Enlarging lens performance at infinity

[sensiblename99]

Anyone interested in enlarging lens performance at infinity? I shot these recently for a quick test and thought it might be useful to others.

EL's are clearly not designed to perform optimally at infinity, they are designed for optimum performance at relatively close range, however, they certainly can be used as 'taking' lenses and some perform better than others at infinity. TBH, I rarely use them at infinity focus as I typically use them for product shots, close range and portrait photography.


this is the scene from which crops are taken (just for context)


With these three lenses (Schneider Componon-S 5.6/100, Rodensock Rodagon 5.6/105 and Fujinon EX 5.6/105) their centre sharpness/resolution is very good regardless of aperture.


With these three lenses (Schneider Componon-S 5.6/100, Rodensock Rodagon 5.6/105 and Fujinon EX 5.6/105) their edge sharpness/resolution is also very good but only when stopped down one or two stops. The Rodagon seems to outperform the other two with the Componon-S the 'least best'.


Osawa Tominon EL 4/60. Centre sharpness is excellent, but the edge is poor and is not great, although OK, even stopped down a couple of stops.

These are 100% crops, shot on an A7R2, handheld with silent shutter (shutter speeds were high enough to not be a problem for sharpness).

 

[E Dinkla]

Sometimes I wonder whether enlarging lenses, calculated for nearby and within 1:10 magnification ratio, could be improved for longer distances by bringing the front element closer to the aperture. The Tessar designs I mean, that have front cell focused cousins on folders and compact cameras. Which brought me to that idea.


Met vriendelijke groet, Ernst
No photographer's gear list is complete without the printer mentioned !

 

[sensiblename99]

Sometimes I wonder whether enlarging lenses, calculated for nearby and within 1:10 magnification ratio, could be improved for longer distances by bringing the front element closer to the aperture. The Tessar designs I mean, that have front cell focused cousins on folders and compact cameras. Which brought me to that idea.

Met vriendelijke groet, Ernst
No photographer's gear list is complete without the printer mentioned !

Possibly, but Tessars tend not to be all that well corrected (for edge performance) compared to more complex designs so even if you did that they might not perform as well as 6/4 designs which are better corrected from the start.

I have the Computar dL 1.9/55 which has a dial at the front to adjust correction for the magnification range in use (from 4x to 20x). It looks like the two cemented elements in the front group are adjusted together as the dial is rotated, which is exactly what you've described.

Diagram of the Computar dL 1.9/55:

http://photocornucopia.com/1073.html

 

[E Dinkla]

Sometimes I wonder whether enlarging lenses, calculated for nearby and within 1:10 magnification ratio, could be improved for longer distances by bringing the front element closer to the aperture. The Tessar designs I mean, that have front cell focused cousins on folders and compact cameras. Which brought me to that idea.

Met vriendelijke groet, Ernst
No photographer's gear list is complete without the printer mentioned !

Possibly, but Tessars tend not to be all that well corrected (for edge performance) compared to more complex designs so even if you did that they might not perform as well as 6/4 designs which are better corrected from the start.

I have the Computar dL 1.9/55 which has a dial at the front to adjust correction for the magnification range in use (from 4x to 20x). It looks like the two cemented elements in the front group are adjusted together as the dial is rotated, which is exactly what you've described.

Diagram of the Computar dL 1.9/55:

http://photocornucopia.com/1073.html

Similar to the Macro Varon: https://www.stemmer-imaging.com/en-nl/products/series/schneider-kreuznach-macro-varon/ Floating elements for corrections at different magnifications.

The Tessars with front cell focusing act as simple zooms. True, the resolution drops more to the edges. On the other hand there were APO designs based on Tessars. If the coverage of the lens goes beyond FF size the aberrations may not be that bad.

A lens designed for short distance plane to plane resolution may show a not so plane focal field at longer distances. That could well be what is observed when the center stays sharp at infinity and the edges do not keep up.

