Small vs larger sensors (and other matters) for close-ups/macros

Started Aug 4, 2013 | Discussions thread
kiwigirl Senior Member • Posts: 1,642
Re: FZ50 vs GH2

gardenersassistant wrote:

Very interesting. Thanks for taking the time to experiment and let us know what you found.

Can I pick at this a bit? Are these both 100%? (I imagine so, but there is I think a contrary, although rather unlikely, reading possible from your words.) Assuming they are both 100%, then the GH2 one would be more of a crop, with the GH2 having 16 Mpix to the FZ50's 10 Mpix. (By and large I would expect a camera with a larger sensor to be able to produce similar quality from a more severe crop compared to a smaller sensor.)

I opened the images in Picasa and set the view at 1:1 and cut with the snipping tool.  To my understanding that is viewing at 100% (otherwise known as pixel-peeping!)?  At 100% the M 4/3 sensor is cleaner, but once you reduce the magnification the smaller sensor catches up.

There is I think also a complication in viewing at 100%. It depends on how much you crop, but for my part I rarely get anywhere near 100% for my outputs, whether prepared for screen viewing or (much less often) for a (usually A4, occasionally larger) print. I think that gives an advantage to the smaller sensor, in the sense that an image from a larger sensor may well be better, for example in the detail it contains, but some of that detail may not be visible at the size the image is viewed at.


And the gain in quality can be cancelled out with the loss of DOF.  I spent a bit of time trying to get good shots of this mantis mymph (only about 1cm or half inch long) eating a black ant.  Only with strong sharpening and down-sizing were the images acceptable.  Otherwise I just could not get enough DOF to get the nymph's head and the ant's body in focus.

An image of the same scene captured with a smaller sensor may look much the same, at that size, but may be right on the edge of how much detail it can reveal. Put another way, you may be able to get a decent quality image of a larger physical (print or screen) size from a larger sensor (I'm having difficulty wrapping words around some of this - hope I'm making sense. And of course if I'm plain wrong then someone can correct me! Please.)

Lenses. Yes, another factor to consider, definitely. It isn't as much difference probably as a prime versus zoom comparison, but I used the 45-200 for a good while with my achromats and then switched to using them with the 45-175, which (subject to possible shutter-shock issues at some shutter speeds, which as it happens I was never aware of, even when testing for them) seems generally to be regarded as a better lens than the 45-200. But for me (and my size of outputs and - generally mild - degree of cropping) , although it had distinct usability advantages with achromats (because it doesn't extend, and also doesn't creep when pointing down), I was never aware of getting visibly better image quality with it.

A couple of forum members (can't remember who they were now) recommended the 45-200 for close-up work.  For regular shooting as a telephoto lens it hasn't blown me away.

The issue of how much lens quality relates to output quality is a bit more complicated in my case, because I use such small apertures (for invertebrates) that diffraction is a very significant issue. With invertebrates I typically use the smallest possible aperture (and hence get the maximum diffraction hit). I read somewhere recently that diffraction is a great leveller as between really good and not so good lenses when they are used with very small apertures. Don't know how true this is, or what sort of apertures you would be using, so of course it might not be an issue for you.

I don't let diffraction bother me too much. With such thin DOF at close range it's probably hard to tell!  I've used F22, but if I have a larger target or zoom out more I will try and stick with F16, simply because "they" say it should be better(?).  Could I tell what aperture I used by viewing the results - probably not!

If you have any, I would be very interested to see (non scientific, like mine) any more nearly whole-image comparisons of somewhat similar close-up scenes/subjects as between the FZ50 and GH2. (Doesn't have to be completely whole image - some of my examples weren't, but none had radical crops. And I don't think the G3 images were on average more cropped than the small-sensor images.)

BTW, I just registered your "not as close" comment about the G3 shot. I'm puzzled. I measured the working range for the 250 on the 45-200 at full zoom on the G3 as about 102 - 118mm (outside this range of working distance, I couldn't get autofocus to work, and I assume manual focus may not give the sharpest results outside of this range), and I measured the same range with the 250 on the Canon SX10 bridge camera at full zoom (and just measured it for the FZ200 and got the same numbers again). For my part, with the 250 (like all my achromats) I first get the camera at a distance where autofocus works (even if, rarely, I am going to use manual focus) to make sure I am within an appropriate working range. Do you do any similar check to make sure you are within the range that will give you the best results?

I almost never use auto-focus - on either FZ50 or GH2.  I use the technique of rocking back and forwards till I have the focus where I want it.  I haven't measured it as such, but I believe the working distance from lens to subject with the Raynox is very similar on both cameras - in the 4-6" range?

The FZ50 is lighter and more ergonomic to use, but the down-side now for me is the poor viewfinder. I have been really spoilt with the superior VF in the GH!

But winter here now, so few willing subjects. Will have to wait a few more months.

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