Forgot Password
Pentax Camera Forums Home
 

Showing results 1 to 25 of 300 Search:
Forum: Sold Items 06-23-2012, 12:46 PM  
For Sale - Sold: Pentax FA 28-70mm f/4
Posted By bc_the_path
Replies: 8
Views: 3,040
I like this lens a lot and use it on three bodies (OK, not at the same time!). You can see a relatively high ISO image of our restless dog Pebble in World Pentax Day Gallery. It was taken using this particular lens (instead of a dozen others!). I fully recommend it...
Forum: Pentax SLR Lens Discussion 05-02-2012, 01:37 PM  
Best 135mm manual lens
Posted By bc_the_path
Replies: 31
Views: 19,445
Just to confuse followers of this thread (!), I would like to mention Jupiter 37A, an M42 Soviet lens (135mm f/3.5) which is said to share its formula with a Leica of the same length. My copy turned out to be a lot better than the ones I compared it (a Takumar and a Pentacon). It is MC and sharp wide open. The rendering of out of focus highlights is simply beautiful. I am planning to test it against my DA Star 50-135mm (with dead SDM) at 135mm. It sure is going to be an unfair test; I just don't know unfair for which!!!
Forum: General Talk 07-06-2011, 12:12 AM  
New PF Look: A sneak preview!
Posted By bc_the_path
Replies: 88
Views: 12,069
The best thing about the change is larger fonts, I believe.
Anxious to see it online :)
Forum: Pentax K-5 04-16-2011, 01:34 PM  
What's wrong with my k-5 raw images?
Posted By bc_the_path
Replies: 56
Views: 8,059
>There's no front focus issue that I know of.
Then, how do you explain that in your original K5 shot the eyebrows are sharper than the eyelashes (UNLIKE those in the K-x image)?
Forum: Pentax K-5 04-16-2011, 12:56 PM  
What's wrong with my k-5 raw images?
Posted By bc_the_path
Replies: 56
Views: 8,059
I do not understand why you don't see the point.
If you are interested in the "look" of K5 images; shoot an eye at f/8 and examine (pixel-peep) the image. If you are not interested in whether the shallow DOF (combined with some FF) is effecting the sharpness of your images; why are you shooting wide open?
Forum: Pentax K-5 04-16-2011, 12:30 PM  
What's wrong with my k-5 raw images?
Posted By bc_the_path
Replies: 56
Views: 8,059
Your K5 is front focusing.
Just look at the eyebrows; they are sharp in your second photo and blurry in your first...
Must be very easy to adjust.
Forum: Sold Items 03-09-2011, 11:57 AM  
For Sale - Sold: Super-Takumar 55mm f/1.8 M42 (US/CAN)
Posted By bc_the_path
Replies: 8
Views: 4,501
A free bump!
This is a must especially for those who have only the kit lens covering this range. The performance of this lens is simply uncomparable. Not only it is fast and sharp, it also produces a very pleasing bokeh. I love mine (and, have a few other primes at this range!).
Forum: Digital Processing, Software, and Printing 03-02-2011, 01:58 PM  
Curve transfer for RAW. Is there such a thing?
Posted By bc_the_path
Replies: 0
Views: 1,711
I understand that a raw developer software works like the clasical darkroom "developer" (solution). There are different varieties producing different outputs from the same negative/raw file. In the film days, companies (like Kodak) used to suggest their own developers for their films. However, experienced photographers have always used their favorite film with their favorite developer without necessarily taking those suggestions into account.

Pentax suggests Silkypix to develop their raw files.

Let us say, I like the look of the raw files developed by Siykypix.
And, let us assume that I happen to like Brand X Raw Developer, which is very good in certain regards. However, "the look" of the developed file (jpeg or otherwise) is not that good.

We know that raw developers apply a curve to the raw data and, like chemicals used in the film days, these curves result in different looks.

My question is this:
Is there a practical way (other than trial and error) to use/copy/replicate the effect of a curve of, say, Silkypix for another raw developer? Or, the curves are hidden, embedded, protected etc.?
Forum: Pentax News and Rumors 01-27-2011, 02:58 PM  
Many K-5s are on their way back home!
Posted By bc_the_path
Replies: 1
Views: 3,508
The Turkish representative of Pentax (Nar Teknoloji) today released a statement which can be summarized as below (they are still to sell their very first "legally imported" K-5 here):
- There is a delay in the customs (which may have nothing to do with Pentax or its representative, by the way).
- The cameras were inspected while they were waiting for customs procedures to complete. Unfortunately, most of them had the sensor stain problem.
- The representative decided to send them back to Pentax Europe and the few remaining ones with good sensors will be used as samples for the press when the procedures are complete.
- Those who want to buy a K-5 from the local markets should wait for some time.


It seems plausible that others are also returning units back as well. I guess the recent signs of shortage of K5s in certain markets may have something to do with Pentax busy replacing the faulty sensors.
Forum: Pentax K-5 01-14-2011, 01:20 PM  
Relevant news re malfunctioning AF under artificial light
Posted By bc_the_path
Replies: 752
Views: 95,355
Well, this is no "news"; but I have a theory after reading many of the comments about FF with especially screw driven lenses under low light.

