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Author Topic: unsharp images on long lenses with IQ180 - tripod or lenses?  (Read 2259 times)
anile4
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« on: November 19, 2012, 06:49:59 AM »
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I use an IQ180 mounted on Contax 645 with full set of Zeisss lenses.

I have found the IQ180 very unforgiving even with the 80mm lens.  Only razor sharp at F5.6 or F8.

With all lenses longer than 120mm all images are well below what be achieved with shorter lenses, even under windless conditions with mirror up remote shutter release.

Tripod problem or does IQ180 outpace the long Zeiss lenses??
Anile 4
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chrismuc
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« Reply #1 on: November 19, 2012, 09:19:27 AM »
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I use the Contax 645 with many lenses (35, 55, 80, 140, 210, 350, 1.4x) and a P65+ back and intend to upgrade to an IQ180. The P65+ is not much less demanding than the IQ180 (6um vs. 5.2um pixel width). Correct focus point and stable tripod or short exposure times are of course essential to achieve sharp images. Maybe you should post some pics to illustrate eventual unsharpness. Here are some by P65+ to show what you can expect.
First samples full frame and 100% crops with Contax 210f4 and 350f4 @ f11.
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chrismuc
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« Reply #2 on: November 19, 2012, 09:21:59 AM »
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Next samples with Contax 140f2.8 @ f8 and with 140f2.8 + 1.4x extender at f11.
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chrismuc
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« Reply #3 on: November 19, 2012, 09:25:32 AM »
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And last set with Contax 80f2 @ f11 and 55f3.5 @ f16. Looks sharp enough to me:-)
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FredBGG
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« Reply #4 on: November 19, 2012, 11:59:00 AM »
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The Contax 80mm F2 is not the sharpest lens around, but it has a very special look to it when used wide open.
The rest of the lineup can hold up against pretty much any other modern lens, with only a few of the modern lenses looking as nice.
IMO no other MF lens has the look of the Contax 120mm when shot wide open for portraits.

You may have either a focus calibration issue (less likely) or a vibration issue.

A way you can see if vibration is an issue is to mount the camera on a very heavy stand with a very heavy head.
best would be a studio column stand. Mounted rigidly on such a  mass will absorb any vibration.

I know a photographer that does a lot of scientific imaging that had a big chunk of metal machined with a camera thread on it
in order to keep his cameras locked down. Nothing works like a nice big chunk of ballast.
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chrismuc
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« Reply #5 on: November 19, 2012, 08:09:10 PM »
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The Contax 80f2 at open aperture is acc. my experience as good as a f2 MF lens can be. Of course not up to let's say the open aperture performance of a Zeiss ZE 100f2 Macro but it is sharper than the Zeiss Hasselblad 100f2 (at least the sample I had).

Contrast and macro contrast are a bit low at f2, but anyhow the depth of field is (especially at shorter working distances) so shallow that this is more the restricting issue. Enclosed to samples of the 80 at f2 at rather short and medium distance.
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chrismuc
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« Reply #6 on: November 19, 2012, 08:13:45 PM »
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At f2.8 the Contax 80f2 improves significantly. More contrast, less color fringing (especially in bw;-), better sharpness but some longitudinal color shift still there. Very useful for any kind of portrait work. Two samples at shorter and longer working distance enclosed.
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mtomalty
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« Reply #7 on: November 20, 2012, 08:34:22 AM »
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Anile

I would be very surprised if the iq180 and its resolving potential is at the heart of your problem.

I would be more inclined to think it comes down to a combination of mirror/shutter bounce.

I used to have a complete Contax 645 system from 35 to 350 apo and used to have extreme
difficulty getting a sharp image,free of movement, with the 210 and 350 when shooting with shutter
speeds from about 1/125 to 1/2 second- tripod,mirror lockup,etc.

Their electronic release would not mitigate the issue and only when I used the electronic release
to trigger the self timer was I able to get reliable results in combination with mirror lockup.

You can verify if you are getting any internal vibration by testing your mirror lockup/release
sequence by testing in a situation where your shutter speeds exceed 1 second.
This allows the system to stabilize a little and the micro vibration is camouflaged in the
longer exposures.

Mark
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Harold Clark
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« Reply #8 on: November 20, 2012, 11:17:14 AM »
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A good way to determine if vibration might be the culprit is to set up a shot indoors with strobe lighting, where you can eliminate all extraneous light ( night time works best ). Set up the shot, turn off the lights and open the shutter. After a minute or two wait fire the strobe. Close the shutter and turn the lights back on. This won't work of course if the floor is subject to vibration.
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BernardLanguillier
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« Reply #9 on: November 21, 2012, 04:24:06 AM »
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A good way to determine if vibration might be the culprit is to set up a shot indoors with strobe lighting, where you can eliminate all extraneous light ( night time works best ). Set up the shot, turn off the lights and open the shutter. After a minute or two wait fire the strobe. Close the shutter and turn the lights back on. This won't work of course if the floor is subject to vibration.

