42 or 58 diameter tubes

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JW
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42 or 58 diameter tubes

Post by JW »

For some time 42 has been the answer to the 'ultimate question', but why not 58mm instead? When using 10X or 20x infinite focus objectives, with the usual reversed Raynox 150mm, does tube diameter matter? I would guess that the larger diameter may help to reduce reflections, etc., but could be wrong. Certainly, stabilizing a system built with 42mm tubes is much easier, however. I am thinking of switching from 58 to 42mm, wanted to get some opinions first.
It's not what you look at that matters, it's what you see - Henry David Thoreau

JKT
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Re: 42 or 58 diameter tubes

Post by JKT »

The only advantage for 42 over 58 I can think of is better availability of parts and lower price.

The larger size is more rigid and allows for all kinds of constructions including light baffles inside to cut reflections.

chris_ma
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Re: 42 or 58 diameter tubes

Post by chris_ma »

I find that Thorlabs SM2 tubes (around 52mm imperial) are the "ultimate" tubes, but they are a bit more costly then no name 42mm tubes.
reflections are reduced with a larger diameter, but since you'd still need flocking the difference is probably insignificant.
the main benefit is a wider fit for lenses if you do exotic setup, but if 42mm work well for you atm then I can't think of any really good reason to switch.
chris

Scarodactyl
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Re: 42 or 58 diameter tubes

Post by Scarodactyl »

It is awfully hard to beat the low price point on generic m42 spacers, adapters and helicoids.

JW
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Re: 42 or 58 diameter tubes

Post by JW »

Thanks for the comments! If I wasn't clear, I currently am using 58 mm tubes, which are strong but not stiff, these things seem to wave in the breeze. Since I couldn't find a commercial solution to clamping them down, I thought about going to 42 mm. I am going to get a 200 mm Arca-compatible lens plate and strap the tubes to the plate with extra thick cable zip-ties, probably with some sorbothane or similar involved as well, and see if this does the trick (currently only the camera is attached to the stacking rail, so the tubes are mostly cantilevered).
It's not what you look at that matters, it's what you see - Henry David Thoreau

rjlittlefield
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Re: 42 or 58 diameter tubes

Post by rjlittlefield »

Now I am curious...

A string of 58 mm tubes with screw threads should be extremely stiff. So, do your current tubes have floppy bayonet connectors, or is something else going on?

--Rik

chris_ma
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Re: 42 or 58 diameter tubes

Post by chris_ma »

I agree - pretty much any tube diameter with screw threads should be very solid. of course larger ones are a bit stiffer, but even 42mm should be very solid.
best practice is to support them at two points spread apart with slip rings, much better then trying to fix it at the camera mount.

speaking of which, anybody knows a decent cheap 42mm or 52mm system with slip rings? (as mentioned, I use the Thorlabs SM2 option, but asking for a friend who is broke)
chris

JW
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Re: 42 or 58 diameter tubes

Post by JW »

Rik, Chris - unfortunately my 58 mm extension tubes are not threaded, they have Canon EF compatible mounts - seemed like a good idea at the time. The configuration is about 120mm of these tubes attached to the camera's lens mount, followed by a reverse 150 Raynox, then either a 10x or 20x objective lens, suitable adapters as needed, and all of this is cantilevered off of the lens mount, with only minimal support about 4 cm out. While stiff (and not waving in the breeze - that was a bit of hyperbole), there is noticeable vibration for even the slightest movement on my rig or bench. The (relatively) heavy objective is probably driving some vibration moment. I do have a set of 42mm threaded tubes and adapters, but would need to get two more sets for the correct length. My choice is either to figure out how to stabilize the current 58mm tube, or finish out the 42mm tubes; in either case needing some mounting brackets. I am leaning towards 42mm, as there are no suitable ready made brackets for 58mm tubes. But first, I am going to try the cable-tie solution to strap the tube to a lens plate.
It's not what you look at that matters, it's what you see - Henry David Thoreau

DavyC
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Re: 42 or 58 diameter tubes

Post by DavyC »

To take the stress off your camera mount with the body flexing being an issue, would M42 bellows be an option? There is only the weight of the camera on load at one end, so better distribution. For the most part with bellows you have increased space, with no need for flocking and you can dial in required length.

Lou Jost
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Re: 42 or 58 diameter tubes

Post by Lou Jost »

I really like wider tubes 58mm or greater. These let me do sensor shifting if I desire, and reduce reflections and are easier to baffle.

JW
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Re: 42 or 58 diameter tubes

Post by JW »

Davy - That is a good idea to use a bellows, I should have thought of that :oops: . My current one has light leaks and the cloth is beyond repair, but I'll look into getting a tube and maybe doing some home repairs on it. Otherwise, its cable ties to strap down the tubes to a lens plate.

Thanks Lou for the confirmation!
It's not what you look at that matters, it's what you see - Henry David Thoreau

DavyC
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Re: 42 or 58 diameter tubes

Post by DavyC »

JW, Not that I know much about macro, as I am very much at the early learning stage, but I came across this load flexing when trying to put a camera/ tubes/ lens together.
Too much stress on the camera mount. I wasted money on a modern budget bellows. Total rubbish.
So I got an oldie Nikon and M42 Pentacon bellows. They new how to build stuff in the old days.
Kidnap victims and felons all agree that cable ties are only ever a temporary solution. Just saying.

lothman
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Re: 42 or 58 diameter tubes

Post by lothman »

may be Adalberts suggestion of using Harley clamps and bolting everything to a long Arca-Plate may help you:
viewtopic.php?f=25&t=39116&hilit=Raynox+on+Harley

JW
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Re: 42 or 58 diameter tubes

Post by JW »

Thanks for the suggestions on using bar clamps - they could work if only the ID was 64mm or larger, which is what the 58mm tubes require. I've been searching everywhere for reasonably priced clamps that meet both the ID requirement and are capable of accepting a 1/4-20 centered (not off-set) screw. There are plenty of clamps (for pipes, tubes, wire bundles, etc.) out there, but either too much $$$ for what they do, or the fastening point is off-set. I've ordered some wide cable ties, will report back how well they work strapping the tubes to a 200mm Arca plate.
It's not what you look at that matters, it's what you see - Henry David Thoreau

lothman
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Re: 42 or 58 diameter tubes

Post by lothman »

JW wrote:
Wed Aug 04, 2021 7:46 am
... There are plenty of clamps (for pipes, tubes, wire bundles, etc.) out there, but either too much $$$ for what they do, or the fastening point is off-set.
so what about tapping a spindle motor bracket from aliexpress ( for 8$ plus shipping) yourself or making (or getting made) an adapter plate.
clamp.jpg

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