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Forum: Pentax Forums Giveaways 01-20-2016, 04:12 PM  
READ ME! Pentax Tips from the Community (55-300mm Giveaway)
Posted By Dr Orloff
Replies: 773
Views: 111,794
The best photographic accessory you can buy is an alarm clock. Get up ridiculously early, it's when the magic happens:

Forum: Pentax SLR Lens Discussion 02-26-2014, 09:08 AM  
Can this be repaired?
Posted By elliott
Replies: 8
Views: 1,429
Bent filter rings happen quite often and there is a tool specifically made to repair it.
Small Lens Vise Tool Repair Filter Ring Professional 30mm to 105mm Steel New | eBay
Forum: Pentax SLR Lens Discussion 02-17-2014, 10:02 PM  
The Bokeh Club
Posted By Eagle_Friends
Replies: 26,005
Views: 2,369,795
FA 77mm f1.8



---------- Post added 02-17-14 at 09:47 PM ----------

Fa 77MM F1.8

Forum: Pentax DSLR Discussion 02-04-2014, 06:04 AM  
Resurrecting Pentax firmware hacking
Posted By Shodan
Replies: 765
Views: 299,142
Resurrecting Pentax firmware hacking

I better start with an introduction as this is my first post. I own a K30 with a load of old manual lenses. I'm also a full time reverse engineer and I'm very interested in rebooting firmware hacking on the Pentax. However I need help and can't do it alone.

I've gone through all the previous posts on Pentax hacking as well as the useful but old Pentax hacking site. Based on this I've seen that the biggest problems for creating a hacked firmware are:
  • Need for experienced reverse engineers

  • Cost of the required tools such as IDA Pro

  • The FP instruction set


Luckily I can help with some of the above. First with experience. I'm a hardware hacker who previously ported CHDK to my Canon Powershot - I've got some experience in hacking firmware on cameras. Next with tooling, for the people who don't know you need an expensive dissasembler called IDA Pro. I have this and the tool that changes assembly into a higher level language - the decompiler. Finally is the instruction set. I've done a lot of work reverse engineering the chip that's inside the K30 and I believe newer models as well. This I think is a Fujitsu Milbeaut MB91696AM. The great thing about this is that it's based around a Dual core ARM Cortex M4 CPU. This means no horrible FP instruction set! It all ARM and that's what I'm good at.

My progress so far:
  • Decrypted the firmware

  • Performed a lot of reverse engineering. Large parts found including memory allocation functions, displaying text on screen etc

  • Found all the debug processing code

  • Found the firmware decryption routines

  • Written custom firmware that allows custom code to be run

  • Started the PHDK project


Useful links:
PHDK Wiki
Paper describing the work so far - very technical
PHDK source code


What I need (so far):
  • Service manual for a K30 (or even a similar model). This would be really useful in understanding how all the debug functionality actually works

  • Datasheet for the MB91696AM or even a very similar ARM based CPU

  • Someone to tell me the offsets to icons/text images in the binary. This would rapidly increase the amount of functions I can find!


How you can help:
  • I will need testers. Be warned there is a small chance of bricking the camera...

  • I need people to help with the disassembly. You'll need a copy of IDA Pro (or maybe notepad - see below).

  • Anyone know anyone at Pentax / Ricoh. I'm considering dropping their marketing team an email.

  • Don't request features. At the moment there is only one feature - get custom code running on the device.

  • Don't request other cameras. I own a K30 and that's what I'm working on.


One of the big things is helping with decompilation of the firmware. It's too big to do alone. Given this I can dump a massive text file with all the functions in C-like code. If anyone has some programming background this might be a good way to help out. Is anyone interested? I still want to play nice with Pentax while i'm requesting their help so I will only PM out the file.

Big issues at present

Icons / text images (fonts)

There are very few strings in the main camera code. All the text is embedded in image data. I suspect that this is as RAW bitmap data directly in the firmware. It would be really useful to get the locations of at least one of these images, then I can find the rest. I'm not quite sure how to find them but The Gimp has an option of opening RAW files and changing the offsets into it. I've had a look but with not much luck.

