No, it does not affect autofocus. The main downside is that it does affect metering. Spot metering will no longer be accurate - possibly a couple of stops out.

It is not at all hard to do, unless your hands are shaky - in which case it's impossible.

Andrew

Oldham and Rochdale have recently started to replace much of the street lighting in both boroughs (about 60,000 columns) with supposedly more efficient lamps types (LED, I think). Practically, in most cases, the contractors installed the replacement fittings on new columns in the same locations as the existing column, to minimise the cost of excavation, cabling and reinstatement.

As the new fittings seem to have far less sideways coverage than the old, low pressure sodium (SOX) fittings, the new lighting is very patchy in some places. They are also radio controlled (I think), at least they don't have a standard photocell on top - looks like a small radio aerial. Unfortunately, there is poor radio reception (and very poor mobile phone reception) in the cul de sac in which I live, so the two new street lamps never switch off. Isn't modern technology wonderful?

Andrew

In the dim and distant, I did have some limited experience in lighting design generally and a little in street lighting and area lighting using street lighting type fittings.

I agree with the comments about AWB. If you want to get an impression of the colour of the lighting, stick to a daylight setting. Some types of street lighting are completely monochromatic (low pressure sodium SOX lamps) - I don't know what AWB would make of those.

I still have a light meter (lux) and popped outside after reading wasleys original post to see if I could learn anything useful about the illuminance (lighting level - lux) provided by the new LED street lighting that was installed a month or so back. Directly under the a street lamp, the level was about 15 - 30 lux (EV 6-7) but midway between lighting columns was less than 1 lux, I know that because the meter read 0 lux - possibly EV -2 or even lower.

I don't know what the councillors really want to know about the experimental street lighting, but whatever it is they would be well advised to go and have a look, rather than rely on photographs, no matter how well considered they are.

If wasleys has a (photographic) light meter and can take readings in EV, then the conversion table at the bottom of this web page might be useful

Andrew

No, I don't think so either - but I have seen it said several times. If it were a Tomioka trademark, you'd expect to see it on their own brand lenses - and it isn't.

Andrew

I've seen it suggested that it is Tomioka. The 28mm f2.8 that I have doesn't have it.

Andrew

One lens on a desert island? I think it would have to be a normal range zoom - and the only one I have is the Pentax 18-55mm MK2 kit lens. A useful range of focal lengths and sharp enough.

There are lots of variants of the Chinon 28mm f2.8 (assuming that is what yours is). Some may be better than others. I have one that is quite nice - sharp across the frame at f5.6. A little softer wide open.

Andrew

I've taken several test shots with the Sigma recently and have discovered that, especially at the short end, it tends to back focus a little giving images that are nothing like sharp. If focussed manually (I have a split image focussing screen) it is perhaps a little sharper than the Pentax 18-55mm ALII kit lens. I doubt that they all back focus, so it looks like I might have a duff copy.

Andrew

I meant that I have relegated it to the top of my wardrobe - not that you should. As rule, I tend to have primes 24mm, 28mm or 50mm on the camera most of the time - so that I'll have the best possible quality if I manage to fluke a decent shot. I use the kit lens for anything wider than that - and a Pentax-M 75-150mm f4 zoom (which is amazingly good) or Vivitar (Komine) 200mm f3.5 if I need something longer.

Andrew

I took a few test photos with the Sigma 28-70 AF-Epsilon f/3.5-4.5 in the garden this afternoon. I think it's about as good as you might expect for an old zoom. Surprisingly there's not a lot of difference between it and my Pentax 18-55mm AL II zoom.

A comparison with primes is a difference story entirely. This is an extreme corner crop from two photos of the same test chart. The fly is on the photo taken by a Pentax SMC-M 50mm f1.7. Nuff said, I think.





Photos of stuff other than test charts, without any direct comparison to similar shots taken by a better lens, look OK.




The bottom line is that it's OK-ish but not at all special. One for the top of the wardrobe, I think.

Andrew