Friday, 15 September 2017

Manual focus adapter problems

Nothing serious, but, on two occasions now, and with different types of adapter, I've had the flange that mates with the lens become loose from the body of the adapter. As might be expected, this results in out of focus shots, and that's the way that I have been able to identify the problem. Unfortunately this also means some spoiled images.

I now carry a small precision Phillips screwdriver that I can use to tighten the fixing screws. I guess a drop of loctite would provide a more permanent solution.

Wednesday, 9 August 2017

Sony NEX 6 death throes

It had been threatening for some time, with a tendency to automatically click through the menus - cured by rotating the top control wheels a few times, probably dirty contacts. Now, however, a more sinister fault has appeared the dreaded "Camera error. Turn power off then on."

Searching on the Internet this appears to be a fairly common fault and may be related to a small spring attached to the shutter mechanism. The cure would probably cost more than my battered camera is worth, but a get by fix is to switch off the Front Shutter Curtain. It clatters when used, but it works a bit.

The camera did well to survive as long as it did under adverse circumstances. I've taken many thousands of shots and it has been carried around on a bicycle, dropped and generally not looked after. The paint has long gone on the corners and the strap looks ready to snap. It did have the good sense to continue working until I had invested in a new Sony a6500.

I've enjoyed the NEX 6 immensely,  I had become tired of lugging a heavy DSLR around my neck. The NEX freed me from the volume and mass of the DSLR while it allowed me to shoot using my old film era lenses, the excellent electronic view finder enabling easy and precise focus. I have always admired the compact and beautifully made Leica rangefinders, but they were way out of my price bracket. The NEX provided a similar shooting experience and I suspect that the Sony sensor was as least as good as that fitted to the more prestigious marque!

So it has more or less died. It has served me well and I have no regrets!

Tuesday, 23 May 2017

NEX 6 versus Sony a6500

I was interested to see how the sensors compared in the two cameras. Was it indeed possible to cram all those extra pixels into the a6500 sensor without losing quality?

I set up a simple test. Both camera were configured for ISO1600, with no exposure compensation, and I fitted a Zuiko 50mm f1.8 lens. I know from previous testing that this lens will blow the standard Sony zoom out of the water, as far as the resolution of detail is concerned. The camera was mounted on a sturdy Manfrotto tripod and a 2 second delay selected. I focused with the lens wide open and at maximum viewfinder magnification, but the shooting took place at f8. Two shots were taken with each camera and the best selected for comparison - actually that was the difficult part as each of the two images taken by each camera looked to be pretty much identical.

I let the camera decide the exposure, choosing aperture priority.

The view is one within my untidy garage, and the lighting supplied by overhead fluorescent tubes. The door was open so there was also a touch of ambient light, but the predominant illumination came from the fluorescent tubes.

The a6500 chose to use 1/25th sec and the NEX 6 1/40th sec.  The histograms were quite different, with the NEX underexposing slightly and the a6500 getting it spot on.

I processed the RAW files using LR and the default setup without any further adjustment, creating 16 bit TIFFs in PS. Again no adjustments were made in producing JPGs from the TIFF files.

This is the overall view (not pretty)

and here are a couple of crops, first the NEX 6

then the a6500

Click on any image for an enlarged view, the crops are 100% pixels.

The a6500 is recording more detail without, in my view, incurring a greater noise penalty. Look in particular at the detail in the cloth, although that may be a result of the longer a6500 exposure.

To get a better idea of the noise performance of the two cameras I have selected a couple of crops showing less detailed areas of plain tone.

First the NEX 6

Then the a6500

The a6500 image looks cleaner to me.

Something else I should perhaps mention, the contrast detect feature on the a6500 was usable at maximum viewfinder magnification whereas it was not on the NEX 6.

You can't read too much into this simple comparison, but, for what it's worth, the a6500 sensor does appear to come out the stronger, you get both more detail and less noise. (Oh, and before you ask, the Acetone is used to make repairs to the ABS components of my caravan, ABS is dissolved in Acetone, so you can make up a repair solution using, for example, Lego bricks.)


Thursday, 18 May 2017

Sigma lens - Dodgy Contacts

I've had trouble with my Sigma 19 mm lens not responding when attached to my Sony mirrorless cameras. I was concerned that this was a warning of imminent failure, but, to date, cleaning the contacts has cured the problem.

I've tried cotton buds and that appeared to do the trick for a while, but after the latest episode of non response, this was not enough.

As a measure of last resort, I used the buds in conjunction with some Eclipse E2 sensor cleaning fluid. This worked, and saved me the cost of a new lens - I believe that Sigma regards these budget lenses as being disposable, and don't offer a repair service ( please correct me if that is wrong!).

Tuesday, 11 April 2017

Sony a6500 - First thoughts

My long suffering NEX 6 has been showing signs of age, in particular there were times when the camera would start clicking through the menu options. This I have been able to fix by switching off and rotating the control dials, so it is probably caused by dirt on the contacts. It's a very intermittent fault, and most of the time the camera is just fine, despite having taken a humengous number (39433) of shots.

So it came to pass that I decided to add an a6500 to this year's tax allowance.

First impressions, it's a bit heavier than the NEX and the grip is more ergonomically shaped and protrudes more. I'm not too keen on the extra mass, but the grip is better.

The electronic viewfinder is very good indeed, I had thought that it might be the same as that used in the NEX 6, but, combined with the extra pixels on the sensor, this does appear to be an improvement. I am finding that, with contrast detect set at minimum, I can now accurately focus using that aid and with the lower 5.9 x viewfinder  magnification. I was never fully confident of contrast detect on the NEX6, but this camera appears to have raised its game in that respect.