My reasoning follows these lines:
- Pentax is no new player in this AF business.
- Pentax has other cameras (functioning properly) with this same hardware.
- Pentax has certainly tested the prototype under low light conditions; as this was meant to be a selling point.
- The range of AF adjustment by the user is insufficient to correct the problem.

Here is my conclusion:
The placement / alignment of the low light AF sensor is faulty.
And, this must be a workmanship and QC issue.
I believe this can conceivably be due to a component being slightly thicker or thinner than the specification (can be about 50-100 micrometers). This results in a misplaced sensor.

Proof?
Of course lacking ;)
However, my recent attempt at buying a K5 has just failed because the seller told me that he could not find a new unit for shipment! Could this be a potential proof?

Bad news?
If my reasoning and *guess* is correct, no firmware fix can resolve the issue. (Yet, all K5s are still under warranty).

Good news?
The issue is resolvable and people with "proper" K5s are going to be very happy owners!
Forum: Pentax Camera and Field Accessories 01-11-2011, 03:04 PM  
Tenpa Magnifier
Posted By bc_the_path
Replies: 25
Views: 13,884
Just for the record:
Nikon DK-21M eyepiece magnifier (approx. x 1.2) is almost the same (optically) as the original Pentax piece (O-ME53); only cheaper (less than half the price of the Pentax part)!
I have been using it for the last couple of years on K10D and K20D. It magnifies just a bit but that certainly helps. I believe it fits on practically all Pentax DSLRs.
Forum: Pentax SLR Lens Discussion 12-22-2010, 04:29 AM  
What causes backfocus or frontfocus?
Posted By bc_the_path
Replies: 19
Views: 5,656
There is also the "aperture value" of the focusing elements. Like lenses, a wide aperture system is more expensive. A narrow aperture system is easier to build and cheaper. Used along with "like" lenses the (inevitable) focus errors are not obvious as DOF is big enough to hide them. The errors usally become a problem when we try to focus using a narrow aperture system (say, f/5.6) with a tele lens at f/2 or so.
Hunting happens when the focus sensor "notices" that the change in positions of the elements produce a poorer contrast.
All the arguments aside, I do not understand why focus adjustment is possible only in the higher end DSLRs. It is a must especially for wide aperture lenses, anyway...
Forum: Pentax SLR Lens Discussion 12-22-2010, 02:31 AM  
What causes backfocus or frontfocus?
Posted By bc_the_path
Replies: 19
Views: 5,656
I see the readers fail to realize that this is more a "mechanical" rather than an optical phenomenon.
The focus sensor and its chip decides that "it is OK" when they sense maximum contrast (or, whatever). Then, the chip sends a signal to the moving parts (outside the sensor, mechanical) to "stop". Every lens (depending on age, brand, focal length, local temperature etc.) reacts just a tiny amount differently. The mechanism comes to a stop "after" a while, where the focused point may no longer be "exactly the same" as that was found good by the sensor&chip. This may or may not alter the focus point noticeably and consistently. Adjusting for back focus and/or front focus can be talking specifically to that lens to account for the delay in its response. If the camera side is weak/faulty/problematic, than you adjust for the camera. Of course, an occasional problem can be out of reach of the supplied adjustment tolerances and sevice may be needed.
The focusing screens of our DSLRs are of no help in showing us the differences in focus resulting due to these events. There are "optical" reasons for that.
Does your car stop the moment you hit the brake?
Forum: Pentax SLR Lens Discussion 12-21-2010, 09:17 AM  
What causes backfocus or frontfocus?
Posted By bc_the_path
Replies: 19
Views: 5,656
As far as I understand, some degree of unwanted movement is inevitable in any two (or more) mechanically coupled moving parts. Stopping one, for example, stops the other only after some time. The more parts the system has the more difficult it is to 'standardize' the potential errors. Also, cheaper, poorly made systems has more "leeway". This resembles, more are less, the situation with the steering wheel of the cars. It is "normal"to have some movement of it, "before" you move the wheels.
Forum: Post Your Photos! 12-12-2010, 03:40 PM  
Macro A Single Lemon Blossom
Posted By bc_the_path
Replies: 6
Views: 1,112
This is almost perfect except, perhaps, for the bright right upper part.
Forum: Post Your Photos! 12-12-2010, 03:38 PM  
Abstract The Yellow Block & The Dog
Posted By bc_the_path
Replies: 0
Views: 958
A rather remote allegory of the first part of Kubrick's "2001 Space Odyssey".
Forum: Site Suggestions and Help 11-23-2010, 08:55 AM  
News We're back!
Posted By bc_the_path
Replies: 48
Views: 2,504
You have been missed definitely :)
Thanks for all the effort.
Forum: Pentax SLR Lens Discussion 10-14-2010, 02:35 PM  
Sigma 17-50mm F2.8 EX DC OS HSM ?
Posted By bc_the_path
Replies: 3
Views: 4,789
If you only want to replace the kit lens; Sigma 17-70mm f/2.8-4.5 is also a viable alternative. It has better IQ (than the kit lens), it is versatile and it is more affordable than the fixed aperture offerings.
Forum: Pentax SLR Lens Discussion 10-12-2010, 01:40 AM  
Sigma 17-50mm f/2.8 EX DC with OS (~SDM)
Posted By bc_the_path
Replies: 2
Views: 2,594
- There is no front- or back focus.
- The lens is internally focusing. The length changes only with the focal length.
- AF is fast. Really, very fast (and, naturally, quiet). This is due in part to the very short focus travel; about 30 degrees, perhaps. So, from 30cm to infinity the barrel takes not more than a 1/10th of a full turn.
- MF is possible but unlikely to be precise, see above.
- Optical stabilization (turning the SR off) is very good and probably a bit better than the in-body system. However I have not done any systematic testing. I already got the impression that OS may be consuming a bit more battery power than the SR. Time will tell.
- The barrel does move during AF but this is hardly a problem since the travel is usually a few millimeters only.
- Resolution and contrast are very good (again, without formal testing yet).
Forum: Pentax SLR Lens Discussion 10-11-2010, 05:14 AM  
Sigma 17-50mm f/2.8 EX DC with OS (~SDM)
Posted By bc_the_path
Replies: 2
Views: 2,594
As a former (happy) user of Sigma's versatile 17-70mm f/2.8-4.5 lens; I have just got the new offering with fixed maximum aperture today. I will report my experiences here soon (perhaps reviving this thread).
In the meantime, you can perhaps look at the two reviews about this new kid on the block (on different mounts):
1) Photozone:
Sigma AF 17-50mm f/2.8 HSM DC EX OS - Review / Test Report

