Teleconverters

[Tony-S]

I was reading a book on the Rollei SLX/6000 series and the author seems to suggest that 1.4x and 2x teleconverters for medium format do not have much, if any, image degradation relative to their 35mm counterparts. Any truth to this? I'm considering the purchase of one or both for my Bronica GS-1.

 

[Ian C]

I can’t understand why a 1.4x or 2x converter on the 6 x 6 cm format could do anything differently than the same magnification converter for the 35mm format. I presume that we’re comparing high grade, dedicated converters made by a major maker in both cases.

The claim might have validity if we’re comparing a 6 x 6cm converter made by Zeiss or Schneider to a 35mm converter made by some generic vendor specializing in the lowest possible prices.

I doubt that a converter by Nikon or any other major brand of 35mm lenses is optically inferior to a Rollei branded converter.

The claim is someone’s opinion. I believe that it’s incorrect.

 

[ic-racer]

It could be an opinion or he could be regurgitating facts from testing, we don't know.

 

[BrianL]

He also might been comparing 2 different generations of design. In the way back, decades ago, teleconventers for 35mm cameras regularly tested as having a noticable degradation of quality. As time went on the reports became more positive. I have one for my Bonica ETRS and find no noticable degradation at least with transparencies.

 

[Sirius Glass]

Any lens extender will never be as good as a fixed length or zoom lens at the desired focal length. If there were, then there would be many more extenders and fewer lenses. However, in absence of correctly measured documented data, stating that MF extenders are better or worse than 35mm extenders would take either a great leap of faith or some really righteous weed.

Steve

 

[David A. Goldfarb]

It's hard to generalize about these things. There are cases where I'd prefer a particular combination of teleconverter and prime lens over a zoom, but I've also used a fairly marginal Komura medium format 2x converter, which was commonly available in the 1970s for many lens mounts, and I can't express much enthusiasm for it. There are two common designs of 2x converters--a six-element and a four-element, and generally the six-element converters are better, and there are some that are matched to particular prime lenses. 1.4x converters are a less extreme proposition, because they don't magnify the flaws of the prime lens as much.

An important question is what your actual options are. If you have a 300mm lens and a 2x, and you need a 600mm lens for the image you want to make, but don't have a 600mm, are you better off using the 2x or cropping the image made with the 300mm? Probably better off with the 2x than cropping, unless you can't afford the loss of 2 stops for other reasons, like you need a higher shutter speed to stop motion. You do what you can with what you've got, until you decide it's worth buying that long tele.

 

[Tony-S]

The Bronica GS-1 converters have 5 elements in 5 groups for the 1.4x and 7 elements in 6 groups. Hmm, more to think about.

 

[JohnArs]

On a smaller neg you see much faster a degradation, then with a larger neg or pos. Also have the extender for the MF cameras almost to be perfect for 2-4 lenses and this are in therms of Bronica only fix lenses no zoom lenses, which help also to get much better results!

Cheers Armin

 

[Sirius Glass]

I have a 2X extender for my Hasselblad. I used the extender one time with the 250mm lens when I needed a 500mm lens. The loss of two stops and a slight amount of sharpness was good enough for my very occasional use.

Steve

 

[tkamiya]

I don't trust any lens reviews unless I know the reviewer. It's so subjective and precise measurements are difficult. To top it off, parameters are often conflicting. I've been mislead so many times both ways. (good to bad and bad to good)

That said...

There were whole bunch of tele-converters for various 35mm cameras that were poorly and cheaply made. If you compare those with ones that were for professionals, I can understand why the latter is better.

 

[Brian C. Miller]

Tony, I suggest that you buy the teleconverter, and sell it if it doesn't meet your needs. Just do a quick elementary lens test with a USAF 1951 target, and compare the results. Only you can decide whether or not the image degradation is acceptable.