George, we must stop agreeing like this.

Dan

Okay, fair point, probably found by myself with my test - but are you not getting acceptable focus with the increased depth of field of a slower lens, rather than critically sharp focus with the shallower DOF of a faster lens?

You're relying on the increased depth of field to allow a little leeway in focusing accuracy, so in essence, yes, I suppose it could be viewed that it would be faster to obtain acceptable focus on a lens with a smaller maximum aperture.

If you want to focus critically though, I would still argue a wider aperture, and the corresponding brighter viewfinder (not necessarily hugely brighter, but noticeably to my eyes), are the way to go.

You could always stop down to f/22 and not bother focusing at all.

Dan

Hi Steve,

Just had a go at your experiment, can't say I got the same results as you. Found it easier to focus critically with a wider aperture. Also tried stopping down my 50mm 1.7 to f/4, focusing, then opening the aperture up to f/1.7 again. Found that what looked in focus at f/4 wasn't at f/1.7, and the focus point was usually just behind the subject.

Also just had a look online at lens test charts here: http://www.photozone.de/8Reviews/. Not looked at this site before, but was the first I came to when I searched, so I'm prepared for a deluge of "that's the worst lens-test website ever!" comments, but it looks fairly comprehensive to me. Had a look through various f/2.8 lenses - their performance all seemed to peak at f/5.6 (apart from the Canon 80-200 IS, which was best at f/8 ). The Nikon 85mm 1.4 was quite a surprise.

I chose to get an 80-200 f/2.8 because at the time I was using manual exposure and focus, and didn't want to have to reset my exposure with every change in focal length (hence the constant aperture), and didn't want f/5.6 at the long end, as I think that would have been too dark to focus accurately in the environment I was using it, and most lenses in this range tend to end up at f/5.6 at the long end. Bear in mind I was usually using a polariser too, so I was already losing two stops to that.

There is lots of mis-information about all aspects of photography, but the best thing to do is to try things out and see what works best for you.

And don't believe everything you read on the web!

Dan

Hi Mac,

Good question, not silly question! One that you can only really answer based on personal experience and techniques, I think.

For me, there are several benefits, and several drawbacks, to large aperture telephotos:

Benefits

1. Brighter viewfinder image (great for focusing - manually or AF - in subdued lighting, e.g. woodland in overcast conditions).
2. Potential for faster shutter speeds, freezing action, if at the expense of optimal lense sharpness.
3. Teleconvertors can be used whilst retaining AF.


Drawbacks

1. Cost (although both my long 2.8s, an 80-200 and a 300, both MF, were secondhand and at reasonable price £179 and £330 respectively).
2. Weight (my 80-200 is currently not in my bag, I took it out when in Scotland a few weeks back and it hasn't found it's way back).
3. Filter size, although my Cokin P fits my 80-200, just, and the 300 has rear filters, but I don't think I'd get a polariser in there.


I use my 300mm with the 1.7x AF convertor, giving me an effective aperture of f/4.8, which is still well within the range where AF will work. If it was an f/4 lens, that would give f/6.8, and AF would probably be a bit more hit and miss. The usability of teleconvertors is a great advantage, because it makes the lenses much more versatile.

I understand it that most lenses are best when stopped down a couple of stops, not necessarily down to F/8-f/11. Hence an f/2.8 lens will (hopefully) give it's best performance around f/5.6-f/8.

Having said that, I read an online review of the Pentax 300/2.8 the other day, and image quality was great at 2.8, and fantastic at 4. I guess you pays your money...


Flexibility is the key for me, I think, but whether the pros outweigh the cons is obviously a personal choice. I have to say, I'll be ordering the DA 50-200 soon - everyone here raves about it, and it weighs less than a quarter of my 80-200. I will miss the brighter viewfinder though.

Dan

...most recently on this one - https://www.pentaxuser.com/forum/viewtopic.php?t=2702&postdays=0&postorder=asc&start=0 - which started out as a 2x convertor question, but just past halfway down suddenly veers into UV filters for protection.

Dan

Sorry Evets, sort of wandered off the point a bit there.

I'm with George on this one - if you feel that your photos don't have the exagerated perspective that a wider lens will give you, then a wider lens is for you. I was used to the perspective a 24mm lens gave me on film, I just preferred the look of it to 28mm. So when I first got my 'D', with kit lens, it didn't seem wide enough, so I later got the 16-45, which gives the same field of view and perspective as my 24mm on film.

As John says, the kit lens is fine stopped down, and for landscapes, to aid composition as well as sharpness, I would advise using a sturdy tripod.

Having said that, if you can try a wider lens for some beach photos, do. The extra wide view might suit your vision. I've got a Sigma 10-20mm, and on the beaches of Cornwall recently I had a great time with it.

Dan

Yes, monkeys, and many of them. The 'figures' are either:

a. An infinite amount of monkeys (and just long enough for one monkey to type it all up, while some others did all the Ruth Rendells, Catherine Cooksons, Jeffrey Archers and Barbara Cartlands).

or

b. An infinite amount of time and one monkey (and an infinite supply of bananas to keep him going. The wife's saying "do monkeys eat bananas?", but quite frankly, after a while, a monkey will eat anything, even, at a push, the wife's cooking ).


But, yes, very true, how can a lens focus to infinity? I may take this up with Pentax, get them to label their lenses properly.

Anyway, enough of this nonsense, time for bed.
Dan

I'm certainly not going to say you're wrong Liam, it's a tried and tested method. However, I've always wondered, when doing landscapes, using a lens that focuses from say, 2 feet to infinity, exactly how far a third of the way to infinity is...

I think that's a question that should be reserved to a loftier forum, one involving monkeys and Shakespeare.

Dan

The Intro2020 price list has the following screens available for the D, DS and DL:

LF-60 (framed matt)
LL-60 (divided matt)
LI-60 (scaled matt)

Doesn't sound like split image with microprism ring, but you never know what might be available for the K10D. Also, third party suppliers (Beattie?) might do one.

Have to say though, that I've never found it a problem to focus manually with the nice, bright, plain screen fitted in the D, and you've always got the focus confirmation to help too.

Dan

Hi Viewfinder,

Welcome to the board, nice to see another EssexMan here.

I don't know about the interchangeable viewfinders, but I'm sure someone does.

The manual was online, but seems to have gone again. However, it can be downloaded from the link here - http://pentaxlife.com/pentax-k10d-manual-download, but note the proviso about 'not the final version...' etc.

Ooh, just had a quick scan through, found the phrase "Pentaprism Finder, Interchangeable Natural-Bright-Matte II focusing screen" in the specs. Guess that answers your first question, assuming one of the other optional screens has your requirements.

I reckon only Pentax know whether the pictures released so far are from production or pre-production units. I'm assuming you mean these ones. They look pretty good to me, so if they're pre-prod ones, things can only get better. Only wish they had some higher ISO ones there too. I seem to recall that one of these was at 400, but the info for that has gone too now.

I'm sure there'll be more answers to your questions along shortly.

All the best,
Dan