It boils down to greater control (*ist D) versus greater speed when writing to the card (*ist DS).

If you like to tell the camera what to do, you will find it easier with the D. If you often take a lot of shots in quick succession, the DS will work better for you.

There are loads of other small differences, but for me, those are the most significant.

The *ist D used to cost more because it came out at a time when DSLR prices were higher. Now, both cameras can be bought for the same money. Both are of equally good quality.

George

(Standing back as others rush in to disagree!)

It's unlikely (though possible) that that one feature is faulty. I should make quite sure that you are using it properly.

G

Pentax have just released updated software - V1.02. You could try downloading that.

G

If they don't show up on a correctly-run hot pixel test, but they do show up consistently on images, then they sound more like debris on the sensor, although I don't understand your description: "+ shaped". Sensor dust usually shows up as light grey smudges.

The easiest cure for sensor dust is to blow clean air at it. You can buy cans of air, but make sure they don't contain any gunge in them.

George

You can see why they do it so as to get nice round numbers, but I wonder if the 77mm Ltd is really 77mm. Perhaps it's really 85mm, but Pentax thought they'd sell more by differentiating it.

G

Many lenses are not exactly the focal length claimed on the box. Manufacturers round up or down to the nearest commonly found focal length, and it is possible in your case that the 300 is nearer to 275 and the 500 nearer to 550. And when you double the 275, lo and behold, you get 550!

Of course, it may be that the convertor is a bit optimistic too.

G

All right, Brian, you don't have to tell everybody. I've got it marked.

G

I would hope for a quiet day on Ebay, when there just happened to be the following on offer:

SMCP-A 15mm 1:3.5
SMCP-FA 31mm 1:1.8 AL ED Limited
SMCP-FA* 200mm 1:4 Macro ED [IF]
SMCP-FA* 600mm 1:4 ED (IF)

If this windfall doesn't materialise, the place of the 15mm will probably be taken by the 14mm; the 31mm might be supplanted by the 35mm, and the 200mm is probably not vital.

But the 600mm? There's a gap that only the real McCoy can fill.

There's a big lottery jackpot this week.

G

The FA 28-105 power zoom, and the F 70-210 are both good zooms at often surprisingly low prices. With a bit of luck you'll get them for about £100 for both, and you'll enjoy much better quality, at the cost of some inconvenience.

The 28-70 f4 is an alternative, but beware of lens separation issues.

(All lenses are Pentax SMC.)

G

I bought one of these about ten years ago, because it was (relatively) cheap.

I have since given it away.

£20 would be my idea of a fair price for it.

G