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Gutted lens as an adjustable tube?
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DesolateMirror



Joined: 12 Jan 2018
Posts: 3

PostPosted: Sun Jan 21, 2018 12:12 am    Post subject: Gutted lens as an adjustable tube? Reply with quote

I've been shopping around for a tube setup with a focusing helicoid for a quick and dirty adjustable tube setup for microscope objectives and reversed lenses, at least until a decent used bellows comes up which are quite scarce in AU.

For the same price of a moderate tube setup there are plenty of old zoom lenses that could be gutted keeping only the zoom function and aperture iris. You could easily add a locking nut for the zoom position too.

The old manual 75-205 or 80-200 front element focusing lenses would be way more than enough adjustment with the bonus of a free manual aperture/iris.


I don't really need the iris/aperture function, but it is a nice bonus. Is there an ideal distance from the objective or sensor for the aperture/iris when using a microscope objective?

Am I missing something obvious that will prevent this from working?

Thanks!
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enricosavazzi



Joined: 21 Nov 2009
Posts: 896
Location: Stockholm, Sweden

PostPosted: Sun Jan 21, 2018 4:45 am    Post subject: Reply with quote

The idea may work, but it takes quite a bit of adapting, with uncertain results, and it is probably both more practical and cheaper to use a set of extension tubes (I have used 52mm, m42 and T2 tubes for this purpose).

If a quick change of length is necessary, the required length change is probably not on the order of bellows length but less, and adding a helicoid (e.g. 36-90 mm) to a set of tubes should be sufficient. This is more than you can get from a typical lens focusing helicoid, in any case.

There is also an Olympus OM telescopic auto tube and similar devices to consider, e.g. see http://savazzi.net/photography/olympustelescopic.html
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Olympusman



Joined: 15 Jan 2012
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PostPosted: Tue Jan 23, 2018 9:07 am    Post subject: Gutted lens Reply with quote

I gutted an old 135mm Nikkor to use as a variable extension tube and it has worked very well for me. You just need to epoxy on a lens mount on the filter thread end.

Mike
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Lou Jost



Joined: 04 Sep 2015
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PostPosted: Tue Jan 23, 2018 10:09 am    Post subject: Reply with quote

The iris will be in the wrong place in these set-ups.
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ChrisR
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PostPosted: Tue Jan 23, 2018 11:12 am    Post subject: Reply with quote

If you want to play, you could buy an old Slide Copier for very few shekels. Ohnar was the make, back in the day. I see they were at some time called Zoom Reversers; how odd.
They come with a 1:1 -1:2.5 lens, of sorts, quite a long tube which usually has a T2 mount at camera end, and a helicoid with significant extension - a couple of inches if I remember correctly. I estimated the effective aperture at f/11 once, though that memory is 35 years old.
The diffuser and slide holder can be usable for other things, too.

I have one somewhere but would never find it now - I obviously need to buy another one.
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Jan Steinman



Joined: 22 Jan 2018
Posts: 21
Location: Salt Spring Island, British Columbia, Canada

PostPosted: Tue Jan 23, 2018 10:20 pm    Post subject: Reply with quote

enricosavazzi wrote:
There is also an Olympus OM telescopic auto tube and similar devices to consider, e.g. see http://savazzi.net/photography/olympustelescopic.html
I second this suggestion! Although it is not a cheap option, going on evilBay for US$100 and up.

But if you haven't used this, you are missing something wonderful! The versatility of a bellows, combined with the sturdiness of fixed extension tubes. Here's some more information about it: http://www.alanwood.net/photography/olympus/telescopic-auto-tube.html

Yet another option, not much more expensive than buying a thrift-store zoom lens to gut, are the various helical focusing barrels found on evilBay. They come in different lengths and mounts, although it seems screw mounts are most prevalent. These range from the low $20s to low $40s, depending on mount and extension length. Most of these ship from China for free, which is a lot closer to Oz than it is to Canada, so they may arrive in less than the five weeks it took me to get one. https://www.ebay.com/sch/i.html?_from=R40&_trksid=m570.l1313&_nkw=helicoid+macro+extension&_sacat=0

Another nice thing about these, if you're using a mirrorless with legacy lenses, you can select one with a minimum extension that will allow you to focus to infinity.
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Lou Jost



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PostPosted: Wed Jan 24, 2018 5:48 am    Post subject: Reply with quote

Those eBay focusing helicoids tend to be very wobbly, though a few turn out alright.
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enricosavazzi



Joined: 21 Nov 2009
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PostPosted: Wed Jan 24, 2018 7:31 am    Post subject: Reply with quote

Lou Jost wrote:
Those eBay focusing helicoids tend to be very wobbly, though a few turn out alright.

That was my experience with the helicoids I bought from a few years ago to over a decade ago.

Things are partially different today. The cheap ones are still available, but if you make an eBay search for brass + helicoid, or high + quality + helicoid, you come up with some moderately more expensive units that do feel better (and heavier) in hand than the old aluminium-only ones.
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dickb



Joined: 05 Jul 2010
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PostPosted: Wed Jan 24, 2018 9:21 am    Post subject: Reply with quote

Jan Steinman wrote:
enricosavazzi wrote:
There is also an Olympus OM telescopic auto tube and similar devices to consider, e.g. see http://savazzi.net/photography/olympustelescopic.html
I second this suggestion! Although it is not a cheap option, going on evilBay for US$100 and up.

