Enlarging lens revisited

Recently black and white photography magazine has been celebrating it's two hundredth edition which gave me impetus to rediscover what was in some of those back issues. While thumbing through one issue, an article about enlarging lenses caught my eye, reminding me that I have been meaning to revisit the subject.

I have written a couple of small articles: Enlarging lens and which aperture  I re-read both before writing this one so as not to repeat myself. But that is not going to be easy as the main issue with enlarging lenses is quality. The rule of thumb is to choose a lens of six or more elements. The Componon-s and Rodagon are two modern designs that work very well - they are two quality makes of the few still available new.

Looking down a focus finder at F5.6- F8

In the 1970s Nikon special optics division set about producing a darkroom lens second to none ( Apo-EL-Nikkors ). It was done in a one off batch, releasing a number to the market over a ten year period until they were all gone. It has been said that at the end of this period they did consider doing another run but stopped doing so because they would have had to sell the lenses for £12,000 each. I do not know if this figure is true or not. If it is, it will have made the original runs price in the thousands and therefore out of the reach for most of us.

The enlarging lens has one job to do and that is to project the the image from the negative to the paper perfectly. The one hindrance to good enlargement method and creativity is poorly maintained or ignorantly used enlarging lens practice. It is not good enough to think if you close the lens right down, like you would a camera lens, that you will increase the sharpness of the image. The rule again is to close the lens down by two F numbers. In a lot of cases this produces the optimum sharpness. One stop more may result in a softening of the grain structure. This does not mean that you will notice a softening of sharpness with the mark one eye ball as the image is projected onto the paper. Like a lot of things in photography the kit is made to a greater quality than can be seen in normal life.

Focus finder

Enlarging lenses should not be treated as second class citizens as they are several time better in quality than the camera mounted counterparts. They do their best work in a very narrow range of magnifications. For 35mm negatives the lens is optimized to 10x its size which equates to an enlargement of 10x8. As you go up the format scale this decreases 6x6cm lenses 6x and 5x4in 4x magnification. As you push past the optimal point it increases the possibility's of grainy photographs. This is not to say you should not push beyond this point as experience has shown. You can negate this by using ultrafine film developers.

Grain at f11

How do you see which is the best apertures to use? You need to complement your lens with a good focus finder. This magnifies the grain of the negative so you can see it. The best way to use the finder is to have the enlarging lens fully open. Place the finder in the middle of the baseboard. While looking down it at the grain, adjusting the bellows until it separates into little defined specks. This will mean that you now have fine focus.

While still looking down the finder shut the lens down a stop at a time. There will be a point where the look of the grain go's slightly soft and becomes softer the more you close it down. You should remember that you are still at optimum focus. To test this you can try to adjust the sharpness in most cases it will get worse and become to difficult to regain any sharpness until you go back to the optimum aperture.

Grain at F16 looking down the focus finder.

What has been described above is my experience with one of my 35mm enlarging lens. I will point out that it is not a well known make. It is one I use often. The softening of the grain in the focus finder is not transferred to a softer looking image on the baseboard that can be detected with the naked eye but you will start to question whether it is affecting the quality of your images. The only way you will know is to borrow or buy a better quality lens and do a comparison.

When considering buying a lens you should spend as much as possible to ensure that you get a good to very good lens. Knowledge that the lens is not what you expected will impact on your photography subconsciously.  

Angles of view with different lenses..

The diagram shows angle of view or angle of acceptance.

I have been looking back through my college notes and came across this series of pictures. I used the colour film you find in the pound/ budget shops. I have had no problems with the way the film has performed.

These pictures show how much of the view in front of the lens is depicted at the negative. As the focal length of the lens increases the angle of view reduces but the object size gets bigger. Therefore as you go up the focal range so the depth of field lessens.

View at 35mm

View at 50mm

View at 80mm

View at 135mm and the cold is getting to me.

View at 210mm

To be sharp or not, how is the question.

Fg 1.
Film FP4+ developed in ID11 printed
on Ilford MG RC gloss.

A subject that is talked about by all photographers. No matter how you like to label it DOF or boken I am surprised that depth of field can be expressed by some in the terms of good and bad. Surely it is subjective and down to the person who has composed the picture.

So what is depth of field and how does it work?

Depth of field relates to the area of the image that is sharp. So the subject  you focus on in the view finder will be in the middle of the sharpness. How much this extends in front of or behind it, is dictated by the aperture you use. Small F number (large opening) very shallow, large F number (small opening) very wide. The other factor to have a bearing is the focal length of the lens used.  For example, with a wide angle 28 mm lens you would not require the focus to be exact because the depth of field would be quite considerable in front of and behind the point of focus even at small f numbers (large apertures). But with a Telephoto lens of 200 mm the point of focus needs to be precise as the depth of field is quite narrow even at large f numbers (small apertures).

