I have said in a couple of threads now that Diffraction is NOT the problem that it was when we shot film, in those good old days there was absolutely nothing that could be done about it, however in the digital age one can simply apply a little extra sharpening on conversion (capture sharpening)....obviously problems related to diffraction become more aggresive as you increase magnification, one of the microscopes I use (very expensive leitz objectives) can only be used wide open and stacked as the mag is so high that extreme diffraction sets in even when stopped down a third.
The image I have posted here was shot at f16, I hope it looks OK as the final processing was done on my backup laptop in CS2 (eek) (My main computer is very badly infected with a virus and I can only get it to boot in safe mode....) but I hope it goes to show that f16 on the 50D and similar mp cameras is, in fact, perfectly useable.....
Good info Phil
By the way the virus is not the one that looks like AVG is it ?
Can you get into system restore?
The one I mention blocks it.
Cheers
John
As always Phil good info, been out today shooting using the advice given earlier in the week, only went to f11 today as needed shutter speed but going to try d300 & Nikon 105mm macro at f18 next time and compare results. Impressed with f18 here so hopefully be able to get that bit extra doff, thanks for all advice
Good info Phil and a fine example to show off the tech you describe. Super eye detail and I'm looking forward to getting out there in the next day or two..
Superb detail and lovely BG. Hope you get your virus sorted.
Posted by Andy Astbury on June 29, 2010 at 6:17 PM
Phil, I've just got to add a wee qualifier to your words "...and similar mp cameras".
Just because you can get away with f16 on a 50D (as you could with a 40D, or at least on Guy Rogers you could) it doesn't automatically follow that you'll get away with it on any DSLR with the same Meg count. Diffraction limit is dictated by photosite size not megapixels.
For instance, 12MB on a full frame has a different limit to 12MB on an APS-C 1.5 crop.
I can squeeze the D3 to f19/20 at a push with a 180 macro but the image quality with the same lens on my D2Xs crop body collapses past f11.
The reason is purely a size thing - the D3 photosite size is a whacking 8.19um whilst the D2Xs is a lowly 5.52um.
Similarly f11 is the limit with the same lens on a 24MB D3X - the D2Xs and D3X photosites are pretty much similar in size even though the sensors are of different formats and the megapixel counts are vastly different.
Sorry for nit-picking ( I'm not, not really )
I like the image comp and the DoF is just perfect - spot-on
I think I am not explaining this all too well .... After nearly 30 yrs experience in this macro and high macro malarky (possibly not much longer) I have battled with the effects of Diffraction on an almost daily basis, many of those using film where we could do S B all about it, we had specially modified screens where we could view the ariel image and then back off when diffraction set in...
I am not saying that diffraction doesn't set in, what I am saying is that although the effect is there and that we should be 100% aware of the quality issues, with care in the post processing with digital the negative effect of diffraction can be compensated for... please note I say care as it can all too easily be overdone, certain sharpening methods are also much more effective such as convolution.
My 5D here at work is permanantly at f25 unless I am using the MPE-65 (that only goes down to f16) or it is mounted onto the Leitz Macroscope...
You are right I should have stated similar mp & sensor sized cameras (it was late and I was getting frustrated with my main computer )
Hi Phil, I can certainly see where you're coming from regarding the MPE-65. Everytime I use that lens I make the conscious decision to trade off a degree of sharpness for some more DOF. When I shoot at 5x I will often push it and use f9 or even 10 whereas I know the image would be sharper at f5.6 but at those magnifications it's essential, to me, to get more DOF (given how limited it is at those magnifications) and to accept that I will have to sharpen a bit more aggressively when PPing. As you say, with film that latter option simply wasn't possible. I can imagine this must be an even bigger issue when using a macroscope
If you need help with the PC, then I'd be happy to look at it for you. Only problem is... I'm away at the moment, but will be back weekend of the 10/11th, but then away again on the 12th for that working week.
Possibly of no use to you if you cannot wait, but I thought I'd offer anyway.
Discussion
11 repliesI have said in a couple of threads now that Diffraction is NOT the problem that it was when we shot film, in those good old days there was absolutely nothing that could be done about it, however in the digital age one can simply apply a little extra sharpening on conversion (capture sharpening)....obviously problems related to diffraction become more aggresive as you increase magnification, one of the microscopes I use (very expensive leitz objectives) can only be used wide open and stacked as the mag is so high that extreme diffraction sets in even when stopped down a third.
The image I have posted here was shot at f16, I hope it looks OK as the final processing was done on my backup laptop in CS2 (eek) (My main computer is very badly infected with a virus and I can only get it to boot in safe mode....) but I hope it goes to show that f16 on the 50D and similar mp cameras is, in fact, perfectly useable.....
HTH
Phil
By the way the virus is not the one that looks like AVG is it ?
Can you get into system restore?
The one I mention blocks it.
Cheers
John
Brett
Heath
Hi Phil,
Super shot, love the angle! Just a few dust spots around.
Cheers,
Lewis.
Just because you can get away with f16 on a 50D (as you could with a 40D, or at least on Guy Rogers you could) it doesn't automatically follow that you'll get away with it on any DSLR with the same Meg count. Diffraction limit is dictated by photosite size not megapixels.
For instance, 12MB on a full frame has a different limit to 12MB on an APS-C 1.5 crop.
I can squeeze the D3 to f19/20 at a push with a 180 macro but the image quality with the same lens on my D2Xs crop body collapses past f11.
The reason is purely a size thing - the D3 photosite size is a whacking 8.19um whilst the D2Xs is a lowly 5.52um.
Similarly f11 is the limit with the same lens on a 24MB D3X - the D2Xs and D3X photosites are pretty much similar in size even though the sensors are of different formats and the megapixel counts are vastly different.
Sorry for nit-picking ( I'm not, not really
I like the image comp and the DoF is just perfect - spot-on
I think I am not explaining this all too well
I am not saying that diffraction doesn't set in, what I am saying is that although the effect is there and that we should be 100% aware of the quality issues, with care in the post processing with digital the negative effect of diffraction can be compensated for... please note I say care as it can all too easily be overdone, certain sharpening methods are also much more effective such as convolution.
My 5D here at work is permanantly at f25 unless I am using the MPE-65 (that only goes down to f16) or it is mounted onto the Leitz Macroscope...
You are right I should have stated similar mp & sensor sized cameras (it was late and I was getting frustrated with my main computer
Hope you are well & speak soon
Matt
If you need help with the PC, then I'd be happy to look at it for you. Only problem is... I'm away at the moment, but will be back weekend of the 10/11th, but then away again on the 12th for that working week.
Possibly of no use to you if you cannot wait, but I thought I'd offer anyway.
Lovely shot btw, and interesting reading - Thanks
Kev