FZ300 Aperture and Closeup Lenses

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Stephen Barrett Contributing Member • Posts: 696
FZ300 Aperture and Closeup Lenses

I have been using a Canon SX50 since 2014 and have been very happy with it.

Most of my images are focus-stacked, using the Raynox 250 and Raynox 150 closeup lenses, as well as 317 mm and 600 mm closeup lenses that I made from binocular and telescope objectives.

My wife got me a Panasonic FZ300 for Christmas because I was eager to use a camera that wasn’t “diffraction-limited”. There is a lot of discussion about the poor contrast that most bridge cameras yield because of their narrow apertures. Cambridge In Colour has a calculator to determine the limiting aperture for avoiding the dreaded diffraction. As a rule-of-thumb, the numerical aperture N should not exceed 2 times the pixel pitch. The SX50 and the FZ300 have pixel-pitches of approximately 1.5 microns, so the numerical aperture should not exceed f/3. The SX50 has, at widest, f/6.5 at full zoom and f/5.6 near 75% of full zoom. The best that the SX50 can achieve is f/3.4 at the wide end, which is not of much use with closeup lenses. I usually avoid full zoom on the SX50 with the closeup lenses because the images appear sharper and have more contrast if I back off to where the aperture is f/5.6. I tried some experiments using a reverse-mounted 50 mm prime lens as a closeup lens on the SX50 so that I could try f/4 at low zoom (f = 28.4 mm, EFL =159.6 mm) and the results looked promising.

The one bridge camera that is not “diffraction-limited” and not too terribly expensive is the Panasonic FZ300, with its widest aperture of f/2.8 available throughout its whole zoom range. My hope was that the FZ300 would give me sharper details and better contrast than the SX50 at the same magnification.

FIRST TEST - FZ300 vs SX50 Using Seedy Bread-Crust

My preliminary findings, using a seedy bread-crust and the Raynox 250 and Raynox 150 closeup lenses, were that the FZ300 at f/2.8 was LESS SHARP than the SX50 at f/5.6 but that the FZ300 at f/4 was SLIGHTLY SHARPER than the SX50 at f/5.6. While the FZ300 seems to be a fine camera, this was a bit of a disappointment because I was expecting big gains that did not materialize.

SECOND TEST - FZ300 vs SX50 Using Kalanchoe

Just to be sure, I repeated my comparison test using a Kalanchoe, a small flower that just fits into a 1-cm square. I reached the same conclusions with both the Raynox 250 and 150 closeup lenses: that the FZ300 at f/2.8 was worse than the SX50 but that the FZ300 at f/4, it was marginally sharper than the SX50 at f/5.6.

THIRD TEST - FZ300 at f/2.8, f/4, f/5.6 & f/8 Using Raynox 250 Kalanchoe

The following images are all focus-stacked using the Raynox 250 closeup lens.

The FZ300 was set to f = 94.0 mm and ISO 100.

The tests were all done at this focal length without moving the tripod.

Only the aperture and exposure times were changed, not the lighting.

The images are:

  • f/2.8, 94.0 mm, 1/200 s 72 shots, focus-stacked 0.05 mm apart
  • f/4, 94.0 mm, 1/125 s 77 shots, focus-stacked 0.05 mm apart
  • f/5.6, 94.0 mm, 1/60 s 45 shots, focus-stacked 0.1 mm apart
  • f/8, 94.0 mm, 1/40 s 45 shots, focus-stacked 0.1 mm apart

The focus of the shots was changed using a macro rail with an added adjusting screw to obtain focus distances in steps as low as 0.05 mm. The larger apertures required a smaller step size because of the shallower depth-of-field. The focus stacking was done with Zerene Stacker.

The first shot shows the whole image (for f/4) but the view was the same at all apertures.

The Kalanchoe fits into a 1-cm square - or about 14 mm from petal-tip to opposite petal-tip.

No processing was done, other than the focus-stacking.

100% Crops (1200x900 pixels)

f/2.8, 94.0 mm, 1/200 s 72 shots, focus-stacked 0.05 mm apart

100% Crop (1200x900 pixels). The image was darkened slightly to better match that of f/4.

f/4, 94.0 mm, 1/125 s 77 shots, focus-stacked 0.05 mm apart

100% Crop (1200x900 pixels). No brightness adjustment.

f/5.6, 94.0 mm, 1/60 s 45 shots, focus-stacked 0.1 mm apart

100% Crop (1200x900 pixels). The image was brightened slightly to better match that of f/4.

f/8, 94.0 mm, 1/40 s 45 shots, focus-stacked 0.1 mm apart

100% Crop (1200x900 pixels). The image was brightened slightly to better match that of f/4.

CONCLUSION

From these four 100% crops, my conclusion is that:

The “ORDER OF GOODNESS” is: f/4, f/5.6, f/2.8, f/8

I would put both the sharpness and the contrast in this order.

If you wish to check this for yourself, it would probably be best to download the images full-size from my gallery and view them all together on the same screen or rapidly in succession.

(If you just scroll from one image to the next, it is harder to judge the differences.)

COMMENTS

-I am not sure whether I am making a big deal about nothing. Some people may find that the differences are not significant.

Usually, though, my problem is the opposite - that real photographers are much more sensitive to sharpness, contrast and image quality than I am.

-I find that my SX50 at f/5.6 is about the same sharpness as the FZ300 at f/5.6.

-I like the colour and contrast (set to default values) better on the SX50 but perhaps that is a matter of making adjustments to the light balance and contrast settings on the FZ300.

-The FZ300’s sensor is noisier than the SX50’s. This is quite visible in the dark areas next to the petals.

-I feel a bit disappointed that the hoped-for gain in sharpness and contrast that would result from f/2.8 have not materialized - only a very modest gain at f/4.

Where is the “diffraction-limitation” effect that we are supposed to see?

-A possible explanation of why the FZ300 at f/2.8 with the Raynox lenses is less sharp than at f/4 is that the wider f/2.8 aperture samples more of the outer portions of the closeup lenses, which may be less perfect than the central portions. In other words, it may be the fault of the closeup lenses, rather than a fault of the FZ300.

SUMMARY

In three sets of tests, I have consistently found that f/4 gives me better results than f/2.8 on the FZ300 when used with the Raynox 250 & 150 closeup lenses.

Theoretically, this should not be the case, and I do not know whether this is the fault of FZ300 or the Raynox lenses.

Obviously, f/2.8 offers advantages for action shots and low-light conditions, but I would be very interested to hear from others about their experience with sharpness and contrast,

 Stephen Barrett's gear list:Stephen Barrett's gear list
Canon PowerShot SX30 IS +3 more
Panasonic Lumix DMC-FZ300
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