Give me a few weeks and I hope to be at the point where I can write custom firmware which can then execute a file on the SD card containing additional functionality. I want to perform my code changes inside the debug mode routines, this should mean it's safer as this code is not called by default. At this point some brave soul will need to Flash their camera. Once that works all we will need to do is update the executable on the SD card. Well that's the idea any. Other options are to find a method in the existing debug routines which allow this or alternatively look for an exploit.

Brain dump over.
Forum: Pentax SLR Lens Discussion 01-16-2014, 06:30 PM  
DXOMark - Best lenses for K-3
Posted By falconeye
Replies: 46
Views: 12,140
DxO scores are bad and confusing. But not as bad as some comments here suggest.

The DA15 scores last for a reason and I'll explain why. I personally love that lens, it is a unique offering in the Pentax line up noone else has.

DxO has 3 easily accessible scores:

- A: The DxO score which is a score of how much human visible information a camera/lens can capture in very low light. Here, a fast lens always wins if it is reasonably fast wide open. Here, the DA15 is rated low already because it is a slow lens.

- B: The P-MP score, which "only" averages some sharpness at the best aperture, weighting over the entire image field.

- C: Often overlooked but my preferred score: Mid light use case score, same as DxO score but for very good light.

While the DA15 scores only "14" at A, it scores a solid "30" at C, both scores taken at F/5.6 btw ...

The DA15 would score somewhat better if it wouldn't have extremely soft corners (I'd call them unusable) fully open. Clearly visible at the DxO field map. I am surprised actually that the mid light score didn't peak at F/8, an fstop I always try to use with that lens. The DA15 is great, but for it to be this small, it is only really useful at daylight. The DxO score reflects that.

So, in summary, the DxO scores do make sense but are incomprehensible to normal photographers.

My #1 complaint: the DxO scores violate the principle of divide and conquer: First, divide a problem into manageable subproblems, then solve each of it individually. We already know what a slow aperture means. We do not need no stinking DxO physicist to factor this well known fact into the question how sharp a lens it, making the resulting answer a mess.
Forum: Pentax SLR Lens Discussion 11-19-2013, 09:29 PM  
Next step up from Tamron 70-200mm f/2.8?
Posted By SpecialK
Replies: 42
Views: 4,521
I may have missed something, but if the correct exposure was 1/320, f4 at ISO 12,800 with the Tamron, those will be the same settings for any other lens. You don't miraculously change photon physics simply by going to Canikon.
Forum: Pentax DSLR Discussion 08-01-2013, 12:49 PM  
Pentax DSLR-Specific Landscape Shooters Checklist
Posted By mikeSF
Replies: 12
Views: 2,119
This is a great reminder, again, especially if you are in a rush to arrive at your location before the light changes. Often, the first shot I fire off is the keeper before the good light is lost.
Once, I was racing to shoot a brilliant orange morning twilight sky and only had time to take one long exposure before the colors faded...I had been shooting a kids birthday party the night before using my WB set to FLASH and did not have a spare moment to look at the camera settings...well, not only did I like the resulting blue and pink effect, I ended up selling several of these happy accidents:



This one was so popular, a few months later, I returned to shoot a companion image using similar settings:

Forum: Pentax News and Rumors 07-02-2013, 04:02 AM  
Who are we?! We aren't Pentaxians anymore!
Posted By Fogel70
Replies: 9
Views: 3,538
If going by the name of the company that produce the camera we have not been pentaxians for long. It was only between 2002-2008 that Pentax Corporation produced cameras. Before 2002 it was Asahi optical co that produced "Pentax" cameras.

For most of the time "Pentax" has only been a brand of the cameras, lenses and other products, but not the company.
My Pentax K7 is produced by Hoya. my K10D is produced by Pentax Corporation and my MZ-5n is produced by Asahi Optical Co.
Forum: Pentax News and Rumors 01-26-2013, 02:13 PM  
PentaxForums at CP+ 2013, Interview Question Suggestions
Posted By mikemike
Replies: 189
Views: 28,125
Adam, any chance that you could give us a rundown of which questions you like/plan to ask so far from this thread? Thanks.

