Author Topic: Schneider - Kreuznach Symmar 1:5,6/210 <> 1:12/370 ???  (Read 3181 times)

Seapy

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Schneider - Kreuznach Symmar 1:5,6/210 <> 1:12/370 ???
« on: January 27, 2016, 17:54:51 »
Some time ago I acquired this lens, I don't know what it is really, I assume it's for a technical camera, 5-4 or suchlike.  I am interested if it has any use relative to Nikon digital, possibly for UV?

The base mount thread is about 68mm od, the filter thread is definitely 58mm.

I can readily fit the lens in reverse on my PB4 bellows which has slight tilt shift facility I already have a 58mm to 52mm step down ring and a 52mm Nikon F bayonet adaptor.

I am assuming there should be a third part, I think I have the 210mm assembly, presumably there would be a different back part for the 370mm assembly?  The front part is marked 210 would the front part be exchanged if so why is the aperture setting marked for both the f12 and the f5.6?  The 210 marking is on the aperture ring...  I find this a bit confusing.

The iris has 20 blades and the aperture appears quite round at any setting.

Would it be worth using extension tubes and a helix for focusing, I could turn up a custom tube on a lathe if it's worthwhile.  The mounting collar screws off and actually has a detachable flange held with four screws.  The actual lens mounting thread is 39mm.

Please can you comment if it is it worth fitting/using or is it not worth bothering with?  It seems a decent lens but my opinion is worth nothing compared with you guys, it may be good lens but totally unsuitable for me...











Thanks for looking.
Robert C. P.
South Cumbria, UK

charlie

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Re: Schneider - Kreuznach Symmar 1:5,6/210 <> 1:12/370 ???
« Reply #1 on: January 27, 2016, 18:08:01 »
I'm not familiar with this particular lens, I wonder if it is an old enlarger lens with an adapter mounted to it. Does the silver part of the lens separate from the black mount?

When I come across lenses like this I'll attach some K rings to a body to get the right amount of extension to focus on something then just hold the lens up to it and snap some photos. That should be enough to get a rough idea if it is worthwhile to find a permanent mount for it.

Seapy

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Re: Schneider - Kreuznach Symmar 1:5,6/210 <> 1:12/370 ???
« Reply #2 on: January 27, 2016, 18:16:18 »
Hi Charlie,  Yes, the rear element housing unscrews from the front part, then you can unscrew the mount which is 39mm, but the rear element housing is much larger than 39mm, it's about 54mm od. There is no shutter.
Robert C. P.
South Cumbria, UK

Bjørn Rørslett

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Re: Schneider - Kreuznach Symmar 1:5,6/210 <> 1:12/370 ???
« Reply #3 on: January 27, 2016, 18:26:00 »
Dual-purpose lenses are not uncommon in the large-format world. Often they were designed so one could replace the rear section to get  the long focal length. Nikon had a whole series of telephoto Nikkors designed with this principle. I have the 360mm f/8/ 500 mm f/11 Nikkor-T ED from that series.

Why? You had a second lens at disposal and needed only bring with you a smaller rear component, almost like having a TC of today. As the combination was specifically computed the 'short' and 'long' could both have excellent performance, but the 'long' version would always be 1-2 stops slower. However, for view cameras, 'speed' is not a major factor.

No idea what purpose this particular Symmar served, but the 'Symmar' designation usually meant symmetric designs with excellent performance. There also were APO-Symmars and the few of them I used back in the old film days were fantastic. 

The lens might have originally been mounted in a leaf shutter unit.

Seapy

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Re: Schneider - Kreuznach Symmar 1:5,6/210 <> 1:12/370 ???
« Reply #4 on: January 29, 2016, 23:10:38 »
Deep breath!  I have made some test exposures with this lens.



Using the D300s, PB4 bellows and some assorted extension tubes.  I can't (yet) mount the lens properly, that the right way round.  It's reverse mounted using the 58mm filter thread and a BR2.  I don't want to embark on an engineering job to mount it properly until it seems I have a fighting chance of ending up with a half decent lens.  My ultimate objective is UV, but for now I just want to establish if it can resolve normal spectrum to a usable degree.

