positive elements and 2 negative, one would think that it would not be afocal but be able to form an image by itself. Not so. This means that the 2 negative elements are high refractive index, high density glass. The positive elements are most likely low dispersion, low index glass. In the telescope world, a simple 2 element achromat is used to extend the focal length of the scope. They are known as Barlow lenses. The 1.4 and 2X converters for the 67 do the same thing. So why didn't Pentax use a 2 element Barlow design as TCs? They just do not correct the off axis aberrations well enough to be used for photography. The corners would be too soft.

I was surprised at how few lenses this converter will fit on. Sure it fits the 200 Pentax, 300 Takumar, 400 Takumar and 600 Takumar but it will not fit the zooms, 105mm, 150 Takumar, 165 LS or 45mm. It was obviously designed for the longer lenses. As such, I suspect the use of ED glass in this converter. Strangely enough, when mounted on the 600 Takumar, it does not increase color fringing. It seems to actually reduce it. How can this be? The converter intercepts the rays before they reach the focal plane and before the colors can separate further. It does not allow them to separate as it would, had there been no converter in place. There is quite a distance between the rear element in the 600 and the film, so putting a highly color corrected converter in between is effective. One will get amazing results with the 600 + 1.4X when using the 600 stopped down as mentioned below. With the 200 Pentax, this 1.4X retains the sharpness of the lens. When used with the 600mm, the lens must be stopped down to at least f/13 to reduce color fringing. With the 400 Takumar, (another outer bay lens like the 600) the 1.4x converter works well at all stops. Using the 1.4x with outer bay lenses and the outer bay extension tubes is a bit strange. The setup will not fit if one tries to put the converter on the lens and then attach the tubes. This seems logical because the optics generally go in front of the tubes. But the tubes must be in front of the converter. This configuration seems to work okay though.

I have found that after having this converter for awhile now, that I seem to use it for my longer lenses and not as much for the 200 and 300mm.

When using the 1.4x with the Pentax 200, the sharpness results rival the 300mm EDIF-- Amazing. With the 200mm at f/11 + 1.4X, the estimated sharpness is 85-90 LP/mm.

Since this converter does not increase aberrations, it begs the question, how did they do that? The obvious answer is that the designer had to correct all seven aberrations within this converter so as not to add any at the focal plane. They were successful and created a great converter.
   
Junior Member

Registered: May, 2009
Location: S. Ontario
Posts: 30

2 users found this helpful
Lens Review Date: June 20, 2011 I can recommend this lens: Yes | Price: $175.00 | Rating: 10 

 
Pros: No image degradation with use. Only 1 stop lost.
Cons: None really.

Be aware that the stock photo used is actually the 1.4x converter for the 800 EDIF lens. The normal 1.4x converter looks exactly like the new 2x converter and has Pentax 67 rear converter 1.4x - on the side of it.

Excellent coatings and performance. Shooting with this in place will not degrade the performance of the lens. I don't thing the 90 lens will work with this converter either.

It's a great way to gain another "lens" with actually doing so. The 200 lens at f/4 now becomes a 280 lens at f/5.6. Gets you close to a 300 lens, yet is still sharper (newer 67 version of the 200) than a 300 lens.

I've used this on my 400 EDIF lens for astrophotography making it a 560mm lens at f/5.6. Still fast enough for astro work, does not add or cause any aberrations, and stars are still sharp almost to the very edge of the film.

When adding this converter to an f/4 lens - the extra glass causes the reduction in light and the lens therefore becomes f/5.6. Just remember to leave the f stop on the lens at f/4. If you change it to f/5.6 thinking to match the converter setting - you will have just made the lens into f/8.

It's a handy item to have to extend existing lenses. But since getting the two Pentax zoom lenses, I rarely use the converter now except for astrophotography. This converter will not fit on the two zoom lenses.
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