Here is another feature suggestion/idea that I think I saw somewhere else around here but should include in this thread. A lens adjustment auto calibration mode. Here is the basic rundown of how I see it basically working, the user prints out a test chart for a specific focal length and tapes it to a surface, puts their camera on a tripod at a specific distance and angle from the chart, enters calibration mode, and the camera then focuses using PDAF (records where it is on the focal range), flips up the mirror and uses CDAF (records where it is on the focal range), then stores the delta as a lens adjustment. Maybe it could be repeated with different focal points, at different distances, or under different lighting conditions but that is basically the gist of it. Seems doable and it would be a useful unique feature, right? It would also probably save them a bundle on service costs if people send cameras or lenses in for FF/BF problems.
Forum: Pentax News and Rumors 09-12-2012, 05:47 AM  
So what happened to the K-3 ?
Posted By LaurenOE
Replies: 372
Views: 47,931
The K3.

Pentax never announces a new camera alongside other products. Not a single camera of recent memory has had to "share the stage" with another. There has always been a spot light that shines on a new camera alone.

The K5 has been a great camera to me, and I'm very happy its being continued. If they fixed problems with the AF - problems I never had - then great.

As for the announcements? It makes sense. What has been released, almost 2 weeks prior to Photokina is nothing "spectacular".

We knew about the Q adapter.
We knew of the Super Zoom.
We knew of the DA560.
We knew the 645 lens was coming.

So all that news was just finishing up what was already known.

The Q10 news is odd in that it's a new camera and is not getting the spotlight treatment. To me that means that something bigger and better overshadows the Q10.

The Q10 just doesn't have enough gravitas to pull in whatever limited Pentax advertising funds are left for 2012. Like the K5 it appears to be a "refresh" more than anything else.

Somehow I think there is something bigger and better coming in a week or so.

If not, then I have to wonder about who thought it was a good idea to "spill the beans" almost 2+ weeks ahead of a huge photo conference. 8/9 products, over the course of a fews days, would be great releases DURING a conference.

Yep. I'm thinking they had to get the word out sooner about the less flashy releases.

I'm thinking the K3 or whatever will surface at Photokina.

If not. Wow. Epic face-palm, which would go against the great Pentax marketing of recent history.
Forum: Pentax News and Rumors 09-06-2012, 06:34 AM  
Watch out Full frame leak from Pentax Australia twitter
Posted By Transit
Replies: 135
Views: 27,872
Nice :)



3 mths better :)

Forum: Pentax SLR Lens Discussion 06-20-2012, 06:14 AM  
IQ of Legacy Lenses
Posted By Lowell Goudge
Replies: 85
Views: 15,014
We really should look at the whole question in several parts.

first of all there have been technical advances in materials and processes, that allow the lens designer to do things differently today.
- computer aided design, this was first fully exploited in the late 1970's with the vivitar series 1 70-210 F3.5, which today still remains a top performer in terms of sharpness and contrast.
- different optical lens machining processes which allow for thinner and more precise optical elements
- different optical materials, such as low dispersion elements, and plastic elements which offer the ability to make optical designs, when combined with the lens machining above, that were simply not possible in the past.

The above 3 points all go to making lenses cheaper, lighter, and with less CA especially.

Then there are changes in optical designs themselves. Many of these changes are the result of different levels of automation.
- the first optical designs were simple 3-5 element designs, with the aperture close to the front element. requiring manual activation
- these designs gave way to auto aperture designs with the aperture moved further back in the lens design to permit automatic aperture with minimal linkage, and open aperture focusing.
- we then began to see fixed rear element designs, (like the K28/2) which were the forerunner of internally focused designs, (useful for AF, and weather sealing)

Then there are the coatings. these have improved substantially over the past 60 years (35mm SLR era) and these continue to improve, reducing flare internally, which results in improved contrast, improving light transmission, and allowing more elements to be installed, permitting more complex optical designs.

overall as lens designs progressed, the center sharpness has not changed, but what has changed is the sharpness at the side of the image, the freedom from CA especially, freedom from vignetting, etc...

but the real thing, as I posted earlier, that is never considered is the rendering of the lens in the out of focus areas i.e. the bokeh. this is largely what keeps older lenses in use, the out of focus rendering. Lenses that have pleasing bokeh will always remain popular.

