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Poor man's DIY Speed Booster
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Posted: Tue Mar 26, 2013 9:57 pm
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Posted: Tue Mar 26, 2013 9:57 pm
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DIY-Speed-Booster made from an cheap TS (Teleskop-Service, a German rebrander, most stuff made in Thailand) 2" Focal Reducer (2 multi-coated elements) made for astro-photography (so optimized for long focal lengths I guess).
Costs on Ebay.de are ~50€ new.
Lens used was old Helios M42 44-2 58/2, jammed into an an M48-T2 adapter (focal reducer has M48 filter size)
There's currently no way to focus to infininity as the focal reducer "tube" is much longer than the actual glas elements inside of it and I haven't found a good way to mount it on nex without adding too much space.

Handheld wide open

1/160s, ISO1000


Handheld, DIY Speed-Booster
1/160s, ISO800, don't know aperture, slightly stopped down, maybe "F4 or F5.6" but faster than F2 effective speed!

Last edited by ForenSeil on Sat Apr 20, 2013 1:17 pm; edited 4 times in total


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Posted: Tue Mar 26, 2013 10:34 pm
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Posted: Tue Mar 26, 2013 10:34 pm
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ForenSeil, I very much appreciate your deed. In my plan (perhaps for the distant future?) is a reducer from 6x6/6x9cm to 24x36mm FF.
Keep going! Smile

Nowadays, if we use a medium format lens at a FF camera, we are just cropping the middle of the lens's image circle, and aren't exploring full lenses' capabilities and how they portray the picture.
I hope, some interest to this area will grow in our community (probably, heated up by the metabones? Smile)


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Posted: Tue Mar 26, 2013 10:59 pm
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Posted: Tue Mar 26, 2013 10:59 pm
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I'm also considering a 0.5x focal reducer like this one.
It would be indeed very good for adapting 6x9 lenses on FF or APS-C.
It looks like corner sharpness is not that good, but corners are out of focus anyway and it's difficult to draw a conclusion.
Would you post a photo with corners in in focus, please? It will help very much.


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Posted: Wed Mar 27, 2013 1:52 am
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Posted: Wed Mar 27, 2013 1:52 am
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That's a great idea, thank you.
The application I'm thinking of is to mount behind a large format lens on its lensboard, to turn a 10.5 cm or 90mm into a 50mm or so, sort of a poor mans rodenstock apo grandagon. Only it will be an f/2-f/3.5 grandagon.
A Barlow lens you say? Hmm.


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Posted: Wed Mar 27, 2013 9:41 am
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Posted: Wed Mar 27, 2013 9:41 am
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This is really great! Could you please draw design / elements scheme of your DIY adapter?


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Posted: Wed Mar 27, 2013 12:58 pm
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Posted: Wed Mar 27, 2013 12:58 pm
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Most of those consist of 2 elements in one group.


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Posted: Thu Mar 28, 2013 1:26 am
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Posted: Thu Mar 28, 2013 1:26 am
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Actual magnifcation/reduction depends on distance between the sensor and the focal reducer
I don't think this is 0,5x - focal length looks much smaller than 30mm imho!
I will measure actual speed/iso wide open next time to get and idea of the actual focal length.

I still haven't found a way to mount the adapter proberly Sad
I would love to test it with my Novoflex 400/5.6 and 600/8 - they have plenty of space for focusing to infinity and also a fair coverage but they are in Minolta MD mount and I don't know how to adapt them to M42 or T2 (the only two mounts I can currently adapt) Sad

Pancolart wrote:
This is really great! Could you please draw design / elements scheme of your DIY adapter?

Sorry, the two elements I bought are cemented together, there's now way to draw you a sheme as long as I don't destroy it Sad
As said they don't cost thaaat much, around 50€ on Ebay.de

luisalegria wrote:

A Barlow lens you say? Hmm.

??? Who said barlow lens? What you need is an focal reducer - the opposite.


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Posted: Thu Mar 28, 2013 5:30 am
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Posted: Thu Mar 28, 2013 5:30 am
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Sorry, I misunderstood.
Barlows are used to reduce the focal length of the eyepiece, so I got that confused.


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Posted: Thu Mar 28, 2013 8:45 am
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Posted: Thu Mar 28, 2013 8:45 am
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Barlow is the same as a teleconverter.

The picture with the focal reducer looks really nice in the center, but from these photos I have a feeling that the edges will be very soft.


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Posted: Thu Mar 28, 2013 10:49 am
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Posted: Thu Mar 28, 2013 10:49 am
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Yes, barlow lenses are producing a longer focal length, not a shoter
sammo wrote:
Barlow is the same as a teleconverter.

The picture with the focal reducer looks really nice in the center, but from these photos I have a feeling that the edges will be very soft.

Soft edges are also caused from coverage of the Helios 44 - it's only made for ~2,4x3,5cm (35mm film) and with ~0,3x reducement it's on NEX like it's used on 5x7cm medium format film! I need some P6 lenses Smile


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Posted: Thu Mar 28, 2013 12:48 pm
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Posted: Thu Mar 28, 2013 12:48 pm
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Try an enlarger lens of 75mm or more, they have an image circle big enough.


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Posted: Thu Mar 28, 2013 12:59 pm
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Posted: Thu Mar 28, 2013 12:59 pm
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Update:
I removed the cemented elements from the focal reducer tube (very easy) and jammed them with tooth picks into an Minolta MD - NEX Adapter
I attatched an Minolta MD 50/1.4 and got an ~35mm F1 lens which is glowy wide open and sharp in center from F1.4 onwards Smile


BTW, the lens works fantastically as close-up achromat! It's on Raynox niveau! I wonder if reversed achromats can be also used as focal reducer!? Basically a focal reducer is not much more than a loupe, right?



