I had the same trouble as you when I went digital. Don't know if it helps but I've tried various solutions including split screen focusing screen, external monitor, Pentax magnifier flip up thing and homemade focus widget. This magnifier nearly poked my eye out a few times and only shows the centre of the view, the external monitor is too much of a faff to always connect and the split screen isn't great with pre -a lenses above about f/8 or so (bottom goes dark). The focus widget is a ring round the focus barrel with 2 arials sticking out on opposite sides for 50cm. It's the best thing I have for highly accurate incremental focus adjustments (ie getting stars as focused as possible in startrails using a zoom that extends beyond infinity). Nowadays I'm doing stuff in which the focus is the hardest I've ever tried (ultra macro) and I've found the totally clear screen to be the biggest help. And quite a lot of maximum magnification chimping .

I usually crop to get around my own equipment inadequacies - I don't have every lens going.

As in, if there's a shot begging to be taken by a 400mm for maximum impact, and I've only got a 300mm, then I'd crop that to give a 400mm field of view.

The flipside would be not to take the pic cause I don't own the perfect lens for it. Beggars can't be choosers

A lot of people have a go at this because it's a fun, cheap way to get beyond 1:1. That's how I started too. Time permitting, one of my winter projects should be to churn out a comparison for people using the various (cheap old) lenses I have that are suitable, -k, -m, -a. I also have 3 -a 1.7s so that'll be an interesting opportunity to test reversed lens sample variation at the same time.

The el-nikkor 50mm f/4 has a poorer reputation in extreme macro circles. The one to get is the 2.8 II (newer plastic version, better coating etc), about £50 on eBay. It's a really cracking little performer. Compared to 10 or so Pentax lenses I have in the 24-50 range, it's sharper, more contrasty and doesn't give you the bizarre strange lightplays I get in some OOF areas with some Pentax lenses. 2.8 is also brighter and easier than 4, although the actual shot tends to be taken at 5.6 or 8.

But it's all relative. Ie if you've never used the f/2.8, the f/4 is pretty wow. And there's variation within lenses - you could get a lousy f/2.8, which is worse than a fab f/4. And, the difference is less than you think, so it takes an experienced eye to see it. Reversing an enlarger lens is a specialist tool, you don't need to buy it unless you really get into it. As in Pentax lenses already give you a good 90% of the performance so they're perfectly fine if you don't do this regularly.

I use a reversed Nikon el-Nikkor 50mm f/2.8 enlarger lens.

Thanks all, appreciated. I got lucky

5000 impressions today on my pathetic little Flickr account, the 3rd busiest day ever, because of this, which BBC chose as one of their readers pics of the day. Reversed lens macro on 65mm extension. But I do so wish Pentax had that MPE-65 in their lineup

Not quite. I'm a moderator there. And I'm a member here. I hope that this illustrates the fact that usually there is more going on than people think when moderation occurs.

It actually got closed by a colleague over there because some guy joined PF just and apparently only in order to enter into the fray on that thread, trying to stoke it up. Including a snide comment about how out of all the people on that thread, only 1 person is even a "respected" Pentax shooter.

We've got better things to do than to talk about the recent PU dingdong over at PF. We're there to talk about photography, Pentax, all the good stuff, not to bicker. They're both fine communities. And I think that everyone should perhaps remember that and just get on with making photos.

And that's all I'll say about the matter.

Well, have a look at http://www.kenrockwell.com/tech/full-frame-advantage.htm to see what we're missing. Also, the field of view is nicer. In terms of ISO performance, FF cameras have access to the same technology. So the next gen FF will have amazing ISO. I'm not remotely insecure about my stuff. But yes I'd go for a Pentax FF if it came out.

Rating systems are easily abused. I never bother to enter any photography thing if there's an element of 'get your friends to vote for you' on it.