Edit note

while optical coatings have improved flare resistance and contrast, there is one thing to consider here, and this has been shown over and over again in posts. Contrast and flare resistance can be greatly improved simply by adding a lens hood. This is NOT a trivial matter, and not to be taken lightly, because the lens hoods for legacy lenses in many cases are shorter than optimum even for 35mm format, let alone for the APS-C format we currently use. As a minimum, when I use legacy lenses, I step the hoods down one focal length or more. for example, I use the hood from a Takumar 200/4 on my 85/1.9, i use the 105/2.8 hood on my 50/1.4 etc.

There is also a spreadsheet that I posted on the forum, called hoodcalc. which can be used to calculate the hood length limit before vignetting at the corners. It is worthwhile looking at this because it can help eliminate internal reflections and loss of contrast.
Forum: Pentax News and Rumors 04-21-2012, 10:52 AM  
Photo Forum Russia - Pentax stand - and info about new DSLR
Posted By VladimirYo
Replies: 459
Views: 78,634
On two press-conferences Anton Melnikov didn't say this to the audience. I was on both. But of course 645D is an old enough camera and price cutting is logic step.
Forum: Pentax Full Frame 02-21-2012, 01:01 PM  
How to push the Pentax Full-Frame Idea and get that FF out faster...
Posted By Eigengrau
Replies: 1,493
Views: 184,511
Citations? Claiming that everything after the K10D sold worse and saying that the largest portion of current Pentax users are manual focusers are both things that require pretty heavy backup. Great claims require great proof and all that. Also, you've got a lot of people here that are willing to make a forum post or hit "like" when it comes to FF, but how many will lay down the cash when the time comes?




The D800 offers only 25,600 ISO when boosted, which is matched by the K-5. Of course, we all expect the D800 to have less noise, but only a few years ago we had 6400 MAX iSO, and that was scarcely useable. The point here is that APS-C has made more dramatic improvements than FF did over the same time period. The gap is indeed smaller - I've never said it isn't there, but it is 100% true that it isn't nearly as big as it once was.




I'd agree with you, all else being equal, but it isn't. FF glass is bigger, more expensive, and harder to make. A FF sensor doesn't count for anything if you don't have the glass to support it, and while the used market is substantial for Pentax, none of those used sales put dollars in Pentax' pocket. And as nice as the limiteds are, APS-C is a lot kinder to them than FF will be. Releasing a FF body without competitive lenses to sell with it wouldn't work (see Sony). Putting all the resources into manufacturing those lenses isn't going to be cheap.



If Pentax has to go in that direction, I most likely won't be following, but Sony isn't the only sensor manufacturer out there. They've worked with Samsung before if I'm not mistaken, and maybe something good will turn up. That's more problematic for FF than APS-C, though - finding a quality FF sensor to put in a camera body is harder than an APS-C one, so that isn't convincing.



"Good enough" is subjective, and APS-C viewfinders are good enough for most - just look at the market sizes. Not everybody needs a V8, and not everybody needs a massive SLR to haul around. Where is the most growth likely to be? I've yet to see a convincing argument that big viewfinder full frames are the largest area for new camera sales. Don't make the mistake of assuming that the majority of the market has the same values that you do.




True, but to make a comfortable profit in a high margin environment isn't easy to do - everybody would be otherwise. Pentax has less resources than the competition, so it would be easy for them to be undercut if they really started to rock the boat. Probably the most successful company in this regard is Apple, who offers design and appeal that somehow lets them operate on way larger margins than everybody else. You can try to do that just out of nowhere, but as a for instance, VW tried to move upmarket recently with their Phaeton, and it flopped horribly. If Pentax could do it, great, but that's a big, big if.




Prove it! You have no way of showing that losses are due to the lack of a full frame camera, and your doomsday claims are the same exact things that people have been saying for years. You've got no evidence to show that right now is any different.



Again, baseless conjecture. I personally was really considering moving to a D700 until the K-5 came out. I wanted something that could do a really solid job in indoor light and during wedding receptions, and while the k20 and k-7 were lacking, the k-5 is everything I could ask for. I (like many people) don't care about whether my camera is the best, I care about whether it is enough to do what I need it to do. That is the case for the K-5 in basically all of my use cases.

