Yeah, well. I had a go taking apart a Sigma A 28-200 manual focus zoom. I got it for almost nothing on eBay, but I was still a bit disappointed when about 4 days after it arrived, the aperture stuck open. Cosmetically it wasn't going to win any awards, so I thought, I'll just see what happens if I take these screws out...

... I did get it back together without damaging it eventually, but now the aperture ring doesn't rotate either.

It was more a curiosity than anything else, but its resale value is now nil, despite being optically perfectly Ok. Anyone wants it, they can have it for postage.

Not at all. It was intended purely as a light-hearted compliment.

As a forum, we should probably insure you.

Fortunately, not too clever for our own good though.

It is scary, though.

You can just see it, can't you...

Well, depending on the software, I'd say eliminates, rather than disregards. It does it according to an algorithm, not randomly.

But
Absolutely.

No it's not.

It's showing a 1024x768 pixel image in a 1024x768 pixel space.

The original may have been 3008x2008, but what you're seeing isn't that.

This is why people claiming to be able to compare anything but the grossest of sharpness differences by looking at full frame images on a computer screen are sadly mistaken.

It's not the screen that does it. It's whatever software is converting the graphics file for screen display, and/or whatever the graphics card hardware does. But the excess pixels are discarded, and/or replaced with averages of the neighbouring ones.

No such thing as half a pixel.

Well yours looks a lot better with a bit of levels and sharpening. I don't think it sucks as much as you think. The sharpening doesn't of course create any new detail, just gives the illusion.

Also, a full moon such as yours always looks flatter than one either just before or just after, since the lighting is direct, and so you don't get the crater shadows that give it texture.

Also of course, your shot (like my first one) is a 100% crop, so it's right at the limit of what the lens and sensor can produce. So there's no leeway at all: any focus error - and it only has to be incredibly slight - and the shot is ruined.

I took three shots last night, and although I had focus confirmation for all of them, two were just rubbish.

So I'd be inclined to blame the focusing first, having looked at dozens of my bad results.

At 1/20s and 300 mm, movement blur isn't going to be terribly significant, but ideally you want shorter exposures, since any tripod shake will also ruin it. You're using the 2s delay, so hopefully that isn't a factor.

At the end of the day, though, image size is very limiting. A guy on PentaxForums.com posted a moon shot taken with his Bigma out at 500mm, and it's clearly quite a lot better than mine, even though he hasn't displayed it any larger.

Edit: lens quality is a factor, though. I have a Sigma 600mm mirror lens, and the best moon I've had with it is not as good as the best from the Sigma 400mm that I was using earlier in the year, even taking the greater enlargement required.

It's not really sharper, of course.

But do you agree that it looks better on a monitor?

Inspired by George, I put down the magnifying glass, and looked out of the window...




K10D, SMC-A 400mm F5.6

I'll probably poke about with it a bit more (or maybe a bit less) in Photoshop, but this'll do for now.

That would be H-bar. A for 'orses, obviously.

I'm possibly one of the more sympathetic folk around here to what you're saying.

I'm not ashamed of my personality quirk, which is that a small niggle will tend to occupy a disproportionate amount of my attention. The now well-known metering issues with the K10D and pre-A lenses is such a niggle, and although I've taken steps to no longer use them, it still irritates.

The thing about niggles is that they have to be real.

Even leaving aside the incredibly minor real-world importance of what you're saying, I don't think you've shown that your niggle is real.

You appear to be ascribing reasons for what you see, beyond the justification available from the evidence.

I can live with slightly obsessive people, I am one myself when the fancy takes me.

But bad science really bugs me, and you haven't shown that that's not what you're doing.