Hands-on: Topcor 2x Converter & Horseman FA Extension Back

[ic-racer]

I recently assembled this combination to test:
a) Topcor 150mm LF lens
b) Topcor 150-300mm "Teleconverter" [sic]
c) Horseman FA rear extension bellows
d) Horseman FA camera

My goal was to do some 4x5 format portraits. I had intended on just using my 300mm plasmat on the SHEN-HAO 8X10 but they don't make a reduction back.


First thing I had to do is go over all the pieces as everything was used and likely contained hidden issues. During the analysis and cleaning of the above, I also re-worked my Horseman FA's groundglass back, as it looked like the prior owner tried to pry it off with a screwdriver or something...( http://www.largeformatphotography.info/forum/showthread.php?t=86549 )

[ic-racer]

The 150mm f5.6 Topcor lens
Topcor is perhaps the least known of the Japanese LF lens manufacturers. Looking at the Spec sheet it seems like it would be similar to the other two Japanese LF lenses out there: the Nikkor 150mm 5.6 and Fujinon 150mm 5.6.

TOPCOR 150mm LF Specs:
Construction: 4/6
Circle: (open/f22) 174mm/210mm
Angle: (open/f22) 60deg/70deg
Shutter: Copal 0
Weight: 340g
Length: 61mm
Front diameter: 60mm

[ic-racer]

Comparison Nikkor specs the SAME except here:

Weight 230g
Length: 50mm
Front diameter: 54mm

[ic-racer]

Many different Fujinon 150s. This is what I think I have, outside lettering, EBC-NWS and the specs are all different than the Topcor:
Construction: 6/6
Circle: (f22) 224mm
Angle: (f22) 76deg
Weight: 235g
Length: 57mm
Front diameter: 57mm

[ic-racer]

This is how the extension back attaches to the back of the camera. The ground glass frame is removed. The ground glass and viewing shade are removed from the frame and attached to the back of the extension bellows. The extension bellows fits on the back of the camera where the rotatable frame was.
http://img.photobucket.com/albums/v670/ic-racer/2012/BackAttachment.jpg

[ic-racer]

There are actually six extension rails for the back. Two short little ones and 4 longer ones. With just the two short ones there is just enough extension to focus a 300mm lens at most distances just using the front bellows:
http://img.photobucket.com/albums/v670/ic-racer/2012/ShortExtension.jpg

[ic-racer]

Adding two of the longer extension rails allows some close-ups with the 300mm lens:
http://img.photobucket.com/albums/v670/ic-racer/2012/MediumExtension.jpg

[ic-racer]

Putting all the extension rails together gives about 700mm total extension:
http://img.photobucket.com/albums/v670/ic-racer/2012/LongExtension.jpg

[ic-racer]

This is the Topcor 150mm f5.6 lens with the long focus converter that turns the ordeal into a compact 300mm lens. The maximum aperture is f11:
http://img.photobucket.com/albums/v670/ic-racer/2012/150Converter.jpg

[ic-racer]

The 150mm's shutter is held to the lensboard with a special large locking ring. It is this big locking ring, onto which the converter fits. It does not screw on to the rear cell.
http://img.photobucket.com/albums/v670/ic-racer/2012/ConverterOff.jpg

[ic-racer]

The Topcor 150mm is not the only lens that can be used with the converter. Just about any 150mm lens with a rear cell small enough will probably work.

[ic-racer]

This particular example was a Bargain from KEH at $90. It turns out the 150mm lens elements are all clear and scratch-free. The shutter is perfect. There are some dings on the lens filter rings both front and rear.
The reason it was so inexpensive is probably the 300 converter. The converter is a seven element lens and one of the 14 surfaces had the dreaded fog that won't come off.

In terms of the negatives and prints I have done with the lens I can say:

The Topcor 150mm is as good as any 150mm standard 4x5 lens out there.
I really don't know what to compare the converter to as the design is a one-of-a-kind. I can say that this particular example gave a lower contrast image. The sharpness is about 1/2 that of the native 150 lens. Almost as if you just did a crop with the enlarger from the 150mm view.

My intention is to use the lens for some portraits and so far they have been very satisfying.

[ic-racer]

Print from a negative taken with the 300mm combo. F22 actual (f11 indicated). Printed on Ilford MG Fiber. T-max 100 film.
http://img.photobucket.com/albums/v670/ic-racer/2012/300converter22.jpg

[ic-racer]

Another, same specs:
http://img.photobucket.com/albums/v670/ic-racer/2012/300converter11.jpg

[Dan Fromm]

The Topcor 150mm is not the only lens that can be used with the converter. Just about any 150mm lens with a rear cell small enough will probably work.

IMO, what's limiting is the shutter. The Topcor 2x Converter is made to attach to a #0 shutter. There are 150/5.6 plasmats in #1 shutters, and it won't work on them. There's no reason why a determined owner couldn't have a front plate -- what you call the large locking ring -- to fit a #1 made for the thing.

There's another limit, focal length. I've tried my converter on a variety of lenses. Whether it will work at all and magnification given when it works are unpredictable. It really is just for 150 mm lenses.