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Old Jan 22, 2009, 12:25 PM   #1
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Hello all,

after Dawgs comparison of long range tele zooms I thought I do some testing on my own, mainly to decide which lenses I'll (have to) keep and which have to go. This is all very unscientific, I haven't got a good test setup and so on... still here are the first images, maybe this is interesting for you, too.

Comments welcome.

The participants:
- Pentax 45-125/4
- Pentax K 135/2.5 (I'll keep that, works as a reference)
- Pentax 75-150/4
- Pentax M 200/4
- Kiron 80-200/4
-Vivitar 70-210/2.8-4 (model 3)
- Tamron 70-300/4-5.6 (the only modern AF lens here)

And some TC experiments with a Vivitar 2x macro TC:
- Pentax M 85/2 --> 170mm
- Vivitar 90/2.8 Macro --> 180mm
- Pentax K135/2.5 --> 270mm

What do people think is a good test object for such comparisons?

Regards,
Th.

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Old Jan 22, 2009, 12:35 PM   #2
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TEST 1 - f/4

Same tree shot with all lenses. Shutter speed fixed at 1/1000, Auto WB, all lenses set to f/4. Full manual mode on camera (Pentax DL2), handheld. I manually focussed until the camera told me things were "in focus".

RAW processed in Raw Therapee (color noise reduction, minor local contrast enhancement, nothing else, same settings for all shots).

Cropped, basic histogram adjustments, minor adaptive noise reduction in L-Channel to help file size, caption in PL32. No other changes.

First unexpected result - the color reproduction and image brightness is VERY different. I'll have to meter with every new lens combo next time, still I left the images that way as I found it interesting.

I might have messed up the Pentax 200/4 shot a bit, it looks way too soft to me... other images show a similar performance, though. In general I don't care if an image is a bit softer... as long as the details are there and can be recovered with postprocessing.

I was surprised about the TC results, too. See for yourself.

You see 1:1 crops from the image center.

1.1 short range




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Old Jan 22, 2009, 12:36 PM   #3
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1.2 200mm


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Old Jan 22, 2009, 12:37 PM   #4
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1.3 TC

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Old Jan 22, 2009, 1:16 PM   #5
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1.4 shots, that surprised me

(please don't tell me, that one can't set the Viv 70-210 to f/2.8 at 210mm, at least on my lens this is possible, don't ask me why)
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Old Jan 23, 2009, 5:26 PM   #6
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thkn777 wrote:
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1.4 shots, that surprised me

(please don't tell me, that one can't set the Viv 70-210 to f/2.8 at 210mm, at least on my lens this is possible, don't ask me why)
Is your 70-210 an "A" lens? In Auto aperture mode with the lens and camera set there, turn the F/stop dial to the lowest it will go while at 210mm focal length. You should get a reading of no lower than F/4 as the setting at this focal length will be an f/4 equivalent. In manual mode you can turn it to F/2.8 but the actual amount of light entering will be an f/4 equivalent. The Group 1 and Group 2 Vivitar Series 1 lenses are constant aperture lens which give a true 3.5 or any other f/stop setting you wish to use throughout the focal range.

As to a subject for these tests ...how about a block or brick wall at the closest focus range of the lens with the longest focus range. Good sunlight needed for them though.

Dawg
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Old Jan 25, 2009, 2:04 PM   #7
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you need to get an A35-105/3.5
you can use it as a benchmark

roy
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Old Jan 25, 2009, 3:40 PM   #8
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robar wrote:
Quote:
you need to get an A35-105/3.5
you can use it as a benchmark

roy
hehe, I know your preference for that lens :G
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Old Jan 25, 2009, 7:51 PM   #9
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thkn777 wrote:
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robar wrote:
Quote:
you need to get an A35-105/3.5
you can use it as a benchmark

roy
hehe, I know your preference for that lens :G
if you used one you'd understand..
also the smc A70-210/4
the M200/4 is also a great lens but i'm afraid to put it up against the vivitar200/3.5.. the viv is twice the weight of the pentax and mainly comes in M42 but it's sharp as a tack at f3.5.. i've had about 8 of them, all for under $22 delivered.. there's also a viv 200/3 that's suppose to be even better......

roy
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Old Jan 26, 2009, 10:52 AM   #10
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The Viv 200 f3.5 TX can be a PK mount with open aperture metering and focus if you can find the adapter for it. Supposedly very sharp wide open to f16.

Dawg
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