Focal Reducers - Squeeze all your FOV and Light on your GH1 Sensor

pix2pixels said:
From further reading, I gather that the NextGen 0.5 needs 55mm between the sensor and flange distancel to get 18mm an image circle where they are optimised for best image performance.
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300$ is a bit too expensive for the first test. And 18mm is a bit too small. But they are made for very long lenses - maybe the size of the image circle and the working distance is totaly different with our short lenses.

For serious tests we have to wait till the GH1 is available.
I think I can make a more or less hard mountable and adjustable ghetto reducer out of T2 rings and this adapter:
http://www.japanexposures.com/shop/product_info.php?products_id=262
 
Hopefully I will get in touch and speak to this local (oz) manufacturer and get more information, hope, or a cold shower.

As I mentioned before, just holding a 16mm lens in front of the adaptor, I could see a decent image as you did with yours. Wish I had a GH1 right here, right now.


There a discontinued Optec 0.5x available for ~$90.
 
MatzeB said:
Without the mirrorbox there should be enough space for an adapter.
I doubt it would be good enough for 12MP photos, but downscaled to 1080 or 720 it might look good.
Here is a quick test of a DIY compressor - just to show, that it should be possible. Looks like it's compressing ~0,7x or 0,8x
Don't judge image quality. It's only to show the effect.
Click to expand...

The distance afforded between Canon FD and µ4/3rds is a mere 22mms. For most focal reducers the critical spacing to maintain is at least 55mms between the sensor and the shoulder (or rear spacer, if required) of the focal reducer coupling. Each focal reducer has a set distance the element should be placed. For the Meade .33x focal reducer it's around 88mm, Optec 0.5 & Borg requires ~55mm. Astronomical image sensor cameras are not designed to a standard distance between the camera interface and imaging sensor, so to have these focal reducers work you will need to consider the spacing very carefully.

What might be easiest is a combination of a bellows system with multiple adapters that can accommodate the assortment of lenses and mounts (Horseman, Novoflex, etc). This way you can adjust the exact distance between the focal reducer and the sensor. A Nikon F-mount with a FFD of 46.5mm might be easier to adapt then a Canon FD, or maybe even Medium-format lenses (RB/RZ/645 etc.) or a PL.

Another thing, there are many ways to implement this beyond the astronomical focal reducers being discussed here. If you would remember the Nikon-Fuji E2/E3 used a similar system, except the focal reducer was aft of the where the sensor/film would be. The Kodak patent I showed previously in this thread was designed around the same time, to adapt 35mm full-frame lenses to smaller CCD sensors. What these companies figured out was that the negative impact of these focal reducers optically wasn't worth the added cost, and as APS-C & 4/3rds sensors started to be released it was more desirable to release lenses catered to those formats rather then implementing complex methods in reducing the image circle on existing lenses.

With that said, I'd be very interested in seeing what results you achieve with your endeavors. . .

FujixE2Smdm.jpg

opticalillus.jpg
 
Thanks Steve for these insights. I've never heard of the E2/E3 before.
From a commercial point of view it makes not sense to hassle with a converter and have a bucket full of compatibility issues when you can sell new lenses or larger sensors.
This is a pure DIY project. It's quite probable that the results will be disappointing. But maybe it rocks or at least give a certain "look".

I have a collection of FD lenses. Therefore I will try these first. But you're right it's easier with Nikon.
I thought about a bellows, but it's too long for a compact adapter. The T2-System is very versatile and I already own a couple of different rings.
 
There are at least a few professional broadcast reducers out there - thought no one that compresses a 35mm full frame 0,5x.

Vantage Film (Hawk Anamorphics) has two different 0,7x reducers for long lenses.
They gain 1 stop!
http://www.vantagefilm.com/en/news/index_12.shtml
http://www.vantagefilm.com/en/news/index_08.shtml

Abakus sells several different converters - even for c-mount.
http://www.abakus.co.uk/Format_Converters.htm

A suitable converter would be 1000$ minimum from these companies. Probably alot more.


Steven Mogg ( http://moggadapters.com/astro/adapter.asp ) sells inexpensive focal reducers and custom SLR-mount adapters.
@pixel2pixel is that the Oz manufacturer you've mentioned?
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This is how Kubrick managed to shoot Barry Lyndon with Candle light with a Zeiss F.07 50mm lens. it was a Fast medium Format lens with this contraption on the back. the problme was the camera had to be modified to move the film plane because the real element was only a few mm away from the gate..... ti does work... watch barry lyndon.
 
MatzeB said:
Steven Mogg ( http://moggadapters.com/astro/adapter.asp ) sells inexpensive focal reducers and custom SLR-mount adapters.
@pixel2pixel is that the Oz manufacturer you've mentioned?
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Click to expand...


Yes,

Unfortunately, all my attempts to contact him via email were not successful to date. Still hope to get in touch with him. His expertise and advice would be great.

Looking at Hawk adapters, it seems that the long lenses are suitable to be dealt with. It's worth looking into it to see what would the shortest focal length acceptable.
 
He's flogging a DSLR focal reducer for 75 bucks.

If anyone can give me an extra stop without too much degradation I'm all ears and shallow pockets.
 
squig think about an anamorphic reducer...
the wide field is already there on full frame lenses.
You just have to squeeze it.
 
Hasselblad Lenses?

Hasselblad Lenses?

If there is not enough place why not use a medium format lens, the focal flange distance with those is way longer because of the larger film and mirrorbox...

Just my 2 eurocents:)


Matthias
 
yeah it could be easier, but you have to compress them stronger.
something about 0,25x - 4 stops gain.
A 50mm f4,0 Flektogon would become a 12,5mm f1,0.
I don't know if such a strong compression is possible.
 
No - I don't think so.

You get lower f-stops. That could give you shallower DOF.
But if there's enough light it's probably better to stop the lens down.
 
extremely interesting thread :)

Matze ::thumbup:

ick komm nach Berlin in 2-3 Wochen, können wir uns mal kurzschliessen???
 
Just fo the record:

I´m using medium format Zeiss primes on my LEX.
They behave exactly what the numbers say.

Like a 80mm medium format looks like a 80mm 35mm lens.
Same DOF and FOV.

But of course the collect a much bigger circle than the GG can show.
A stronger condenser or a bigger gg would do the trick.
I would prefer a biger GG thou because of the grain.
I could zoom out much more and maybe the grain would vanish at all without spinning or vibrating the GG.

An anamorphic reducer would be the cream thou.

Frank
 
Postmaster said:
Just fo the record:

I´m using medium format Zeiss primes on my LEX.
They behave exactly what the numbers say.

Like a 80mm medium format looks like a 80mm 35mm lens.
Same DOF and FOV.

But of course the collect a much bigger circle than the GG can show.
A stronger condenser or a bigger gg would do the trick.
I would prefer a biger GG thou because of the grain.
I could zoom out much more and maybe the grain would vanish at all without spinning or vibrating the GG.

An anamorphic reducer would be the cream thou.

Frank
Click to expand...

perhaps im misunderstanding... do you have a focal reducer on your medium format lenses? because a 80mm would look like a 105 or 110 on a 35mm Film plane.
 
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