35mm F1 - focus shift towards the corners is massive and there's a strong glow


35mm F1.4 Smile - looks usable for me Smile
(no PP)
Price of this adapter is only about 65€ Smile

Last edited by ForenSeil on Sat Apr 20, 2013 1:18 pm; edited 12 times in total


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Posted: Thu Mar 28, 2013 1:19 pm
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Posted: Thu Mar 28, 2013 1:19 pm
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Same DIY Minolta MD speed booster with Novoflex 600/F8 (handheld through a window!)
It does work much better with slow lenses than with fast lenses Smile




(I had to crop a very little as the lens hasn't enough coverage)


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Posted: Thu Apr 18, 2013 7:00 am
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Posted: Thu Apr 18, 2013 7:00 am
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ForenSeil wrote:

I wonder if reversed achromats can be also used as focal reducer!?[/b] Basically a focal reducer is not much more than a loupe, right?

Yes, they can. You can count the power of the achromat needed to obtain a new focal length from an old focal length with the formula:
achromat diopters = (1 /new focal length in m.) - (1/old focal length in m.).
The register distance of the lens is reduced accordingly.
More achromats can be used in stack and using more achromats of low power is, in theory, better then one of great power (less spherical aberrations).

I did some tests with acheomats in my attempts to adapt some medium/large format lenses to Sony-NEX.
Here are some tests with 150mm f/4 Mamiya SF lens (for Mamiya RB) with 2 Leica Elpro achromats, one in front of it and one behind. The achromats combined power is +6,5 Diopters and the lens becomes a 75mm f/2 - very convenient as a portret lens on APS-C or FF.
The lens is a soft focus (one of the best ever, in my opinion) and its overall character is very much preserved.
Test samples are at f/4 and f/8 (or f/2 and f/4 in terms of the lens it becomes) on the 24mpx sensor of the Sony NEX-7.
From f/4 to f/8 the lens is a soft focus and from f/8 it becomes a normal lens. This behavior is preserved when using it with achromats.

At f/4 (f/2) - behaves as a soft focus (maximum softeness) :


and the 100% detail:



At f/8(f/4) - behaves as a normal lens:


central 100% detail:

corner 100% detail:


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Posted: Thu Apr 18, 2013 4:04 pm
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Posted: Thu Apr 18, 2013 4:04 pm
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hmmm really good results at F8 (F4) sharpness is superb


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Posted: Sat Apr 20, 2013 8:41 am
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Posted: Sat Apr 20, 2013 8:41 am
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Awesome work!! I am very very tempted to try something like this myself although I would be happy to get a slightly more modest focal length reduction X.7
there is one model of 2" focal reducer available on Ebay by the brand "antares" for ~$90 worth a shot?


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Posted: Sun Apr 21, 2013 6:12 pm
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Posted: Sun Apr 21, 2013 6:12 pm
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Probably is better to wait a little because the cheaper Chinese Speed Booster, named Lens Turbo, will be shipping in May according to this:
http://www.43rumors.com/rumor-is-correct-cheap-seepd-booster-alternative-exists/
Hopefully it will be the real "poor man Speed Booster".


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Posted: Wed Apr 24, 2013 5:55 pm
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Posted: Wed Apr 24, 2013 5:55 pm
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....oldlenses.blogspot.ca/....talks a little bit about the chinese version


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Posted: Sat Aug 24, 2013 2:34 am
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Posted: Sat Aug 24, 2013 2:34 am
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dan_, you did some amazing work with this lens and just the thing I was thinking about soft focus with a focal reducer. Color me impressed and tel us more.


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Posted: Sat Aug 24, 2013 8:03 pm
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Posted: Sat Aug 24, 2013 8:03 pm
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randreev wrote:
dan_, you did some amazing work with this lens and just the thing I was thinking about soft focus with a focal reducer. Color me impressed and tel us more.

Thank you randreev.
As I don't want to hijack ForenSeil topic my answer will be brief. I have extracted the front and back lens blocks of the Mamiya 150mm SF(which is huge and very heavy) and remounted them in a much smaller and lighter special lathe-made barrel to which I added at the correct central position an old multi-petals diaphragm, the front and back achromats and a focusing helicoid. It works very nice like that as a soft focus lens but I left the work unfinished because I intend to buy soon a Speed Booster (for my Leica R lenses) and see if it doesn't work even better with it and only a front (or back) achromat (to get the 0.5 reduction factor).
When it would be finished I'll present it in a new topic here because I really think this Mamiya RB lens is one of the best SF ever.


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Posted: Wed Aug 28, 2013 7:23 am
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Posted: Wed Aug 28, 2013 7:23 am
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Amazing ingenuity!


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Posted: Mon Sep 09, 2013 1:26 pm
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Posted: Mon Sep 09, 2013 1:26 pm
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dan_ wrote:
Probably is better to wait a little because the cheaper Chinese Speed Booster, named Lens Turbo, will be shipping in May according to this:

Hopefully it will be the real "poor man Speed Booster".


Any more progress? I'm very interested in the added compression from focal reducing a longer medium format lens.


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Posted: Mon Aug 21, 2017 11:17 pm
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Posted: Mon Aug 21, 2017 11:17 pm
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Some years later, Im going the same way... still wondering how to step down M48x0.75 to M42x1... (because of the M42 AF confirm adapters I have). No solution for sale, too... Kipon has m48x0.75 to EOS, but no AF confirm...

Added: Purchased 42x1 male to 52x1 female step up, will glue to the booster bast´r
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