#camdiox

It turned out that the end of the day was really nice for photography, with some nice light and clear sky. I also got a couple of pictures inside Kings Cross station which has been completely re-built since the last time I went into London.

I’ve post-processed these in Lightroom using my usual steps

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Clock on the mantlepiece

The bookcase

Oil lamp

Golden shread tin

Planes

Music on the Piano

A bowl of flowers

Emma tinkling on the piano

Composing a chapter

Blacksmiths tools

The apothacary’s room

Toy boats

The gunsmiths toolbox

The baker

Waiting for the bread to rise

The bakers

Provisions

Provisions

Spinning some wool

Wool waiting for weaving

The jesters cap

The pictures above are all ones which I feel were helped by using the manual lens kit I took with me rather than a standard kit zoom.

Each of these pictures was taken a with one of the manual lenses I listed in my original post and the thing which was most affected by that was, surprisingly enough, the focus. For all of these pictures I feel the focus had been nailed and that’s something which I haven’t been able to say reliably for a long time using my Pentax and the autofocus lenses I’ve been used to using. Of the 1000 odd photos I’ve taken in the last week only about 5 are not focused exactly on the subject I wanted. If I were to rely on the autofocus on my Pentax I would be lucky if I could count less that 30. Of course it could be that the Pentax is not a good autofocus camera, and I know a lot of canon and nikon shooters say their brand is particularly good, but I would suggest any photographer would be pleased with 5 poorly focused shots out of 1000.

These pictures are all predominantly indoor shots. Normally with my Pentax this is the sort of shot where it is normal to find the camera hunting around as it tries to get focus at probably f/3.5 or f/4. Also the autofocus would often lock on to a part of the picture which is not the main subject I’m interested in. Using manual focus I’ve been able to choose exactly the area I want and focus it precisely. The majority of these shots were taken with a Soligor 28mm f/2.8 or Takumar 28mm f/3.5 (fitted to a camdiox wide angle adapter which adds a stop approx so probably f/2.8 also) but the real killer feature has been the focus peaking of the nex. With the focus peaking on and using the viewfinder I’ve been much more successful than I’ve been in the past relying on autofocus.

I have to also comment on the optical quality of these lenses. I feel they have been outstanding and some of the images above are really well defined, contrasty images. The particular lens I would say which has really stood out for me has been the Soligor 28mm which I always felt was the weakest of the bunch but has actually turned out to be a star. I’m definitely on the look out for some more examples of Soligor C/D lenses now.

The other advantage of using faster lenses of course has been the greater depth of field available, and although there are only a couple of shots above that show it, there have been several times over the last week where I’ve got some nice blur to really make a subject stand out. It goes almost without saying that the extra couple of stops that the faster lenses have afforded has resulted in cleaner images because that has been directly related to a lower iso.

I think the only thing which has been a negative really has been the more frequent lens changes necessary. This has probably (certainly actually) been a contributing factor to getting a dust spot on the sensor very early in our trip which resulted in trying to shoot everything below f/8 to minimize the amount the spot shows up, but all in all when I balance up the fact that I have had less weight to carry around it’s not such a big deal. I’m also happy to say that the lens change recording technique which I worked out before I left worked out really well and I have managed to tag all the images with the lens used for the picture. I’m going to use a small lightroom plugin to convert these tags to exif image data.

Ickworth House in Suffolk

Today we spent a day at Ickworth House in Suffolk which is a National Trust property and I took a series of pictures with my Takumar prime lenses in preparation for out holiday when I intend to only use fixed focal length prime lenses.

It was quite a cold day, although dry and I set out with the full compliment of lenses. Since we were away all day, I’ve not had time to…

Bike rack in Stevenage

The walkway by the railway line

Stevenage town centre

Stevenage town centre

Cottered in Hertfordshire

Cottered in Hertfordshire

Cottered church

Cottered church

Cottered in Hertfordshire

Cottered in Hertfordshire

Cottered in Hertfordshire

This is the only time I’ve come across the famous ‘blue spot’ and I had to shoot directly into the sun to get it.

In this post I’m going to review my reasons for purchasing a focal reducer and give my assessment of the performance of the Camdiox unit.

What is a focal reducer?

When I was a teenager (quite a few years ago now I’m sorry to say) I used to own an add-on lens called a tele-convertor which fitted behind any lens on my Zenit B slr and doubled the focal length of the lens. I used it with an inexpensive telephoto lens to try to take pictures of birds feeding in our garden but it was less than successful because the unit was very cheap, (I believe it was a prinzflex which was sold in Dixons at the time) and the images had huge amounts of purple fringing. Also the tele-convertor reduced the amount of light reaching the film because the image projected by the lens was much bigger, so the shutter speed had to be reduced to compensate, leading to much more chance of blurry images.

