All Forum Comments
Comment by johnwhit posted on What is the best monitor? at 27/04/2011 - 16:52
I got one recently from a PU member and I'm loving it, despite having a DA*16-50/2.8. Very sharp even wide open, no more distortion than the 16-50 at the wide end, lovely punchy colour rendering. Occasionally will not lock focus between 50-70 but the finger on the focus ring techbique works every time, very fast focus most of the time even when shooting steam trains hurtling towards me at 60mph+. Oh and the close focus setting is a bonus, a fine walkabout lens IMHO.
John
John
Algernon wrote:
From the wide views I would say the Pentax SMC FA 28mm f/2.8 (at f/8 ) looks about the best, but I haven't seen the full sized shots.
Cracking lens, but a little soft wide open, vignetts a bit at f/2.8 as well. Still, I wouldn't part with itFrom the wide views I would say the Pentax SMC FA 28mm f/2.8 (at f/8 ) looks about the best, but I haven't seen the full sized shots.
John
Comment by johnwhit posted on Fast 28-30mm lens comparison at 25/04/2011 - 12:16
cbrog wrote:
Thank you all for your responses, there is a lot in them for me to think on.
JohnWhit: Basically I am talking sharpness, at the same time having looked through scores of (unsatisfactory) shots, I am very aware how difficult it is to separate depth of field from achieving optimum sharpness at true macro! Regarding the 16-45, the comparison here was using the Sigma as a prime (and why not? ). I wanted to make up a reference picture of a large number of different Helebore blooms mounted on wire mesh. I used the Sigma as it was the best quality lens I have. At the same time I duplicated each shot with the 16-45 set up to produce the same image size. There was virtually no difference in IQ between the two lenses.
Hi Roger, Thank you all for your responses, there is a lot in them for me to think on.
JohnWhit: Basically I am talking sharpness, at the same time having looked through scores of (unsatisfactory) shots, I am very aware how difficult it is to separate depth of field from achieving optimum sharpness at true macro! Regarding the 16-45, the comparison here was using the Sigma as a prime (and why not? ). I wanted to make up a reference picture of a large number of different Helebore blooms mounted on wire mesh. I used the Sigma as it was the best quality lens I have. At the same time I duplicated each shot with the 16-45 set up to produce the same image size. There was virtually no difference in IQ between the two lenses.
I've owned both the 16-45 and Sigma 105 (not DG model) at one time, I found the 16-45 very good, the Sigma was very sharp even wide open at 2.8, in fact I only sold the Sigma because I wanted something slightly shorter to go between a DA-70 and FA-135. Whether the difference would be noticeable in macro work well I don't really know.
It may be worth checking the micro focus adjustment as your camera supports the feature and adjusting accordingly, you would need a test chart for this. The advice offered by others regarding tripod/lighting is relevant, any slight movement at such high magnification will have a major affect on your images.
John
Comment by johnwhit posted on Macro Lens Image Sharpness at 25/04/2011 - 10:06
cbrog wrote:
Please, could somebody suggest a practical method of determining the 'sharpness' of a macro lens? By that I mean proving that the image quality is what one would expect of a particular lens namely, in this instance, my Sigma 105 EX DG.
Roger.
Hi Roger, are you talking sharpness or Depth of Field? Some sample images may help. Please, could somebody suggest a practical method of determining the 'sharpness' of a macro lens? By that I mean proving that the image quality is what one would expect of a particular lens namely, in this instance, my Sigma 105 EX DG.
Roger.
If talking DoF then most macro lenses retain most of there resolution down well beyond f/5.6 my Tamron 90mm will do very nicely at f/16 and I'm sure the Sigma will too, before diffraction sets in and reduces image quality. At such small apertures you may well require the support of a tripod for the slow shutter speeds or some additional light, ring flash etc
The 16-45 will have greater DoF due to the shorter focal lengths involved, is this what you are seeing in your results?
John
Comment by johnwhit posted on Macro Lens Image Sharpness at 24/04/2011 - 09:59
davem wrote:
Its interesting to see no mention of the Sigma lenses. The Samyang lenses seem to be increasing in popularity as a whole.
Dave
The Sigma fisheye is rather expensive, I think I'd prefer the Pentax 10-17 if I were spending that kind of money, but for a lens that I use rather infrequently the £200-220 Samyang was just what I needed, in fact I'd say it was a bargain. The Pentax mount version has full auto aperture control from the camera body, has the "A" setting on the aperture ring. Focusing consists of setting the distance to 1.5-2m and everything is in focusIts interesting to see no mention of the Sigma lenses. The Samyang lenses seem to be increasing in popularity as a whole.
Dave
John
Comment by johnwhit posted on fish eye at 23/04/2011 - 20:41
Dangermouse wrote:
The Samyang 8mm seems well thought of, but if I was after something wider than 18mm I'd probably go for their 14mm instead. It's full frame compatible so would double as a fisheye on film
Not really as it's rectilinear, you would end up with an ultra wide angle lens.The Samyang 8mm seems well thought of, but if I was after something wider than 18mm I'd probably go for their 14mm instead. It's full frame compatible so would double as a fisheye on film
John
Comment by johnwhit posted on fish eye at 23/04/2011 - 14:11
1. Yes, but it's an occasional lens, I had a 16mm Sigma fisheye that I used for film and enjoyed it.
2. Samyang 8mm CS Fisheye, lovely build, great optics, manual focus. Some sample test images here:
https://www.pentaxuser.com/forum/topic/samyang-8mm-fe-torture-test-21179
Full test here (on C***n):
http://www.photozone.de/canon-eos/526-samyang8f35eos
John
2. Samyang 8mm CS Fisheye, lovely build, great optics, manual focus. Some sample test images here:
https://www.pentaxuser.com/forum/topic/samyang-8mm-fe-torture-test-21179
Full test here (on C***n):
http://www.photozone.de/canon-eos/526-samyang8f35eos
John
Comment by johnwhit posted on fish eye at 23/04/2011 - 08:34
Some user comments:
http://stans-photography.info/LongComments.html#28-105%20f/4.0-5.6%20FA%20%28p%29
John
http://stans-photography.info/LongComments.html#28-105%20f/4.0-5.6%20FA%20%28p%29
John
Comment by johnwhit posted on FS: SMC Pentax FA 28-105/4-5.6 Power Zoom at 21/04/2011 - 19:02
John