However the apparent increased sensitivity of the contrast detect function sometimes means that, even at the minimum setting, the focused image is a mass of colour, making composition more difficult. It would be useful if contrast detect could be switched off when not using a magnified view. I have programmed a button (C3) to allow me to quickly change the contrast detect mode, but I'm not sure if I will be making much use of it!

Then there are the menus, an overwhelming array of choices, but, for heritage lens users, the camera now appears to default to release without lens. whereas previously you would need to set that parameter.

I like the fact that you can program a button (C1 in my case) to select the focal length in use, in body stabilisation is a real boon for users of old lenses. It's early days as yet, but IS brings a real improvement to the use of heritage lenses on this camera. I've not carried out any rigorous testing, but I've used my 75-150 Pentax zoom (112-225 mm FF equivalent)  at 1/100th and obtained crisp results. It's not a panacea, if you bounce on the shutter release you will get blurred shots!

It also seems that you need to remember to change the focal length to be used with the IS system. I've inadvertently left it set at 150 mm and taken shots using a 12mm lens resulting in some motion blurred images. Of course this only applies to manual focus lenses, auto lenses automatically inform the camera of the focal length.

A further improvement is the ability to set the minimum shutter speed to be used with auto ISO, again I have programmed a button (C2) to set this. I need to do some rethinking about what those minimum values should be, now that I have IS in camera, but for static subjects, and shorter focal lengths, the previously available (NEX 6) 1/60th minimum is far too pessimistic.

Actually my needs are few, I normally shoot raw using auto ISO, and aperture priority, with the occasional descent into shutter speed priority and manual operation, so I don't need all those menus etc.

One slight negative, possibly due to my ignorance of the camera's capabilities, is the need to restore full frame magnification before shooting, whereas my NEX would jump back into shooting mode at a half press of the shutter. The manual states that this should happen with the a6500 too, but for some reason mine does not. It's probably user incompetence!

Update - a helpful chap on the DPreview forum pointed out that AF in Focus Mag. = OFF will enable the shutter release to cancel the magnification mode and jump back into shooting. I don't know if there are any drawbacks as yet, but my autofocus lenses seems to work fine with this setting.

My old lenses appear to be coping well with the increased pixel density, although the edge definition provided by my Pentax 28mm f2.8 is not great on distant views. It's fine close up, so I wonder if this is a field curvature problem?

I've now published the results of a quick test comparing the NEX 6 and a6500 at ISO1600

Revised 12-8-17

Friday, 17 March 2017

Jesmond Flint Mill

I walked from Newcastle's Freeman Hospital to Gateshead, following the valley of the Ouseburn.

Once this was a major trading route from the river Tyne northwards, the valley providing a steady incline for the horse drawn vehicles of the day. Years ago the burn was enclosed in a culvert, south of Armstrong Park, and material heaped above, so blocking off the road. You can still walk the route but it involves climbing over the substantial man made barrier that stands in the way.

I had to ask for directions as I approached the covered section and was fortunate to come across a local resident who knew all of the history of the area, and who drew my attention to the site of Jesmond Flint Mill, close to where he lives. Sadly I didn't get his name, but this information and photos are down to his kindness.

The flint mill was built to grind flint, carried as ballast by colliers on the London trade. The ground material was used in the local pottery industry, presumably including the nearby Malings factory.

Originally the mill was powered by a water wheel, supplied by a mill race dug alongside the Ouseburn to an upstream location near Jesmond Dene.

Later a stationary steam engine was installed, rumoured to have been engineered by a young George Stephenson, who was at that time employed as a colliery engineer nearby. The photo above shows the site of the mill and the plinth in the foreground might have been the engine base.

Further evidence of the mill seen in this stone wall built into the west bank of the burn.

The stone arch may have been the discharge from the water wheel.

Sony NEX 6, Pentax lenses.

Friday, 3 March 2017

Spectacles and Photography

In my late sixties I need reading glasses, but my distance vision is not too bad. How does this impinge upon my photography?

Well I find it difficult to read the control dials on the top of a camera, and data on the rear screen, without the aid of specs.

However my compact mirrorless Sony NEX 6 camera can be controlled almost exclusively from the electronic viewfinder (EVF), as that has a built in dioptre correction that enables me to see all of the necessary information without using glasses. I also find that I can manually focus using the 9.6x magnification that the camera provides through the EVF.

Moving from camera to computer screen it's a different story. I need to use glasses to clearly see what I am doing. Question is, what is the best solution overall?

I've tried bifocals and varifocals. My bifocals were setup to allow me to read at a close distance or see my computer screen, i.e. two distinct degrees of magnification. This worked well enough, but further deterioration in my eyesight has meant that I now need assistance for viewing middle distance objects, i.e. small road signs maybe 20 yards away etc.

Solution, a pair of varifocals, providing a continually variable range of magnification from close up to distant viewing.

Nothing is perfect, there are pros and cons.

They are great for reading, and using a small computer tablet, while in the car they allow me to read the Satnav clearly, and give an enlarged view of those middle distance objects. In the shops I can read the prices on the products etc. So far so good.

How about the negatives?

In order to best use the range of magnification, you need to look through different parts of the lenses. I.e. Lower down for close up and higher for distance. This involves moving your head.

They are not good for reading the large computer screens that I use for image processing. This involves far too much head movement to keep the required zone of vision in focus. Similarly they are not good for reading music, there I've enough to worry about without having to constantly adjust my line of sight! For distance vision they do provide a slightly enlarged image, but at some expense in the level of contrast and brightness. As a consequence I tend not to wear them when out and about.

The computer screen/music problem has been resolved by the purchase of a pair of specs of fixed magnification optimised for objects  18 to 24" away. They are far superior to the varifocals within their limited range of application.

Now everyone's eyes are different and what works for me won't necessarily work for you. Consult a qualified optician for advice!