All Forum Comments
Comment by Frogfish posted on Why buy Pentax? (k5 mini review) at 15/02/2012 - 02:58
pentaxian450 wrote:
I never get bored when I see pictures depicting a different lifestyle. I really enjoy your pictures. Nice work.
Ditto Yves comments. #1 and the last for me.I never get bored when I see pictures depicting a different lifestyle. I really enjoy your pictures. Nice work.
Comment by Frogfish posted on Pakistan Street Photography - 3 at 14/02/2012 - 17:17
Lovely set Alan. That Treecreeper is, as everyone else has noted, a wonderful shot !
And again - how on earth did you find all these one on excursion !?
I though it was the ducks eyeing up the fox in #1
And again - how on earth did you find all these one on excursion !?
I though it was the ducks eyeing up the fox in #1
Comment by Frogfish posted on Wildlife from the weekend at 14/02/2012 - 16:55
Very nice set Naim. I really like #5, the man and the arches work very well for me.
Comment by Frogfish posted on Pakistan street photography - 1 at 13/02/2012 - 13:50
I hope that Falk Lumo doesn't mind me re-posting his thoughts here :
Ok, the plot thickens that we are seeing a 4" telescope design here. The length (very long for a tele lens but normal for a scope) being the fifth hint or so.
So, I'd like to contribute a bit more insight about what to expect of such designs.
Let me assume for the best which seems to be an optical 4 element Petzval design plus maybe an additional LFF (Large Field Flattener). A Pentax scope of similiar specification is the Pentax 100 SDUF or Pentax 105 SDP. In this PDF, you'll find a scientific measurement of the resolution of this Pentax scope (German!). The Petzval design dates back to physicist Jozef Maximilián Petzval and was first used in 1841.
The best direct comparative tests of such a scope design and an advanced 10+ element photo tele lens design I could find was conducted by Samir Kharusi from Oman who has an amazing pool of devices
In the first test, he compares 140mm optics (as opposed to 100mm) using what appears to me being the 21 MP Canon 1DsmkIII FF camera.
In the second test, he compares 60mm optics (as opposed to 100mm) using the 10 MP Canon 40D APSC camera.
Note that in the first test, he uses a Petzval design plus additional Large Field Flattener. Also, he clearly misses exact focus sometimes with the tele lens.
Direct sources are here (sorry these links won't work on copy/paste) :
-> televue_canon
-> TV-60is
From this and other sources I conclude that a good scope design has the same excellent optical performance in the center and at infinity focus compared to a more complex photo tele lens design. However, it's performance drops off when approaching the edges or a closer focus. OTOH, contrast and clarity in the center seems to even outperform the more expensive 10+ element tele lens designs.
So, I think I can summarize the pro and cons of the forthcoming 560/5.6 already:
SUMMARY
IMHO (based on preliminary information as of today) the Pentax DA 560/5.6 is a tele prime lens at a good price point (sub $2000) which rivals the optical performance of much more expensive glass, near the center and at infinity focus, good enough to be used with a tele converter and with good clarity and contrast. OTOH, the lens is very long (and possibly heavy) and the performance will degrade towards the edges of the image field which makes it better suited for APS-C than full frame although it most likely would cover a medium format image circle. Or all in one: Be Different .
Ok, the plot thickens that we are seeing a 4" telescope design here. The length (very long for a tele lens but normal for a scope) being the fifth hint or so.
So, I'd like to contribute a bit more insight about what to expect of such designs.
Let me assume for the best which seems to be an optical 4 element Petzval design plus maybe an additional LFF (Large Field Flattener). A Pentax scope of similiar specification is the Pentax 100 SDUF or Pentax 105 SDP. In this PDF, you'll find a scientific measurement of the resolution of this Pentax scope (German!). The Petzval design dates back to physicist Jozef Maximilián Petzval and was first used in 1841.
The best direct comparative tests of such a scope design and an advanced 10+ element photo tele lens design I could find was conducted by Samir Kharusi from Oman who has an amazing pool of devices
In the first test, he compares 140mm optics (as opposed to 100mm) using what appears to me being the 21 MP Canon 1DsmkIII FF camera.
In the second test, he compares 60mm optics (as opposed to 100mm) using the 10 MP Canon 40D APSC camera.
Note that in the first test, he uses a Petzval design plus additional Large Field Flattener. Also, he clearly misses exact focus sometimes with the tele lens.
