25 April 2012

couldn't resist

After walking past a fine slab of marble, I slowed down and came back to it.

From such things are new forum icons created!
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Comparing macros: conclusion?

Wait a minute - plenty of testing remains to be done, and some retesting as well!  


The whole time I was doing these tests the Tamron was sitting on a few forum sites seeking a buyer.  If it did not sell I would finish all sorts of additional tests, and if it did my budget would be in much better shape.  It sold today, so the testing has reached an unimpressive conclusion.

This is quite unfair to both lenses, but perhaps mostly to the SP 90mm.  Now that I have pinpointed the true center-AF point on my K-5 I should check if that was the reason for the more frequent focus hunting that I experienced with that lens.  That was really the closest thing to a complaint that I had, and it probably accounts for many of the Sigma's missed-focus events as well.

So it's really not possible to say either lens is a winner here - I am the overall winner, for several reasons:
  • I had two nice lenses to choose from, so no losing for that
  • I now have a 50mm lens that I find satisfactory
  • I improved the bank balance going from the 90mm to the 50mm
  • I have more space in my bag with the smaller, lighter Sigma - and
  • I still have a 1:1 macro lens that gives me excellent results!

So farewell to an excellent lens, and greetings to another!

21 April 2012

comparing macros: part two½

Part three intended to swap back to the Sigma right after the Tamron, so I could verify what I thought was different about the two lenses.  Alas, my health failed me so I only took a few images with the 50mm.  So much for plans and some degree of rigor.. but the points that I have hit so far were not refuted.  Focus hunted less with the Sigma and missed a time or two.  A squirrel photo-op with the 50mm came along just like with the 90, but I was at f/3.2 and the focus missed.  To be fair to the Sigma, I believe I have learned that the center focus point on my K-5 is almost precisely at the lower-right corner of the square that displays in the viewfinder.  The Sigma's hit rate shows more success with that in mind (I found this out after the squirrel scene, sadly).  I need to verify this with the Tamron and other lenses, since that is something that should not drift from lens to lens!

After further review - yes the Tamron also prefers the lower-right area of the center-focus square.  And a new item pops up that I had never tested when using the aperture ring on an A-enabled lens.  I had presumed that if I were in Av mode and using the aperture ring in non-A mode, the camera would still know what aperture was set.  It does not - on playback all shots show the max aperture of f/2.8.  Not a big deal, just leave A-enabled lenses on the A setting - but a good thing to know!  I probably knew this back in 1995 with my Program Plus.. but my favorite lens back then was an SMC-M 24-50 so maybe not.

18 April 2012

macros compared: part two

A day with the Sigma
Carrying the 50mm macro was nice, a good match to the k-5.  Focus locked in pretty quickly. Let me rephase: the lens was quick to lock down on a point of focus, but a few times the subject I intended was not in focus. I kept the camera in center AF mode.. so this is odd. When it's off it is always back focused, and refocusing did not change the lens' opinion about the point of focus (AF confirms with no lens movement). At other times it locked perfectly though, so microadjusting the lens to a new focus would not solve this. It was easy to see when it happened in the viewfinder so I could shift back an inch or less and get a sharp image - so for me tne workaround was not a major pain. It should not be necessary though!

Exposure and color were nice, and overall I liked working/playing with the Sigma. I did not put on the hood so shading on extreme closeups was less of an issue.. plus it allowed me to use the lens cap (yes, still annoyed by that).

A day with the Tamron
A similar walk with the 90mm came the next day. Right off the bat (a bit before 7am.. both lenses were used at sunrise and noonish) I would say the Tamron hunts more but nails focus more consistently.  If this persists it will make a more interesting choice between these two copies.  Which would I prefer: to rock back for the occasional closeup shot at 50mm, or hum along with the occasional AF whine at 90?  More study needed!

I find the Tamron a bit bulky, but I know that I'm more sensitive than most about size & weight. In fact the Rikenon 70-150 weighs 40g more but is quite skinny, which suggests that bulk is as big a factor to me as weight.   This is an interesting discovery (to me, probably less so to you!).

My lunchtime stroll showed more of the same: great images and a few focus hunts along the way. I did not use the focus limiter with either lens so time to focus was as bad it it gets. Still, it is broad daylight though overcast, so it's too bad an f/2.8 lens is working so hard. A patient squirrel posed for a few shots; the extra reach of the Tamron helped here but I still have a lot of cropping space.

macros compared: part one!

