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

Welcome to the forum. Your efforts sound really interesting, I would say very exciting.
Please keep us in the loop if possible.
Looks like cine lenses in PL mount with a flange distance of 52mm can be a good candidate for the 4/3 format.
BNCR is even longer.
 
Yes, hopeless_4ever please post the focal reducer you were using and the mounts that you used to get it to work. Any sample pics as of yet?
 
I used a Vixen 0.6x C-mount reducer. Funny enough, it never actually worked with my C-mount lenses. The rear fit into a C-mount just fine, but the front (female part) was made for 1.25" eyepieces. It might be good for astronomy and telescoping, but pretty useless for general photography. It was expensive too, something like $185 used if I remember correctly. I know there are cheaper reducers out there, but I bought this one thinking it will work with C-mount lenses, as the name implies. I was wrong. This reducer has been discontinued now and is almost impossible to find online.

I unscrewed the actual reducer from its original mount and put it through a regular C-mount to micro 4/3 adapter that I got off Ebay. I filed the adapter's opening to allow for the reducer's larger diameter. Then, I had to file the front and back "hoods" to get the optic closer to the sensor, and closer to the lens. It is all held in place by superglue. When mounted, it's a very tight fit; I really can't get the reducer any closer to the sensor without hitting something or getting it jammed.

Here is how it looks like:

jswreducer1.jpg




Today, I took a few test shots right after I came back from work. The sun was setting down, so the lighting was changing quickly. ISO800 for all pictures, camera set in P mode for automatic shutter selection. Because I'm still working on attaching a permanent Nikon mount to the reducer, the following pictures were taken holding the lens manually in front of the reducer. Any blur or flare you see is probably caused by me tilting the lens or not holding it steady enough; It was REALLY hard for me to keep my hands steady. There also seems to be some light pollution, causing lower contrast. I'm confident that these problems will not show when I finally attach a proper Nikon mount to the reducer. If there is anyone in Chicago area who wants to help me, please let me know!


The lens hood from the fisheye is always seen in the frame with the reducer on. It doesn't show on APS-C, which means that the coverage is slightly bigger than APS-C but definitely not full frame.
jswreducer2.jpg

jswreducer3.jpg



The flare seen in the photo with the reducer on is not common. I think it happened as a result of light coming in from the side as I was holding the lens by hand. When I try to seal off the combo to prevent straight light from coming in, I notice no flare and the contrast gets better too - but I needed a free hand to snap the picture!
jswreducer4.jpg

jswreducer5.jpg



For this last one, I was trying to test depth-of-field at equal focal length, so the photos were taken at different distances. Obviously, with the reducer on, I had to move the camera closer to get the same view.
jswreducer6.jpg

jswreducer7.jpg



I really hope to finish a proper housing for this combo soon. I have some old Nikon macro extenders that, when stacked, get pretty close to what I want, but still a few millimeters short of what I need for infinity focus. I wish I was a machinist... Haha.

Any suggestions or ideas?
 
Last edited:
You really have to read the whole thread to "get it" or understand what this is about. All of this is just an experiment to prove that it's POSSIBLE to use a focal reducer on a micro 4/3 camera. Actual photography results might not be great yet, but maybe someone out there can make something of better quality.

Anyway, I already asked people to hold judgement until I make a proper adapter. The pictures above were taken with the lens being held by hand, so there's all sorts of problems (focus shifts and stray light, in particular).
 
Round 2 focal reducer test

Round 2 focal reducer test

Hello everyone! Just like I promised, I finished my m4/3 focal reducer adapter. This is how it looks like:

m43reduceradapter.jpg


It fits my E-P1 like a glove to a hand! I calibrated it for infinity focus with Nikon lenses (actually, it goes past infinity, but only slightly). Image quality is *MUCH* better than before. No blur, no tilt/shift effects, no stray light pollution. Lens speed is increased, and it's pretty sharp for what it is, although contrast is slightly decreased. Here's a test I did last night... it was shot at ISO800 to avoid blur from my handshake, but I'll have some low-ISO shots soon for you guys:


ROKINON FISHEYE 8/3.5 NO REDUCER:​
ep1noreducer.jpg

OLYMPUS E-P1, F3.5, P MODE, -1.7 EV, ISO 800, 1/13 sec ​



ROKINON FISHEYE 8/3.5 WITH 0.6x REDUCER:​

The vignetting seen above is not from the reducer but the lens. The fisheye lens is DX format, made for Nikon's APS-C, so it creates a smaller circle than a lens designed for a full-frame would. If you remember from my previous post, there was a dark edge around the frame caused by the lens hood; I shaved off the hood to get more coverage for this test.

Here is a vignette test for this fisheye with the reducer: http://img822.imageshack.us/img822/5453/ep1reducerfisheyevignet.jpg
And here is a test with the same lens on full-frame (Canon 5D) and APS-H (Canon 1D) cameras: http://www.360pano.de/en/samyang_5D_1D.html

As you can see, the lens coverage with the 0.6x reducer is somewhere between APS-C and Canon's APS-H. This means that some of Nikon's DX lenses will vignette with this reducer.