Direct sources are here (sorry these links won't work on copy/paste) :
-> televue_canon
-> TV-60is
From this and other sources I conclude that a good scope design has the same excellent optical performance in the center and at infinity focus compared to a more complex photo tele lens design. However, it's performance drops off when approaching the edges or a closer focus. OTOH, contrast and clarity in the center seems to even outperform the more expensive 10+ element tele lens designs.
So, I think I can summarize the pro and cons of the forthcoming 560/5.6 already:
SUMMARY
IMHO (based on preliminary information as of today) the Pentax DA 560/5.6 is a tele prime lens at a good price point (sub $2000) which rivals the optical performance of much more expensive glass, near the center and at infinity focus, good enough to be used with a tele converter and with good clarity and contrast. OTOH, the lens is very long (and possibly heavy) and the performance will degrade towards the edges of the image field which makes it better suited for APS-C than full frame although it most likely would cover a medium format image circle. Or all in one: Be Different .
Comment by Frogfish posted on New 560mm weather sealed? at 12/02/2012 - 15:41
sterretje wrote:
Could not find prices for Canon equivalents. So we sacrifice a stop (or less) and the price gets down to GBP2000 (1/3 of the Nikon 500/4); sounds like an excellent deal to me.
The Canon's are all around the same price as the Nikons.Could not find prices for Canon equivalents. So we sacrifice a stop (or less) and the price gets down to GBP2000 (1/3 of the Nikon 500/4); sounds like an excellent deal to me.
For one stop (f4/4.5 to f5.6) not only does the price drop dramatically but of course the reason for that is that it is a much smaller and lighter lens too.
Comment by Frogfish posted on New 560mm weather sealed? at 12/02/2012 - 13:36
fritzthedog wrote:
Actually I have the 120-400 and it is as sharp as a tack. An extremely good lens and I have read comparisons that claim it is the sharpest of the 3. I have not owned the 50-500 so have no personal comment to make but I have owned the older version of the 150-500 and have to say that came nowhere near the standard of the 120-400 but the newer version is supposed to be improved..
As for prices telling you all you need to know - if you take SRS as an example - one of our favorite suppliers - the 150-500 is £599 and the 120-400 is £689 - the 120-400 is often more expensive than the 150-500.
Carl
Hi Carl.Actually I have the 120-400 and it is as sharp as a tack. An extremely good lens and I have read comparisons that claim it is the sharpest of the 3. I have not owned the 50-500 so have no personal comment to make but I have owned the older version of the 150-500 and have to say that came nowhere near the standard of the 120-400 but the newer version is supposed to be improved..
As for prices telling you all you need to know - if you take SRS as an example - one of our favorite suppliers - the 150-500 is £599 and the 120-400 is £689 - the 120-400 is often more expensive than the 150-500.
Carl
I think the empirical evidence is out there. I am on a few birding forums as well as other photographic forums and the comments always seem to be the same. It's not that the 120-400 is not capable of sharp shots - it clearly is - but the 150-500 and more so the 50-500 edge it and perform under more varied conditions. Of course hitting that sweet spot in the range is always going to help !
Comment by Frogfish posted on Sigma Long Lenses at 11/02/2012 - 05:48
Plenty of mojo in those shots John.
Comment by Frogfish posted on Canal Walk at 11/02/2012 - 05:40
We can only hope David, but we'll know soon enough !
Comment by Frogfish posted on News of new lenses at 11/02/2012 - 05:38
1. 50-500
2. 150-500
3. 120-400
The price tells you pretty much all you need to know and with these 3 it doesn't lie !
2. 150-500
3. 120-400
The price tells you pretty much all you need to know and with these 3 it doesn't lie !
Comment by Frogfish posted on Sigma Long Lenses at 10/02/2012 - 19:17
Red : easily customised to your preference in the custom menus.
50-150 ? I assume you are talking about the Sigma 50-150/2.8, my go to lens on the K5, it's a great lens and is of course stabilised on Pentax DSLRs.
Travel kit - well I'm actually on holiday as I write this (rest day after driving through the mountains all day yesterday) and I have two kits, one is the walkabout kit which is a K5 with 4/5 lenses in a Tamrac messenger bag (50-150 and 3/4 primes), I never feel this gets heavy (and I'm not a young buck any more !) and in the mountains a large backpack with 2xK5s, 50-150, *300 and 4/5 primes, not good for long treks but if drive/trekking for a few kms then it's great.