I took this exposure last night with all the extension I could muster, about 250mm in all. this gave me a working distance of 600mm subject to lens.  Taken of my computer screen 46mm wide and 32mm high, very roughly 4 times the area of the D300s sensor.  It is of course the NikonGear banner.  The exposure was made at f 5.6 and ISO 1600.  With the bellows it was something of a challenge to get the assembly solid so there may be some camera movement.

Apart from a VERY slight crop this image is straight from the RAW file, no sharpening or adjustments.



Today I decided to try to make some normal exposures over the estuary.  As Oakdale is bang in the middle of the vista I focused on the rigging using live view on my most solid tripod in a half gale!

This image was exposed at f11 1/80 sec ISO 200 with the D300s.  I adjusted the exposure, contrast and de-hazed, some increased clarity but specifically no sharpening



These give some idea of the lack of contrast in the image, I have annotated the images with the relevant data, these are at 100% crop:



And:



Today I felt that f11 was a reasonable aperture for quality. f5.6 seemed a bit soft and f8 lost speed but didn't gain that much sharpness.

Two more crop images.  Again, no sharpening and remember this lens is reverse mounted.  I gave the f5.6 images exactly the same processing as the f11 images, perhaps I could have got more from them individually but I didn't want to complicate things.



The halo on the lifebelt on the f5.6 image shows the difference between the apertures.



Here the general impression of the f11 image is much stronger than the f5.6 image. This lens goes to f45 so I am scarcely scratching at the surface as yet.

I have made some UV exposures and I am cautiously enthusiastic about them, however, please will you lens experts comment on what I have found/done so far in the visible spectrum before going beyond visible.
Robert C. P.
South Cumbria, UK

Bjørn Rørslett

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Re: Schneider - Kreuznach Symmar 1:5,6/210 <> 1:12/370 ???
« Reply #5 on: January 30, 2016, 02:37:38 »
I think these results are quite good, all things considered. The lens is likely able to cover 4x5" format on a view camera and you reverse-mounted it :D plus of course didn't sample the image with a 4x5" sheet of film, but by a tiny (relatively speaking) DX sensor.

The low contrast is unsurprising and may be caused by the simple coating of a vintage lens or flare from spherical aberration, or both factors in combination. Try to mount it in the correct orientation to learn whether the performance improves.

Bjørn Rørslett

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Re: Schneider - Kreuznach Symmar 1:5,6/210 <> 1:12/370 ???
« Reply #6 on: January 30, 2016, 02:52:36 »
Lots of info on your lens. A few starters here;

http://photo.net/large-format-photography-forum/00YGWb

https://www.schneideroptics.com/info/vintage_lens_data/large_format_lenses/symmar/data/5,6-210mm.html

The lens obviously is designed for mounting in a leaf shutter unit size #1.

Seapy

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Re: Schneider - Kreuznach Symmar 1:5,6/210 <> 1:12/370 ???
« Reply #7 on: January 30, 2016, 10:20:42 »
Thank you kindly Bjørn, so I'm not flogging a dead horse then. ;D

The front (rear as should be) element is pretty exposed, as would be expected for a view camera rear element, it may be that an improvised lens hood would improve the contrast, no matter which way round the lens is mounted.

Given that encouraging start, I will post the results of my UV tests later.  I am hoping the minimal coatings will help this lens to transmit UV to a usable degree.  One thing I have noticed that there does not *seem* to be much, if any focus shift in UV.  The test exposures were taken at 600mm same as the NG screen logo and are passably sharp, not perfect but neither was the tripod/ball head/spongy floor setup.  I need to do a tape measure test under better conditions to  check for focus shift.

I felt the exposure times for the test images were quite fast at f5.6 the optimal exposure was 1.3 seconds, ISO 400.  Suggesting, to me at least, the glass and coatings aren't impeding the UV too much perhaps?  I will post the images later, have other stuff to do right now.  :(

I will check out those links you have posted, thanks again.
Robert C. P.
South Cumbria, UK

Bjørn Rørslett

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Re: Schneider - Kreuznach Symmar 1:5,6/210 <> 1:12/370 ???
« Reply #8 on: January 30, 2016, 11:03:08 »
It's presented in the literature  as a symmetric 6/4 design so elements *are* cemented. However, given its age the cement might not block UV too much.

A Copal #1 isn't excessive large and hopefully can be purchased separately or as part of a large-format lens. But mounting the lens via a shutter unit to a lens board might not be any easier than the rig you currently have for it.

