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Mounting threadless lenses

 
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Miljenko



Joined: 01 Jun 2013
Posts: 87
Location: Zagreb, Croatia

PostPosted: Fri Aug 24, 2018 7:58 am    Post subject: Mounting threadless lenses Reply with quote

During the last two years I have purchased and tested more than 50 lenses for macro compliant characteristics. At least half of those were industrial, microfiche and scanner lenses and only couple of those had any sort of mounting thread. Only few of those threadless had outside diameter close enough to standard filter size so I could machine an appropriate thread. But what to do with the mayority of those nice smooth black barrels? How to mount them to extension rings or whatever?

The solution lies within 3D printer; an affordable and useful tool these days. Cheap Chinese kits can be bought for as low as $200 but if you didn't plan to buy one, you can always ask a friend to print your stuff or pay for printing services.

Printing the precise plastic adapter for a threadless lens is a piece of cake IF you have an exact design file. Unfortunately, if you are not a CAD software expert, learning how to do it takes much longer than assembling a 3D printer. In order to help you, I have studied dozen of CAD programs and foud a solution for adapter design with zero effort.

You just need to download FreeCAD software and install it. Measure precisely your lens' outside diameter. Canibalise one UV filter with a diameter compatible with your extension tubes/bellows/relay lens, removing the glass element. Measure the filter glass diameter. Open FreeCAD, select Part Design. Find Part Design pull down menu and select the last option: Shaft design wizard (see the pic 1). On the left side is simple table with 3 parameters for each of two segments. The second will be the plate replacing filter glass, while the first one is just the extension tube supporting firmly the lens. The length of that one should be about 5mm, while the plate can be just 1mm long (thick). Of course, plate dia should be the same as the removed glass diameter. Now here is a tricky part which probably won't succeed in a first run. Inside diameter should match your lens outside diameter. Unfortunately, 3D printers are not precise enough to follow exact design measurements. Your first print will be too loose or too tight to mount the lens. You'll have to make a couple of additional prints, slightly adjusting inside dimensions for both segments in 0.2mm increments. The good news is that size "microadjustment" (as percentage) will comply to all the adapters you want to print with the same printer. Of course, you should choose black plastics and PLA variety is perfectly OK for this task. When printed and cooled down, you just have to mount the adapter to the filter ring, using the original threaded inside ring.

Happy printing!








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Last edited by Miljenko on Fri Aug 24, 2018 8:59 am; edited 1 time in total
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ray_parkhurst



Joined: 20 Nov 2010
Posts: 1730
Location: Santa Clara, CA, USA

PostPosted: Fri Aug 24, 2018 8:10 am    Post subject: Reply with quote

Very nice! I've often considered getting a 3D printer for such work. I generally find an adapter that is close, then use tape to make up the difference. Or I use double-stick tape to stick the lens to an adapter. If I end up wanting a more permanent solution I order something from Raf. The 3D adapter would give an intermediate solution, maybe even permanent...

On a side note, have you kept track of the results for the 50 lenses you tested last 2 years? The last shootout post I saw from you was back in 2014. Would be great to see a list of the lenses you tested and some results. They don't even need to be extensive...a list and some notes on coverage, sharpness, etc would be useful. Which ones were worth pursuing, and which were not? Several folks are doing a similar vetting procedure.
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Miljenko



Joined: 01 Jun 2013
Posts: 87
Location: Zagreb, Croatia

PostPosted: Fri Aug 24, 2018 8:56 am    Post subject: Reply with quote

ray_parkhurst wrote:

On a side note, have you kept track of the results for the 50 lenses you tested last 2 years? ...Would be great to see a list of the lenses you tested and some results.

Ray, I was afraid someone is going to ask that because it was a secret plan to publish a series of posts with all those results. Now I can't lie or deny. I have done 90% of all the tests planned, I need just another week or so to finish tests and prepare data for publishing. As a teaser, let me just say it will be very informative, precise and useful. Many well known lenses are included and many more less known but available. Btw, I'm glad I'm back to these forums!
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dolmadis



Joined: 07 Dec 2011
Posts: 517
Location: UK

PostPosted: Fri Aug 24, 2018 9:13 am    Post subject: Reply with quote

I am sure that we would also welcome any contributions you can make here;

http://www.photomacrography.net/forum/viewtopic.php?t=37666&highlight=printing

BR

John
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ray_parkhurst



Joined: 20 Nov 2010
Posts: 1730
Location: Santa Clara, CA, USA

PostPosted: Fri Aug 24, 2018 9:32 am    Post subject: Reply with quote

Miljenko wrote:
ray_parkhurst wrote:

On a side note, have you kept track of the results for the 50 lenses you tested last 2 years? ...Would be great to see a list of the lenses you tested and some results.

Ray, I was afraid someone is going to ask that because it was a secret plan to publish a series of posts with all those results. Now I can't lie or deny. I have done 90% of all the tests planned, I need just another week or so to finish tests and prepare data for publishing. As a teaser, let me just say it will be very informative, precise and useful. Many well known lenses are included and many more less known but available. Btw, I'm glad I'm back to these forums!


I can't wait!
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RobertOToole



Joined: 17 Jan 2013
Posts: 1054
Location: United States

PostPosted: Fri Aug 24, 2018 4:19 pm    Post subject: Reply with quote

50 lenses!

