Photo Jottings

This is a comparison between the lenses listed below, all crops were taken from the center of the image at 300mm.  If the image box is empty, that means the aperture listed is not available on that lens.  The camera used for this comp is the Sony A900.

When looking at the crops, keep in mind the following information:

The subject is the larger cover sticker from a book of “forever” US stamps, with a piece of cloth on the right, both against a white cardboard box background.  My crops aren’t exactly lined up, but close enough for our test purpose here.  The green item is a thumb tack.

The distance from the lens to the subject is about 32 feet, or 9.75 meters, which might be about the same distance as you would get to a bird or small animal.  Tele-converter shots were tested from the same distance.

For all lenses, focusing was done manually, and samples were taken until the best possible sharpness was obtained, then the shot sequence was taken.  The reason manual focus was used is because the camera’s focusing system was not always accurate enough when looking at 100% crops of 24mp images.  Also, the focal length may appear less or more on certain lenses, that’s because of the focusing mechanism, which changes the effective focal length on that lens slightly.

Guide for beginners

In case you aren’t all that familiar with the nuances of image quality, I’ve added some circles with numbers to help point out areas that you’ll want to take note of.  This image was taken closer than the real crops below, so I could enlarge it and put in the numbers for you to see.

1.  Look at the very fine detail here, or lack thereof between the crops.

2.  This block of lines inside the circle is 3mm across, and don’t forget the distance is 32′ or 9.75m from the lens.

3.  Look along the white border on the stamp, with the less expensive lenses, it almost vanishes among the white from the cardboard box background.  A good lens will more clearly delineate the transition (acutance).

4.  These letters are all fuzzed up on the less expensive lenses, and clearly discernible with the good ones, even at wide open apertures, it’s the same issue as no. 3 above.

Summery of each lens.

Sony 75-300mm F/4.5-5.6.  This is easily the least desirable lens when you look closely.  There is almost no definition between the white border and white background.  The tan letters off to the left are not recognizable in the F/5.6 crop.

Sony 70-300mm F/4-5.6 G.  This is a step up to the above lens, and should be for about three times the price.  I see an improvement, but not as much as I would have guessed before putting these crops side-by-side.

Sony 70-400mm F/4-5.6 G.  Taken at 300mm.  These crops show a big step up from the above lenses.  I see very nice micro contrast and acutance, and obviously this zoom is holding its own when comparing it to the 300mm primes.  There is no AF when using the Sony tele-converters.

Minolta AF 300mm F/4 G.  This lens shows very well when compared to the 300mm zooms, and seems to have the same resolution as the 70-400mm, but not quite the contrast.  Sony tele-converter use results in more color fringing and loss of contrast, plus no AF with the 2.0x TC.

Sony 300mm F/2.8 SSM G.  This is a very expensive lens, and it shows amazing image quality—as it should.  It easily beats all competitors here.  Also notice (as compared to the Minolta 300mm F/4) it seems to be designed to perform best at wide apertures, as F/5.6 is sharpest, and degrades rather quickly as you stop down.  The Sony 300mm F/2.8 lens works very well with the Sony tele-converters, check out the crops farther down the page.  This lens is made for shooting at large apertures, like fast action sports that require high shutter speeds, and it looks to me like it will satisfy even a picky chat room twit looking at 100% crops on his computer!  It will auto-focus with both TCs.

Reminder; these crops were taken indoors with controlled conditions and at a fairly short distance.  When you go outside and start shooting at distant objects, atmospheric haze and heat shimmer can destroy fine detail, so the differences you see in my indoor crops may not be so noticeable at long distances outside.

The lenses pictured below are the ones actually used in this comparison.

Text for above crops is at the top

Below we’ll check out the differences with the Sony tele-converters attached, first up, the 1.4x.

Note; the distance to the subject in all tele-converter shots is the same as the shots above, or about 32′ (9.75m).  Here I’ve upsized the Sony 70-400mm images to match the 420mm crops of the two primes when you add the 1.4x TC.  The Sony 70-400mm crops are not from a TC, they are from 400mm, and sized to match 420mm, got it?  It’s clear to me the Sony 300mm F/2.8 SSM G makes the best use of the TCs as it holds the contrast better.  It looks like the Sony 70-400mm at 400mm, and the Sony 300mm with the 1.4x TC have about the same resolution, but maybe the 70-400mm has a little more contrast, since it isn’t using a TC.  Using the TCs on the Minolta AF 300mm F/4 introduces additional color fringing and loss of contrast, making it unable to closely compete with the other two lenses.

Check out the two very thin lines at the bottom of the bell, a closer view is at the top of the page.  You can just make them out with the 70-400mm and Sony 300mm F/2.8, but the Minolta is struggling.  The 1.4x TCs do help increase resolution on all three lenses, and definitely look sharper as opposed to simply upsizing a non-TC shot.

Another note; when adding the tele-converters, you add one stop of light loss for the 1.4x, and two stops for the 2.0x.  For example, the Minolta AF 300mm F/4 would become a 600mm F/8 with the 2.0x TC installed, and the Sony 70-400mm would be an 800mm F/11 zoomed all the way, because the maximum aperture at 400mm is F/5.6.

Below we’ll use the 2.0x.

This time I used a 2.0x on the 70-400mm, for a total of 800mm.  Based on past zoom results using the 2.0x, I thought the Sony 300mm prime would look a little sharper even when considering the loss of 100mm.  But not so with the Sony 70-400mm, which produced slightly sharper images with the 2.0x, indicating very good optics.  The older Minolta AF 300mm F/4 is lacking contrast, although the F/16 shot shows good detail.  I don’t have any F/16-22 crops for the Sony 300mm, that’s why the spaces are blank, the images degraded past F/11.  This time check out the very thin lines directly above and below the text that wraps around the upper part of the bell, best seen in the 70-400mm F/11 crop.  Again, look at the larger image at the top of the page for a better idea of what I’m talking about.

In reality, you can’t use this much focal length (600mm-800mm) hand held at F/16-22 unless you want to ramp up the ISO.  Even on a good tripod it’s hard to keep things sharp.  I had a heck of a time with these crops, and used mirror lock up with a corded remote indoors!  Go outside with your tripod in the wind with no corded remote and you won’t be able to get sharp shots past F/11.  Unless you shoot test charts all day, the only lens I’d recommend using with the 2.0x TC is the Sony 300mm F/2.8, and more importantly, it’s the only lens here that can use auto-focus with the 2.0x.