Sunday, April 3, 2011

Tokina 90mm f/2.5 - Some Sample Images

Sphalerite - Tokina 90mm f/2.5 (Stacked with CombineZM)

The "Bokina" Hype - Is It All It's Cracked Up To Be? (Quick Answer: YES)

Over the past few months I have been watching the prices for the famed Tokina 90mm f/2.5 (nicknamed the "Bokina" for it's ethereal, soft rendering of out of focus regions of your images) climb through the roof as if these lenses were becoming extinct. Just last year I picked this lens up for $180 from KEH in Nikon N/AI mount and the macro extender, case, and hood for an additional $50 on eBay. I read a forum post where someone had found their Minolta MD mount version complete and like new for $75 from KEH. Within the last 60 days (of writing this) two complete N/AI mount Tokina 90mm lenses sold for $600 on eBay. Given that this lens tends to come up anytime there is talk of great macro lenses, I suppose I shouldn't be surprised. It truly is a phenomenal lens. Whether or not you would pony up $600 is all about how bad you want it...

The past few months for me has been quite a blur. In my freelancing and internship, I have found the Tokina 90mm to be a particularly important asset to my kit. It is an excellent lens for food photography, allowing portions of the dishes to appear crisp and clear while the backgrounds fades away seamlessly into overlapping veils of color. More on that another time. I do want to show some samples from my other project though.

In my internship, I was given the opportunity to shoot a subject that is right up my alley: macro images of minerals. Our hydrologist at work was giving a presentation on mineralogy and asked if I could make her some better images for her powerpoint. Since she (and another co-worker) have an extensive personal collection of minerals they were able to provide me with very nice samples of the various minerals she was looking for. Hardly a job I could complain about!

The Macro Rig

Why the sketch instead of simply photographing the setup? Originally I left my equipment at work when I began drafting this post and being that I wanted to illustrate the setup, I did just that, illustrate! I have since brought the setup home but figured I may as well still use the drawing! Anyway, these minerals I was photographing are considered "micro-mount" which means they are very small samples, probably around 25mm across in total. The average field of view in the images below is only a few millimeters, an even smaller portion of the already small mineral sample thus the reproduction ratio is considerable. Despite this extreme magnification, the Tokina 90mm yields sharp, detailed images!

The Tokina's ability to render subjects crisply amidst a beautifully shallow depth of field (wide open) is perhaps the lens' greatest capability, though this is slightly opposite of what I needed in this situation. The biggest issue with photographing a subject that is so small is a shallow depth of field. I really needed to be able to see more of each mineral in focus, but I did love a soft background that falls off. This is where image stacking comes in. I mentioned this method before on the blog using a program called Helicon Focus. While that is a great program, it costs, and I don't believe it is available for PC. At work we use PC's and thus I found a great (and better yet, FREE) alternative: CombineZM. Image stacking is a process of making multiple images, each focused consecutively "along" or "into" the subject, which is then imported into the stacking software, which essentially does just as you would think, combines all the images, using algorithms to determine what is in focus in each image, to the eventual output: an image with a much greater depth of field than any single image could have depicted. Such a capability certainly begs many curious ideas of what to photograph. This process works amazingly well with static subjects such as minerals but can become difficult with live subjects that move (though it is quite possible!). Below are the minerals. Typically they are comprised of between 10-20 stacked images. I made most of them around f/11-16 for optimal sharpness and since my DoF was already so shallow, it wasn't like I had to worry about blurring the background. Enjoy!

Wavelite - Tokina 90mm f/2.5 (Stacked with CombineZM)

Strengite - Tokina 90mm f/2.5 (Stacked with CombineZM)

Dufrenite - Tokina 90mm f/2.5 (Stacked with CombineZM)

Dufrenite - Tokina 90mm f/2.5 (Stacked with CombineZM)

Macro Season is Upon Us!

And so macro season approaches. Today, a strong, but warm wind (90ยบ warm!) blew through St. Louis piquing my macro-senses (and my tennis senses as well, but that's a different story). While the wind factor is hardly the ideal condition for outdoor macro work, the warmth and newly active wildlife is. The enormous bumble bees which populate our backyard gardens emerged and struggled to make the best of our windy, but beautiful day. I recently picked up a new geared tripod head which has become my go-to support for macro work. It has revolutionized my ability to efficiently make macro images. I will have more on this soon. Once again, apologies for my recent absence!

1 comment:

  1. Many thanks for this inspiring work, brilliant