Sweet spot

Thanks for sharing the pictures. Its obvious the high f-stop does produce a softer image.. but thats nothing new. Just the price of doing business with f32...

When I used to care a lot more I would visit websites that would help me to find the sweet spot in my lenses. For instance, my 28-200 tends to perform best at f8-f11 at 28mm.

This site in particular was good: http://www.slrgear.com/reviews/index.php

I also visited this site for the same kind of thing: http://www.photodo.com/

At the end of the day, I have found that my choices tend to be dicated by my circumstances rather then my desire to fit in on the best part of a graph. When photographing MRR stuff I use the highest f-stop number I can use becaue its more important to have everything in focus then to worry about small losses of sharpness and such. However, I think its good stuff to be aware of..

Now I worry more about good light and composition and tend not to worry technical thing so much.

Chris

helicon focus changes everything

I feel that the softness at f32 was not bad, especially when you consider the overall depth of field. You have to consider the extreme magnification of the lower images.  But it is true for ultimate sharpness you should use optimum lens aperture.  As you say, before Helicon Focus this wasn't an issue as f32 was the only solution. But HF has changed the whole equation. 

So the next step is a test with a Helicon Focus shot at f8 and f32 and maybe f16 or f22 so see where the fall off starts. I may also try a comparison of my macro and zoom lens to see what they compare. The nice thing about shooting at f32 with HF is that the program has more sharp image area to work with. That allows a little more leeway in doing the stacking. With a smaller DOF with each f8 image, there is a possibility that there will be areas where there isn't sufficient overlap. You can shoot the images more closely spaced, so you can avoid it if you are careful.

One other thing to think about, the 5D has a 20 Mega-Pixel sensor with full frame CCD, so the photosites are probably slightly bigger than other digital cameras with APS sized CCDs. (30 percent more pixels but 60 percent bigger sensor compared to my previous Canon D60.) I suspect that results with other digital cameras may be more susceptible to diffraction effects as small apertures due to the smaller photosites on the CCD. So you should probably do a test with your own camera to see the delta.

Very cool stuff!

Facsinating stuff.  Looking forward to following this thread.

Helicon Focus is the real deal it seems!

Thanks for sharing Bernie.

One other thing to think

Umm, the 5D had 12.8 mpixels. The 5D mkII has 21.1. I'm assuming you're talking about the 5D mkII here. The D60 is a model from 2002 with 6.3 mpixels. So the 30% more pixels comment doesn't seem to match the rest of your comment.

Not that I'm disputing the effects of diffraction.

btw. there are a ton of lens reviews with resolution at focal lenth and f-stop charts on http://www.photozone.de

Cheers,

Charlie

I thought it was an optical issue

I could be dead wrong.. but I thought the whole issue with image quality when using very small aperatures was an optical one and was only about the lens. The relative resolution of two sensors would be a whole other issue not related to f-stop.

I think its an interesting question, though, of whether your over-all image quality using helicon would be better using more images with larger aperatures or fewer images with smaller aperatures. I suspect that the image quality is better with whatever method is easier and actually helps you produce more images since I found the quality sucks on images you never bother to make!

Chris

Good catch!

OOOPS,  the 5D is 12.8 MP, I made a typo.  I think i was subconsciously drooling over s 5DII when I typed that!  

Although I have looked at many lens reviews,  etc.  I find that many pro photo websites don't look at photography the way model RRers do, so I thought a test would be in order of a model RR subject.

circles of confusion

The lens and aperture combination set the size of the circles of confusion. The size of the photosites in relation to the circles of confusion generated by the lens determine when a digital camera starts to be affected by the lens properties. So a lens could behave differently on different digital bodies.

One thing that camera designers and therefore consumers have learned is that digital sensors don't behave exactly like film and that lens designed for film camera bodies might not work well in a digital body.