Schneider Kreuznach Enlarging Lens Aperture Ring Replacement

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RobertOToole
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Schneider Kreuznach Enlarging Lens Aperture Ring Replacement

Post by RobertOToole »

A couple of months ago I picked up a nice Schneider Kreuznach APO-Componon HM 4/45 enlarging lens for almost nothing mounted on an Aviiva camera for a line scanning industrial application. The lens was perfect optically and the body was really clean but it had a damaged filter thread. FYI this type of SK lens uses a plastic body and aperture ring.

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Hiding in my optical junk pile I found a Schneider Componon-S 5.6/100 lens with the worst case of Schneider-itus in history but the rings looked identical. Don't pay more than $5 for a lens like this. This one was actually free!

BTW anyone have any info on the cause of Schneider-itus or lens separation and de-cementing like this 5.6/100 above? Heat damage?

The aperture ring with the filter mounting threads looked exactly the same as the 45mm.

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Using a $11.99 Ebay spanner (ebay search term DSLR spanner wrench) I pulled the lens apart to see what was involved in a swap operation.

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For disassembly I held the outer notches in the front of the lens with the spanner and spun the lens body around to loosen the ring. The optical parts are contained in two very east to remove cells. Once the front cell is loose it lifts out. Then you can lift out the aperture ring with washer, wire clip, and aperture scale. Note: the aperture ring section is upside down in the picture above and below.

I practiced swapping rings with the 5.6/100 and a junk 4/80 a few times before I opened the 4/45. Than I removed the damaged ring from the 4/45 APO-Componon. The lens cell, far right, was in perfect condition!

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Here are the two rings, 4/45 on the left and 5.6/100 on the right.

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Success! This is the APO-Componon HM 4/45 before and after the ring swap.

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Notes:

Optical performance shouldn't be changed with a swap like this since rings are identical and the front lens cell just lifts out and screws back in. I actually shot a test image using the lens before and after for peace of mind.

Cover the spanner blades with something like tape to prevent any nicks or scratches. I used no residue masking tape.

If you do not have click stops or the aperture ring is binding on reassembly this usually means that the aperture ring is not seated properly due to the wire clip next to the aperture scale ring not being seated. I used a very small thin metal ruler to push the wire ring back into place so the ring will seat then re-tighten with the spanner.

These Schneider enlarging lenses use more plastic than say a Rodenstock, but the lens cells make service really quick and easy. On a Rodenstock the filter mount and aperture ring are all metal and it looks like the lens cell will not come out as one unit. The real cell is the same way. On the Schneider it just unscrews and its off. The Rodenstocks I have all have a metal main barrel and the rear elements mount into the body held in place by a retaining ring. The rear cell is not removable like a Schneider.

Comments and questions welcome.



Robert

Chris S.
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Post by Chris S. »

Another excellent documentary post, Robert! :D Thanks.
RobertOToole wrote:Using a $11.99 Ebay spanner (ebay search term DSLR spanner wrench). . . .
These spanners are handy, aren't they? I don't reach for mine often, but when I do, I need it badly--otherwise, whatever project I'm working on would grind to a halt. In my experience, these spanners are needed not just for working on lenses, but also for manipulation of retaining rings on a wide variety of precision opto-mechanical assemblies. So I'd recommend that any optical tinkerer keep a good spanner in his or her toolkit.

Quite a few of the spanner models on eBay look attractive; hopefully, a fair portion of these may be sound purchases. But it is difficult to predict manufacturing tolerances of no-name tools on eBay. I was unlucky when I took my shot on an eBay spanner and received a piece of fiddly, misaligned junk that tended to slip off retaining ring notches and threaten to mar a lens. I quickly cast aside my eBay spanner; presumably, your eBay spanner is of much higher quality.

I replaced my specimen with an Edmund Optics Spanner Wrench Set, which costs considerably more than most eBay spanners. It is a very well-made tool that does its job with quick, authoritative precision; it is not at all fiddly or prone to slip.

--Chris

enricosavazzi
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Post by enricosavazzi »

Strictly speaking, Schneideitis is the detachment of black paint from the girdle (or other part of an optical element) painted black and not meant to transmit/reflect light. It is usually seen as mirror-reflecting areas along the girdle of an element. In your lens, this does seem to be the case around the element(s) in the front cell of the lens. There seems to be more going on, however, in addition to Schneideritis.

Element separation is when the glue cementing two optical elements detaches from one of the optical surfaces. The glass-to-air or glass-to-vacuum interfaces behave differently. Element separation is sometimes very difficult to see by eye, although it often deteriorates image quality.

As you have demonstrated, Schneider and other lens makers often re-use some barrel components in multiple lens models.
--ES

Peter De Smidt
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Post by Peter De Smidt »

Nice job!

SK Grimes also makes spanners, and they do a lot of custom machining for photographers: http://www.skgrimes.com/.

RobertOToole
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Post by RobertOToole »

Chris S. wrote:
I replaced my specimen with an Edmund Optics Spanner Wrench Set, which costs considerably more than most eBay spanners. It is a very well-made tool that does its job with quick, authoritative precision; it is not at all fiddly or prone to slip.
Nice link Chris thanks, that Edmunds unit has a lot better selection of tips than my present wrench.