2) Lenstip (a useful Polish site) :
Sigma 17-50 mm f/2.8 EX DC OS HSM review - Introduction - Lenstip.com

A comparative analysis with Tamron 17-50mm f/2.8 would be nice (as the Pentax lens with the similar range is pricier than both). I believe the reported user experiences with the Tamron was very good.

My first impression is positive and the lens seems to be focusing normally (no front- or backfocus). More will follow :)
Forum: Sold Items 08-27-2010, 12:48 AM  
For Sale - Sold: P645 Viewfinder Magnifier for Critical Focusing (very rare) (Worldwide)
Posted By bc_the_path
Replies: 7
Views: 2,830
I have one of these and I use it practically always!
If you routinely shoot using a 645, this is a really nice, helpful accessory...
No connection with the seller, by the way :)
Forum: Pentax SLR Lens Discussion 08-06-2010, 12:55 PM  
Tamron 17-50mm .. is it REALLY worth it?
Posted By bc_the_path
Replies: 36
Views: 7,311
How about the the recently announced (and seemingly available) Sigma 17-50mm f/2.8 EX with OS/USM/SDM, whatever?
Forum: Pentax SLR Lens Discussion 07-21-2010, 01:51 AM  
Sigma 55-300mm or Pentax 55-300mm ?
Posted By bc_the_path
Replies: 17
Views: 5,511
I have used both.
Sigma is bigger &heavier of the two.
Towards the tele end, both deteriorate a bit and loose contrast; Pentax remains somewhat better.
For most other focal lengths there is ittle difference between them. Still, Pentax always feels better.
Overall, I am pleased by the Pentax one (I have more Sigma glass which I like) and sold the Sigma.
Forum: Sold Items 06-25-2010, 11:46 AM  
Wanted - Acquired: Pentax 35-105mm 3.5 SMC-A Zoom
Posted By bc_the_path
Replies: 11
Views: 3,591
PM sent...
Forum: Pentax SLR Lens Discussion 06-17-2010, 12:35 PM  
Tamron 17-50mm f2.8 or Tamron 28-75mm f2.8
Posted By bc_the_path
Replies: 19
Views: 7,999
You say:
P.S. I am also interested in Sigma 17-70 but I have a Sigma 70-300 APO and I feel that Sigma's ring (to zoom in/ out) is tighter to move, in other words not as smooth as Pentax lens so I am thinking to give Tamron a try.

I have used both of those. The 70-300mm was the first lens I have sold. The 17-70mm served me nicely for quite a long time. Its construction, ease of use and optical quality are noticeably better than the tele one. I have no idea about the Tamrons, though people seem to be happy with them. The Sigma 17-70mm also allows for close focusing, which you may enjoy.
Search took 0.17 seconds | Showing results 1 to 25 of 300

 
Forum Jump


All times are GMT -7. The time now is 10:45 AM. | See also: NikonForums.com, CanonForums.com part of our network of photo forums!
  • Red (Default)
  • Green
  • Gray
  • Dark
  • Dark Yellow
  • Dark Blue
  • Old Red
  • Old Green
  • Old Gray
  • Dial-Up Style
Hello! It's great to see you back on the forum! Have you considered joining the community?
register
Creating a FREE ACCOUNT takes under a minute, removes ads, and lets you post! [Dismiss]
Top