Interesting discussion here on the the use of enlarger lenses at infinity; http://forum.mflenses.com/enlarger-lenses-at-infinity-t56679,start,15.html

For example; Shorter focal length ones made for smaller negatives still print to the same paper sizes and by that have a design for magnification ratios that come closer to infinity scaling.

Met vriendelijke groet, Ernst
No photographer's gear list is complete without the printer mentioned !

 

[ThomasB]

Thanks for posting your examples.
I'm loving my Rodenstock Apo-Rodagon 50/2.8 which delivers tack sharp pictures from edge to edge on my A7R II at infinity as well.
It's a very capable lens for landscapes and very easy to adapt.

 

[sensiblename99]

Thanks for posting your examples.
I'm loving my Rodenstock Apo-Rodagon 50/2.8 which delivers tack sharp pictures from edge to edge on my A7R II at infinity as well.
It's a very capable lens for landscapes and very easy to adapt.

Thanks. It seems the APO's generally do well at infinity, presumably because of greater correction overall. I've tried a couple of my APO's in the past and they seem to do very well, but if I get a chance I'll test/compare a few of them (in identical light) and post here at a later date.

I did take some test shots of the above scene with my Schneider APO-Componon HM 4.5/90 but a day later and in different light so not worth comparing directly with the previous images. However it is the sharpest of any of the lenses I've tested so far and it only loses sharpness/resolution as you stop down further. It's a superb lens.

 

[ThomasB]

Well, I've tried longer focal lengths as well but I stick to the 50mm APO-Rodagon because it's very handy and easy to operate as well. Due to the register distance of 46mm at infinity it's easy adaptable with a 39 to 42 mm ring on a M42 to Sony E focusing helicoid adapter with a very practical focusing distance from close focus to infinity without any further accessories.
For longer focal lengths I prefer to use macro lenses instead. These lenses (like e.g. the Minolta MD 100/4 macro or the Tamron SP 90/2.8 macro) are likewise excellent from close to infinity but much handier to use for outdoor shooting.
However, that's mainly a matter of taste. ;-)

 

[ProfHankD]

These are 100% crops, shot on an A7R2, handheld with silent shutter (shutter speeds were high enough to not be a problem for sharpness).

The shutter "speed" is really the time during which a pixel is exposed, but it's a delay between curtains, not speed of curtain movement (which is generally a constant). The A7R2 takes a little more than a 1/30s to move the electronic equivalent of a curtain across the frame, so you can get motion distortions comparable to blur for a shutter speed of around 1/30s even if the shutter speed is set to 1/8000s.

I don't think it's an issue here, but yeah, there are tradeoffs between full electronic, EFCS, and full mechanical.... EFCS is best for avoiding shake (but causes bokeh anomalies), and mechanical does better than electronic for shake you're producing (as opposed to shutter shock it produces). The take away message: use a tripod and electronic shutter to ensure no camera motion... oh yeah, and use a manual lens so that there is no aperture servo moving either. ;-)

 

[DeltaLenses]

Thanks for posting your examples.
I'm loving my Rodenstock Apo-Rodagon 50/2.8 which delivers tack sharp pictures from edge to edge on my A7R II at infinity as well.
It's a very capable lens for landscapes and very easy to adapt.

Thanks. It seems the APO's generally do well at infinity, presumably because of greater correction overall. I've tried a couple of my APO's in the past and they seem to do very well, but if I get a chance I'll test/compare a few of them (in identical light) and post here at a later date.

I did take some test shots of the above scene with my Schneider APO-Componon HM 4.5/90 but a day later and in different light so not worth comparing directly with the previous images. However it is the sharpest of any of the lenses I've tested so far and it only loses sharpness/resolution as you stop down further. It's a superb lens.

Yes - a great lens. And a great initial question. I've actually referred to this thread in my article for www.16-9.net which aims to answer this and many questions in the same vein.

http://blog.16-9.net/enlarger-lenses-choosing-using

 

[Gesture]

Thanks. Nice web site and work.

