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Pentax Lens Review Database » Film Era Pentax K-Mount Lenses » Pentax K-mount Teleconverters and Adapters
Rear Converter-A 1.4x-S Review RSS Feed

Rear Converter-A 1.4x-S

Reviews Views Date of last review
7 38,926 Mon February 12, 2024
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Recommended By Average Price Average User Rating
86% of reviewers $131.00 8.14
Rear Converter-A 1.4x-S
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Description:

Pentax Super Multi Coated 1.4x teleconverter with KA mount lens information contacts.

Features of this teleconverter:

  • Manual Focus
  • Supports Tv or P exposure mode (in addition to M and Av), if the camera and lens allows
  • The converter does not transmit focal length and MTF information from lens to camera
  • Designed for lenses up to and including 300mm, with some exceptions.

The following lenses are NOT supported:

  • FA* 200mm F4 Macro
  • F* and FA* 300mm F4.5
  • F* and FA* 250-600mm F5.6
  • K 135-600mm F6.7
  • All other lenses above 300mm
  • K and A 15mm F3.5
  • K 18mm F3.5
  • M 24-35mm F3.5 zoom

The above lens compatibility information is from 2006 and predates the introduction of D FA, DA, DA L and DA* lenses. Compatibility with these newer lenses is not readily available.

 

Rear Converter-A 1.4X-S
© www.pentaxforums.com, sharable with attribution
Image Format
Full-frame / 35mm film
Lens Mount
Pentax K
Light Loss
1 stop
Magnification
1.4x
Optics
5 elements, 4 groups
Mount Variant (Rear)
KA
Mount Variant (Front)
KA
Focusing
Manual
Coating
SMC
Weather Sealing
No
Case
HB-90B or S70-70
Diam x Length
64.5 x 21.5 mm (2.54 x 0.85 in.)
Weight
145 g (5.1 oz.)
Production Years
1984 to 2005
Notes
Engraved name: REAR CONVERTER-A 1.4X-S
User reviews
The converter retains all exposure modes supported by the attached lens.
The converter does not relay information about focal length, MTF, or lens name to the camera.
The converter is designed for lenses 300mm and shorter, but it is not compatible with the FA* 200mm F2.8 Macro, the F* and FA* 300mm F4.5 lenses, other lenses and zooms with a reach beyond 300mm, the K and A 15mm F3.5, the K 18mm F3.5, the M 24-35 F3.5 zoom, and various other wide angle lenses due to the protruding rear elements of these lenses.
Variants

Initially the converter was supplied with a hard case, later with a soft case.

Features:
Automatic ApertureFull-Frame SupportDiscontinued
Price History:



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Author:
Sort Reviews by: Date | Author | Rating | Recommendation | Likes (Ascending) Showing Reviews 1-7 of 7
Loyal Site Supporter

Registered: November, 2007
Location: Sparwood, BC, Canada
Posts: 12,385

4 users found this helpful
Review Date: January 26, 2012 Recommended | Price: $140.00 | Rating: 8 

 
Pros: Genuine Pentax coatings, good glass, works will with my lenses
Cons: It is a teleconverter. it was designed for shorter lenses

This adapter works well with any of my lenses, maintaining all exposure functions. It cannot, of course, turn either of my M lenses into an A series lens.

My use for the adapter these days is with the M400/5.6 which becomes a quite nice M560/8 with the adapter on the back. The IQ is not horribly degraded with the adapter. The quality is better than an equivalent crop with the 400 on my K10D, despite the adapter being designed for use with lenses no longer than 300mm.

It would be better if the lens could be fitted with the -L adapter, but they are not physically compatible because the projection on the -L is bigger than the throat of the M 400.
   
Loyal Site Supportaxian

Registered: September, 2013
Location: Texas
Posts: 503
Review Date: December 3, 2016 Recommended | Price: $110.00 | Rating: 8 

 
Pros: Great performance, Better compatibility with lenses than others.
Cons: None, other than no Data or AF connection.

Unlike its 2x brother, which is a diva that only plays well with certain lenses, this rear converter plays well with most, including many modern lenses.
Sharp and contrasty, small in size. This along with the 1.4x L version are the very best of all the classic Pentax Rear converters, only surpassed by the modern HD DA 1.4 Rear Converter.