You can also attach a laser pointer to the hotshoe.

I had similar issues with my Mamya ZD, never got a sharp image with the 300mm APO in cold weather, it seems the thermal dilatation of the mount and lens was a bit different which introduced some play. The shutter alone was enough to induce enough blur to turn the 22mp sensor in little more than a high DR iPhone.

Cheers,
Bernard
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A few images online here!
julienlanoo
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« Reply #10 on: November 29, 2012, 06:02:06 PM »
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Anile

I would be very surprised if the iq180 and its resolving potential is at the heart of your problem.

I would be more inclined to think it comes down to a combination of mirror/shutter bounce.

I used to have a complete Contax 645 system from 35 to 350 apo and used to have extreme
difficulty getting a sharp image,free of movement, with the 210 and 350 when shooting with shutter
speeds from about 1/125 to 1/2 second- tripod,mirror lockup,etc.

Their electronic release would not mitigate the issue and only when I used the electronic release
to trigger the self timer was I able to get reliable results in combination with mirror lockup.

You can verify if you are getting any internal vibration by testing your mirror lockup/release
sequence by testing in a situation where your shutter speeds exceed 1 second.
This allows the system to stabilize a little and the micro vibration is camouflaged in the
longer exposures.

Mark

About this,
I went to Photokina, this year, as i wanted to upgrade to a 180 to, but because i use mostly  technical wide angles, I had some questions about the colorshifts/aberations.

After asking around I saw 7 people at the stand, finally talking to a "engerneer" who of the most part was a salesman i think.
He said: the 160 an P65 are perfect, bla bla bal,
but i kept on insisting on info on the 180 , 
Untill he said: Look when the H20 came out people said it wasn't good for the same reason, but our engineers worked on it very hard and resolved it.
I said, so there is a real problem ? Frimware ? .. will it be resolved ?..
Wel like the H20 the engineers are working, and they will find a solution

- So honestely, i think, it's the backs fault, as that isn't the only situation one can get the problem with. The problems mostely appear to be with other camera's than the phase/mamiya system..
I would stay with the P65+, and w8 until the engineers solve the problem in the firmware;..

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ErikKaffehr
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« Reply #11 on: November 29, 2012, 11:10:41 PM »
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Hi,

What do you mean with "Only razor sharp at F5.6 or F8"? Lenses normally are best at those apertures. You could also check the MTF curves for the lenses, to see if they match your experience.

Does the 645 have a leaf shutter or a focal plane one? I have a Pentax 67, and that camera has a lot of issues with vibration from the shutter. I had a lot of problems on my Manfrotto 055 (aluminium) tripod even after going up to the heaviest Manfrotto head. Than I bought a Velbon Sherpa 630 Pro carbon fibre tripod and the problems went away.

So looking over the tripod may be a good thing. Look for leg joints, anything that can flex, strive for metal to metal mounts without cork plates or rubber. Arca swiss type plates work great.

Best regards
Erik


I use an IQ180 mounted on Contax 645 with full set of Zeisss lenses.

I have found the IQ180 very unforgiving even with the 80mm lens.  Only razor sharp at F5.6 or F8.

With all lenses longer than 120mm all images are well below what be achieved with shorter lenses, even under windless conditions with mirror up remote shutter release.

Tripod problem or does IQ180 outpace the long Zeiss lenses??
Anile 4
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chrismuc
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« Reply #12 on: December 03, 2012, 09:21:25 AM »
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Two more examples:
First with 350f4 lens, AF, handhold, @f4, 1/1000s, ISO 100
Second with 210f4 lens, MF, tripod (Manfrotto MT057C3-G + 405 geared head), @f8, 8s, ISO 200, mirror up + cable release
Both considerably sharp. So I don't see the problem of getting sharp pics with the long C645 lenses either handhold with short or on tripod with long exposure times.
(2nd pic is a quite terrible motive, just the opposite building of my hotel in total darkness, not the favorable situation for the P65+ DALSA chip but acceptable result)
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chrismuc
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« Reply #13 on: December 03, 2012, 07:00:34 PM »
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Same scene as night shot before:
Contax 210f4, AF, tripod, @f11, 2s, ISO 50, mirror lock up + cable release
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