 

[D Cox]

I have had good results with the EL-Nikkor lenses, especially the 63mm.

Don Cox

 

[sensiblename99]

Thanks for posting your examples.
I'm loving my Rodenstock Apo-Rodagon 50/2.8 which delivers tack sharp pictures from edge to edge on my A7R II at infinity as well.
It's a very capable lens for landscapes and very easy to adapt.

Thanks. It seems the APO's generally do well at infinity, presumably because of greater correction overall. I've tried a couple of my APO's in the past and they seem to do very well, but if I get a chance I'll test/compare a few of them (in identical light) and post here at a later date.

I did take some test shots of the above scene with my Schneider APO-Componon HM 4.5/90 but a day later and in different light so not worth comparing directly with the previous images. However it is the sharpest of any of the lenses I've tested so far and it only loses sharpness/resolution as you stop down further. It's a superb lens.

Yes - a great lens. And a great initial question. I've actually referred to this thread in my article for www.16-9.net which aims to answer this and many questions in the same vein.

http://blog.16-9.net/enlarger-lenses-choosing-using

Nice job on the web page/blog. You write very well and I would agree with probably everything you've written about ELs. Not sure if you mentioned it, you probably have, but ELs are great as portrait lenses because of their combination of relatively good performance at portrait distances combined with their variable and often 'funky' rendering. Anyway, great article.

 

[ProfHankD]

http://blog.16-9.net/enlarger-lenses-choosing-using

The one thing sorely missing from your discussion is the fact that many enlarger lenses are NOT designed for visible light. Most B&W paper was not sensitive to red light (remember red darkroom safelights?), and some have sensitivity tuned toward the NUV end of the spectrum. In fact, some graphic arts materials use NUV light for exposure and can actually be handled in normal incandescent room lighting without fogging. This does mean enlarger lenses tend to be better than average for NUV photography.

Of course, humans tend to focus based on visible light, so many B&W enlarger lenses have APO-like agreement between the average visible focus plane and the NUV focus plane... it's just that red may be way off. In fact, central hot spots are particularly common for NIR light through an enlarger lens. Wide open was also explicitly intended primarily for composing and maybe focusing; enlarger lenses were generally used between f/8 and f/11. After all, exposure times were generally measured in seconds anyway, and all that mattered was having a crisp, high-contrast, flat plane of focus.

Only from about 1-6' projection distance was practical with most enlargers (although a few could be tilted to project on a wall somewhat farther away), so coverage is tuned to the negative format and standard print sizes at those distances. Thus, lens focal lengths are around 50mm generally are for 135 film, around 80mm for 6x6cm, around 150mm for 4x5, etc. There were really quite a few standard film formats; for example, around 100mm tends to be for 2 1/4 x 3 1/4. Basically, they're long normal lenses for small film formats getting somewhat wider as you get to really large film formats, at least in part because larger formats can stand making bigger prints. 35mm enlarger lenses were either for formats like half-frame 135 or even 110, although some are wide-angle 135 lenses for making bigger prints using an enlarger that only offers less than 3' maximum projection distance (up to 6' was usually done by projecting on the floor).

Enlarger lenses are designed for the light to be coming into the back of the lens. This means that reverse-mounted they tend to make nice flat-field optics at a 1-6' subject distance (not quite macro). However, facing forward flare resistance wasn't a designed feature. More importantly, many enlarger lenses have lighted aperture numbers using a plastic light pipe to send some enlarger light to backlight the aperture dial -- well, those pipes work in reverse to fog the image when using the lens on a camera. I recommend painting over the rear light ports with a couple of coats of Black 2.0. For example, my really excellent 50mm "Color Enlarging" Rokkor-X lens:



Actually backlights the selected aperture using such a port:



The port isn't even obvious looking from the rear of the lens; it's just a spot on a flat rear surface that happens to be the ground-flush surface of the plastic light pipe inside the screw thread. However, this pipe will fog images using this as a taking lens.

