Search This Blog

Loading...

Monday, August 22, 2016

FILTERS - PROS AND CONS






During a visit to Leica in Germany a while ago, I had the opportunity to get a personal tour of the facilities and to ask a lot of questions.  At one point my contact person and guide introduced me to a gentleman who was working in the lens design department.  I took the opportunity to ask a lot of questions about Leica lenses which also led me to ask about filters.  My question was met with a very stern face with him saying,

     “If we had intended our lenses to have flat pieces of glass in front, we would have designed them that way.”

Indeed there used to be a Leica lens that was designed to be utilized at times with a filter. 

From the very beginning, Leica lenses have always had a very high reputation for their sharpness and their special tonal performance.  This was a prerequisite, demanded by Oskar Barnck and realized by Max Berek with even his first lens designs for the Leica.

As a matter of fact, Leitz had been criticized from time to time for not having any good portrait lenses.  Many Leica users thought that the Leica lenses were often too sharp for portrait work.  That gave the impetus for Max Berek to design the Leitz Thambar at the beginning of the 1930s.

 

The Thambar was a soft focus lens, displaying some rather unique characteristics, which made it one of the premier portrait lenses of the time.  The soft focus effect was the result of the lens having been purposely designed with a considerable amount of residual spherical aberration.  The name Thambar was derived from Greek, meaning “something that inspires wonder”, or wonderful.  The lens was comprised of four elements, with the two central elements cemented to form one group.  A very similar formula was later chosen for the 125mm Hektor for use on the Visoflex.

 
Leitz Thambar on a Leica IIIc with VIDOM viewfinder

The spherical aberration of the lens was produced primarily at the outer perimeter of the lens.  Stopping it down to smaller apertures would reduce this effect and it was totally eliminated at f/9.  To further enhance the soft focus effect, the lens came supplied with a special, clear filter that had a one centimeter mirrored spot in the center which eliminated the sharp image created by the center of the lens.

 
Element configuration of the Thambar with installed filter on left

 
Leitz New York Thambar brochure

The maximum aperture of the lens was f/2.2.  This was reduced to f/2.3 with the center spot filter in place.  For that reason the Thambar had two aperture scales, one in white for the f/stops without the filter and one in red for the stops with the filter installed.  The red scale went from f/2.3 to f/6.3 because above f/6.3 the filter became useless.  The maximum soft focus effect was obtained with the lens wide open and with the filter installed.  Stopping the lens down would diminish this effect, thus giving the photographer full control over the amount of soft focus.  Photographing with back lighting or lighting that produced flare would further increase the soft focus effect.  The distance of the subject also had a significant effect on the softness.

The Thambar actually was relatively difficult to use because the rangefinder of the camera did not allow the soft focus effect of the lens to be seen.  Subsequently a fair amount of experience was necessary to use the lens effectively.

The production of the lens started on 1935 and ended in 1949.  According to company records, about 3000 lenses were produced.  Today the Thambar is one of the most sought after pieces by Leica collectors.  Even though a production of 3000 lenses is not all that rare, it is difficult to find complete sets with the original filter, and sets complete with the filter and the original red boxes are quite rare.  The Thambar is indeed a legendary piece of equipment among Leica enthusiasts.

But what about filters in general?  The camera accessory market offers an abundance of filters that we can screw on, slide on or otherwise attach to our lenses.  Along with it there is the never-ending discussion about their necessity.  Filters certainly are not some frivolous item that sinister accessory manufacturers have dreamed up to get their hands onto more of our photography budgets.



For instance, there are color correction filters.  These have lost a lot of their importance with the advent of digital photography where white balancing has virtually eliminated their need.  But especially among Leica users, film and film cameras are still widely used and so are color correction filters.  Anyone who has ever shot under fluorescent lighting appreciates the FLD and FLB filters that get rid of the ugly green cast common under those lighting conditions.  We have the choice of daylight and tungsten film, but have the wrong film in your camera, and you will appreciate a proper color balancing filter to be able to keep on shooting without ending up with overly red or blue images.  Excessive amounts of blue also occur when shooting during winter with snow covered ground on bright, sunny days.  The blue of the sky reflecting off the snow will generally cause an excess amount of blue, something easily corrected with a skylight filter.

