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Forum: Pentax SLR Lens Discussion 06-25-2019, 03:49 PM  
Poll: Do you install a UV filter on all of your lens
Posted By pentageek
Replies: 85
Views: 4,525
I use them for protection only on virtually all lenses, with exception of macro, which have deeply recessed front elements. As per IQ, I observed negligible loss in case of telephoto.
Forum: General Photography 05-10-2019, 12:25 PM  
Why A BIG Camera When The Latest Smart Phones Are So Capable?
Posted By pentageek
Replies: 120
Views: 6,143
I use Samsung S9+, so probably it does not qualify as 'latest and greatest'. For me, 'big' camera offers mainly more convenient controls, better control of depth of field and exposure parameters, and ability to use tele or macro lens. Having said that, I really see no point in using 'big' cameras in general photography - smartphones are so good that for 99,9% of people who take picture the gear is not a limitation at all. In other words, for many people smartphones are so easy to use, and produce so good results, that idea of getting 'big' digital camera became pure nonsense (film is entirely different story).
Forum: Monthly Photo Contests 03-16-2019, 05:25 AM  
Poll: Expired Contest Poll VOTE NOW - Photo Contest #150 Poll (Machines in Motion - February 2019)
Posted By pentageek
Replies: 63
Views: 4,822
I wonder if #12 was deliberately published upside down - quite surprisingly it's a good picture regardless the orientation:)
Forum: Pentax Medium Format 02-26-2019, 12:29 PM  
Medium format needs a lot more light?
Posted By pentageek
Replies: 61
Views: 3,530
There are at least two approaches:)

1. 'traditional' 1/f rule - ignores format
2. 1/f rule with crop factor - this is the scenario where you could use slower shutter. Basically it means that 1/50s should be fine for every 'standard' lens regardless the format.

To shed a light on the latter: 1/50s should (on average) yield sharp images in following configurations: 35mm / APS-C, 50mm / Full Frame, and 90mm / 6x7, in short with 'standard' lens for given format. In reality, it depends on photographer and equipment used - I use option 1, but this is my personal choice, and of course YMMV. Weight of the camera may affect minimal shutter speed, but again this is matter of personal preference, albeit most people claim that heavier cameras are more stable. The weight may differ significantly even within same class of MF - for example Mamiya RB 67 is around 50% heavier than Pentax 67.
Forum: Pentax Medium Format 02-26-2019, 10:56 AM  
Medium format needs a lot more light?
Posted By pentageek
Replies: 61
Views: 3,530
I wonder which question I should answer first - let's start with amount of light. MF lenses do have longer focal lengths in order to preserve proper field of view, for instance 'standard' for 6x7 is either 90 or 127 mm. Using 1/f rule, it means slowest shutter speed of 1/90 or 1/120 s. Moreover. these lenses are slow - f/1.8 for Mamiya 645 is the fastest one, the rest for this system offers something like f/2.4 at best. Lenses for 67 are even slower, typically around 3.5 or 4. When you take bellows into account, like in Mamiya RB/RZ, additional 0.5 or 1 stop of light can be lost. Is MF practical? Well, it depends on how you are going to use it, and which MF we talk about. In general 645 SLR can be considered heavy and beefed up version of 24x36. Mamiya RB 67 is like a heavy shoebox:) but it is capable camera. 6x9 rangefinder (i.e. Fuji GSW) is large, but light. I haven't had Pentax 67 so I cannot tell anything about it.
Forum: Pentax News and Rumors 02-13-2019, 03:21 PM  
CP+ interview question suggestions
Posted By pentageek
Replies: 129
Views: 9,212
I second this: so far virtually all camera manufacturers (with exception of Sony) seem to ignore the fact that modern cameras are actually specialized image processing computers. What about operating system for cameras? Ricoh could be the first manufacturer offering such novel approach. Project Lantern has been providing something similar, but this is not official Canon software.

