I used it several times on my K200D and have used it for a few test shots on a new K30. It mounts and demounts easily. You can see from the photo of the bayonet end, that there is no "Ricoh pin", which was the cause of Rikenon programme "P" lenses jamming on Pentax DSLR bodies.

If it is the same lens as mine: XR Rikenon APO 1:4.5 300mm (from the lens focussing ring), I peronally would have no qualms about mounting it on a K5.

Andrew

I have a M 75-150mm f4 and use it occasionally. I have never noticed purple fringing on any of the photos I have taken with it - though I don't remember taking any wide open where the problem, if it exists, is likely to be most obvious.

There is a thread in the forum here that includes photos taken by the lens. A good sample is *very* sharp. It is one of my favourite lenses. Don't hide it away (or worse give it away) without testing it thoroughly.

Andrew

I have exactly that lens and use it occasionally on Pentax DSLRs (K200D and K30). It does not have the Ricoh pin and does not get stuck on a DSLR. Though it is pretty obvious from the photos, you haven't mentioned that it has a tripod mount and a built-in lens hood.

Potentially a collectable - they are VERY rare. This is the only one I've seen advertised anywhere for a couple of years.

Andrew

I don't think you are doing anything wrong. It's a matter of expectation, I think.

The Sunny 16 rule suggests that you'd be shooting at f/16, 1/1600 at ISO 1600 in full sunlight. Unless I've made a mistake, 1/50, f/4.5, ISO 1600 is 8.5 stops increase in exposure.

Full sunlight corresponds to an illuminance of around 80,000 lux. In a typical living room, lit by a few tungsten lamps or low energy lamps, illuminance is likely to be 20 - 40 lux, which is 11-12 EV (stops) lower.

So ....... if the light is around 11-12 EV less than full sunlight, but your exposure is only 8.5 stops more then you could be underexposing by 2.5-3.5 stops. I reckon there's a strong chance that this is why your photos are too dark - they are just under exposed.

This is a photo I took around New Year, in my living room using a Pentax K30 with M50 f/1.7. It was taken at f/8, ISO 100 for 30 secs, which is about 12 stops up from a "Sunny 16" exposure.




The room was lit by a few Xmas tree lights and 3x 11w low energy lamps about 20ft from the tree.



Andrew

The lens I have is the F 35-70mm. They also come up regularly on Ebay. I have heard from some on this forum that the Pentax A 35-70mm f4 is even better, though I have no experience of it.

One thing to remember is that auto-focus might not be spot-on on some samples of lenses. If you have microfocus adjustment on your camera, setting it accurately might transform a lens.

As an aside, I'm not sure your comments about the waterwheel mill shots on your gallery are entirely fair - the sun is shining in the shot taken by the Sigma but not in that taken by the kit lens.

Cheers
Andrew


Andrew

I spent quite some time today comparing the Sigma 28-70mm Epsilon with both the Pentax 18-55mm MK2 kit lens and also the Pentax F 35-70mm.

The Sigma focussing seems much more reliable after cleaning the contacts on the lens. Focussing seems more accurate too, at or near infinity, but it still does fail to find focus occasionally (maybe one shot in 10). When it does nail focus, at 50mm (probably it's best focal length), at f5.6, it is close to and maybe marginally better than the kit lens at the same settings (the kit lens's worst focal length). I'd need to do more testing to be sure, but that is quite encouraging.

I also compared the Sigma with the Pentax F 35-70mm at 70mm and at f/4.5, f/5.6, f/8 and f/11. Frankly, the Pentax F walks all over the Sigma. It isn't just better, it is a lot better. The Sigma is a little better at f/8 than the Pentax is wide open. The Pentax, however, is clearly sharper at f/5.6 than the Sigma at any aperture and it improves further at f/8.

The Sigma is much better than I thought it to be and at some time, I might well sell it without worrying about it. For now, though, it stays on top of the wardrobe.

Andrew

I'm sure that you'll love it - enjoy!!

Andrew

The shot was taken at 18mm, so I was a lot closer to the tree than you'd think. I stopped down to try and maximise depth of field. I had intended to take the shot at f/16 not f/14 - just haven't yet got used to where the wheels are on the K30, must have nudged one unintentionally.

For this shot, I set exposure to manual with single point spot metering. I set aperture to f/16 (or so I thought) and metered off the snow - adjusting shutter speed to indicate two stops over-exposure.

If you don't need to throw the background out of focus, you'd be better off sticking to f/8 and onwards.

From f/11 on, the kit lens is as sharp as just about anything you can buy.

As an aside, I tried out the Sigma 28-70mm Epsilon this afternoon - but thoroughly cleaned all the electrical contacts first. It seems to focus a bit better than it did on the K200D. I'll try it out again in the daylight tomorrow.

Cheers
Andrew

We had a bit of snow this morning, so I thought I'd go for a wander. This was taken near Besom Hill in Oldham.




This is a 100% crop .......




It was taken with a Pentax K30 and 18-55mm Mk2 kit lens. The kit lens sure looks sharp enough to me.

Andrew

I have a Pentax F 35-70mm lens too and it also is as sharp as a tack. It is, though, no sharper than my 18-55mm kit lens at 35mm, f/5.6. If your kit lens is much worse, then you might indeed have a duff one.

Andrew