Adequately long lens hood should be applied no matter what spectral range you work with. Do remember this is a design with 70 degrees field of view, thus acting as a moderate wide-angle lens on a 4x5" or larger camera. On your DX camera, most of the field of view will just impart stray light to the capture unless a long hood blocks off the peripheral areas covered by the lens.

Seapy

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Re: Schneider - Kreuznach Symmar 1:5,6/210 <> 1:12/370 ???
« Reply #9 on: January 30, 2016, 23:26:58 »
The UV side of things.

I have three main concerns:

1 - Reasonably sharp images.

2 - Reasonable transmission of UV.

3 - Understanding of the focus shift for this lens.

I have taken some UV exposures with the lens, reverse mounted, somewhat limited because my study is in turmoil due to home alterations and renovation.  I am using a converted full spectrum D200 with a clear glass (fluoride?) in front of the sensor.  Subject to front element ~600mm, extension rear of lens to front flange of camera: ~250mm.

I photographed an envelope in a dark room lit only by a Nichia 365nm lamp with a fluoride focusing lens.  Right now Dandelions are not flowering, here at least.  First without a filter. Note the fluorescence of the post code imprint below the barcode, visible as a row of short orange lines, they are not visible on the second and third images filtered by the Venus filter.  To me that seems to confirm the Venus filter is doing it's job.
1)


Then I added my Baarder 'U' Venus 300-390nm filter in front of the Schneider lens. This is straight from the camera, unprocessed. The exposure was 1.3 seconds @ f5.6 (wide open).
2)


This is the same exposure desaturated and with adjustments to refine but NOT sharpen the image.
3)


Without proper checking, from these images I thought the focus shift was minimal, however this evening I made a better check and at about 600mm subject to front element, there seems to be about 12mm deepening shift of the focus point.

I set a tape measure at 45º to the axis of the lens and focused on the 300mm mark in the visible light, made an exposure then fitted the Venus filter, made a second exposure and compared the difference in DoF points along the tape.  I estimate according to the markings on the tape the difference was 22mm but allowing for the tape being at 45º according to my calliper that means a net focus shift of about 13 to 15mm @ 600mm subject distance.

The yellow tape measure is in visible light, red is in UV.
4)


So, I think I have at least partly answered some questions.  The images seem to me to be reasonably sharp, I think the transmission of UV is pretty good with an exposure time of 1.3 seconds @ f5.6 for what I consider to be an optimal exposure and I have a rough starting point for focus shift.  In the past I have used the bottom slide of the PB4 to crank the camera/lens assy forward by say 15mm in search of the best focus point, with a longish lens like this that won't make much difference to the framing.

The thumbnails of the images used to determine the best exposure. the yellow exposure was 10 seconds, through to the darkest brown at 1/15th second.  I selected the bottom left at best exposed @ 1.3 seconds.
5)


Please offer any comments or suggestions as to how I can further refine my research into the suitability of this lens.  I can't afford the time right now to make a solid extension to mount the lens the correct way round.

The only thing I can add is that the normally front element of the lens is 49mm Dia. the rear element is 43mm Dia. That might have some bearing on the lack of contrast in the outdoor normal images I posted above.  Presumably it will reduce the light gathering capacity of the lens, the loss in element area by presenting the rear element to the subject is 0.23, almost a quarter of the available light lost. (Because the lens is reverse mounted.)
Robert C. P.
South Cumbria, UK

Bjørn Rørslett

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Re: Schneider - Kreuznach Symmar 1:5,6/210 <> 1:12/370 ???
« Reply #10 on: January 31, 2016, 00:17:01 »
If the optics truly are symmetric, the exit and entrance pupils should be equal.

Seapy

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Re: Schneider - Kreuznach Symmar 1:5,6/210 <> 1:12/370 ???
« Reply #11 on: January 31, 2016, 00:27:31 »
If the optics truly are symmetric, the exit and entrance pupils should be equal.

In that case this lens is either almost symmetric or asymmetric!  Perhaps it's symmetric in principle? Ie. matching design of entry and exit with the asymmetric aspect dealing with losses (or gains) through the lens? Focusing a greater proportion of the light in a smaller area?  I don't know!   Thanks for the observation anyway.
Robert C. P.
South Cumbria, UK