My main point is this: This online forum, dpreview, and the FF fanatics that have been yelling about it for years, are a very vocal but very limited demographic. Many of these folks shoot on old manual glass, and even if a FF body came out they might not have the cash to buy one (not to mention lenses). You can tell me all you want about you and your friend and this other guy you know who will lay down preorder money for a FF, but talk is cheap and, more importantly, we aren't a very representative group here on the forum.

For Pentax to prosper, they need to find profitable market segments where they can put out class leading products and make lots of money. I've seen little actual data or supported argument explaining why FF is somewhere that Pentax could do well. There are no end of opinions about halo products and people going for Nikon or Canon because of a lack of high-end options, but there's no data I've ever seen to back that up. If a high-end halo product is all that a manufacturer needs to motivate buyers, then Sony should've done great.

The case for FF used to be really good IMO, but it seems to me that it is less solid now than it once was. Sony has had a failure in that segment, there's more competition there than there used to be, and APS-C has been improving a lot. The biggest area of growth right now seems to be on the other end of SLRs - mirrorless and other small SLRs.
Forum: Pentax News and Rumors 02-08-2012, 09:16 AM  
New Lenses?! - Pentax Re-Hiring Engineers
Posted By Asahiflex
Replies: 171
Views: 23,757
They're still on the 2012-2013 roadmap, so I guess they're still being made. I think your country's distributor does not have enough stock.
Forum: Pentax News and Rumors 02-08-2012, 08:53 AM  
New Lenses?! - Pentax Re-Hiring Engineers
Posted By fikkser
Replies: 171
Views: 23,757
BTW. Semi off topic.

Is the FA limiteds getting discontinued?

No major reseller in Sweden has the FA 43. It's only found in two stores online, lowest price is shockingly 1500$. The FA 31 is 2000$+, it used to be around 1500.
Forum: Pentax News and Rumors 01-16-2012, 02:56 AM  
Tethering for APS-C? Pentax USA open to the idea
Posted By tkos
Replies: 38
Views: 7,495
Hi, I don't know why you so waiting for my info. I didn't receive any informations from Pentax US last time. One year ago I ask Pentax US, UK, DE, Japan for any information about communication protocol or any halp in development PK_Tether. I received answer only from Pentax US that they not develop DSLR at all and I should contact Pentax Japan. From other Pentax offices I didn't get any answer. Maybe in near future I will try once again ask Pentax US, but I don't expect nothing new. My experiences with big company is that - manager is telling what she has to or want, and it's not always consistent with what engineers are able to do.
Forum: Pentax News and Rumors 01-05-2012, 05:04 AM  
The Register: K-5 second best DSLR of 2011
Posted By gazonk
Replies: 41
Views: 9,596
This is just very, very wrong, of course having a faster lens will help the AF, and of course you'll get more light in, which is easy to observe in the viewfinder when using a fast lens compared to a slow lens. If I mount e.g. my M-135/3.5 with a 2x TC on my LX, the focusing screen is miserably dark compared to if I had used a fast 270mm lens. In fact, it's also so dark that the micro prisms just turn black and aren't usable for focusing anymore. So even manual focusing is difficult with a slow lens.

(However, some fast lenses have low contrast wide open, this can make AF more difficult)
Forum: Pentax K-5 & K-5 II 12-04-2011, 03:37 AM  
K-5 for sports-photography
Posted By dosdan
Replies: 1,741
Views: 343,454
Ron, might be difficult using the FF's sensor greater sensitivity in sports. The theoretical improvement in SNR (18%) due to the bigger sensor is 1.2 stops (assuming the same quantum efficiency for each sensor).

Take your 300 mm FL f/4 lens. The equiv. FOV on a FF will require a 450mm FL. To get the equivalent DOF on FF, which has a shallower DOF at the same FL & aperture, with that lens you will need to stop down 1.2 stops i.e. f/6.3.

Say you are willing to accept a shallower DOF. Say your 450mm FL lens has a f/5.6 max aperture. Ev = Tv + Av (APEX formula), so the exposure is determined only by the shutter speed & the aperture. Take a shutter speed of 1/1000s & f/4 on APS-C. To get the same exposure on FF with your f/5.6 lens fully open, you will need to drop your shutter speed to 1/500s, and thus enjoy the 1.2 stops better SNR.