My 75mm Wetzlar Wilon 6x6cm format enlarging lens does something similar, although it uses colored plastic light pipes and is a bit more obvious looking at the rear of the lens -- it's mounted on my Beseler 23CII Dichro-head enlarger, so no photo of it for now. The interesting thing is that the Beseler lensboard also has a lightpipe to cast light on the aperture setting of any mounted lens. Most enlargers don't; for example, my other enlarger, a Spiratone Doublogram II, has a very plain lens mount for which the backlit lens aperture is a really nice feature.

Kind of surprising Spiratone missed this feature... the design is otherwise very clever, and I still use mine as a copy stand:



... while my 23CII sits collecting dust.

 

[DeltaLenses]

Thanks John. I've been idly collecting enlarger lenses for a decade, but only in the last couple of weeks collated tests and started to publish articles. At present I've only got first-hand results with thirty or so models (some in multiple samples) but will be uploading them in the next few weeks, and continuing to track down good copies of lenses that are important. The whole survey of 50+ lenses should be complete by spring. At some point, I'm going to have a lot of enlarger lenses for sale!

 

[DeltaLenses]

You raise some good points - thank you. I will need to write something in the introductory article about visible light and enlarger lenses. “Apo-like agreement” is a great expression I'm tempted to lift. Photo Cornucopia already has plenty of information about setup (mounting, helicoids, bellows, etc) but I'll need to reprise that for completeness – sorry John!

There's a need for a discussion of modifications. I've put out some feelers for co-writers who might also be interviewed for some YouTube videos on the subject. As you point out, the main issues are light-tightness. If you'd like to contribute an article, or participate in a tutorial video, it would be welcome. Please let me know.

The Fujinon EX and Rokkor C.E ranges you mention deserve a seat at the top table as much as Focotars and Apo Schneidenstocks - but they each have different (in some cases multiple) light-handling problems to be fixed. Fortunately, the remedy is usually simple.

 

[sensiblename99]

http://blog.16-9.net/enlarger-lenses-choosing-using

The one thing sorely missing from your discussion is the fact that many enlarger lenses are NOT designed for visible light. ....

Whilst I agree with most of your comments I think the above is essentially misleading. It's true that '...many enlarger lenses are not designed for visible light...' but this is mainly true of either older ELs (when colour printing was not popular) and specialised duplication/process lenses (as you've mentioned). Most early ELs have an emphasis in the blue/UV range because that's where B+W papers were sensitive but they still had to be focused by eye. It's not true of 'later' enlarging lenses and those intended for colour work. So I think you are painting a picture which is misleading if applied to MOST ELs from the (roughly) '80s and later, in other words most decent enlarging lenses. IIRC the extended UV response was intentionally reigned in at some stage (I don't have a reference at my fingertips but I think around late '80s to early '90s) to behave properly with modern multigrade papers. Ctein wrote an article about the extended UV response of some ELs causing miss-focusing with multigrade papers at certain filter grades, maybe this led to a change or action, I don't recall now.

In my own experience with over a hundred ELs from the 1940s to various modern APO ELs I've found them all quite variable in how they behave as taking lenses but that, after all, is most of the appeal of such lenses. I wouldn't characterise ELs as an entire group as 'not being designed for visible light' which is the take away from your comment (I know it's not exactly what you said but is likely the way some people will understand it).

 

[sensiblename99]

You raise some good points - thank you. I will need to write something in the introductory article about visible light and enlarger lenses. “Apo-like agreement” is a great expression I'm tempted to lift. Photo Cornucopia already has plenty of information about setup (mounting, helicoids, bellows, etc) but I'll need to reprise that for completeness – sorry John!

...

No problem, I think I stopped updating the 'adapter' type information many years ago, so certainly worth updating.

