Forgot Password
Pentax Camera Forums Home
 

Showing results 1 to 25 of 300 Search:
Forum: Pentax K-1 07-08-2016, 09:04 AM  
Been banned from DPReview
Posted By osv
Replies: 133
Views: 11,006
:lol: i didn't look at any of the af pics, but given the rhetoric that constantly gets posted by some people on this forum, i suspect that there is more to the dpr discussion than what we are reading in this thread...

the community needs to post up their own *credible* k1 af data.
Forum: Pentax K-1 07-08-2016, 08:28 AM  
Been banned from DPReview
Posted By osv
Replies: 133
Views: 11,006
i've had some epic arguments with rishi, he's a smart guy, and overall he's done more good at dpr than all of the mods/admins put together.

i would suggest that rather than bemoaning the dismal state of affairs at dpr, the pentax community publish their own sets of af tests, using the same criteria that dpr did.

it sounds like a lot of that testing has been done already, just need to present it somewhere.
Forum: Pentax SLR Lens Discussion 07-07-2016, 05:15 PM  
My understanding of putting FF lens on crop body
Posted By osv
Replies: 47
Views: 2,705
lol... i suspect that people have already reached the bottom of this discussion, you can't make it any worse.

and no, for the record the ink cost argument isn't very convincing :D
Forum: Pentax SLR Lens Discussion 07-07-2016, 04:15 PM  
My understanding of putting FF lens on crop body
Posted By osv
Replies: 47
Views: 2,705
the o.p. didn't mention any specific focal length, so he clearly wasn't asking for a comparison between specific 50mm lenses, like you are doing... stop trying to confuse the intent of the thread with misinterpretations of what it's about.

---------- Post added 07-07-16 at 04:29 PM ----------



:lol: he did state: "I can see a point in the future when I may go FF"

so if equivalence doesn't matter, why did pentax rate the lens for aps-c use? even sony has both a fast 50 and a slow 50 for ff, it's not like a slow 50 should cut into the sales of fast 50's.
Forum: Pentax SLR Lens Discussion 07-07-2016, 03:58 PM  
My understanding of putting FF lens on crop body
Posted By osv
Replies: 47
Views: 2,705
i don't think you are trolling, but at this point i'm convinced that english must be a second language for you.



why do you keeping failing to understand the implications of that? stop pretending that sensor size doesn't matter... i'll explain it once again, per the link: " Total Light = Exposure Effective Sensor Area. The same total amount of light will fall on the sensor for equivalent photos but, for different formats, this will necessarily result in a different exposure on each format, since the same total light distributed over sensors with different areas will result in a lower density of light on the larger sensor."

your claim that "the amount of light per square millimeter is the same" is disingenous, it's not the same with equivalence, because the differences in sensor sizes must be compensated for with differences in exposure.

sure a 50-watt bulb puts out the same amount of light regardless of what size of sensor takes the pic, but that doesn't mean that sensors of different sizes will use the same camera settings to capture the same pic... quite the opposite in fact.
Forum: Pentax SLR Lens Discussion 07-07-2016, 03:10 PM  
My understanding of putting FF lens on crop body
Posted By osv
Replies: 47
Views: 2,705
no, it's you who are confused and wrong, despite all the factual link information that's been posted.



correct, no one ever claimed otherwise... what you fail to understand is that it's the effective focal length(aka angle of view) that was proven to change with sensor size... at least othar got that part right, i'm kind of shocked that you don't know better.

don't tell us how p&s cameras have an equivalence rating, then turn around and claim that there is no such thing as an equivalence rating for aps-c cameras... the same exact principles apply in both cases.



totally wrong, you are confusing aperture with exposure... "Aperture is the size of the opening in the lens." Aperture in Photography Defined | explora it's a physical measurement of size, period.

aperture size is like focal length, it can't be changed, but like focal length, the effect of aperture size is altered with sensor size, which you yourself admitted with your correct post on the sensor-sized differences in the onset of diffraction(wrt aperture numbers on the aperture ring).



once again you contradict yourself... a 50mm ff lens on ff is also a 50mm lens on p&s cameras, so why do the manufacturers put equivalence ratings on p&s lenses... hint: it's to prevent people like we have in this thread from getting confused, lol
Forum: Pentax SLR Lens Discussion 07-07-2016, 08:14 AM  
My understanding of putting FF lens on crop body
Posted By osv
Replies: 47
Views: 2,705
wrong... you need to read the link i posted.

