Thursday, October 30, 2014

C-Mount Lenses for MFT Cameras

This topic can be found online all over the place. Cheap and cheerful C-mount video lenses on micro-4/3 (MFT) systems. In particular BMPCC users seem t love those lenses.
Some months ago, I bought my first C-mount lens, a 25mm f/1.4, which was fun to play with for a day, but quickly found its way in the bag to stay there.

Recently, I came across 2 more lenses which caught my attention, ad 16mm f/1.6 and a 35mm f/1.7.

Here is a photo of my C-mount lenses, the MFT adapter and 2 macro-rings, which came with the 35mm lens.
16mm, 25mm and 35mm lenses, respective adapter and macro-rings

The 35mm Fujian immediately became my favorite. The 70mm equivalent fast glass makes a beautiful portrait lens! At f/1.7, the aperture is perfectly round, creating wonderful Bokeh-balls. Down to f/4, the aperture stay reasonably round. At f/5.6 a slight zig-zagy-ness crawls in, which stay down to f/16, which is the official end of the scale. However, the lens can be stopped down further, with the aperture getting more and more rectangular.
The adaptation of the Fujian, using the adapter ring shown above, was no problem at all. Actually, the moves beyond the infinity focus.

The 25mm I did discuss previously on this blog, so I will skip this particular lens here.

Finally, the 16mm Cosmicar... Honestly, I had my issues with this lens!
It is clearly visible from the image above, the Comsicar is the biggest of them all. Not sure why the lens was build that way, since the front-element is hidden deeply inside the huge lens-hood.
Using the shown adapter, the Cosmicar could be focused on extremely proximate objects only, meaning, it did not screw all the way into the adapter, I figure.
At this point in time, I thought I just wasted €20, made my peace with it a put the lens aside.
For an unapparent reason, I picked the thing up again and had a look if it could not be modified (to serve whatever purpose... e.g. put in front of a webcam, for long-exposure astro-stuff.
When looking at the back of the lens, it seems that the rear lens group can be unscrewed. There is not actual image of the unscrewed lens group, sorry! The process of unscrewing the group took a long way, which gave me the idea, that the group could be fixed at a place where the lens would focus on my MFT sensor. After some trial and error, I found the infinity focus position.
For the time being, said infinity focus position is fixed by small stripes of gaffer's tape stuffed in the threads.
Cosmicar 16mm f/1.6 with displaced rear lens group
Of course, I could have dropped in a bit of Loctite, to secure the position... however, I am not yet sure if I want things to be like this, hence, I decided for a temporary solution.
Optically, and in terms of handling, the lens is fine. The equivalent 32mm are too short for comfort, however. The lens shows black vignetting, indicating that the image is too small for the sensor.
Olympus added a "digital tele-converter" function to their E-PM2, which I used for the tests. Here, the lens displays a decently flat image over the entire frame. When shooting in RAW, this does not help at all, in contrast to shooting video.
The Cosmicar being a very smooth lens what controls are concerned, will probably be the best of the bunch for video work, provided Olympus' digital tele-converter is used.
For use with the BMPCC, which is provided with a smaller sensor, this lens my just be the hero... the 20 bucks hero that is.

Poppy-Uppy Flash Mini Soft Box

Lately, I have been asked by some friends, why the flash of their compact camera creates such "crappy" images. Assuming that the problem was flat images with lots of hard shadows and a cold color cast, my answer was always the same: the tiny built-in flash-tube create really hard light.
Hard light, i.e. light that comes from a light source being (much) smaller than the subject, creates a flat appearance and pretty harsh shadows in the background.
Using the built-in, is therefore only good for "fill flash" when shooting in bright (sun) back light.

There are a very simple solutions to make most of the flashes useable, even with the tiny flash being the only light source.
  1. diffuse the flash
  2. redirect the flash
  3. tone the flash
  4. redirect the flash with a tone
Options 1 and 2 are obviously referring to making the light softer, which cannot be corrected in post processing, while options 3 and 4 are just an added bonus, and can be added in post.

Options 1, 2 and 4 can easily be achieved by a very simple device... a translucent film canister.

the translucent canister

One simply has to create a template of the cross-section of the poppy-uppy flash's footprint and create a corresponding cut-out in the canister. The cut-out should actually be a bit wider, so that the canister can lean a bit to the front of the camera.
Somewhat like this:

template and modified canister

Going from here, the optional reflector can be created. I experimented a bit with the dimensions of said reflector. And here is my solution:
  • length: 43mm (fitting the canister lengthwise)
  • width: 23mm (creating a 45-ish degree angle)
the internal reflector

The reflector inserted into the "soft box" looks somewhat like this (red side up):

the internal reflector inserted into the soft box

And there are some of the resulting images, showing one of my messy book shelves. The LX7 was on aperture priority f/2.8 @ ISO1600:

reference shot, bare built-in flash
diffuser (no internal reflector)
white side of the internal reflector
red side of the internal reflector
The difference might be hard to see on the given examples, in particular since blogger will "improve" the photos again, I fear.

An assortment of different reflectors, such as different colors, aluminum foil, etc. can make the mini soft box really useful.

Enjoy photography!

The original design gave a lot of spill towards the back of the camera. To keep this a bit under control, I attached aluminum tape to the inner backside of the canister,  such that is directed more towards the upper front.

Saturday, October 25, 2014

Updated Chardonnol Recipe

Presently, the C41 film is drying.
So far, results look OK, still a little faint though.
I overexposed the film by 2 stops...

Right, here is the recipe:
1/4l Chardonnay
1 tsp ascorbic acid
3/2 tsp soda

I developed for 20 minutes, with agitation ever minute.

As soon as the film is dry, I will scan images and present those here.

Thursday, October 16, 2014

Mechanical Cameras (chemical that is)

Some time ago, I got myself a collection of 4 "untested" (i.e. defect) vintage cameras for real cheap from a world renowned auction site.

The jewel of the collection was a Minolta A5, with a jammed shutter (blocking the film advance lever). I slowly pealed the layers off that thing, and like an onion, it presented the guts, ever so slowly. Finally, I got the lens barrel holding the shutter mechanism separated from the rest. Some tweaking even got the shutter back to work... However, to the present day, I was unable to reassemble this particular camera.
Main problem: I can't get the lens back into the threaded mount. Potentially this camera is a total loss :-(

Second in place was an Argus C3. This camera had a problem with the cocking mechanism, which opened the shutter incidentally. Not good, that for sure. Also the tripod mount was fill with a broken off screw, which is not good either.
The quick fix for the shutter cocking mechanism was to tighten up the shutter release and fix it in the timed position. OK, now, the bulb mode is gone ... but what is a bulb mode good for, if you can't use a tripod? Mind you, the broken screw in the tripod mount.

In third place, a Fujica Half. Actually, this camera was the main driver to place a bid! Again, the shutter was jammed, blocking the film advance lever, similar to the Minolta A5.
Seems that fixes are much simpler with the Fujica. Carefully removing the black rubber, the front-plate of the camera, which is held by 4 screw only, can be easily removed. W/o the front cover, the shutter release mechanism is exposed. Upon wiggling said release a bit, it loosened up and finally released, allowing for cranking the shutter.
The Fujica Half is back in business! Even the automatic exposure stuff seems to work.

The forth and final camera in the bundle was some cassette film plastic thingy not worth any further mention....

At the end, 2 out of 4 cameras a working fine. A third may potentially be rescued, although, I doubt if there is any incentive to rescue this particular Minolta A5 over just trying to get a working one for cheap.

Long live 135 film!