However, if you don't want to drop your shutter speed, and use 1/1000s instead. Let's bring ISO into it. Using a LV of 14 as an example:

LV 14 = 1/1000s, f/4, ISO100 (APS-C kit)
LV 14 = 1/1000s, f/5.6, ISO200 (FF kit)

So to keep the shutter speed up on the FF system you will also need to increase the ISO 1 stop. So the sensitivity difference has almost disappeared.

Under the same lighting conditions to fully use the greater sensitivity of FF you need either to:
  • Lower the shutter speed (difficult for sports)

  • Find a 450/F4 lens and accept the shallower DOF (will probably be very expensive)

  • Alternatively, keep using a 300/F4 lens and accept the lower "magnification" (wider FOV) on FF (I know this is a DA lens, but I'm speaking generally)

  • Use a 450/F5.6 lens and increase the ISO

Generally, FF's sensitivity advantage will be best in situations where you can tolerate slower shutter speeds.

Dan.
Forum: Pentax SLR Lens Discussion 11-14-2011, 07:34 PM  
Pentax to Canon EF adapter question
Posted By borno
Replies: 13
Views: 5,711
Hey thorir,
I wish I could remember the seller I got mine from, but most of them look pretty similar. I am pretty sure it was $25 or $30 dollars if that helps. I really wanted to use my pentax 50mm f1.4 I had since 1984 on a full frame so I had to modify it. I don't use it a whole lot though because my eyes aren't too good for MF any more. Anyways it helps me to not miss the FA31mm I sold a while back.:)

Forum: Pentax SLR Lens Discussion 02-25-2011, 06:55 PM  
Looking for advice: landscape lens(es)
Posted By Duplo
Replies: 92
Views: 19,455
Well there is a lot to be said about landscape photography and the lenses to go with it.

IMHO it very much depend on what you want with your landscape images and how you like to shoot.

You will often hear the famous mantra:



(14-24mm in 35mm terms), but it is not really true.
The range can be excellent for landscapes:
(nikon D3 and nikkor 14-24/2.8 @14mm)


But it also has an amazing ability to include everything adn that is not necessarily a good thing, at least to me landscapes is for a large part about simplicity, shape, light and composition.
The simplicity bit in particular is very difficult with ultra wide angle and requires a lot of work.

In my personal experience the best landscape lens is one that has a focal length or range of focal length that works well with how one see things. A lens that makes you "connect" with your surroundings.

Formost people these focal lengths are somwhat longer... For me personally I resonate really really well with the the regular wide angle range of 28-35mm in 35mm terms or 18 - 24mm range on APS-C, with my sweetspot in the middle of the range.
An example from the K-7 and DA21ltd, from a trip to Arches NP:


Now the long normal to short tele range is another often overlooked range.
that is extremely useful for landscape photography, especially when working in areas that are very large, It provides a sweet balance between forground and background elements andhelts retaining simplicity and balanced compositions
Here an example from theFA43ltd mounted on the K-7 from a trip to Nerlerit Inaat:



The tele range should not be forgotten either, It can be highly efficient as a landscape too., either to compress huge scenes in to simple and efficient compositions as in this example shot at 135mm on a nikon D3 at the Ilulissat Icefiord:


The telerange is extremely useful to pick out details, shapes, textures and colour in landscape settings,asseen in thisveryrecent sample shot with theFA77 on a k-7 in Ittoqqortoormiit Fiord:


Above images may not be perfect samples, but theywere what I was able to quickly find in my online galleries.

What really matters when selecting lenses in these ranges is their performance and I tend to look primarily at the lens renderings
Renderings is to me how the lens "draws" the image to the sensor.
As I print large and have clients looking for largish prints I tend to look at how they render when stopped well down, as I need it to get sufficient DOF.
Next comes the middle range of f5.6-f8 and finally the larger than f5.6 range.

Generally lenses with good contrast (micro contrast in particular), colour accuracy and tonality are preferred.

Resolution is another important thing to look at, you want a lens that is sharp enough, but it does not have to be razor sharp wide open IMHO.

