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johnriley
Posted 06/07/2011 - 17:23 Link
You're looking at two very small images there. When we get to A3 exhibition prints we can expect to notice which is which!
Best regards, John
Pentaxophile
Posted 06/07/2011 - 17:52 Link
This is right in the corner of the frame? My 18-55 goes mushy in in the extreme corners... at 18mm anyway.

Example: http://i786.photobucket.com/albums/yy148/willdb_photo/1645%20vs%201855/18-55-l.j...

16-45mm comparison: http://i786.photobucket.com/albums/yy148/willdb_photo/1645%20vs%201855/16-45-l.j...
[link=https://500px.com/will_brealey/[/link]
Edited by Pentaxophile: 06/07/2011 - 17:52
johnwhit
Posted 06/07/2011 - 17:52 Link
It must be an old 35mm lens you were using, or a bad sample, my FA-35/2 will match the MkII kit lens easily giving away 2 stops, f/4 v f/8

John
PPG link

In LBA hiatus.
Algernon
Posted 06/07/2011 - 18:07 Link
johnriley wrote:
You're looking at two very small images there. When we get to A3 exhibition prints we can expect to notice which is which!

These are 100% 1:1 crops and each pic is about 370 pixels wide. The K-5 frame is 4928 pixels wide so each pic is 4928/370 say 1/13th of the frame. On my monitor (19") each pic is 110mm wide so the full print would be 110mm x 13 = 1.460 meters wide. A3 is 420mm wide so what I'm looking at on the monitor is roughly 3 1/2 times as wide as A3

You wouldn't see any difference in A3 prints

Tozza27 has just posted a shot of a seagull in the Entries for fortnightly competition #71 WILDLIFE taken with the Kit Lens and it shows what it's like for bird shots.
-
Half Man... Half Pentax ... Half Cucumber

Pentax K-1 + K-5 and some other stuff

Algi
Edited by Algernon: 06/07/2011 - 18:20
Algernon
Posted 06/07/2011 - 18:15 Link
Will: .... very wide angle lenses always look awful at 1:1. It's well known that the 16-45mm is better below 24mm than the 18-55m after that they are similar. You can see the PF on the 16-45 though. The 18-55mm doesn't look in focus ( look at the downspout )

John: You must have a very good 35 and a bad Mk2 Kit lens
Half Man... Half Pentax ... Half Cucumber

Pentax K-1 + K-5 and some other stuff

Algi
Edited by Algernon: 06/07/2011 - 18:21
johnriley
Posted 06/07/2011 - 18:29 Link
You still haven't told us which 35mm lens you're talking about?
Best regards, John
johnwhit
Posted 06/07/2011 - 18:32 Link
Algernon wrote:

John: You must have a very good 35 and a bad Mk2 Kit lens

Nope, kit lens performs as expected, better than the MkI I had. The FA-35/2 reaches it's outstanding optimum resolution by f/4, so does the FA-50/1.4. I believe the FA-31 Ltd and FA-43 Ltd do as well, but I don't own either unfortunately. This is where fast primes really come into their own, when they can give away 2 stops and still match the zoom

John
PPG link

In LBA hiatus.
Edited by johnwhit: 06/07/2011 - 18:35
Algernon
Posted 06/07/2011 - 18:49 Link
johnriley wrote:
You still haven't told us which 35mm lens you're talking about?

This one:

http://www.flickriver.com/search/35mm+flektogon/

which as you can see is an Excellent lens with a lot of
character and gorgeous bokeh. nice colours as well

One sold for £190 the other night on ebay.... not even
mint
Half Man... Half Pentax ... Half Cucumber

Pentax K-1 + K-5 and some other stuff

Algi
Edited by Algernon: 06/07/2011 - 18:50
johnwhit
Posted 06/07/2011 - 18:52 Link
Algernon wrote:
This one:
http://www.flickriver.com/search/35mm+flektogon/
which as you can see is an Excellent lens with a lot of
character and gorgeous bokeh. nice colours as well

Highly overated IMHO.

John
PPG link

In LBA hiatus.
johnriley
Posted 06/07/2011 - 18:55 Link
Thank you. The 35mm Flektogon was a relatively inexpensive East German lens, designed for film and never having much of a reputation in its day.

In some circles it has gained a reputation, but in my view it is not a deserved one. I would certainly not pay £190 for one and the pictures linked to don't inspire me to desire one.

Clearly we are looking at very different things in a lens, so we shall have to agree to differ.
Best regards, John
bwlchmawr
Posted 06/07/2011 - 19:34 Link
What's most interesting here is the extraordinary quality of the Pentax kit lens, esentially a lens which was "given away" with various cameras.

I have no axe to grind on this one: I don't own any expensive or exotic limited lenses nor ever will.

I must be very lucky with my version of the mk1, although I nearly always use it at moderate apertures albeit throughout the full zoom range.