Tamron 90 shot with Sigma 50, and vice versa

So both lenses are now in hand and been given a few simple tests. 
What have I learned in 40 minutes of play?

Well, nothing magical or decisive (not a surprise to me).  Both lenses show very nice color and contrast, decent blur to either side of focus, and similar enough focus speed and noise for me not to comment after changing lenses.  Weight is almost exactly 100g different on our kitchen scale, 300g and maybe 405g with front caps on.

Having used the Tamron for a few months it has the upper hand here, as surprises with that lens were revealed in my distant past. The Sigma surprised me with its screw-on hood: with the hood screwed on, the lens cap cannot attach!  Some would find that a thing worth doing, but Sigma chose not to make it so. Bummer. I suppose the hood protects the lens nearly as much as a cap, but still..

I was using auto WB for these tests so color variation may appear with more detailed testing - but I liked the colors captured by both of them. We had two Easter baskets on the table so it was easy to capture color!  We will wait a while for specifics on bokeh as well, but both easily fall into my "more than good enough" rating.

A few test shots outside with the Sigma were good, but not all.  I shot a twilight-silhouette tree at f/4 to check for fringing; it was evident (green) on a strongly front-focused image, but when the tree was in focus only a smidge of red-cyan was evident.  My torture-test image of power lines showed no big issues.  On a few plant shots I seemed to see some evidence of back focusing, so that will need to be explored and adjusted (thank you K-5!) before honest answers can be had.  Later indoor shots did not show the back focusing, so I will need to pick my adjustments carefully.  A tripod certainly will be helpful too!

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14 April 2012

comparing macros: Sigma 50 and Tamron 90 (part zero)

Part zero?!?
Well, this is the part that can be done without touching or using either lens. Just the basic listing of specs to see how they compare.  Note that I chose not to call it Sigma 50 vs. Tamron 90, as they are not intended to compete with each other - Sigma makes other macro lenses closer to the 90mm focal length.  I just want to own one macro lens, so this comparison is intended to help me (and maybe you - no guarantees though!) to pick the most suitable of the two.

For several months now I have owned the Tamron SP 90mm f/2.8 macro. It is model 172E and not the most recent Di model 272E, but the only difference is in the coatings - Tamron itself says so. Tamron has made 90mm macro lenses for quite some time, and has been very good at it - so making major optical changes isn't likely!

I have enjoyed taking much closer close-up images with this lens, and it has delivered great results.  Let's be clear about that!  However, I decided that 90mm didn't quite fit my 'needs'. (BTW never ask a photographer what their 'needs' are, the answer won't really make sense to anyone else!)  When I want to use AF zooms I have that covered well enough, and in primes I have a 28mm and either a 40 or 50 - several of these in fact, none of which quite meets my 'needs'. I also have a great 70-150 f/4 zoom with prime-like image quality, and that lens usurps the Tamron fairly often. Given these two concerns, I found a Sigma 50/2.8 macro that could prove to be a great fit. I bought it after two people contacted me about the 90 when I put it up for sale, so figuring it was as good as gone I made the purchase. My loss is the web's gain, as I shall have both for at least a few days to compare them!

So on to specs: check the table below for highlights. Both are f/2.8-32, both have aperture rings with the auto 'A' setting in Pentax mount, and both take 55mm filters. Both also have focus-limiting switches to speed AF for general-purpose use. Add to this the various reviews online, where for each "my lens has a lot of chromatic aberration" at least three others have very little - that goes for both lenses, as does the comment that "there are no bad macro primes".

ModelTamron SP 90 #172ESigma EX DG 50
Lenses Construction10El/9Groups10El/9Groups
Angle of View27°46.8º
Diaphragm Blades97
Min Aperture(F)3232(PK)
Min Focus in.(m)11.4(0.29)7.4(0.19)
Max Mag. Ratio1:11:1
Filter Diameter5555
Diameter x Length2.9x3.8"2.8x2.5"

To no one's surprise the 50mm is smaller and lighter. It also has no manual-focus switch, that's done on the camera body. The Tamron requires the body switch plus a second push-pull cam to achieve manual focus; Canon/Nikon users need only use the cam but Sony/Pentax folks are forced to take two steps. These come across as slight wins for the Sigma 50, but nothing major. My copy is the EX DG model, which means that unlike my Tamron it does have 'for-digital' coatings; we shall see if that has meaning in my shots! They have a different number of aperture blades, which could make a difference - again consulting the web, many people swear that blades affect bokeh far less than optics so let's not get excited over this quite yet.