What does all this have to do with a focal reducer? Well a focal reducer is the opposite of a tele-convertor, in fact a more accurate name might be a wide-angle convertor. Instead of a magnification of 2x, a focal reducer typically has a magnification of around 0.7x which makes the image circle projected by the lens smaller and therefore increases the view angle of the camera. Although this would have been possible years ago there had not been a market for such a product before because on a film camera this would have resulted in the image projected by the lens being smaller that the film frame ie very severe vignetting. The reason it is available and popular now is the result of the change to crop sensor cameras with no mirror box like the Sony Nex and Fuji X-E1 etc.

Because mirror-less cameras have a much shorter distance between the sensor and the back of the lens (the registration distance), it’s possible to fit older, classic SLR lenses to them with an adaptor. Many photographers have these lenses from their 35mm film days, and others are discovering what gems are available for only a few pounds. Obviously, the automatic functions of the camera such as auto-focus won’t work and the lenses have to have the aperture set with the adjustment ring on the lens rather than the dial on the camera, but many people look on this as a nostalgic advantage! With these lenses fitted to an APS-C camera it’s possible to take great pictures, but the lenses will always have the crop factor of the lens applied and so will appear to be longer that they actually are.

This is where the focal reducer comes into play. With a magnification of 0.7 or so the lens will be brought back to something close to the ‘real’ focal length of the lens. How does this work? Well as an example suppose I’m shooting with a classic 50mm lens. On my nex 6 I would need to apply the crop factor of the lens so my 50mm would give the same angle of view as a lens of 50 x 1.5 on a 35mm film camera. This makes my pictures look like I’ve taken them with a 75mm short telephoto lens. If I now fit a focal reducer however, I will have an effective focal length of 50 x 1.5 x 0.7 which is 52.5mm so I’m just about back to my 50mm! The focal reducer has removed the crop factor of the sensor.

There is another advantage to this as well. Since the aperture is just the focal length of the lens divided by the opening in the front of the lens, because the focal length has been reduced the aperture has increased! Now when I first heard this I assumed this was some mathematical calculation and didn’t actually make a difference in real life – but I was wrong. There is actually more light reaching the sensor and any exposure you make will be able to have a faster shutter speed or lower iso as a result. This is because all the light is now falling on the sensor rather than some of it being wasted outside the dimensions of the sensor.

This second effect is the reason the best know of these devices is also known as the speed booster – there is an effective boost in the speed of the sensor.

So this device is a way of getting some great old 35mm film lenses back to their original focal length, restoring a wide angle view, and getting a slightly faster lens into the bargain.

Reasons for purchase

So the last sentence above gives a pretty good indication of why I decided to buy one of these devices – now we come to why I bought the unit I did.

The first focal reducer available, the one which gave the idea the name ‘speed booster’ is the Metabones Speedbooster. This is the first unit I considered because it has been fully reviewed and has a solid reputation. However it is also the most expensive unit at something like $600 (about £370 + postage), and I couldn’t easily find one for sale in the UK.

The next unit I considered is called ‘Lens Turbo’ and is made in China by a company called Mitakon. These are a more attractive price range at about £130 and I could get one with UK delivery, but only in M42 mount. Now, M42 would be a useful mount to get, but I do have some K mount lenses which are designed for full frame cameras so it would make sense to get a unit which would also allow K mount lenses to be fitted.

It was at this point that I decided to do a bit of research into the most adaptable unit to get. I know it isn’t possible to get a K Mount to M42 adapter, at least not a K mount lens to M42 body, so I thought about getting a K mount unit. This would allow me to fit K and M42 lenses but after a bit more research it found that the most adaptable mount is actually the Canon EOS mount.

It’s possible to get cheap metal mount adapters to both K mount and M42 to EOS. These are simple metal ring adapters without glass elements and some quick research suggests it should be possible to get similar adapters for Olympus OM and Nikon which would also open the possibility of fitting other lenses.

So I decided to get an EOS to Sony Nex focal reducer and tried to find one with UK delivery. The one unit I could find is made by Camdiox, so that is the unit I ordered.

Now the obvious question, bearing in mind my problems with a cheap tele-convertor, is why not go for the best unit available since this is going to fit behind a top quality lens?

Well there are several reasons :

Another supposed advantage of these units is that they are meant to increase image sharpness because of the way they compress the number of lines of detail in the sensor area. I’m not sure that I believe that, but I will find out more when I do the review section of this post.

I think the Metabones unit is too expensive. To have the unit delivered to the UK would cost almost the price of another Nex 6 body and that is simply too much.

Another big reason not to spend excessively is that my only real world use case for this device is to restore my wide angle lenses to a wide angle view. I wouldn’t use a focal reducer on a 50mm lens for example; I’d use a 35mm lens and use the crop factor to give me an equivalent of 52.5mm.

I’ve had my Nex 6 for about 2 months now and I’ve been hugely impressed with it. So much so that I can see my next upgrade path will obviously be to a Sony A7 full frame or the camera which replaces it. If that happens I can still use all my manual lenses and they will have their original focal length anyway, so I will have no need for this unit.