I rate this an 8. It's very good, but not outstanding. It is sharper than the 1.7x AFA.
   
Forum Member

Registered: February, 2016
Location: Moab, Utah
Posts: 90
Review Date: January 31, 2017 Recommended | Price: $150.00 | Rating: 10 

 
Pros: Sharp, maintains clarity
Cons: somewhat rare

A very useable teleconverter. This 1.4x is quite a bit sharper and more practical for maintaining image quality than rear converter-a 2.0x-s or other 2x converters I tried. Feels like an a series lens because of the grip. No m series 1.4x option. Works well with M* 300 f4, which is where I almost exclusively use this. Images are still acceptable in quality for all photo editors so far.
   
New Member

Registered: November, 2018
Posts: 1
Review Date: December 4, 2018 Recommended | Rating: 8 

 
Pros:
Cons: somewhat disappointed with the image quality

I had this for about four years but did not use it until I bought a Pentax A* 300mm f4. I am somewhat disappointed with the resulting image quality because it is rather soft. Downsizing from 24 to 12MP with some software sharpening improves the images. Web publishing looks good without any tweaking.

The following were taken with the Pentax A* 300mm f4 + 1.4X-S TC



(100% crop)




(100% crop)
   
Senior Member

Registered: January, 2012
Posts: 244

2 users found this helpful
Review Date: March 13, 2020 Not Recommended | Rating: 5 

 
Pros: Pentax brand
Cons: Disappointing shots

While this does what it’s intended do, I am very unimpressed. Every time I use this, I find myself thinking, “dang, that shot is not very clear...”. And as soon as I remove it, my shot is very clear and sharp.

I wish I hadn’t spent the money, which I did based on the reviews here.

I use * lenses and a K1.

So I’ll be selling this one. I don't remember what I paid, but it was not a bargain.
   
Site Supporter

Registered: October, 2008
Location: Vancouver, Canada
Posts: 8,085
Review Date: October 15, 2021 Recommended | Price: $235.00 | Rating: 8 

 
Pros: Works well on my soft-focus lenses.
Cons: Don’t see myself ever using it on any other lens I own.

The A1.4X-S Rear Converter was released in 1984 as part of the new A Series cameras and lenses. It, along with the -L version, were the first Pentax 1.4X rear converters. The A1.4X-S Rear Converter remained in production till 2005.

Usage:
I bought the A1.4X-S rear converter exclusively for use on my Pentax Soft Focus lenses, the F85/2.8 Soft & FA28/2.8 Soft. Adding the A1.4X-S rear converter gives me approximately an 120mm & 40mm lens and results in a couple more soft-focus shooting options. The rear converter works really well with these two soft focus lenses and actually enhances the soft-focus effect. It also gives good results when using these soft-focus lenses in their “sharp” mode.

On the negative side there is an 1 stop loss of light. These soft-focus lenses are designed with a slower automatic aperture, so this results in a slightly darker viewfinder.

CASE: The A1.4X-S Rear Converter was originally sold with the HB-90B hard lens case and then later on with the S70-70 soft case.

Summary:
The A1.4X-S Rear Converter is nice to have if I want to increase the focal length of my F85/2.8 & FA28/2.8 Soft Focus lenses, but I really don’t see myself ever using it on any other lens I own. I have way too many Pentax lenses in various focal lengths under 300mm, that I just don’t need it. As well there are the usual negatives associated with any rear converter.

Price:
I bought my A1.4X-S Rear Converter at a local camera store and was NOS. (New old sock) It came with the S70-70 case and I paid $300.00CDN.
   
Loyal Site Supporter

Registered: October, 2018
Location: Quebec City, Quebec
Posts: 6,493
Review Date: February 12, 2024 Recommended | Price: $20.00 | Rating: 10 

 
Pros: Does not degrade images at medium apertures
Cons: Loss of Autofocus, loss of one f-stop

I took the upper image with a K3 III + FA* 85 mm f/1.4 @ f/13 and ISO 100. I added the A 1.4X-S converter, selected ISO 200 and shot the second picture after setting f/11 on the 85 mm lens in Manual mode. No visual degradation of the image is perceptible. You lose Autofocus and one f-stop but I think it is a good 20 $ investment ...




Another Nature image taken with the FA* 85 mm f/1.4 + A 1.4X converter : Very sharp !!

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