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10-16-2018, 07:08 PM - 2 Likes   #1
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Join Date: Oct 2018
Location: Calgary, Canada
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Ricoh GR or GRII Teleconverter

Hi all,
I experimented a little with a tele conversion lens I have in my collection. It's a vintage Petri 1.5x teleconverter. If you don't know Petri, it was a Japanese camera manufacturer that produced very nice quality cameras and lenses up to the late 1970s. Their rangefinder cameras from the 1960s are very nice quality. This teleconverter was intended for a fixed lens rangefinder with 45mm focal length and f1.9 aperture. The converter has a simple 43mm thread. I attached it to the Ricoh GH-3 via a 49mm-43mm step down ring. Here is what it looks like on the camera (I think it looks kinda cool):

The converter vignettes bad if I leave it on the Ricoh GRII's 28mm setting, but the vignetting goes away 99% if I switch to the GRIIs 35mm setting. Now I have a 50mm equivalent with 10mp. Here are some samples (Please forgive the bad photos, they are just to show the image quality and have no artistic value). All photos in full res. on Flickr:

f2.8: Center is already bitingly sharp, but as expected falls off to the edges and corners.

f5.6: Center is fantastic and the edges start to clear up.

Here is a reference shot with the GRII's lens without the converter:

Now with the converter and a 50mm, 10mp equivalent:

Now with the converter and a 75mm, 5.6mp equivalent:

Close-ups work very well, too. Here the 75mm, 5.6mp equivalent:

50mm, 10mp equivalent:

So far, I'm really encouraged by the results. I think the image quality is very usable. What do you think?

Those Petri converters are not the most common items to find, but they do come up on Ebay from time to time if you are interested in one. They don't go for much, I bought mine two years ago for $15. Some even come as a kit with wide angle converter and external viewfinder.

10-16-2018, 09:24 PM - 1 Like   #2
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Join Date: Jul 2012
Location: Mosquito Creek, Australia
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I agree. The combination works very well. I got the complete kit as a way to get the external viewfinder. I think the converters will screw on to a Zeiss Tessar 50/2.8 but I haven't played with them much. The receiving lens needs a recessed front element, as you would have found. I thought the tele converter could be useful as an option to carry when an extra lens can't be justified.

Last edited by PJ1; 10-16-2018 at 09:29 PM.
10-18-2018, 09:05 AM   #3
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Join Date: Jul 2016
Photos: Albums
Posts: 3,288
Nice results!

These kinds of convertors can be fun.

I've got a Canon WC-DC58 -- a 0.8X convertor with a 58mm thread. It does a decent job on 28mm lenses on APS-C to create 22.4 mm lens of the same f-stop. On FF with a 28 mm lens, the converter vignettes and has horrible corners.

There's also a Canon TC-DC58 -- a 1.5X convertor with a 58mm thread. I've not gotten much chance to play with this one.

Last edited by photoptimist; 10-18-2018 at 09:12 AM. Reason: typos

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