The last reason more than any meant that I didn’t want to spend £300 – £400 and so I settled on what I thought was a Chinese copy which I could get from the uk. I suspect there isn’t a lot to choose between any of the copy units so decided I might as well give the one I found a go.

Description of unit

Camdiox unit with box

Eos Mount

Nex mount

Optical Element

Eos mount release pin

Side view of unit

However it turned out that the last sentence above is actually untrue – the Camdiox unit I bought is actually made in Germany not in China. Just after I placed the order I received a confirmation e-mail which listed the web site of http://www.roxsen.com so I’m not sure if this is made by Roxsen and sold by Camdiox or the other way round. One thing I can say it that the unit Roxsen sells looks very similar to the unit I eventually received.

I received the unit packaged in a small jiffy bag about 5 days after I placing the order on Ebay. Inside the bag the unit itself is supplied in a small round cardboard container with a push on lid. It looks fairly solid in construction and is supplied with plastic protectors fitted to both mounts.

The first impressions, which struck me when I first opened the box, were the size of the lens in the unit and its weight. For some reason I thought the lens element would be much smaller, although when I think about it that is a bit silly. The lens is about an inch across and has obvious coatings as it has purple/blue reflections when looked at an angle. I noticed the weight when I fitted the unit to the Nex 6 because it was noticeably heavier than with the nex – m42 adapter.

The unit fits to the Nex 6 with a solid click and there is no noticeable slack in the fitting. The lens also clicks nicely into place on the adapter so the whole combination feels pretty solid. The pin which releases the lens from the adapter wiggles about a bit, but that seems common with lens adapters as a whole, and it seems to work well to release the lens.

Adapter tests and sample shots

So now we come to the actual tests of the adapter for which I used my Takumar 28mm f/3.5. I used this lens chiefly because this is the lens which will be most typically fitted to the unit. The process I used is as follows.

I set up a still life arrangement in our conservatory and set the Nex on a tripod with the Takumar fitted via a standard nex-m42 adapter. I then took pictures in aperture priority at all the full stop apertures the lens offers with the iso set to 100. For the purpose of the tests I ignored my usual rule of only shooting in RAW and used Jpeg’s straight from the camera. These pictures are my ‘control group’ and are the best images I can expect from the camera and lens combination.

Next I replaced the nex-m42 adapter with the Camdiox adapter and shot another series of shots in aperture priority at all the same settings and with the iso still set to 100. These shots give the performance of the focal reducer. Obviously the angle of view will be different because the lens will be closer to it’s film setting of 28mm, so I also produced a series of crops in Lightroom which show how the adapter has affected the particular areas of the image we can compare.

Then I replaced the lens / adapter with the standard sony kit lens and set the focal length to 19mm which gives an effective focal length of about 28mm. This was to see if the takumar and focal reducer actually performed better than the kit lens (which is certainly something I’d like to know before I start shooting lots of images with it). A feature of the camera of course is that corrections are automatically applied to jpeg images when the kit lens is fitted, so those shots below will have those corrections applied.

The results of these sessions are shown below arranged in F stop order and I recommend that you look at them in full screen to draw your own conclusions of the tests.

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f/3.5 Takumar

f/3.5 Takumar + Camdiox

f/3.5 Takumar + Camdiox – crop

f/4 kit lens @ 19mm

f/5.6 Takumar

f/5.6 Takumar + Camdiox

f/5.6 Takumar + Camdiox – crop

f/5.6 kit lens @ 19mm

f/8 Takumar

f/8 Takumar + Camdiox

f/8 Takumar + Camdiox – crop

f/8 kit lens @ 19mm

f/11 Takumar

f/11 Takumar + Camdiox

f/11 Takumar + Camdiox – crop

f/11 kit lens @ 19mm

f/16 Takumar

f/16 Takumar + Camdiox

f/16 Takumar + Camdiox – crop

f/16 kit lens @ 19mm

Conclusions

So I come to my conclusions. Obviously you are able to make your own conclusions from the pictures I’ve supplied, but these are my findings:

Blurred/Softened corners - The Camdiox adapter has softened the corners of the pictures at the widest aperture of f/3.5 even within the cropped area shot however this is less noticable at f/5.6 and almost gone at f/8.0

Stop extra speed – The shots with the camdiox fitted do seem to generally be about a stop faster as measured by the shutter speed recorded.

Definition - When I look in detail in Lightroom at the shots it does seem to me that the center detail in the camdiox shots is slightly improved over the straight Takumar shots.

The kit lens seems to have produced a slightly warmer picture compared to the other images.

I think the camdiox is a pretty good performer for the £70 I paid. It certainly hasn’t blurred images to the point of making it unpleasant to use but obviously I’ve not yet explored it fully so I intend to use the takumar / camdiox combination over the next few days and give a fuller description of my findings with more real world examples in my next post.