I very recently did a little testing of some of my lenses.
I tested the following:
1. 300mm f4.5 zuiko at f8
2. 300mm f4.5 zuiko atf8 + 1.4xTC
3. 500mm f8 Tamron mirror lens
4. 180mm f2 Zuiko + 1.4 TC
The test subject was a hillside some distance away - OM4Ti, self timer, spot
metering the same area and a tripod. I stuck with f8 as my primary aim was to
compare 2 and 3.
I used Fuji Reala as that is what was in the camera at the time and I wanted
results
I could scan.
Of course there was some variation in the prints thanks to the processor doing
it's
thing and so I intend to repeat the test with slide film.
However I may also get the prints re done as I learnt afterwards that the
processor
can be set to provide no exposure or colour adjustment.
Despite the processors input I think the results are meaningful enough for some
tentative conclusions.
I personally am more interested in contrast than sharpness so I would rank the
results as 1,4,2,3.
In terms of sharpness I would rank the results 4,1,2,3 though 4 and 1 and 2 and
3 are a close calls. Projecting slides should settle it.
The colour balance with the zuikos was very consistent. The Tamron produced a
slight but distinct magenta cast to the image which I find distasteful. I
personally prefer 2 over 3. Although the superior contrast and sharpness of 2
over
3 is very slight, there is a certain "something" (flatness?) about the image
produced by the Tamron which puts me off.
The image which clearly strikes me as the best is 1. Laid side by side it
clearly
stands out from the rest.
This may sound heretical but I am beginning to think that cropping and
enlarging an
image taken without a TC may give superior results to using one.
I have used the 2 combination wide open and the results are perfectly
acceptable to
me. However, I will bet they wouldn't touch the image quality with a Tamron
400mm f4
with a barge pole but a lens in your hand has got to be worth 100 you don't
have.
As I said, I think we might be better off with enlargements rather than TCs.
I would like to emphasise that my results are tentative as my methodology was
imperfect. I shall report back when I have done a better job with slide film.
Giles
> I have read Gary's test results for the 300mm + 1,4x and 2x Oly TCs, also
> I've seen that the 1,4x is matched for the 300mm. From Gary's tests I gather
> that both TCs will cost two stops in exposure time, and that it's difficult
> to focus with the diafragm wide open. Can anyone shed a light on this from
> experience? I.e. how do you think it focuses and performs in actual wildlife
> shooting as opposed to the test bench. Also, the F-grades with the diafragm
> wide open are slightly worrying. Is performance really that poor?
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