I bought it with a K100 and fully expected to see its limitations exposed when mounted on my "new" K10 with its more densely populated sensor but, if anything, the results are even more pleasing to my untutored eye.

I've flirted with the idea of replacing it with one of the above mentioned lenses (well, it's nice to dream) but every review one reads seems to contradict another or to reveal some deficiency or other. So I haven't felt the need to part with in excess of a week's wages.

I do use lots of my cheap pre-digital, manual focus primes, not because the results are superior, but because it's fun to do so.

Good luck with whichever lens you decide to buy; you'll always have your kit lens as a reliable back-up.
Best wishes,

Andrew

"These places mean something and it's the job of a photographer to figure-out what the hell it is."
Robert Adams
"The camera doesn't make a bit of difference.  All of them can record what you are seeing.  But, you have to SEE."
Ernst Hass
My website: http://www.ephotozine.com/user/bwlchmawr-199050 http://s927.photobucket.com/home/ADC3440/index
https://www.flickr.com/photos/78898196@N05
ChrisA
Posted 06/07/2011 - 19:45 Link
johnriley wrote:
The distance to the subjects at the edge of the frame might be a factor. If they fall outside the depth of field then sharpness would suffer.

Coming in a bit late on this one, but just to pick up John's point...

I thought the whole point of a rectilinear lens was that the focus distance refers to the perpendicular distance from the film plane, to a plane (containing the subject), which is parallel to the film plane.

In other words, the focus distance of something at the edge of the field is the same as the focus distance at the centre of the field.

I've tried to illustrate it with this diagram:

Comment Image


The fact that the slant distance, ie the distance from the camera to the object at the edge of the frame, is greater than the focus distance, is completely irrelevant - or should be if the optics are perfect.

So if an object is within the DOF at the centre, it should be within it at the edge - and if I understand it right, edge softness is when the optical quality means that reality doesn't match the theory.
.
Pentax K-3, DA18-135, DA35 F2.4, DA17-70, DA55-300, FA28-200, A50 F1.7, A100 F4 Macro, A400 F5.6, Sigma 10-20 EXDC, 50-500 F4.5-6.3 APO DG OS Samsung flash SEF-54PZF(x2)
.
Edited by ChrisA: 06/07/2011 - 19:45
Pentaxophile
Posted 06/07/2011 - 20:00 Link
Algernon wrote:
It's well known that the 16-45mm is better below 24mm than the 18-55m after that they are similar. You can see the PF on the 16-45 though. The 18-55mm doesn't look in focus ( look at the downspout ):

Hmmm... the shots were at f8 and live-view focussed on the same spot. Could it a be curved-field effect? But anyway, I have noticed in general use that the kit lens can be ropey in certain challenging conditions where the 16-45 can be relied upon at pretty much any setting, apart from that CA which is banished in a second in PP. There is CA on the 18-55 shot too, more of a blurry cyan/red type.

bwlchmawr wrote:
What's most interesting here is the extraordinary quality of the Pentax kit lens, esentially a lens which was "given away" with various cameras.

I have no axe to grind on this one: I don't own any expensive or exotic limited lenses nor ever will.

I must be very lucky with my version of the mk1, although I nearly always use it at moderate apertures albeit throughout the full zoom range.

I never had any complaints with my mk1 Andrew, but I think that may have had to do with the smaller 6MP sensor of my istDL, and that I hadn't yet succumbed to the peculiarly futile and joy-draining pastime of pixel-peeping back then

I think the kit lens is good, but I think people are overstating the point when they say it's 'excellent' etc. It's certainly good enough that a great photographer can make it shine, as you certainly do.
[link=https://500px.com/will_brealey/[/link]
Edited by Pentaxophile: 06/07/2011 - 20:09
Algernon
Posted 06/07/2011 - 20:03 Link
bwlchmawr wrote:
I must be very lucky with my version of the mk1, although I nearly always use it at moderate apertures albeit throughout the full zoom range.

Having seen your work Andrew, it's obvious that your Mk1 is one of the good copies, similar to the one I had. There's no point in buying a Mk 2.. you won't see any difference.... I couldn't
Half Man... Half Pentax ... Half Cucumber

Pentax K-1 + K-5 and some other stuff

Algi
Algernon
Posted 06/07/2011 - 20:10 Link
Chris I think you have it more or less in a nutshell

A real torture test for any lens is to photograph a large lattice railway bridge square off from the side and then see if the rivets at the edges are as sharp as the ones in the middle and if both edges are the same.

Tougher still turn the camera so the bridge is on the diagonal and see if the centre and corners are sharp.
Half Man... Half Pentax ... Half Cucumber

Pentax K-1 + K-5 and some other stuff

Algi
Edited by Algernon: 06/07/2011 - 20:11

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