Teleconverter contest - all four rounds ! Winner announced!

[Anu]

I decided to compare my multiple m42-mount teleconverters. The test shots were shot at about 3 meters, with Carl Zeiss Jena 135/3.5 lens on a Pentax K20D. I chose a test target of a 10 euro bill (which was not harmed in any way during shooting of the photographs). In hindsight, I should say, that I probably should have chosen a target of even finer detail, but at least this is a target everyone can compare themselves on their equipment.

I took every shot on a tripod, focused with the live view and viewfinder. Light was controlled - I had three lightsources: the light on the ceiling - it has almost on influence, a small table top light aimed at the 10 euro bill provided some typical indoor light, but most light was provided by the built-in flash unit of the camera. All the shots were made wide open (maximum aperture) . There were some adjustments in the black-point and exposure (all the 2x's got identical adjustments). Possibly I'll post totally unprocessed images at some point.

The raw-conversion software I used was Lightroom 3 beta - I didn't do any CA-correction or such. I did however use sharpening - maybe I'll post images without sharpening too someday, but I'm rather lazy.

All the crops are 100%, cut from center area - using teleconverters typically means shooting at subjects that are in the center area, so corner performance is rather irrelevant. Actually I've not even checked what the edges looked like in each case. Maybe I will someday.

I hope to do outdoor long (and close) distance shooting someday, but it may take quite a while until I finally will achieve this - I am still lazy.

There were some surprises in this first test - specifically one lens performed worse than I expected and some better than expected.

The contestants:

Vivitar 1.5x (the only 3 element converter - all the others have 4 elements)
Prakticar 2x (made in Japan)
KOHBEPTEP K-1 (multicoated, Soviet-made) 2x
Weixdorf 2x (DDR made, almost identical to the last TC in this list:)
Carl Zeiss Jena 2x (finally I got one!)

Here are sample images:

Vivitar:


Prakticar:


KOHBEPTEP:


VEB Optisches Werk Weixdorf:


Carl Zeiss Jena:


For comparison here is CZJ 135/3.5 Sonnar image without a teleconverter - remember to upsize it if you want to see if it provides more or less details than the above teleconverters:


Observations:

The DDR-TCs seem to give the largest magnification (by a hair).
Even though the DDR-TCs look almost identical, it is clear that the one with the more famous brand is a lot better.
I expected the Weixdorf do much better - before this test I regarded it superior to the other contestants (but not CZJ which I only received a few days ago).
On the other hand, I expected the Prakticar to stink, and the 1.5x to stink a lot
The top-3 2x teleconverters are all nice indeed - there's still plenty of room for sharpening.

Because of the close result among the top-3 doublers, I will definitely have to do testing at different subject distances and study the edges too. And maybe also try another lens to use them with too.

If you have a teleconverter and 10 euro bill (yes, I know the chance of both these conditions to be true are close to zero... ), I would not mind seeing more crops. Opinions are also welcome.

[cooltouch]

I'm up for this. I have five TCs -- well, six, if you include my FD-EOS converter, which gives about 1.25x.

I decided to put my results in a separate thread. It can be found in the adapters section.

[Pancolart]

You should collect more converters - this test is interesting. Here part of mine (all for sale - i don't really trust them): Weltblick, Revue, PORST, Soligor, VEB...

[Abbazz]

[cooltouch]

Since Anu is testing M42 TCs, I decided that my tests are not adding to the topic, so I've moved them to their own thread in the Adapters section.

[dave_t]

I also have the KOHBEPTEP 2x converter and must say that I'm relatively pleased with its performance as well.

[Anu]

Today I decided to do more testing with the top-3 performers of the first test: Prakticar, KOHBEPTEP and Carl Zeiss Jena. All four elements, all (more or less) 2x magnify.

Outdoors the weather was such, my feeling was such and the squirrels were such, that instead of TC-test, I just spent my limited time shooting images such as this:

(CZJ 135/3.5 Sonnar, Sciurus vulgaris)

So I decided to shoot some more in my "studio". This time I changed a couple of parameters: the lens I used the three converters with was not CZJ 135/3.5, but intead it's big brother (or sister?), CZJ 200/2.8 Sonnar (again wide open, f/2.8 ). Shooting distance was increased a bit, to maybe 4 or 5 meters. The target was changed - from a single 10 euro bill to a couple of 5 euro bills

This time I also payed attention to the edge performance. No chromatic aberration processing was done, nor black point moving (I had to push 1 stop though), just some capture sharpening. I did however try some CA processing too, but am too lazy to post a zillion more images. Here are the crops:


This time the Prakticar could not repeat the surprise of round 1 - already the center area was inferior to the other two lenses and this area pretty quickly turned into mush, that no postprocessing could salvage. Usually edge performance is not relavent with TCs, but this time the performance dropped way too far from the edge. I would not want to know how a full frame sensor would fare.

The other two lenses are clearly superior to the Prakticar. While the center of the CZJ seems to be just a little bit better, though probably still within the margin of error in my testing procedure, the edges of the Soviet teleconverter are superior. CA is also less of a problem with the CCCP-item than it's DDR-counterpart, though it can pretty much be corrected in PP. Both of the lenses performed really well.

In round 3 and round 4 I will only test these two teleconverters as it is clear that they are the best two of the bunch. These two rounds will be used to study performance at the minimum focus distance and at infinity. I am still lazy, so it may take quite a while till I have the energy/motivation.

[cooltouch]

Very interesting results, Anu. The Russian TC seems to be holding up very well against the CZJ. It's nice seeing these reviews, too, since here in the US, all three of those brands of TCs are uncommon. I've always avoided buying 3- or 4- element 2x teleconverters, though, because it has been generally believed for many years that they do not produce as good of results as the 7-element 2xs do. However, yours seem to be doing very well.