Equally important, especially to film photographers, are filters that will change the tonality of the resulting photographs, for instance a yellow, orange or red filter to darken the sky.  These certainly are helpful to assure better photographs.  The same is the case with polarizing filter which can eliminate reflections of surfaces that are not electrically conductive.  This can often also lead to more intense colors.

Then there are a myriad of special effects filters.  These do apply to equally to film as well as digital photography.  The need or value of them can only be assessed by the individual photographer.  It’s an eye of the beholder thing.

Finally, there is the issue of lens protection.  Many photographers have UV filters permanently attached to their lenses as a means of protecting them in case of a mishap.  They certainly offer a certain amount of protection and the argument that it is a lot less expensive to replace a filter than a lens does make sense at face value.

Hearing the “If we had intended our lenses to have flat pieces of glass in front, we would have designed them that way” comment caused me to research the topic once I had returned home.  After all, how bad can a flat piece of glass in front of a lens be?  Flat is the keyword here.  Unfortunately, some filters are less flat than others.  Ideally, a filter is made of high quality, optical glass and ground from a blank, just like any lens element.  The only difference is that the two surfaces have no curvature.  The same precision and tolerances should be applied as with lenses.  Only that will give the assurance that the two glass surfaces are perfectly parallel to each other.

Unfortunately that is not always the case.  For one thing, there are two distinctly different production methods.  One is the grinding process.  This is an expensive process that is only applied by the top filter manufacturers.  Unfortunately, the majority of filters are made in a much cheaper way.  Here large, flat, narrowly rimmed surfaces are filled with glass granules and then heated to melt the glass into a large sheet.  To make the actual filters, these glass sheets are again heated to the point where they become pliable and the filters are stamped in a process not unlike a cookie cutter.  Cheap but not very precise.  For one thing, the two glass surfaces are not nearly as parallel as can be assured with the grinding process.  Secondly, the stamping does add a considerable amount of physical distortion to the edges of the filter which in turn does adversely affect lens performance.

Spectral transmission is another, important issue.  Many filters need to be made with certain colorations to assure their proper effects.  Here too we find considerable differences in accuracy.  High quality filters are always dyed in the mass, meaning the glasses which the filters are made from receive the correct coloration during the process of making the glass.  Unfortunately this process too is subject to considerable differences in accuracy.

A much less desirable approach is to sandwich dyed gels between two pieces of clear glass to achieve the proper coloration.  Not only are there differences in accuracy regarding the spectral accuracy of the gels, but the problems of parallelism of the filter surfaces are doubled.  This is actually an old, outdated approach and hardly any filter manufacturer still uses this process.

  
Another criterion is the thickness of a filter.  Regardless how perfectly flat a filter is made, it will add a certain amount of distortion to any lens it is used on.  The only variance is the focal length of the lens, with wide angle lenses being more affected by this than lenses of longer focal lengths.

The worst of all filters are the ones made of acrylic rather than glass.  By nature these need to be a lot thicker to assure the desired effects.  In addition, even the best acrylics are not nearly as clear as good, optical glass, thus adding to the undesirable effects of these less expensive alternatives.


The problem lies in the fact that when light hits the filter, it does not transmit straight through unless the light hits the filter in a 90 degree angle.  There will always be a certain offset of the light path.  The steeper the angle and the thicker the filter, the more pronounced this is.  The only filters ever made to prevent this are curved filters.  These are designed for certain focal lengths where the curvature is such that the light path through the glass is always reaching the filter in 90 degree angles.  These filters are prohibitively expensive.