Another question: what about true wireless flash system? In my opinion even budget radio systems (like Yongnuo which I use) are superior in terms of range and reliability to optical ones, and Ricoh could consider K-1 III 'Flash Commander' version:)
Forum: Photographic Industry and Professionals 02-04-2019, 01:43 PM  
Need help for amateur wedding and equipment.
Posted By pentageek
Replies: 40
Views: 2,243
Don't you think you should rather take part in the ceremony and enjoy the wedding? Someone else can take pictures. As per gear, I did similar gig with K-S2 and 18-135, newly-weds were very satisfied with results. Of course every excuse is good to buy K-1:)
Forum: Pentax SLR Lens Discussion 01-18-2019, 12:15 PM  
Macro Lenses Suggestions
Posted By pentageek
Replies: 73
Views: 3,576
I use F 100/2.8, sometimes also M 50/4 (both macro), albeit the latter offers only 1:2 reproduction rate. Both are relatively cheap, and because I use manual (i.e. cheaper one without P-TTL) macro flash, support for flash metering is irrelevant. In the past I was considering DFA 100 WR, but it does not work with bellows. On the other hand, while in the field WR lens is definitely an advantage.
Forum: Pentax DSLR Discussion 12-27-2018, 08:06 AM  
In-Body vs. In-Lens stabilisation - pro's and con's?
Posted By pentageek
Replies: 27
Views: 1,659
I compared ILS in Sigma 150-500 with IBIS in K-S2 and K-1, and the ILS turned out to be slightly more effective, probably due to being tuned up to specific lens. The difference was minimal, but I decided to create separate user settings just for Bigma with IBIS turned off. 'Stabilization' of optical viewfinder is nice side effect. As per shorter FLs, I definitely appreciate ability of IBIS to stabilize virtually anything, with exception of old zooms which I do not use anyway.
Forum: Pentax News and Rumors 11-01-2018, 09:27 AM  
Ricoh Imaging Square Shanghai opens
Posted By pentageek
Replies: 20
Views: 5,058
Good to know that Ricoh decided to open new centre at Luban Road. The location is famous for camera shops, and presence of Ricoh will show their commitment to Pentax:) and photo industry in general.
Forum: General Photography 08-31-2018, 02:58 PM  
Purposely out of focus
Posted By pentageek
Replies: 105
Views: 4,644
You're not:) Focus and intentional out of focus are just means to create a picture.
Forum: General Photography 08-29-2018, 02:07 PM  
SR and ext tubes
Posted By pentageek
Replies: 27
Views: 830
Your question inspired me to look for an answer - here's my take on this, I used this article as a source. Effective f/stop in macro can be approximated* as per following formula:


(1) effective f/stop = f/stop x (1 + magnification)

The formula for f/stop is simple:

(2) f/stop = focal length / aperture diameter.


It means that at given diameter, if we increase focal length twofold, f/stop will increase proportionally. Let's take a look at common macro lens as example: 100/2.8. Its aperture at 2.8 has diameter of roughly 36 mm, if we increase FL to 200mm, f/stop will be 200 / 36 = 5.6. If we compare it to (1), we can see that at 1x magnification effective f/stop becomes twice as high as original one (for instance f/16 instead of f/8), just as we were increasing focal length twofold. Putting all this together, we can derive formula for approximate focal length:

(3) effective FL = FL x (1 + magnification).

I wonder what your opinion is - please let me know if you find such reasoning correct or flawed.


*) precise value can be computed when pupil magnification is known, for details, please see the aforementioned Cambridgeincolour article.
Forum: Pentax SLR Lens Discussion 08-25-2018, 04:30 PM  
What do all the graduations and markings mean on lenses?
Posted By pentageek
Replies: 17
Views: 1,405
Our beloved Ken Rockwell wrote on this here. And yes, you can still see lack of sharpness in hyperfocal range.
Forum: Pentax Camera and Field Accessories 08-02-2018, 10:04 AM  
Best cross-body strap for D-FA*70-200 on K-1?
Posted By pentageek
Replies: 26
Views: 1,485
Thanks for sharing, I didn't know about them.
Forum: Pentax SLR Lens Discussion 08-03-2018, 12:31 PM  
What the Duck! D-FA* 50/1.4
Posted By pentageek
Replies: 42
Views: 3,381
The goose, appreciating quality of the lens, was willing to cooperate:) I thought that 50mm is not my favourite FL, but pictures taken with DFA 50/1,4 are so good, that I feel how LBA kicks in.
Forum: Pentax SLR Lens Discussion 07-22-2018, 11:45 PM  
Hello looking for some Pentax DSLR advice
Posted By pentageek
Replies: 28
Views: 1,311
1. I have K-S2, and I used to consider upgrade to K-3 I or II. I asked forum members whether such upgrade would affect image quality, and the answer was 'you will not see significant difference'. 2. Average body with good lens will produce better results than good body with average lens.
Forum: Pentax Film SLR Discussion 06-23-2018, 01:09 AM  
Pentax Spotmatic features in cool new Steve Carell movie
Posted By pentageek
Replies: 28
Views: 2,031
I think you guessed it right:) - the part with 'Asahi Pentax' is pretty bulky, like in M42 cameras, and there is a hotshoe, introduced in Mark II.
Forum: Pentax Film SLR Discussion 06-03-2018, 01:29 PM  
Pentax 645n/645nii vs 67
Posted By pentageek
Replies: 35
Views: 3,656
I second this. I had the same dilemma in the past, and I think you should decide whether you are going to use 645, or rather 67 (regardless actual make). Once you make your mind, it is going to be much easier to select the gear.