[Anu]

[Anu]

The last two contenders climbed to a local hilltop and started shooting.

First a nasty surprise: KOHBEPTEP does not quite allow forusing to infinity with CZJ Sonnar 135/3.5 that I used for the test. Stopping down increased depth of field enough to allow for infinity, but that was not what this comparison was about.



Some other lenses may achieve infinity focus with the KOHBEPTEP - at least mirror lenses - I don't know what the IQ is with those. I hope to test both with the Soviet 3M-5CA 500mm f/8 mirror lens someday. As a reminder, I must say, that I am lazy, so it may take awhile. Problem with the mirror lens is that it's resolution is, while perfectly fine (about part with Canon 350D resolving ability), it's nothing compared to the CZJs used in this comparison.

Ayhow, I decided to take some medium distance shots too. This time it seems that I just might have missed the focus with the CZJ so I may need to rehoot the scene with it. The subject was maybe 100 meters away or so - especially the bottom edge used for comparison might be OOF.



Here KOHBEPTEP is clearly better at the edge (assuming CZJ focus is right), and maybe just a hint better in the center (sorry for the lousy target - I should find a better one).

This concludes part 3. Part 4 will be about minimum focus distance on CZJ 135/3.5 Sonnar.

[no-X]

Anu: Thanks for these tests, they are very helpful

[Anu]

[Anu]

This is the last part of the comparison. The best of the best are up against each other at the minimum focus distance shootout.

Camera: Pentax K20D
Lens: CZJ 135/3.5 Sonnar
Teleconverters: CZJ and KOHBEPTEP

I shoot diagonally a 50 euro bill (I am so rich!) so that focus errors would not come to play.

Light was provided by the built in flash.

Focus was about 1 meter, the minimum of the lens.

First 100% crops from the center:



Now, crops from the very extreme edge (long edge) at f/11 (f/5.6 on the lens).



The Soviet teleconverter seems to be just a little bit better there.

Conclusion of the great teleconverter comparison:
On a crop camera (1.5x or more - most DSLRs of today), a simple 4 lens teleconverter can provide excellent image quality - far more details of the subject that what could be achieved without a teleconverter. However, not all of them are created equal.

Had the Soviet KOHBEPTEP managed to focus to infinity, I would have been happy to announce the superiority of communism to... wait... ah, well, I would have been happy to announce that it is the teleconverter I'd happily recommend for everyone for all purpouses. However, since it is not necessarily useful for for example shooting moon-images or landscapers, I must give the glory to the Carl Zeiss Jena-teleconverter from East-Germany - the western counterparts could not survive the optical superiority of the eastern block. I do have to emphasize, that I had no chance of testing the western 7-lens teleconverters or other of the zillion m42-teleconverters by a zillion different westen companies, so maybe there are gems hidden there. But in this comparison east prevailed.

First place: CZJ - solid for all purpouses. The other DDR made teleconverters look almost identical, but at least the copy I had didn't match the performance, though I do suspect it was a lemon copy. The CZJ-teleconverter is very rare - occasionally available on eBay: I got mine for under 8 euros (plus postage), but I've seen prices go up to ridicilous sounding 60+ euros.

Second place: KOHBEPTEP - when it was good, it was really good, arguably the best of the bunch, but the lack of 100% compability (infinity) ruined it's race. Still, if infinity is not your target, this is the teleconverter to get. It is easily available on eBay, though you may need to trust Russian salesmen. Price is typically under 20 euros I think.

[exaklaus]

I think, that the Carl Zeiss jena converter is doing good, assuming that it was made by Ludwig!!

Klaus

[estudleon]

Thanks for the tests.

nice theme.

What is only theory and what's the reality about TC's?

Rino.

[Anu]

[estudleon]

Thanks again, Anu.

I guess that it's the way appropiate to know the reality, the diary use ot the TC's.

Comparision between crop and tc's is a good idea.

Rino.

[dave_t]

My KOHBEPTEP manages to focus to infinity, unfortunately, it's gotten a bit scratched up and I rarely use it anymore. I will say that I was always pleased it with it though, especially when I paid close attention to focus. Unfortunately, it (of course) exposed the flaws of my Pentacon 500mm even moreso, and therefore I can't use it for a budget 1000mm option.

[nemesis101]

Whilst I applaud your desire not to harm innocent currency, I have to take exception to your blatant Euro-centric attitude as Euro bills of any denomination are not easy to come by (as you imply) for everyone, especially us poor souls marooned in soaking wet, dollar infested Oregon!

Doug

[LucisPictor]

I like the name "KOHBEPTEP". They just named their converter "converter".

[estudleon]

Not creative but efficient.

Rino.

[rbelyell]

hey anu

this is a very helpful thread, thanks. i have a vivitar m42 2x: did you not include that because it is awful? i havent used it much, but the little i did produced mixed results...now that i am using ff, i thought i might use it more w my zooms and jupiter 200....i was thinking of the canon 2x that costs around $100 but dont know if its a significant upgrade from the viv. i would be very intd in your thoughts
tony

[nemesis101]

I have a Asahi Pentax 2x.. given this is an M42 thread I'm surprised they were omitted? I have used this with the humble A series f2 /50mm with great results, also with a PK/A adapted Adaptall 70-210mm Tamron...

Doug

[Russ]

It would have been nice to see test results from the excellent 7 element Vivitar "macro-focusing" teleconverter, the superb 7 element Kiron 2x teleconverter and the Panagor macro teleconverter. Maybe I'll do that testing someday...



Russ