Machining of filter mounts and
finished mount, ready for anodizing

Finally, there are the filter mounts.  Needless to say, we should stay away from plastic ones. They simply don’t offer enough precision to be worth any consideration.  Most filter mounts are made of aluminum.  However, most high quality lenses also use aluminum for the lens barrels.  Aluminum against aluminum unfortunately has a huge amount of friction.  This quite easily leads to filters being very difficult to remove.  The best filter mounts are the ones made of brass.  Brass against aluminum has a very low coefficient of friction and therefore brass mount filters are always quite easy to remove.

This brings us back to UV filters, permanently attached for protection.  Do we really want this, do we really need this?  Based on the flat glass comment at Leitz Wetzlar, I never use any filters unless absolutely necessary and I have done so for years.  None of my lenses have ever been hurt because I take other safety precautions.  The main one being that I always use a solid lens shade.  That gives any lens a considerable amount of protection because the glass surface of the lens is recessed by a certain amount.  This greatly eliminates the possibility of physical harm.  Of course accidents can happen.  I look at my insurance as a measure to protect my lenses in those cases.

Of course when shooting under condition where these measures are inadequate, a UV filter is definitely a good idea.  For instance when shooting under extremely dusty conditions, or when wind whips up a lot of dust and fine sand, we should not subject our lenses to such ill treatment.  That is where a high quality UV filter is definitely helpful.  But personally, I leave it at that.

Should we all use just Leica filters?  The simple answer is no.  Leica is not a filter manufacturer.  To my knowledge most of their filters are made by Schneider through their B+W division.  B+W have proven to make some of the highest quality filters money can buy.  Equal in performance are the Heliopan filters.  Heliopan is owned by Zeiss.  Staying with those two manufacturers will always give you the assurance of keeping the ill side effects of filters to a minimum.  The top quality filters from Hoya could be added to that category as well.


Considering the overall performance of Leica and other high quality lenses it just doesn’t seem right to put flat pieces of glass in front of them except  unless absolutely necessary.  It especially doesn’t make any sense at all to have the light pass through a cheaply made, low quality filter before it even reaches the lens just to save a few bucks.  That approach has served me well over the years and will continue to do so.



________________________________________________________________________________________

To comment or to read comments please scroll past the ads below.
All ads present items of interest to Leica owners.


 


 
www.classicconnection.com                                     www.oberwerth.com

 www.mgrproduction.net                                              www.leicastoremiami.com

     
                                             www.eddycam.com                                       

                                                                      


 
 www.lenstab.com                                                                   http://www.tamarkin.com/


                          
                             For rare and collectible cameras go to:               http://www.tamarkin.com/leicagallery/upcoming-shows
                                 http://www.tamarkinauctions.com/

Click on image to enlarge
Please make payment via PayPal to GMP Photography

Click on image to enlarge
Please make payment via PayPal to GMP Photography

Click on image to enlarge
Please make payment via PayPal to GMP Photography







Saturday, August 20, 2016

ANSEL ADAMS





Some readers might wonder why Ansel Adams is the topic on the LEICA Barnack Berek Blog.  After all, as far as we know, among the large number of cameras he has worked with, a Leica was never one of them.

As Leica enthusiasts, we sometimes have a tendency to get too wrapped up in our equipment.  The fact that Ansel Adams apparently never did any work with Leica equipment in no way diminishes his accomplishments.  To the contrary, all photographers, including Leica owners, can learn a lot from him.  His approach to photography with the Zone system, which he created, is still as much up to date today as it was when he worked his magic with black and white photography.  This is part of what makes him of great interest to the Leica community, because Leica these days has probably a much wider number of followers still using analog photography than any other camera out there.  By applying his techniques, I have certainly been able to produce better black and white photographs than I would otherwise have been able to.

 

 
Ansel Adams at work

This is not going to be an article on Ansel Adams’ camera and darkroom techniques.  For that he is doing a much better job in his books than I ever could.  Instead this is a remembrance of one of the giants of photography, an individual that will forever be remembered as one the absolute masters of his craft.