P.S. I decided to use Mamiya RB 67 for its rotating back and ability to change the film mid-roll.
Forum: Pentax DSLR Discussion 05-29-2018, 03:05 PM  
Need a recommendation for my first pentax DSLR (used or new)
Posted By pentageek
Replies: 43
Views: 2,857
I paid around $100 for the fix for aperture block alone, and as far as I can tell it was pretty decent price. $325 for the camera seems to be very good deal.
Forum: Pentax SLR Lens Discussion 05-24-2018, 12:29 PM  
Going on business trip to china..worth looking camera shops at Shanhai or..
Posted By pentageek
Replies: 11
Views: 662
Yes, this is very interesting place, definitely worth visiting - too bad I did not know about second building when I was there! In first building (the one closer to traffic lights) I encountered Pentax shop on top floor where there was no customer at all, and the place did not look like a centre of photographic or commercial activity:( As per prices, 'made in China' stuff is cheap - of course asking price is high, but if you are going to buy something, you can check the price at taobao.com, add 10%, and get such price after short negotiation. Taobao is in Chinese, but search engine accepts Latin script.
Forum: General Photography 05-24-2018, 12:38 PM  
Eagle steals rabbit from fox photos
Posted By pentageek
Replies: 9
Views: 843
Outstanding pictures, thanks for sharing! Poor fox lost the supper that day:(
Forum: Pentax K-1 05-14-2018, 03:42 PM  
What happens when you have your K-1 upgraded
Posted By pentageek
Replies: 26
Views: 2,834
Thanks for sharing. The procedure seems to be pretty straight-forward, and I wonder why Ricoh was presenting it as nearly magical mumbo-jumbo worth 500 EUR/USD - probably it is mostly the cost of the PCB.
Forum: General Photography 01-14-2018, 10:46 AM  
Inside one of America's last pencil factories
Posted By pentageek
Replies: 15
Views: 1,246
I've heard the story before, and this was more complex - before we move on, I have to admit that I do not know whether original story was result of lax approach (to say the least) of Russians to safety protocols in their space program. The pencil aboard a spaceship is pretty risky idea - when writing, minute amount of graphite dust is released, and sharpening releases graphite dust (again) and splinters of wood. Early spacecraft had oxygen atmosphere which unfortunately makes many things very flammable. So we have oxygen atmosphere, splinters of wood (very flammable under such conditions), and graphite dust (flammable and conductive - may cause shortcuts) - this is dangerous combination, and NASA probably did not want to take the risk.
Forum: Pentax DSLR Discussion 05-14-2018, 11:33 AM  
So I've shot my first "commercial" gig - thoughts
Posted By pentageek
Replies: 11
Views: 999
It depends on shooting situation - I think a comparison of 28-105@28 and 15-30@30 would be a good starting point, as you have got both lenses, and 28-105, albeit slower than 24-70, offers decent AF performance. The other option (which I use with Irix 15mm), is hyperfocal distance. Manual focusing has already landed you more keepers, so with little preparation hyperfocal method could solve the problem.
Forum: Troubleshooting and Beginner Help 04-20-2018, 03:32 AM  
Image Stabilization
Posted By pentageek
Replies: 11
Views: 1,023
For anyone interested in effectiveness of SR, RawTherapee provides interesting information - in main editor screeen, one can find EXIF information called 'SRResult' (it's under EXIF -> Maker note -> Shake Reduction).
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