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Author Topic: Anyone Handled A P+ Back Yet?  (Read 10818 times)

pss

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Anyone Handled A P+ Back Yet?
« Reply #20 on: March 17, 2007, 10:16:42 pm »

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not sure why some of you guys are wasting your time quibbling online, i have an actual legitimate question; I want to purchase the P21 back when it comes out but my colleague says that the P series backs are giving him alot of Moire issues when he shoots fashion, which is what i will be shooting, DOES ANYONE KNOW IF THE PLUS SERIES BACKS WILL ADDRESS THE MOIRE ISSUE?
[a href=\"index.php?act=findpost&pid=107218\"][{POST_SNAPBACK}][/a]

i can only speak for the P30 and yes it does show moire....does it show less then the two last backs i owned: leaf 17 and a P20? yes, a lot less then either...so much less that it just is not an issue anymore...if it does come up, the C1 moire removal works great and is always one click away...
all backs show moire to some degree, some more, some less....but they all do...shooting tethered usually makes thing easier as well...you will see it right there, maybe change the f-stop, move the camera forward or back a couple of inches....
i had one shot in 18months with the P20 that could not be saved (in my opinion...the client ran it anyway, it never showed in print) with the P30 i know that won't happen....

i am in line for my P+ upgrade since they announced the price increase for the upgrades....only after i was assured that i would have plenty of time to check the new backs out before actually switching....like james said...the P30 is pretty much perfect now, hard to make it a lot better, but....i won't buy it for a better screen or for one extra stop...neither is worth the price for me....i would rather wait for the next generation.....

by the way i was promised the P+ back for end of may/june....so as far as i am concerned there is no delay....yet....

waiting for CS3 is MUCH harder....the brushsize bug drives me crazy.....
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neil snape

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« Reply #21 on: March 18, 2007, 04:44:19 am »

I'm just reading with the usual lusting for a medium format back so I can free up fridge space of all the about to expire film....

The big camera retailer here in Paris have all the + models slted for June /July delivery.
http://www.legrandformat.com/Neuf/MFnu.htm     but be aware of their buggy site!
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Camdavidson

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« Reply #22 on: March 18, 2007, 09:21:50 am »

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I'm just reading with the usual lusting for a medium format back so I can free up fridge space of all the about to expire film....

The big camera retailer here in Paris have all the + models slted for June /July delivery.
http://www.legrandformat.com/Neuf/MFnu.htm     but be aware of their buggy site!
[a href=\"index.php?act=findpost&pid=107250\"][{POST_SNAPBACK}][/a]

I am new to shooting medium format with a digital back.  I purchased a P30 + for my Mamiya Kit and am quite happy with the P30 loaner I am using.  The major fault of the P30 back is the LCD screen.  For such an expensive item, it is less than desirable and takes a while to understand it - checking the histogram is easy and the speed seems fine to me.  My dealer told me that the new back will deliver in the early summer, so I expect that to be true.  

The Plus version has a better LCD, is faster and offers higher ISO's.  That is enough for me.

I am very happy with the results of shooting with a 16 bit back and the larger sensor size.  If the new 1DsIII is 14 bit with all the improvements made in the 1D Mark III - then the gap between the two will have narrowed quite a bit.  Enough for me to consider not using the medium format back and to shoot exclusively with the Canon.

Time will tell.  But for now, the P30 is rock solid and a joy to use.
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Mort54

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« Reply #23 on: March 18, 2007, 11:38:27 am »

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DOES ANYONE KNOW IF THE PLUS SERIES BACKS WILL ADDRESS THE MOIRE ISSUE?
[a href=\"index.php?act=findpost&pid=107218\"][{POST_SNAPBACK}][/a]

Unlike all current DSLRs, most digital backs do not have an anti-alias (A/A) filter and are therefore susceptible to moire to some degree or another. I doubt the P+ backs will be any different. For many users, the lack of an A/A filter is a good thing, since the image is a good bit sharper right out of the back when no A/A filter is smearing the image. But for some users, especially fashion users, moire is a problem that's going to be hard to eliminate with current lower MP backs. Higher MP backs are another story, as described below.

Moire is simply a digital sampling artifact. Any time the spatial sampling frequency of the back is lower than the spatial frequency found in the subject, moire can happen. The spatial frequency of patterns in clothing material is very high, and is often higher than the spatial sampling frequency of most backs, so fashion photography is especially susceptible to moire. An A/A filter, if present, lowers the spatial frequency in the subject below the sampling frequency of the backs (it's a low pass filter and smears or softens the image a bit), eliiminating (or mostly eliminating) moire.

As backs become available with higher and higher MP, the photosite size gets smaller and smaller, and the spatial sampling frequency of the back goes up and up. In other words, higher MP backs with smaller photosites sample at higher spatial frequencies, and moire becomes less and less likely. This is why people with lower MP P20/H20 backs see a lot of moire, and people with higher MP P30 and P45 backs see less moire. Interestingly, at higher spatial frequencies, lenses start to act like weak A/A filters (the contrast in the higher frequency regions of the MTF curves starts to tail off). So, to reduce or eliminate moire with digital backs, use a higher MP back with smaller, more densly packed photosites, and/or use poor glass with louse MTF specs :-) Another person in this thread mentioned that you can reduce moire by changing the aperture - this is basically just the lens acting as a weak A/A filter. In effect, changing the aperture changes which part of the MTF curve you are operating the lens, either increasing or decreasing the high spatial frequency MTF falloff.

