Aliasing effects with the M8 - How much of a problem?

[asabet]

I am looking for someone to remove the AA filter from an Olympus E-420, and I was wondering whether M8 owners here tend to feel that the lack of an AA filter was a good choice for that camera. Any links to full-res samples and crops, demonstrating either the benefits or downside to the lack of an AA filter, would be appreciated. I've seen plenty of examples from the Kodak SLRn, but I 'd like to see some from the M8 as well. Either way, if someone with expertise is willing to do it, especially if they give me a "guinea pig discount," I'd like to go ahead with the E-420 surgery. I understand the benefits of an AA filter, but I see no reason to have one in all of my cameras. The 5D has a weak one, and aliasing rarely troubles me with that camera.

 

[helenhill]

I had read an article in 'The Online Photographer' /12 October 2007 'Live Dangerously' article
re: removing AA filter
maxmax.com does this for a fee of $450.00
cheers! helen

 

[asabet]

Thanks Helen. The Olympus cameras are not on their list of supported models for the procedure, but I emailed them an inquiry.

 

[Jack]

I think it depends on the kind of imaging you do. For me, the AA filter is a negative more than it is a positive: in landscape, I rarely worry about moire artifacts (though they can occur), same for street and travel. However, if you shoot people a lot, the weave pattern in many fabrics can generate unpleasant artifacts the AA filter does mitigate the occurrence of this significantly.

Cheers,

 

[asabet]

Thanks Jack. I got a reply from MaxMax that they would modify the E-420 for UV+Vis+IR but did not currently have the necessary glass to simply replace the AA filter (i.e. Hot Rod). They said that I could use a color correction filter on each of my Oly lenses to enable normal visible light photography without IR contamination, but I am wary of going that route.

 

[jaapv]

That is basically the same as a Leica M8 or Nikon D70. Just put a IR/UV cut filter (sometimes sold as "digital filter") in front of all your lenses. You are only moving the filtering from in front of your sensor to in front of your lens. It can take the place of a protective filter. The added advantage is that you can remove it when not needed, i.e. when there is little IR light around and you can put on an IR pass filter to do real IR photography. A small drawback is that there is a bit more danger of flare and reflections in adverse lighting situations. I'm sure you will see a great increase in apparent resolution if you go this route.

 

[asabet]

Thanks Jaap. There is a post here that had me concerned about loss of visible light with the CC1 filter. Does it act as a partial ND filter causing me to need to use higher ISOs as that post suggests?

 

[jaapv]

No- UV/IR filters cause no appreciable loss of visible light.
I am a bit confused about the thread you pointed to. The guy uses a CC1 filter, which does indeed cause light loss, to compensate for the colour shifts he sees to "replace"his sensor filter he says.. Even if the 5D sensor filter were the colour of a CC1 filter (which I seriously doubt) the light loss would be the same as an unmodified camera, making for no difference in normal shooting. So I suppose he is simply using a filter that is different from the original filter array and is not aware of the existence of proper filters. If you remove the IR filter from the sensor and replace it by a filter in front of the lens, even if this would give a colour shift in the raw conversion of thevisible light image because of some esoteric colour of the sensor filter, this is just one mouseclick correction in Raw conversion in your computer.

 

[asabet]

I appreciate the explanation Jaap. The MaxMax folks actually told me specifically that if they do an IR-visible-UV conversion on my E-420, that I would need a CC1 filter to produce normal looking visible light photos. I had multiple concerns with this including light loss, darker/color shifted optical viewfinder, and the possibility of less sharp images if IR blocking is not complete. The EXIFs on this page suggest that the CC1 filter has the same effect on exposure as the native IRC sensor filter. However, my other questions remain. I think I will defer this process as I have no interest in IR photography. I just want the AA filter replaced for maximal resolution.

 

[doug]

I am looking for someone to remove the AA filter from an Olympus E-420, and I was wondering whether M8 owners here tend to feel that the lack of an AA filter was a good choice for that camera. Any links to full-res samples and crops, demonstrating either the benefits or downside to the lack of an AA filter, would be appreciated.

As Jack wrote, it depends a lot on your subject choice. I'm using the DMR to photograph wildlife. As you probably know the DMR does not have an AA filter. For mammals I've never seen any aliasing artifacts. Birds are another matter, because the fine feather detail is a regular pattern. I've seen moire in several of my photos, but only because I'm looking for it. In most cases, nobody else has seen it.

The worst example of moire I've seen has been with photos of two quail species, Gambell's Quail and California Quail. I don't know why quail are more of a problem than other birds, maybe they tend to keep their feathers preened better than other species. I'm using a software moire reducer from fredmiranda.com which tames the problem enough that it's barely noticable:

I've seen photos of this species made with the D300 that show moire more than this photo does.

 

[woodyspedden]

Hey Doug

What is the name of the Moire reducer from Fred's site. I should have one for the few occasions where this has come up with the M8. I am also not surprised that the D300 (and probably †he D3) shows this as well. Anecdotally it would appear they have weak AA filters.

Woody

 

[doug]

Woody, I believe it's just called Moire Reducer.

 

[asabet]

Doug, thanks for the information. Interesting that those quail present a special challenge for aliasing. It seems that there is no one available to do the AA filter replacement on an Olympus DSLR unless I go the IR conversion route, which I don't want to do.

 

[helenhill]

Amin/asabet

What are your thoughts about the oly 420 in general
Thanks in advance....... Cheers! helen:grin: