Cat Labs Focus Tab

I bought my Laowa 10mm F 4.0 lens for use as a compact backup lens. But with its compact size and wide field of view came came some handling problems. My modestly sized fingers would occasionally "photo bomb" my images. The situation was made worse when I added a 55mm polarizing filter and requisite 39mm - 55mm step up ring. The additional diameter of the filter created a trough that made it even more difficult to access the already narrow focusing ring.

Buy yours here.

A company called CatLABS offers its Lens Focus Tab, a rubber focusing ring with a raised finger hold. It comes in three diameters to accommodate lens focusing rings As it turned out, the 1.5" size fits the Laowa perfectly, the internal "teeth" engaging the focusing rings knurling to assure good traction between the ring and the lens.

The raised focusing tab isn't a new idea. It is featured prominently on many of the Leitz lenses where a little extra gripping surface would be helpful. In keeping with the whole rangefinder vibe that permeates the Fuji world, this product was a natural. While lacking the traditional metal construction, its stretchy rubber composition makes it adaptable to a wide variety of lens focusing rings.

Laowa lens without (left), and with (right) the focusing ring installed.

I've used this tab for several weeks, and can report it has been very helpful. Unfortunately, when used on the Laowa, it completely covers the distance scale. That might not matter, were it not for a problem specific to this Laowa lens: The infinity stop is not properly adjusted, allowing the user to potentially focus past infinity. The image at the upper left shows where the lens physically stops when the infinity symbol is past. In the few situations when I don't verify focus using the viewfinder, I simply rotate the focusing ring as far as it will go, and then back off a bit. which allows me to take advantage of the broad depth of field. It hasn't eliminated my finger's tendency to intrude into the frame, but has reduced its frequency.

All in all, I'm happy with this accessory. Its rubber construction is easily detected when my fingers wander about this compact lens, and if I'm completely lost, the raised thumb tab stands very proud to the focusing ring. And to prevent finger intrusions, I always do a final viewfinder check before pressing the shutter release. It's a pretty simple solution.

Polarizers Part 2

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I started out thinking that my long-forgotten polarizing filters could add something in my photos: skies rendered dark and in intense shades of blue.

I decided to test my polarizer in a parking lot in a recreational area in Richmond. For this exercise, I placed my camera on a tripod to ensure that all of the images were identical in framing. I used a  Fuji X-E1 body and my newish Laowa 10mm F 4.0 lens. I chose the Aperture Priority exposure mode.  I can't give complete exposure information because manual lenses do not provide aperture values for the EXIF data, but if memory serves, the aperture was set to F 8.0. No adjustments to exposure (Levels) were made in post processing.

Camera Position: If you look closely at the orange pole, you notice that it has no visible shadow. The camera was positioned to yield perfect front lighting conditions. If the "Finger Point Rule" is followed, one's extended thumb would trace a line parallel to the horizon. This was meant to minimize the uneven darkening of the sky seen in my earlier side-lit photos that I made in Sausalito.

First Pair, Exposure Compensation  Value = 0: The photo on the left was made without the polarizer, the one on the right, with. After making the first shot (left), I rotated the polarizer to achieve the maximum effect, and held it in front of the lens while the exposure was made (right).

Second Pair, Exposure Compensation  Value = -1 Stop: The photo on the left was made without the polarizer, the one on the right, with. You can see that the polarized image on the right has a dramatically darkened the sky. But when compared to the unpolarized image on the left, reducing the exposure by - 1 stop produced a similar effect. 

My dad used to say the every black and white print needs to have one true white and one true black. I have applied this rule to my color shots. A black and a white reference point helps to convince the viewer that the colors are "true", even though the use of the polarizer and the overall underexposure yield a saturated, almost surreal, interpretation.

Conclusion: For the moment, it appears that one full stop of underexposure can nearly duplicate the effects created by a properly oriented polarizing filter in a perfect, front lit environment. Earlier, less formal testing demonstrated the limitations of the filter when used in side lit situations. Also, the banding, shown here in a photo made during the late afternoon appears to validate the Finger Point Rule (band of maximum darkening following the arc indicated by the outstretched thumb). It may also validates the warning about using wide angle lenses with polarizers, but the images made in Richmond seem to show that " It ain't necessarily so" in all circumstances.

In this final shot (same lens, with polarizer), you can see that I changed my position. The shadows indicate that the sun is coming from high over my left shoulder, but the image is basically front lit.  The top edge of the frame has been darkened, and is darker still in the upper left and right corners, no doubt due to lens vignetting. It's still a pleasing photo, subject matter notwithstanding. But knowing what I know now, I will be more likely to underexpose the image before reaching for my polarizing filter and its requisite adapter ring.

This fun video for dpreview.com gives you a quick, fun, summary of everything you really need to know about polarizers. I thought it would be a fun way to end this post!