Thats some work!

Looking forward to seeing the results of the testing if and when you share the info.

FYI, I got really lucky with that Tominon if anyone else decides to try one. Thorlabs SM1 threaded tube slips right over the barrel. These SM1 tubes can be had for less than $10 on Ebay. I pick them up all the time.





https://www.closeuphotography.com/tominon-26mm-lens/
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Miljenko



Joined: 01 Jun 2013
Posts: 87
Location: Zagreb, Croatia

PostPosted: Fri Aug 24, 2018 10:06 pm    Post subject: Reply with quote

Robert, your tests were most inspiring although I'm doing lens lab tests since 2004. in very much different way. I tested for national photo magazine ordinary lenses for many years, switched to macro lenses only two years ago. You'll see the outcome soon enough!
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RobertOToole



Joined: 17 Jan 2013
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Location: United States

PostPosted: Fri Aug 24, 2018 10:52 pm    Post subject: Reply with quote

Miljenko wrote:
Robert, your tests were most inspiring although I'm doing lens lab tests since 2004. in very much different way. I tested for national photo magazine ordinary lenses for many years, switched to macro lenses only two years ago. You'll see the outcome soon enough!


Sounds Great.

Already aware of your background and experience through reading all your previous posts here in the forum over the years.

Thanks for the info.
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Chris S.
Site Admin


Joined: 05 Apr 2009
Posts: 3070
Location: Ohio, USA

PostPosted: Sat Aug 25, 2018 12:04 am    Post subject: Reply with quote

Great post, Miljenko! Very Happy This kind of sharing is what moves us all forward.

And I, too, look forward to hearing about your tests.

(Interesting that you found FreeCAD useful. I briefly tried it and disliked it greatly--though I'll confess that I no longer recall why.)

-Chris S.
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Miljenko



Joined: 01 Jun 2013
Posts: 87
Location: Zagreb, Croatia

PostPosted: Sun Aug 26, 2018 8:42 am    Post subject: Reply with quote

I'm not the fan of FreeCAD either, Chris. It just happens to have that Shaft design wizard tool which will help total beginners to produce those adapters without spending days learning CAD programming. ;-)
Best regards, Miljenko
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Andy



Joined: 21 Sep 2018
Posts: 12
Location: Derby UK

PostPosted: Tue Oct 23, 2018 12:48 pm    Post subject: Reply with quote

For those who are having difficulty can I once again recommend SolidWorks on a student license or WHY. It is so easy most students complete extensive tutorial by midday. How difficult can it be to spin a shape around an axis? Or take a tip from me and start with a bar and remove material as in turn and bore; pretending you are working a lathe.
The very simple round components may be made on a second hand model makers lathe such as Axminster Model Engineer Series C2-300 Mini Lathe for example which can produce threads from 0.4 to 2mm pitch. There would then be no need to buy and or learn CAD or buy a 3D printer with the added bonus that the components do not look like they have been extruded through a tiny toothpaste tube. Materials could be plastics, delron, nylon or metals.
Another route I am planning to investigate are 3D printing clubs at local Unis as here in Derby UK - if they will allow 68 year old guests!
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bralex



Joined: 22 Jan 2018
Posts: 33
Location: Colorado, USA

PostPosted: Tue Oct 23, 2018 8:11 pm    Post subject: Reply with quote

I am a hobby machinist. I find that Delrin or UHMW machines very easily and takes perfectly adequate threads. It's not pretty, the way I do it Smile but I've made a couple of adapters for my Mitutoyo objectives that way. I have a tiny lathe that allows me to hand-crank (!) threads, this works great for the very short lengths needed. A couple photos to follow once I take them!

PS. I just snagged a PrimeFilm 3650u at a surplus store for $10; I'll be making an adapter for it in the next couple days...
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ChrisR
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Joined: 14 Mar 2009
Posts: 7956
Location: Near London, UK

PostPosted: Wed Oct 24, 2018 1:39 am    Post subject: Reply with quote

Instead of starting with a filter, one could use a "T2 to camera mount" adapter.
They generally have a T2 (42mm x 0.75) female threaded ring which is held in by three grub screws. The outer diameter of the ring does vary between makles, as does the thickness which is usually about 4-5mm.
Make your plastic adapter fit where the T2 ring was.
Look for the type which use hex head grub screws. From $2 up, on ebay.

As an alternative if you get the diameter right, the plastic can screw into the
T2 thread with some force, without having a thread on its outside.

The "flange wizard" still works of course which I'm grateful to Miljenko for pointing out.
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Macro_Cosmos



Joined: 15 Jan 2018
Posts: 157
Location: Sydney

PostPosted: Wed Oct 24, 2018 3:51 am    Post subject: Reply with quote

A pretty major problem for a near perfectionist like me is optical axis alignment. Some good metal adapters aren't even that great, 3D printing is just on another lower level of precision.

There's still high quality adapters worth considering though:
https://www.thorlabs.com/navigation.cfm?guide_id=73

The prices are about the same as Raf ones. It's great when one can find a suitable one.

These secure threadless lenses via screws. There's also accessories for mainly the astro crowd that allows alignment of the optical axis.

3D printing is getting better and better though, might invest in a mid-range one when I have the time and funds.
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