Okay I just replaced my spanner with an edmunds unit too.

Found a reseller on ebay that sells the edmunds 1457 set for $50. I had a few ebay bucks built up so I got it pretty cheap :-)

They have one set left BTW.

http://www.ebay.com/itm/Edmunds-70751-S ... 1116396003

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RobertOToole
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Post by RobertOToole »

enricosavazzi wrote:Strictly speaking, Schneideitis is the detachment of black paint from the girdle (or other part of an optical element) painted black and not meant to transmit/reflect light. It is usually seen as mirror-reflecting areas along the girdle of an element. In your lens, this does seem to be the case around the element(s) in the front cell of the lens. There seems to be more going on, however, in addition to Schneideritis.

Element separation is when the glue cementing two optical elements detaches from one of the optical surfaces. The glass-to-air or glass-to-vacuum interfaces behave differently. Element separation is sometimes very difficult to see by eye, although it often deteriorates image quality.

As you have demonstrated, Schneider and other lens makers often re-use some barrel components in multiple lens models.
Thanks for taking time to give me an explanation Enrico!

You are also right on the 5.6/100, it did have more going on, the inner surfaces elements were coated with something so much so that they looked like frosted glass but only on the inner lens surfaces, the inner and outer with both front and rear cells were ok! If that wasn't bad enough, I could also see some newton rings!

I didn't pay for the lens though, it was a freebie, so I really cant complain.

Robert

steveminchington
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Post by steveminchington »

That's probably fungus if it is between the lens cells. The fungus spores can't get between the lenses but they can get into the space where the aperture blades are and the fungus can get pretty bad if left for a long time.

The Schneideritis as people call it, is not some kind of disease. It's as Enrico describes. The lenses are cut out of a block of optical glass with a diamond hole cutter which leaves the edges a bit rough. The edges are just painted black to stop reflections, but over time this seems to fade away and leave the rough edges visible through the lens. It looks like small bubbles.

RobertOToole
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Post by RobertOToole »

Chris S. wrote:......

I replaced my specimen with an Edmund Optics Spanner Wrench Set, which costs considerably more than most eBay spanners. It is a very well-made tool that does its job with quick, authoritative precision; it is not at all fiddly or prone to slip.

--Chris
Thanks again Chris!

That Edmunds 70751 Spanner Wrench showed up today and wow, I am glad I ordered one! Now I can see why you recommended it, it very well made and worth the $50 (on ebay).

Here is a better illustration of what you get so others can have a better idea. BTW I left off the included extension bar for larger diameter work.

Image

SK lens for scale only and not included with the spanner :-)

Robert

Chris S.
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Post by Chris S. »

RobertOToole wrote:Now I can see why you recommended it, it is very well made and worth the $50 (on ebay).
Robert--nice score! :D

Like you, I purchased my set of Edmund Optics spanners second-hand on eBay, for a price similar to what you paid. But prior to my purchase, I spent a fair amount of time watching and waiting for the kind of deal you saw.

The completed listing you showed was a good deal for buyers. If one has the luxury of waiting, I'd recommend watching for an eBay sale under low buyer-terms. But in my experience, these fire-sales happen uncommonly; if one needs to work on a lens immediately, I'd advise to simply purchase the needed tool at retail and move forward.
Here is a better illustration of what you get so others can have a better idea. BTW I left off the included extension bar for larger diameter work.
Your illustration strikes me as not just better, but much, much better than what Edmund Optics provides. If EO were my client, I would advise them to license your image and include it on their Web page. My bet is that if EO did so, they would sell many more sets of these spanners.

Image
SK lens for scale only and not included with the spanner :-)
Understood--but your inclusion of the SK lens helps us understand the scale among these lenses, does it not? :D

--Chris

RobertOToole
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Post by RobertOToole »

Chris S. wrote:Robert--nice score! :D

Like you, I purchased my set of Edmund Optics spanners second-hand on eBay, for a price similar to what you paid. But prior to my purchase, I spent a fair amount of time watching and waiting for the kind of deal you saw.
Thanks, I got lucky using google image search (https://images.google.com/) using the spanner thumbnail on the Edmunds site and the auction popped up!
The completed listing you showed was a good deal for buyers. If one has the luxury of waiting, I'd recommend watching for an eBay sale under low buyer-terms. But in my experience, these fire-sales happen uncommonly; if one needs to work on a lens immediately, I'd advise to simply purchase the needed tool at retail and move forward.
Yes true. I bought the second to the last unit and the auction showed seven sold! I wrote to the seller to ask about an ETA on more stock and they told me they don't order they only sell what shows up for sale. So no ETA available. My unit was brand new in packaging, it did not look like B stock or open box. Strange how the seller can get a hold of them from Edmunds, maybe over-stock clearance?
Your illustration strikes me as not just better, but much, much better than what Edmund Optics provides. If EO were my client, I would advise them to license your image and include it on their Web page. My bet is that if EO did so, they would sell many more sets of these spanners.
I think you are right!

Thanks for your input Chris.

Robert

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