Many debates go on about which is the better 'portrait' lens. For those who stick to convention the 90 wins here - but on aps-c cameras it takes 135mm-scale images, which is a bit above the traditional length. The 50 is more like 75mm which is on the low end of tradition. But let's be honest: my 70-150 and 55-300 zooms are fine portrait lenses, and at f/4 in the traditional range I'll probably have the entire face in focus, not just eyes. So I have enough portrait options not to worry, and both would do well enough - so to me this debate has no clear winner and is not a factor.

One other point does have merit. To achieve 1:1 macro imaging the 90mm uses a minimum focus that is further from the subject. The 50mm crowds the subject to reach 1:1, which can cause lighting problems and will spook away many creatures with wings or fast legs. Caterpillars may not care, and flowers definitely do not - but in some cases this will matter. People affected by this are probably seeking 150-180mm macros anyway, but it's worth a paragraph and favors the Tamron 90.

So how shall I test two such disparate lenses that do the same things?  It's fair to shoot a few general images from the same spot, to check both fields on their own merit as well as to see the difference generally.  After that, a torture test or two for chromatic issues, then in for close shots of the same items to the same scale at a couple of apertures.  This always proves to be a challenge to me, as at some point I will fail to keep the playing field level for "rigorous" tests.  ISO or white balance will slip to Auto, and when I learn of it I'll be too pooped to replay the games.  Oh well, I'll do my usual best & complain about it later (maybe by part 3).

Speaking for myself (and it is my blog!), my use of macro will not be a full-time passion. It will be far more common to shoot plants than bugs, and I like one less step to go from AF to MF. And as noted before, I have a 'need' for 50mm in my kit more than 90mm, whether to fit in with the 55-300 or 70-150. So it sounds like I have biased feelings here - which leads to another problem, 'new-lens syndrome'. The most common reason for buying a new lens is because something isn't quite right about the other ones. (That's not always true, I admit/confess!) In any case the newest lens always gets strong press and the benefit of the doubt... for a while at least. Despite this I will resist the temptation to declare a winner in part zero!

One more item about me is worth mentioning: I am not a big-lens fan.  I have found that anything over 500 grams gets left home too often to bother with.  The Tamron is only 410 grams, more or less; the Rikenon 70-150 is 40g more and I'm happy to carry that lens.  The macro is quite a bit thicker though, so on some level it feels larger than it is - and that could be a subconscious factor against it for me.  I'll try not to let it be so.

Finally - never ever forget that I am comparing one copy of the Tamron to one copy of the Sigma! One or the other may front focus a smidge, or have elements not precisely centered.  They may both be absolutely perfect; if so I'm one lucky guy!

So - focus speed and noise, sharpness, bokeh and the like await part one of this series, when the Sigma 50mm is in my hand and on my K-5.  For now I can say that the Tamron is reasonably quick to focus, a bit noisy getting there, seldom hunts, and I find it's a pain to take 2 steps to go from AF to MF.  Image quality is excellent, with truly minimal chromatic issues in my cruel tests designed to reveal such issues.

And that's as much as I will say for part zero!

08 April 2012

so which one's real?

Sure you know the answer - these are just pictures!
But which depicts reality 'best'?  Ah, that trigger word, as though every possible variable can be solved and one answer proclaimed as The Answer.  Art doesn't work that way, and as precise as imagers want their shot to be it's still an artistic rendering of reality.  That's my story and I'm sticking to it.

The shot on the left is 'real' in that the camera took it as is - but then processed it according to the rules I set (or the settings that I forgot to change!), compressed it to fit on my memory card 'better', and that was that.

On the right, our ReDynamix offering.  ReDynamix software isn't true HDR but it sure can look that way if you want it to.  I don't want it to, but sliding a few sliders can take you from the left-side image to wild and crazy HDR effects in a hurry.  This software plugin can do some cool things - it brought out some detail in the flower petals as well as the leaves, and boosted the background but not in a distracting way.  It's a fun product that I enjoy using, and recommend the next time you have about $20 - or just try the free sample, that's what I did.

But while it's fun and revealing of detail, let's face it: I messed up the wonderful color of the bloom. The K-5 did a great job with white balance here!
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