 

[ProfHankD]

http://blog.16-9.net/enlarger-lenses-choosing-using

The one thing sorely missing from your discussion is the fact that many enlarger lenses are NOT designed for visible light. ....

Whilst I agree with most of your comments I think the above is essentially misleading. It's true that '...many enlarger lenses are not designed for visible light...' .... I wouldn't characterise ELs as an entire group as 'not being designed for visible light' which is the take away from your comment (I know it's not exactly what you said but is likely the way some people will understand it).

Perhaps. The better take-away message was a different line in my post:

it's just that red may be way off. In fact, central hot spots are particularly common for NIR light through an enlarger lens.

I've got about a dozen enlarger lenses, but only a couple don't have issues with NIR and most aren't great with reds either. Keep in mind that enlarger light sources were not expected to produce much NIR and papers wouldn't see it anyway -- put another way, there are no NIR focus shift marks on enlarger lenses. ;-)

 

[DeltaLenses]

Unfortunately my project escalated a bit. The rate of progress is a log curve: nothing for ages, then suddenly . . . sixty lenses on my desk generating data from daily tests.

Still tracking down elusive candidates. On eBay UK this week a late model Nikkor Apo-EL 105 salvaged from junked studio equipment made £1006. Just missed it. Shame the other two from the same studio ended up in a skip and got crushed. If anyone has one to lend they're not using, please get in touch. I'm adding articles weekly to the ETLS section of the site (www.16-9.net).

It's been a challenge to gather good samples and I'm still short of Apo Rodagon 75D (both versions), Apo Rodagon 90/4 (which I sold some time ago before properly testing) and the elusive Nikkor Apo-EL 105. If anyone can help with sale or loan of these it would be appreciated.

Meantime here are some initial results from the first 25 enlarger lenses tested. There are several ways of sorting the basic spreadsheet to form league tables. For instance, we could rank them as taking lenses at 50-80cm and average results across the frame from f4-f8 (which privileges the faster lenses), or f5.6-f8 only (which puts them all on a level playing field for performance at a given aperture).

The following places them in order of best performance at middle distance, averaged across 'working apertures' of f5.6-8. The reference lens here is a Sigma 105mm f1.4, which scored 96.3% for averaged sharpness. The best enlarger lenses get to 92%.

Elite: 90% +

Rodenstock Apo Rodagon 105/4 N
Rodenstock Apo-Rodagon 80/4 N
Nikkor 80/5.6 N
Schneider Apo Componon HM 90/4.5

Reliable (85-90%)

Minolta CE 80/5.6
Fujinon EX 105/5.6
Nikkor 105/5.6
Rodenstock Rodagon 105/5.6
Schneider Componon-S 105/5.6

Adequate: 80-85%

Rodenstock Rodagon 80/4
Durst Componon (Schneider) 105/5.6
Vega 5U 105/4
Meopta Anaret-S 80/4.5
Meopta Meogon 80/2.8
Agfa ColorStar 100/4.5
Durst Neonon 80/5.6

Borderline Useable: 70-80%

Nikkor EL 75/4 N
Fujinon ES 90/4.5
Leitz Focotar II 100/4.5
Computar DL 50-80/4.5 at 80mm
Minolta E Rokkor 75/4.5

Vintage-Look: 30-70%

Aico Anastigmat 75/4
Kodak Ektar 75/4.5
Kodak Ektar 100/4.5
Perfex 75/3.5
Wray Supar 102/3.5

Ranking the same lenses for performance at close range gives very different results. Ranking the same lenses for performance across f4-f8 changes the order and ranking again.

 

[DeltaLenses]

The post I made above is out of date. The information at 16-9.net is no longer being updated because the ETLS (Enlarger Taking Lens Survey) has grown into Delta: a much larger catalogue and archive of 'alt-lens' information and reviews of enlarger, projector, process and industrial lenses at www.DeltaLenses.com - if you have anything you'd like to add, please let me know.