---------- Post added 07-07-16 at 08:41 AM ----------



i agree that the lens itself doesn't change, but the effect is not the same, as you admitted, the fov is different, and i'm here to tell you that the aperture numbers on the aperture ring are therefore also effectively wrong.

you claim no disadvantage, then admit that there is a difference, and argue semantics about what the word "disadvantage" really means.

if you want to claim that everything being wrong is not a disadvantage, you are certainly welcome to your opinion... i do agree that with ff lenses on crop, we get used to everything being wrong, but my point is, lets not lose sight of what the truth really is.



that's another contradiction, and it's not correct because the total light falling on different sensor sizes is different... you can't have it both ways... "Saying "f/2 = f/2 = f/2" is like saying "50mm = 50mm = 50mm". Just as the effect of 50mm is not the same on different formats, the effect of f/2 is not the same on different formats... Total Light = Exposure x Effective Sensor Area, and it is the total amount of light falling on the sensor, as opposed to the exposure, which is the relevant measure."

that's why the aperture numbers are wrong.
Forum: Pentax SLR Lens Discussion 07-06-2016, 06:28 PM  
My understanding of putting FF lens on crop body
Posted By osv
Replies: 47
Views: 2,705
that's what i gave him, disadvantages with putting ff glass on a crop sensor... 1)the focal length is wrong, 2)the aperture numbers are wrong, 3)the point of visible diffraction doesn't match the aperture number, etc.
Forum: Pentax Full Frame 07-06-2016, 02:47 PM  
Good landscape lens for Pentax K1 full frame
Posted By osv
Replies: 35
Views: 8,343
the field curvature characteristics are displayed in the photos, so it's best seen on a comparison basis with other lenses of similar focal lengths... here is an explanation of sorts: photo technique magazine Field Curvature

it can get complicated with lenses that have a donut-shaped focus field(aka wavy field curvature), wherein the far edges and the center 1/3rd are the sharpest parts of the picture.



i think that he was referring to this: "Pentax also implemented a built-in flower shaped hood which cannot be removed"
Pentax SMC-FA 31mm f/1.8 AL Limited - Review / Test Report
Forum: Pentax SLR Lens Discussion 07-06-2016, 02:32 PM  
My understanding of putting FF lens on crop body
Posted By osv
Replies: 47
Views: 2,705
no need for equivalence? gee, maybe you'd better email cambridge in colour and tell them that their calculator is all wrong.



in a word, no: "Neither the focal length nor the f-ratio of a lens change as a function of sensor (for example, a 50mm f/1.4 lens is a 50mm f/1.4 lens, regardless of the sensor behind the lens). However, the effect of both the focal length and the f-ratio on the visual properties of the photo very much depend on the sensor, and scale in direct proportion to the size of the sensor.

25mm f/1.4 on mFT (4/3) is equivalent to 31mm f/1.8 on 1.6x (Canon APS-C), 33mm f/1.9 on 1.5x (APS-C for everyone else), and 50mm f/2.8 on FF (FX), where "equivalent to" means:"

Equivalence
Forum: Pentax SLR Lens Discussion 07-05-2016, 06:30 PM  
My understanding of putting FF lens on crop body
Posted By osv
Replies: 47
Views: 2,705
the only true comparisons are at an equivalent field of view, dof, distance, etc., so yes, you chop out edge weaknesses with a ff lens on crop, but what happens to edge quality with the equivalent lens on crop?

if 28mm ff shot at f/2 = 18mm crop shot at f/1.3 Digital Camera Sensor Sizes: How it Influences Your Photography

which lens is going to be the hardest and most expensive to design? forget the difficulty of 18mm at a fast f/1.3 aperture, keep it simple, which lens will generally have the least amount of distortion?
Forum: Pentax SLR Lens Discussion 07-05-2016, 11:08 AM  
Dongzheng Optics Kerlee 35 mm f/1.2
Posted By osv
Replies: 45
Views: 6,813
that was interesting, thx for the link... wish that he would have used a 36mp camera instead of a 16mp camera for the landscape pics.