Fg 2.
Kodak colour plus negative. scanned
 from print.

In understanding the way depth of field works you need to know that when you focus on the subject it is at that point the reflected light arrives at the focal plan as fine points of light (sharp). The subjects closer to the lens do not resolve as sharp until they are beyond this point and those further away reach pin sharp before they arrive, because of this they arrive as discs known as circles  of confusion. The larger the circles the softer the images appearance. By making the aperture smaller (large F number) you reduce the circles of confusion giving the picture the appearance of full depth of field. (sharp from front to back). The eye considers points of light as large as 0.25 mm diameter as sharp. The same applies to the dot pitch of a computer screen. When it come to the manufacturer of lenses for 35mm format cameras this figure is much smaller 0.08, this is because the maker has worked out  that on average a 35 mm negative will be enlarged by twenty times (a print size of 10 x 8.)

The good thing about using a film camera is that  you can check on how heavy the points of confusion will be by pressing the depth of field preview button. The advantage I have is I know what to expect from my lenses at particular apertures. This allows me to compose the picture with the amount of soft focus  I think will enhance it.

For example the three pictures included with this post.

•         Fg. 1 The main reason for the cats paw being out of focus is to add depth and a sense of being very close.

Fg 3.
FP4+ developed in ID11 printed on
Iford MG RC gloss

•         Fg. 2 The main reason for blurring the background is to exclude a large group of people walking towards me. They did not add anything to the picture I had in mind. By adjusting the aperture to a lager one (small F number) they have been removed making for a much better shot.

•         Fg. 3 The depth of field in this picture is very narrow. It took a bit of time in making sure that the whole of the ball was sharp and nothing else.

When taking a picture I consider the 'out of focus' as important as the area to be sharp.

 

A favorite photograph.

Taken at the grand Prix de I'A.C.F.

Like a lot of people I enjoy watching the Grand Prix. By coincidence one of my favorite pictures is by the turn of the century french photographer Jacques-henri Lartigue.

He took this picture while he was still quite young. It is one in a series of a 169 shots taken at the Grand Prix de I'A.C.F. using the comparatively large Ica reflex camera with Zeiss 1:4.5 150mm lens onto a 3 1/2" x 4 1/4" glass negative it had a top mounted focusing screen and a focal plan shutter, it is this set up that accounts for the elliptical shape of the wheel. For me it is the feature that conveys the excessive speed the car is travelling more than his panning of this heavy camera to emphasize the rate of progress.. Originally he thought this picture was a failure because he had not been able to capture the whole car in the frame. This is the other part of the composition that adds to the sense of great speed. It is one picture I do not get tired of looking at, I always wonder what it would have been like to stand there as these early cars thundered by.

Enlarging len which aperture?

The quality of your enlarging lens will lead to better and sharper results at greater magnification. The aperture ( low number = large opening, high number = small opening) you set not only affects the amount of light it lets through but the depth of field as well. A good average aperture is F/5.6 in most cases. If the exposure times are to short a larger F number is needed, this will give you a chance to hold back shadow areas that may become to dark to show any detail. But don't get carried away and close down the lens by too  many F numbers as this may over heat the negative causing it to buckle, making the picture loose sharpness.

Dust in the darkroom.

If you look at a beam of light whether projected from your enlarger's negative carrier or a shaft of light shinning across a room you will notice lots of particals floating in the air. Dust over the course of time will settle on the upper surface's of your enlarger and lens.

It does not take long for a considerable amount of dust to build up on the surface of your lens greatly reducing the brilliance of light passing through it. You should make it a rule that once or twice a year you clean the lens thoughly. It is also a good idea to cover the enlarger at the end of each session with its cover if it has one or a black plastic bag this will greatly reduce the dust build up.

If you have a window in your darkroom that needs to be blacked out it is not a good idea to use curtains as these are dust traps. You are better off using a wooden shutter made of hard board painted matt black or a roller blind made of light tight material that has some way of being sealed along the sides.

What you have on the floor is also important. If it is carpet it needs to be removed, as this is a dust trap too. It should be an easy clean material like lino if you have floor boards or garage floor paint for concrete floors these keep the dust at bay making it easy to mop the floor with water, it also means that you do not have to vacuum very often leaving more time to print.

Enlarging Lenses

Enlarging lens mounted in lens saver.

When choosing your enlarging lens you should choose one that reflects the quality of the lenses you use on your camera. If you do not, that quality will not transfer to the final print. Of course there are other factors in play when making these decisions namely your own financial position; it maybe better to wait a little longer and purchase what you need instead of what fits your pocket at the time.

I cannot repeat this often enough that high quality camera lenses need high quality enlarging lenses, likewise reasonable quality camera lenses need reasonable quality enlarging lens. In other words like for like.