Ixpress 132

[Christopher E]

Hi guys!

I have been working with the Imacon Ixpress 22 megapxl back (on a H1) for a while and I am more than pleased with it - however I do occasionally get the hysterical moiree-effect mentioned in some threads in this forum. Rasterized magazines as well as denim jeans, various suits with a tight woven texture sometimes! produce violently colourful effects...!! I use the latest software as well for the back (recently updated in Denmark) and FlexColor? How have you come to terms with this? Focus adjustments?? I've been told the problem exist because of the combination of extremely sharp lenses (true!!) and CCD- sensor. My 35mm with CMOS-sensor has never had this problem with any subject photographed...?


Someone else must have had this problem? Please help me out as I'm getting tired of making supplemental out-of-focus exposures for tricky textures...

Thanks

/Chris

[SeanFS]

Without the AA filter ( that blurs the image slightly but loses sharpness ) the artifacts you are describing are a fact of life  with bayer type sensors.

Kodak DSLR's never had the AA filter that others have and the chip in most  MF backs have a chip of similar origins. They too produced the problems you mention but could be very sharp.

The only true way around it is four shot capture but thats not practical if people are involved.

There are a number of tricks to deal with them , The easiest I find if it just chrominance moire is to use the brush tool in Photoshop, sample the colour in the dropper tool ( blue if its denim ) , set the brush tool to colour  and then paint the moire away.
Converting to LAB colour then running a guassian blur on the a+ b channels to suit is also effective and emulates what most noise filters do to one degree or another

Luminance moire is much deeper seated - there are other tricks to deal with it using LAB colour inverse channel blends , but I haven't had to use these so I don' t feel able to adequately describe them here.

There is no one size fits all solution and sometimes it takes a combination of techniques.

Hi guys!

I have been working with the Imacon Ixpress 22 megapxl back (on a H1) for a while and I am more than pleased with it - however I do occasionally get the hysterical moiree-effect mentioned in some threads in this forum. Rasterized magazines as well as denim jeans, various suits with a tight woven texture sometimes! produce violently colourful effects...!! I use the latest software as well for the back (recently updated in Denmark) and FlexColor? How have you come to terms with this? Focus adjustments?? I've been told the problem exist because of the combination of extremely sharp lenses (true!!) and CCD- sensor. My 35mm with CMOS-sensor has never had this problem with any subject photographed...?
Someone else must have had this problem? Please help me out as I'm getting tired of making supplemental out-of-focus exposures for tricky textures...

Thanks

/Chris
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[Christopher E]

Thanks Sean!

Yes, for chrominance moiree I make a copy of the affected area in a new layer, add gaussian blur ( a lot), sets the layer mode to color and blend it using transparency, trimming the layer with eraser tool - works very well too... But I'll learn to use your technique as well since different objects require diferent solutions...

Actually I was hoping for a way to eliminate the luminance moire from the very point of releasing the shutter. Digital back adjustments or settings, perhaps - it's strange since one of my colleagues with the exact same equipment has never experienced the level of problems I have...? Guess my lenses are sharper than his, eh... :-D

Thanks anyway! Other experiences from anyone?

[SeanBK]

Contact your dealer and get accepted on the forum that is run only for Hasselblad/Imacon users. The forum is run by Nick Tressider from New Zealand. They are very very good in responding, help & guide each other. Enormous learning experience.

[SeanFS]

Could be as I don't get the expected level of moire with my 132c, although it is there , but nothing like I was used to with the Kodak 760 in particular.

 I use Hasselblad V series gear and find the lenses very sharp - the first shoot I did with it was a furniture fabric shoot and was expecting a fair amount of moire , but with one or two exceptions it never happened and was easily fixed. I get quite a bit of chrominace noise in landscapes but flexcolour noise reduction deals with that really well.

The other trick , if you can identify moire at the time of shooting is to change the camera to subject distance slightly, as moire is caused by the fabric pattern frequency being identical to the  sensor array frequency.

Thats no help if you are shooting something like backlit umbrellas, as i was earlier this year where the shape of the product means if you cure it in one place it reappears somewhere else.
I did that job on a 1ds2 - suposedly a more free camera.

I'll have to try your technique the next time I get moire - I might drag the 760 out to make some suitable images for practise!



Thanks Sean!

Yes, for chrominance moiree I make a copy of the affected area in a new layer, add gaussian blur ( a lot), sets the layer mode to color and blend it using transparency, trimming the layer with eraser tool - works very well too... But I'll learn to use your technique as well since different objects require diferent solutions...

Actually I was hoping for a way to eliminate the luminance moire from the very point of releasing the shutter. Digital back adjustments or settings, perhaps - it's strange since one of my colleagues with the exact same equipment has never experienced the level of problems I have...? Guess my lenses are sharper than his, eh... :-D

Thanks anyway! Other experiences from anyone?
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