I will provide more sample images soon :happy:
 
The extra fov isnt something you could use anyways, even if it was sharp, the distortion is too much, but maybe thats just your fisheye.
 
To widen FOV if you dont like crop factor of GH1 you can do yourself full frame FOV (with for example 50mm lens) so it will be like on 5D.You need biconvex lens on the rear of 50mm lens and move lens closer to the sensor, OR you need plano concave lens in front of the 50mm lens and move lens a bit away from the sensor.
I wouldnt do that on telephoto lenses tho cause sides are blurred ,but it depends of course on size of your biconvex or plano concave lens,it should match your prime lens so you would avoid chromatic aberration and softness.
You arent gaining light IMO, you also have deeper focus after this conversion and its not that shallow anymore,kinda like 35mm lens maybe a bit shallower if your 50mm is 1.8.
 
Last edited:
Does anybody know about an anamorphic focal reducer? Or an anamorphic lens small enough to be used between lens an sensor?

I ordered this x0.5 focal reducer with 2" diameter on Ebay - but shipping form the US will take 2-3 weeks :-(

Hopefully I will get something like hopeless_4ever together - looks pretty good. An additional test with a normal lens would be great hopless... ;-)

Cheers
 
Psyco said:
I ordered this x0.5 focal reducer with 2" diameter on Ebay
Click to expand...

I just ordered the same one last night, but for 1.25" instead of 2". My Vixen reducer is 1.25", so I decided to stay with that diameter as it seems to work well for micro 4/3 sensors. With your reducer, however, you *might* have to increase the distance from the sensor because I think 2" is made for SLRs with bigger sensors and longer flange distances, instead of CCD cameras. I might be wrong though! I went with Antares because I've read that it's pretty good quality, sharp edge-to-edge, and holds good contrast... and because it's 0.5x versus the 0.6x I currently have, so I want to see if I can get even more lens coverage.

This would be interesting if both of us could compare which reducer size works better for micro 4/3. Right now, I seem to be only one experimenting with this, so welcome to the club! :cheesy:

As for testing a normal lens, I really don't have any... The only other Nikon lenses I have besides the fisheye are: Nikkor 105/2.5, Sigma 30/1.4, Nikkor 43-86mm F3.5, and Nikkor 28/3.5. I've tried my friend's Nikkor 50/1.4D briefly and, while the reducer produces a wider image, it doesn't increase lens speed. The reducer only makes slow lenses faster. I think that the cutoff is around F2 or so... When I use my Sigma 30/1.4 lens, for example, the reducer widens coverage but the lens speed is the same, and optical quality is degraded. My sharp and contrasty Sigma 30/1.4, for example, turns into a dreamy soft-focus lens. I wish I could compare directly, but I think that the Nikkor 50/1.4 was sharper and held more contrast, so focal length might be a factor as well, 30mm versus 50mm. I don't think it's a good idea to use it on fast wide lenses...
 
My reducer still isn't here - aaarrghhhh!

I bought the 2" version, because normally lenses give the best picture from the centre part - with normal full frame lenses you don't need the 2", but maybe it just works a bit better.

I don't think it's a good idea to use it on fast wide lenses...
Click to expand...

I really hope you are wrong on that part.

Thats the whole purpose for me: I need a wide and fast lens for my GH13!

At the moment I just can't afford the pancake 1.7/20 or a Tokina 2.8/11-16, but I have nice old Minolta glas right here: Rokkor 1.4/50, Rokkor 1.8/35 and Kiron 2.0/24. If I could just use these lenses with there full frame FOV, I would be vary happy.

We will see - hopefully my focal reducer arrives next week...
 
Do not discount some of the wide angle adapters that can be attached at the front. Some of them deliver very good results, though there is no luminosity gain.
 
I have them all ;-)

At the moment I have some wide angle converters here to test:

- Raynox 0.66
- Tecpro 0.65s
- Century Precision Optics 0.65

These are the widest rectilinear (non-fisheye) converters out there.

All of them show rather bad distortion in picture corners if I use a fast lens (like 1.4/50 or 2.0/24).
It would be plan B for me, but if I can avoid an extra 500g in front of my lenses (they also weight about 400g), it would make things easyer.
 
You lump the Century in with the Raynox?

I find it to be quite good by comparison. (although nothing like clean glass without an adapter in front...)
 
I use a Celestron F6.3 Focal Reducer with my C9.25 , C6 XLT and Apex 127 5" Mak scopes to shoot HD video with my Pentax K-7 and plan on getting the GH2. I am sure I will be having fun with it since the video quality will be much better. Here is a photo of my F6.3 FR on my C9.25 that has a 2350mm FL @ F10 and 1480mm @F6.3.
IMGP2338-1.jpg


IMGP2366.jpg




IMGP2385-1.jpg


 
Last edited:
You must log in or register to reply here.
Back
Top