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Old lens is it any good?

 
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tmihai



Joined: 13 Jun 2011
Posts: 7
Location: Romania

PostPosted: Mon Jan 23, 2012 2:16 am    Post subject: Old lens is it any good? Reply with quote

I have a Schneider Kreuznach Componon 28mm F4.0, here http://www.macrolenses.de/ml_detail.php?ObjektiveNr=181
a very similar lens is shown as being used for magnifications from 4:1 to 20:1 but from some calculation I saw that at f 4 is diffraction limited at 5:1 or 6:1.
Am I missing something can it be correct ?
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naturephoto1



Joined: 13 Nov 2011
Posts: 509
Location: Breinigsville, PA

PostPosted: Mon Jan 23, 2012 2:33 am    Post subject: Re: Old lens is it any good? Reply with quote

tmihai wrote:
I have a Schneider Kreuznach Componon 28mm F4.0, here http://www.macrolenses.de/ml_detail.php?ObjektiveNr=181
a very similar lens is shown as being used for magnifications from 4:1 to 20:1 but from some calculation I saw that at f 4 is diffraction limited at 5:1 or 6:1.
Am I missing something can it be correct ?


Hi,

First of all do you have a Componon 28mm f4.0 lens or do you have an M-Componon 28mm f4.0 lens as you have in your link? These are different lenses designed for different purposes. The M-Componon lenses were high magnification lenses designed for macro work to cover large format and medium format film cameras. The M-Componon lenses have no filter thread and are designed for and optimized to be used in only one direction (not reversed). The regular Compon lenses were/are enlarging lenses and designed to be used in normal or reverse mount orientation depending upon usage and magnification.

Also, the regular Componon and the M-Componon lenses were developed for film but are still quite usable for digital application. Like other lenses they will have diffraction limitations but you will have to experiment/test your particular lens to find out the "sweet spot" and how much magnification is acceptable for your needs. By the way, there are/were also Apo Componon lenses designed by Schneider which were improved versions of the regular Componon lenses which I believe are/were designed for enlarging of film.

Rich
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tmihai



Joined: 13 Jun 2011
Posts: 7
Location: Romania

PostPosted: Mon Jan 23, 2012 2:41 am    Post subject: Reply with quote

On my lens just says Componon 28mm f4.0 and I could not find it in that data base they are very similar but are some differences at the mount and also mine has an aperture with many blades (approximately 19 or so) that makes it very round.
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enricosavazzi



Joined: 21 Nov 2009
Posts: 955
Location: Stockholm, Sweden

PostPosted: Mon Jan 23, 2012 5:28 am    Post subject: Reply with quote

I agree with Richard, if it only says Componon 28mm f/4, then most likely it is not an M Componon, S Componon, Apo Componon or Apo Componon HM, and it is primarily designed as an ordinary enlarger lens (but covers at most only a 18x24 mm negative). The multi-blade aperture, however, suggests that it is a version adapted to some other use (almost always, plain enlarger Componons have 5 aperture blades).

In spite of this, it may give good results in photomacrography, but almost certainly it must be reversed to perform well in this application (unless it is already mounted in reversed position in a non-standard barrel for a non-standard application).

There is a review with test images of a modern Componon 28mm f/4 at http://coinimaging.com/schn_28r.html . I have no way of knowing whether this uses the same optics as yours.

A rather old Componon 28mm f/4 with an apparently multi-blade aperture is/was advertised on eBay: http://www.ebay.com/itm/SCHNEIDER-COMPONON-28mm-F4-ENLARGER-LENS-EXCELLENT-W-BOX-/310372570032 .

Some data at http://www.schneiderkreuznach.com/pdf/foto/vergroesserung_e.pdf

Depending on the acceptable CoC, the 28mm can be used at magnifications up to about 5x-8x without showing IQ degradation due to diffraction. However, probably it performs better optically at f/5.6, which limits the useful magnification to a max of about 3x-6x. The main problem will be illuminating the subject, because the working distance is going to be quite short.
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Peter De Smidt