But if you haven't used this, you are missing something wonderful! The versatility of a bellows, combined with the sturdiness of fixed extension tubes. Here's some more information about it: http://www.alanwood.net/photography/olympus/telescopic-auto-tube.html


I agree, the sturdiness of the telescopic auto tube is wonderful. Its quick way of coarse length adjustment is nice as well, but not as well suited for tiny precise adjustment. The lenses intended for the tube had their own little helicoid. I use mine most together with a Pentax M42 helicoid for precise focus.


Jan Steinman wrote:

Yet another option, not much more expensive than buying a thrift-store zoom lens to gut, are the various helical focusing barrels found on evilBay. They come in different lengths and mounts, although it seems screw mounts are most prevalent. These range from the low $20s to low $40s, depending on mount and extension length. Most of these ship from China for free, which is a lot closer to Oz than it is to Canada, so they may arrive in less than the five weeks it took me to get one. https://www.ebay.com/sch/i.html?_from=R40&_trksid=m570.l1313&_nkw=helicoid+macro+extension&_sacat=0

Another nice thing about these, if you're using a mirrorless with legacy lenses, you can select one with a minimum extension that will allow you to focus to infinity.


Another option, if you are into gutting things is the Vivitar 2x macro focusing teleconverter. The se come in many mounts, and from some of those the optics are easily removed. This leaves you with a very sturdy and smooth helicoid.
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Jan Steinman



Joined: 22 Jan 2018
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Location: Salt Spring Island, British Columbia, Canada

PostPosted: Wed Jan 24, 2018 11:15 am    Post subject: Extending Reply with quote

dickb wrote:
Another option, if you are into gutting things is the Vivitar 2x macro focusing teleconverter.
Have you actually done this surgery?

I have one of these sitting on my desk right now (Olympus OM mount), staring at be accusingly for ignoring it. I scored it on evilBay for $10.

The difficulty I see is in adapting the camera mount. Of course, if you get one with the mounts you want, you're laughin'. Bust most likely, you'll want to do more than simply remove the optics, which are atrocious. (I did look through the thing, and concluded I'd be better off smearing Vasoline™ on a filter, if I want "soft focus." Very Happy)

Any Day Now, I intend to remove the optics and replace the rear mount with a µ4/3rds one.

BTW: for all you budding lens-mount surgeons out there, I buy 58mm lens reversing adaptors, then grind the filter threads off with a stationary belt sander. (I also got some 62mm reversing adapters, then discovered they won't mount on the OM-D line, because of the protruding EVF.) Then it's a fairly simple matter to countersink some holes and mount it to whatever you want, shown here on a Nikon PB-4 bellows:

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Last edited by Jan Steinman on Wed Jan 24, 2018 1:25 pm; edited 2 times in total
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MarkSturtevant



Joined: 21 Nov 2015
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PostPosted: Wed Jan 24, 2018 1:13 pm    Post subject: Reply with quote

Ironically I have just built a super macro lens with the vivitar 2X macroteleconverter. I will be posting on it later, once I get a chance to test it out.
It was very easy to de-glass, but flocking up the insides was a chore.
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ChrisR
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PostPosted: Wed Jan 24, 2018 1:27 pm    Post subject: Reply with quote

Quote:
Have you actually done this surgery?
Yes, twice.
The optic unit simply unscrews.
As a macro converter, the one I tried wasn't at all bad, but I have other options.

As an alternative to the Nikon bellows lobotomy, there are various ebay ways to adapt, such as via cheap Chinese tubes which share a common central thread.
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Jan Steinman



Joined: 22 Jan 2018
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PostPosted: Wed Jan 24, 2018 1:34 pm    Post subject: Reply with quote

ChrisR wrote:
As an alternative to the Nikon bellows lobotomy, there are various ebay ways to adapt, such as via cheap Chinese tubes which share a common central thread.
I didn't want to make the minimum bellows extension any bigger than necessary, by using stacks of adapters, which also tend to wobble.

I sacrificed 2/3rds of an OM --> 4/3rds adaptor on the other end, and ended up with just 1.5mm more extension than is shown on the scale on the side of the bellows, which is kinda neat. (I debated trying to mill things down to make the scale match the extension, but quickly decided that, since I had never really looked at those numbers before, it would be a waste of time. Very Happy )



Using a makeshift clamp made from a couple wood joiners and a screw and wing nut, I drilled through existing holes in the adapter into the Nikon front standard, then tapped those holes for 2mm x 0.4 screws:


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ChrisR
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PostPosted: Wed Jan 24, 2018 1:47 pm    Post subject: Reply with quote

If you wanted a short minimum length, the PB-4 isn't a good start, as it's one of the longest at minimum. Now, if you'd come to the forum earlier..... Wink.
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Jan Steinman



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PostPosted: Wed Jan 24, 2018 3:19 pm    Post subject: Reply with quote

ChrisR wrote:
If you wanted a short minimum length, the PB-4 isn't a good start...
But if you want tilt/shift, it seems like a good place to start!

I also converted a Minolta Auto-Bellows III. It ended up with about the same minimum, but it has nylon slide bearings, which seem prone to breakage.

I also have a Vivitar, which has the shortest distance of the three, but no tilt/shift.

I'm planning to drive the rear standard on the Nikon with a stepper motor, which seems to be a lot more difficult on the Minolta, and more problematic with things like backlash and high peak torque.

What I'd really like is a Hama Kenlock Spiratone bellows, but those are as rare as hen's teeth, and cost an arm and a leg!

Bottom line: short distance wasn't my ultimate goal, but with a little bit of machine work, I could get it much shorter than if it was on an adapter stack.
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