Regards,
Hans.
« Last Edit: March 18, 2007, 11:43:52 am by Mort54 »
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yodelyo

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« Reply #24 on: March 18, 2007, 12:03:16 pm »

Thanks Mort54, this makes perfect sense, I guess now I should decide whether to gamble with the P21 plus back or buy the P30 plus and hope more megapixels sorts out the moire's a bit. Anyone know what the new pentax 645 might offer as far as moire problems? kinda a dumb question since it aint out yet but maybe someone knows about the A/A filter with it.

Quote
Unlike all current DSLRs, most digital backs do not have an anti-alias (A/A) filter and are therefore susceptible to moire to some degree or another. I doubt the P+ backs will be any different. For many users, the lack of an A/A filter is a good thing, since the image is a good bit sharper right out of the back when no A/A filter is smearing the image. But for some users, especially fashion users, moire is a problem that's going to be hard to eliminate with current lower MP backs. Higher MP backs are another story, as described below.

Moire is simply a digital sampling artifact. Any time the spatial sampling frequency of the back is lower than the spatial frequency found in the subject, moire can happen. The spatial frequency of patterns in clothing material is very high, and is often higher than the spatial sampling frequency of most backs, so fashion photography is especially susceptible to moire. An A/A filter, if present, lowers the spatial frequency in the subject below the sampling frequency of the backs (it's a low pass filter and smears or softens the image a bit), eliiminating (or mostly eliminating) moire.

As backs become available with higher and higher MP, the photosite size gets smaller and smaller, and the spatial sampling frequency of the back goes up and up. In other words, higher MP backs with smaller photosites sample at higher spatial frequencies, and moire becomes less and less likely. This is why people with lower MP P20/H20 backs see a lot of moire, and people with higher MP P30 and P45 backs see less moire. Interestingly, at higher spatial frequencies, lenses start to act like weak A/A filters (the contrast in the higher frequency regions of the MTF curves starts to tail off). So, to reduce or eliminate moire with digital backs, use a higher MP back with smaller, more densly packed photosites, and/or use poor glass with louse MTF specs :-) Another person in this thread mentioned that you can reduce moire by changing the aperture - this is basically just the lens acting as a weak A/A filter. In effect, changing the aperture changes which part of the MTF curve you are operating the lens, either increasing or decreasing the high spatial frequency MTF falloff.

Regards,
Hans.
[a href=\"index.php?act=findpost&pid=107284\"][{POST_SNAPBACK}][/a]
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Mort54

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« Reply #25 on: March 18, 2007, 12:17:10 pm »

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Thanks Mort54, this makes perfect sense, I guess now I should decide whether to gamble with the P21 plus back or buy the P30 plus and hope more megapixels sorts out the moire's a bit. Anyone know what the new pentax 645 might offer as far as moire problems? kinda a dumb question since it aint out yet but maybe someone knows about the A/A filter with it.
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Hi Yodelyo. I don't know about the Pentax, but I believe the Mamiya ZD has an optional A/A filter (at least that's what I think I remember from reading the spec sheets). Of course, I read here that the ZD has other problems, so it may not be the right choice for you.

Hans.
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pss

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« Reply #26 on: March 18, 2007, 12:19:58 pm »

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Thanks Mort54, this makes perfect sense, I guess now I should decide whether to gamble with the P21 plus back or buy the P30 plus and hope more megapixels sorts out the moire's a bit. Anyone know what the new pentax 645 might offer as far as moire problems? kinda a dumb question since it aint out yet but maybe someone knows about the A/A filter with it.
[a href=\"index.php?act=findpost&pid=107286\"][{POST_SNAPBACK}][/a]

there are some things we know about the pentax....it has the same chip as the P30 and the hass H31, so most likely it will be the same in regard to moire (although i am pretty sure pentax would have more problems....phase and imacon have decades of software experience, pentax..none..)...and we also know that the camera has not been handled, held or shot....so i would be very surprised to see it in stores before 2008....

if somehow possible i would recommend the P30....the extra money is well spent...i am sure the P21 is great, but the extra resolution of the P30 make a difference....not sure how much the P21+ is, but it might no tbe that much cheaper then a P30....and expect the P30 refurbs to become available right after the + starts shipping....that might just be the best deal on any Dback ever...

no matter what canon comes out with ...it won't be able to compete with:  31mpix 16bit large sensor with 45 raw shots/min....not in terms of quality......and if canon really changes the size/mount/body, which they woould have to to really step it up....there will be kinks to be worked out and i would not want to buy that first "new" canon....at least not depend on it day to day as the  main camera.....the P30 or P21 have none of these problems.....
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Mort54

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« Reply #27 on: March 18, 2007, 12:49:56 pm »

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no matter what canon comes out with ...it won't be able to compete with:  31mpix 16bit large sensor with 45 raw shots/min....not in terms of quality......
[a href=\"index.php?act=findpost&pid=107289\"][{POST_SNAPBACK}][/a]

Hi Paul. I generally agree with you, although I think there are a couple of things Canon could do to make it interesting, at least as far as competing with the 22MP backs goes. Ignoring the rumored MF Canon, and assuming only a 22 MP 35mm full frame update to the 1DsII, if they eliminated the A/A filter (or made it optional) and used 16-bit A/Ds (the 1DIII has already gone to 14-bit A/Ds), then I think 22 MP backs would be in real trouble. The photosite size would be slightly smaller than on the P30, but roughly comparable, so I suspect the image quality would be roughly comparable. But like you said, a P30 would still have the resolution and file size edge.

I'm not pushing Canon by any means (I'm currently a Nikon shooter), but I do find myself stalling on making a MF purchase decision until I see what Canon comes out with next. In fact, I was very disappointed they didn't announce the 1DsIII at PMA, so I can move on.

We certainly live in interesting times. Of course, in some parts of the world, this is considered a curse :-)

Hans.
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