The L-Camera blog has published a two part video of Ansel Adams from 1958.  In this 20-minute presentation you get an insight into his working methods, his own interests and attitude to art, and his gigantic amount of camera equipment.

You will accompany the photographer through the entire process of analog photography, from the precise light reading of the object, the correct exposure settings of the camera and onto the right development of the photos in the darkroom.

But you will also see another, much lesser known side of Ansel Adams, that of an accomplished pianist.  As a matter of fact, he initially planned to become a concert pianist, but the onset of arthritis kept him from doing so.  It wasn't until then that he began his career as a photographer.

The piano music accompanying the video was all played by Adams.  Listening to it is a captivating opportunity to see the other artistic side of this great artist.

I am showing only one example of his work.  It is almost impossible to make a reasonable selection from his many published photographs.  This one stands out because it was taken without the possibility of an exposure reading.  He came upon this scene while driving home from an assignment.  The light was changing quite rapidly and Adams had barely time to set up his camera and tripod.  It is to his credit to be able to accurately determine the exposure simply based on experience.

 
 Moonrise over Hernandez

 For the video go to: AnselAdams

Many people are satisfied just to see and enjoy the incredible images Ansel Adams produced, but for many the question remains, what cameras did he use.  As simple as the answer might seem, that question is actually not easy to answer.  Even Ansel Adams himself had problems with that.  In an interview with John Adams recalled:

"Well, people have asked me what kind of cameras I used. It's hard to remember all of them. Oh I had a box Brownie #1 in 1915, 16. I had the Pocket Kodak, and a 4 x 5 view, all batted down. I had a Zeiss Milliflex. A great number of different cameras. I want to try to get back to 35 millimeter, which I did a lot of in the 1930s. Using one of the Zeiss compacts. In the 20s and into the 30s, I would carry a 6-1/2 x 8-1/2 glass plate camera -- that was a little heavy. And I had a 4 x 5 camera, then of course we went to film, to film pack, things became a little simpler.”


Zeiss Contarex

Hasselblad

Arca Swiss 

We do know that his account is far from complete for no other reason that he also used larger than 4 x 5 cameras.  As a matter of fact, many of his iconic images were taken with 8 x 10 cameras.  I recall a video about Ansel Adams where he briefly shows some of his camera equipment.  There, for 35mm he used a Zeiss Contarex with a variety of lenses.  Medium format photography was covered by Hasselblad.  As a matter of fact, one of his photographs of the Half Dome was taken with a Hasselblad.  In 2014 one of his 4 x 5 cameras was offered for auction.  It was an Arca Swiss with several lenses.  Ultimately, we will never know what all the cameras were that ansel Adams used, and it doesn’t really matter.  What matters is the incredible amount of work he produced.  We are very fortunate that to this day we are able to see this wok on display in museums, galleries and other venues.  Thank you Ansel Adams.

POST SCRIPT

I was just informed by a reader that Ansel Adams at one time used a Leica R4.  He also included a picture of a transcript of Ansel Adams’ auto biography where he clearly states loading his Leica R4 with film.  I am glad to see that this giant of photography has used Leicas as well.


________________________________________________________________________________________

To comment or to read comments please scroll past the ads below.
All ads present items of interest to Leica owners.


 


 
www.classicconnection.com                                     www.oberwerth.com

 www.mgrproduction.net                                              www.leicastoremiami.com

     
                                             www.eddycam.com                                       

                                                                      


 
 www.lenstab.com                                                                   http://www.tamarkin.com/


                          
                             For rare and collectible cameras go to:               http://www.tamarkin.com/leicagallery/upcoming-shows
                                 http://www.tamarkinauctions.com/

Click on image to enlarge
Please make payment via PayPal to GMP Photography

Click on image to enlarge
Please make payment via PayPal to GMP Photography

Click on image to enlarge
Please make payment via PayPal to GMP Photography