In search for: Speedbooster SUBSTITUTE

[Pancolart]

Assuming this is a correct formula (found on Ebay):


And this is Helios scheme:


One could hope to find a low priced (under 50 EUR) lens including the Important part . Any ideas?

[std]

So you are looking for cheap helios?

[Pancolart]

No. For a lens that already "includes" Speedbooster as part of it's design. So i could harvest it. Might be some zoom's rear.

[simbon4o]

I think you actually need wide angle convertor.

[iangreenhalgh1]

Yup, that diagram does look like a wide angle converter.

They are usually way too large to fit behind a lens and most of them reduce IQ quite a lot.

Even if you could harvest something, all you'd end up doing is making a neat device for ruining the IQ of lenses.

[buerokratiehasser]

I dunno, this thing is an anti-teleconverter right?

Can't you simply use a contraption that doesn't stack up to flange distance (with 4/3 etc.)
Like, i got exakta to m39 thingie here..

you will lose the short end (infinity at 3 m or so) but who cares? (okay. people who want these crazy UWW shots with three feet distance do care)

[nukemall]

Simple focal reducer is just strong positive lens. You can try +5 - +10 acromatic macro close-up lens(two +5 lenses = +10).

[nukemall]

Reduction factor(R) of the reducer is a function of the focal length (FR) of the reducer and its distance (D) from the camera’s focal plane:

R=1-D/FR

Focal length of +10 lens is 1000/10=100mm (+5 lens - 1000/5=200mm).
So if you place +10 lens at 20mm from the focal plane it will be 1-20/100=0.8X focal reducer.

[ForenSeil]

A speed booster is nothing more than a good corrected loupe!(!!!)
Hold a loupe in front of your sensor and you will see how simple it works - it makes the sensor looking larger / expandig the sensor optically. (Exactly the opposite of what a teleconverter is doing - it makes the sensor looking smaller)

I would try any decent well corrected close-ups lenses (Raynox etc.) instead of lens parts.
The Helios 44 rear part won't work at all, it's too "specialised" - I guess it will give you small coverage and heavy abberation.

Have you seen this thread http://forum.mflenses.com/poor-mans-diy-speed-booster-t57639,highlight,%2Bdiy.html ?

[dan_]

nukemall and ForenSeil pointed it out very well.
I did tested quality achromats as focal reducers, not to substitute the Speed Booster but to adapt some MF/LF lenses of a focal length of 80-150 mm. to my Sony NEX with a greater reducing factor then x0.7 (~x0.5).
My unscientific conclusions are:
- you get 1-2 f-stops increase in luminosity;
- you get very good central resolution (probably a little increase in central resolution);
- chromatic aberrations are acceptable;
- corner resolution degrades a little. The degradation is proportional with the power of the achromats used. For a power of less then +5D it is acceptable in most real life situations (but not for sharp infinity landscapes, architecture, etc!);.
- spherical aberrations are increasing to corners. More low power achromats are better then a single powerful one. Circles became ellipses as getting closer to the corners. Again, at a power of less then +5D (with 2 achromats of lower power) it is acceptable in most real life situations (and again, not for infinity landscapes, architecture, etc!).

The setup can be successfully used for portraits, close-ups and whenever you want to separate the subject from the background and corners are not so important.
It may be not acceptable for landscapes, architecture, flat objects and whenever the sharpness in corners and geometrical precision are very important.

Considering the financial point of view such a project is hardly feasible. You'll have to pay for the quality achromatic lenses, for adapters, for modifying the adapters to the new register distance (diminished by the achromats), for special rings to mount the achromats in the adapter. The final cost makes the Chinese Lens Turbo very appealing (considering that it is much better corrected).

For my MF/LF lenses I think the best solution is to use a Lens Turbo + low power achromats (better front mounted, for simplicity) in order to get a ~x0.5 reducing factor.

[Pancolart]

Question: wouldn't optimal speed-booster had to be VARIO? I was thinking different scheme & distances (in-between elements and lens to sensor) would be required if you boost tele or ultra wide lens? What do you think?

[calvin83]

[kuuan]

[iangreenhalgh1]

It's a lot of money just to shoot wide open with reduced IQ.

If this was such a good idea, why hasn't Leica or Zeiss or one of the major Japanese makers made something like this?

Cheap Chinese glass is bound to just make all your lenses look like cheap Chinese glass, we've seen what the cheap Canon FD-EOS adapters with glass do to the IQ of lenses. They aren't making these to be as good as they can be, but as cheap as they can be.

Faster but worse, that's a poisoned chalice if ever I saw one.

[calvin83]

I think some people will use it for wide angle resize on web while some other use it on standard/tele lens for portrait to gain soft effect and DOF. It is just a tool for those who need the benefit and can stand for the drawbacks.

[kuuan]

To use my SLR lenses close to the view they had been designed for on a small NEX is just too compelling, and the reducer makes the package even smaller than with a normal adapter.
Reports say and show that center resolution might even be improved and I don't give a damn about degraded corners, won't use a reducer for landscape or architecture shots where that might play a role.

[calvin83]

[eno789]

[philslizzy]

[kuuan]

and thinking of it, using the 'lens turbo' will mean not having to clean the sensor of my NEX all that often any more

[fermy]

It's interesting to note though that diagrams for Speedbooster and Lens-Turbo are very different.
Speed booster:

Lens Turbo:


The first reports on Lens Turbo are quite mixed though, more so than on speedbooster.