Joined: 05 Jan 2012
Posts: 233

PostPosted: Mon Jan 23, 2012 8:25 am    Post subject: Reply with quote

It might be old enough to have a multi-blade aperture. Many lenses from the 1950s, including enlarging lenses, did so. You can check the serial number to figure out the lenses age. There's a chart at Schneider optics USA that'll tell you a lens's age. See: http://www.schneideroptics.com/info/age_of_lenses/
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rjlittlefield
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Joined: 01 Aug 2006
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Location: Richland, Washington State, USA

PostPosted: Mon Jan 23, 2012 10:07 am    Post subject: Re: Old lens is it any good? Reply with quote

tmihai wrote:
a very similar lens is shown as being used for magnifications from 4:1 to 20:1 but from some calculation I saw that at f 4 is diffraction limited at 5:1 or 6:1.
Am I missing something can it be correct ?

The key is in those words "large format", mentioned in another reply. f/4 at 5:1 becomes f/24 effective. That is diffraction limited on an APS-C sensor, but not on say 4"x5" film. Of course on 4"x5" film, 5:1 means a subject that is 1" wide -- easily in reach of an ordinary 1:1 macro lens on an APS-C sensor. This situation appears quite often with older lenses. It is probably the explanation whenever you see a lens with small aperture listed for high magnification.

--Rik
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Charles Krebs



Joined: 01 Aug 2006
Posts: 5800
Location: Issaquah, WA USA

PostPosted: Mon Jan 23, 2012 2:26 pm    Post subject: Reply with quote

tmihai,

That is an excellent little lens. I have a couple of them (as well as the 35/4, which performs in a nearly identical manner albeit requiring a little more extension for a given magnification). The older style mounts were beautiful. All metal, and with apertures that were made up of many blades (I once counted them and I seem to remember that there were 13 blades) that created a nearly perfect circle at any aperture.

Used in reverse, the ones I have are excellent, and show very little difference in performance between f4 and f5.6, so they can be used at f4 if needed. (In fact, these lenses clearly have at least f2.8 size "glass" but the diaphragms are limited to f4. I have seen Schneider literature for an f2.8 "incarnation" of the 28mm Componon, but it was footnoted for having a smaller image circle size at f2.8. This would not really be a concern for the way we use it around here, but I've never seen an f/2.8 version for sale. This being the case, my sense is that at f/4 it is essentially stopped down one stop already. So diffraction effects then become the limiting factor. At f/4 on an APS-C sized sensor that would mean a maximum magnification of about 4.5X which would yield an effective aperture of about f/22. (This is a gray area... depending on your intended usage, your subject, and your personal "tolerance" for diffraction losses you may opt for lower or higher limits, but I think for most purposes about 5X is about the the upper magnification on APS-C sensors for any "nominal" f/4 optic).

The front threads on my older style mounts is 30.5mm. It is pretty easy to find a 30.5mm -52mm step up adapter, which in turn make it an easy lens to reverse mount. (As I type this check out eBay #320831492460, #270823154187 and several others). With one of my older metal style mounts the filter threads were very slightly recessed below the aperture ring, so that the adapter "jammed" the aperture ring from moving. With that particular one I purchased an inexpensive 30.5mm "skylight filter" and removed the glass and used the empty filter frame as a spacer. (30.5mm filters are actually pretty common).


Here are a few shots taken with the Schneider Componon 28/4:
http://www.photomacrography.net/forum/viewtopic.php?t=390
http://www.photomacrography.net/forum/viewtopic.php?t=5564
http://www.photomacrography.net/forum/viewtopic.php?t=3706
http://www.photomacrography.net/forum/viewtopic.php?t=6299

And a couple taken with the Schneider Componon 35/4 (which I have found to have nearly identical quality and "look" as the 28mm images)
http://www.photomacrography.net/forum/viewtopic.php?t=12120
http://www.photomacrography.net/forum/viewtopic.php?t=11998
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tmihai



Joined: 13 Jun 2011
Posts: 7
Location: Romania

PostPosted: Tue Jan 24, 2012 2:11 am    Post subject: Reply with quote

Thank you every body for your replies.

Charles without knowing that is advisable to mount it in reverse I have already started to do so and I have machined on an lathe an adapter to fit in the filter tread of the Componon. I do not remember the diameter but the step of the tread is 0.5 .
Once again thank you for pointing some of your results with this lens it makes me even more willing to finish my setup with this lens.

Mihai
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