How the lens handles bright lightsources in the frame is very important too. Occantionally you want the sun or orther bright light sources in the frame and just outside the frame.
Primes tend to do better than zooms here. As an example The DA*16-50 is a particular poor lens in this regard, below is an example from teh DA*16-50 on the K-7 of what I do not want from a landscape lens:


Bottom line is that there are a lot of excellent lenses out there for landscape photography, IMHO primes are generally preferred IQ wise:
Thus any of the limiteds, the Zeiss ZK range, the DA14, A and FA*24 will all be excellent landscape primes As will likely a whole host of M42 and other K, M, A, F and FA lenses.

The lenses that stands out to me is the DA21 and FA43 though, they are without a doubt my most used lenses for landscapes.

A long winded reply but hopefully it made sense.
Forum: Pentax SLR Lens Discussion 01-23-2011, 11:19 AM  
What fast lens would you choose for portraits (if you were me)?
Posted By newarts
Replies: 23
Views: 6,386
Steve Eastwood posted a suberb series that shows the effect of focal length on portrait perspective for a full frame camera: see Stephen Eastwood|Beauty and Fashion Photographer | Tutorials



The above were taken with a full-frame camera, to have the same perspective you should be at the same distance from the subject; this implies dividing by the crop factor for your camera (or multiplying by 2/3 for a Pentax; ie your uncropped 67mm portrait's perspective will look like Eastwood's uncropped 100mm portrait's perspective.)

Dave
Forum: Pentax DSLR Discussion 11-21-2010, 09:38 PM  
batteries, rechargeable or not?
Posted By UnknownVT
Replies: 28
Views: 6,133
Of the common AA battery formulas - lithium are the "king" for cold temperature usage -
since climbing has been mentioned this may be relevant:

Battery Life

although anecdotal, most recognize that lithium are the way to go.

To be more factual the rated operating temperatures are as follows:

eneloop 0 to 50 deg C
alkaline -18 to 55 deg C
lithium -40 to 60 deg C

So alkaline will work better than eneloop in the cold -
and lithium will out perform alkaline.

Might also want to consider what Pentax actually say about using alkaline batteries in the manual:
K200D


and even the latest K-r when using AA batteries:
Forum: Pentax SLR Lens Discussion 11-15-2010, 08:24 AM  
Binocular Lens Macro Rig
Posted By Paleo Pete
Replies: 13
Views: 5,510
yeatzee - thanks, I wish I could claim it but it was actually a friend's idea. He's been using it with his Nikon for a while and told me about it. I happened to have a junk pair of binocs lying around, the rest is history. I also happen to be a machinist and have a friend with a full machine shop, so I was able to use his lathe to turn mine down a bit shorter, most people will have to rely on a hacksaw.

I know these probably won't match your macros, yours are usually just amazing, but this rig does turn out some nice shots I think.
Forum: Pentax K-5 & K-5 II 10-21-2010, 05:24 AM  
I am a pro shooter and here is why I am so excited for my K-5 to get here tomorrow
Posted By benisona
Replies: 102
Views: 28,344
akanarya,
to get good HDR it is critical to capture the entire dynamic range of the scene. This s only possible with good exposure bracketing, and while this can be done manually in camera (takes a long time) it can also be done using AEB, which luckily for us pentax offers some of the best in the business (so glad there is a dedicated assignable button again, that would have killed me). exposure can be tweaked in photoshop, but no camera in the world has near enough dynamic range captured in one exposure to really allow very successful HDR in this way, unless the scene has very little DR to begin with, in which case HDR really isn't necessary. I think this is one reason why HDR gets such a bad rap, because it is miss understood, abused, when it should only be a tool to help create images similar to what the human brain creates. The brain integrates hundreds of exposures every few seconds into a high dynamic range image merged in the visual cortex. Because of this, the human eye can simultaneously perceive somewhere near 44 stops of exposure. The best camera sensor can only get near 13 in a single exposure. This is why, when used properly, HDR can actually approximate true human vision in a much more "realistic" way. People often criticize tonemapped images as "unrealistic" but IMHO this is only because the vast majority of HDR shooters impliment it poorly. If used well it can create images much closer to what humans percieve in high dynamic range scenes and is only really "surreal" because we are so accustomed to "traditional" single exposure photography.

here are some prime examples:

Lofty Vacancy | Flickr - Photo Sharing!
Near the Shadow of Hope | Flickr - Photo Sharing!
Reflecting Windows | Flickr - Photo Sharing!
Math Machine | Flickr - Photo Sharing!
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