---------- Post added 07-05-16 at 11:10 AM ----------



lol... he didn't provide any evidence either way, but it would be interesting to see how they all compare.
Forum: Digital Processing, Software, and Printing 07-03-2016, 05:31 PM  
Where to get poster-size print?
Posted By osv
Replies: 10
Views: 1,059
costco for 20x30 is the best option, by far, you can proof the images on your monitor using the downloadable printer profiles, as was mentioned earlier, and also print smaller size test pics beforehand, to verify the processing.

unfortunately 20x30 is the biggest size they have, and even their lustre paper is pretty reflective.
Forum: Pentax SLR Lens Discussion 07-02-2016, 12:18 PM  
Question to owners of FA 31mm f1.8 ltd.
Posted By osv
Replies: 29
Views: 2,288
exactly... in both shots of the cat sitting on the patio, the grass two feet in front of the cat is clearly in better focus, than the area next to where the cat is sitting.

why is it that no one else on this forum can see what we see in those pics? it's really obvious.

the o.p. could easily trim the af point compensation in the camera, using those pics at 100% view in the lcd, as the determining factor.
Forum: Pentax SLR Lens Discussion 07-01-2016, 10:01 AM  
Question to owners of FA 31mm f1.8 ltd.
Posted By osv
Replies: 29
Views: 2,288
make sure to evaluate the sharpness using live view for focusing, not af.
Forum: Pentax Full Frame 07-01-2016, 09:55 AM  
Good landscape lens for Pentax K1 full frame
Posted By osv
Replies: 35
Views: 8,343
filters would be a problem, and i don't recall seeing anyone post solutions for it.

i think that pentax owners are a bit spoiled when it comes to legacy glass for landscape shooting, because it leads one to believe that canikon/minolta/konica/oly/etc. made just as many lenses that had just as good field curvature characteristics, but that's actually not the case.

minolta slow 28mm lenses all suck, their legacy 35mm primes are nice mechanically, but have mild wavy field curvature and weak corners... i've had four oly wides, all but one were decentered, and the good 28/3.5 that i just got has weak corners that never fully clean up... etc.

fa31 looks like it does a lot of things really well, i think that it's overpriced only because modern technology has created some incredible alternatives, many of which are not available in k-mount.
Forum: Pentax SLR Lens Discussion 07-01-2016, 09:15 AM  
Pentax lags in 3rd party FF lens availability
Posted By osv
Replies: 34
Views: 2,203
i like those action photos: Photos of "Power and Speed". I love my K-1!: Pentax SLR Talk Forum: Digital Photography Review

sony owners get the same b.s. comments about shooting action... you can't do this, you can't do that, it's only good for landscapes, blah blah :confused:

when someone starts whining like that, it just proves that they don't know how to use a camera.

---------- Post added 07-01-16 at 09:21 AM ----------



lol... it's star wars technology! :D

if they can turn out better q.c. than what samyang is offering, those lenses could be a real home run.

i thought that it was ironic that here we are in a thread about no 3rd party glass for pentax, when in fact it's sony that's getting the cold shoulder with these lenses, not pentax.
Forum: Pentax SLR Lens Discussion 06-30-2016, 09:15 PM  
Pentax lags in 3rd party FF lens availability
Posted By osv
Replies: 34
Views: 2,203
they are offering it in canikon and pentax mounts so far, but not sony.

made in korea tho, i wonder if it's just a rehashed samyang.
Forum: Pentax Full Frame 06-30-2016, 09:22 AM  
Good landscape lens for Pentax K1 full frame
Posted By osv
Replies: 35
Views: 8,343
disagree, the fa31 is a good choice for landscape shooting, because it has minimal field curvature issues, see the test photo shot on an a7r: Sony a7R 28mm Lens Shootout - FM Forums

it's easily on a par with the smc 28/3.5...

people who don't have experience with the fa31 on 36mp won't be able to fully appreciate what this lens has to offer.

i had the smc 24/2.8, it sucked for landscape shooting on 36mp, although it was strong with centered objects... it was so bad that i wonder if my copy wasn't decentered, but the takinami lens test also showed it to be weak: http://www.takinami.com/yoshihiko/photo/lens_test/pentax_superwide.html

however, the o.p. wants to shoot nightscapes, so he needs minimal coma, the 15-30 is probably going to be the best choice.

---------- Post added 06-30-16 at 09:32 AM ----------



it's as good or better than the nikon 14-24: Prepare to be impressed: Tamron 15-30 F2.8 vs. Nikon 14-24 F2.8: Digital Photography Review
Forum: Pentax K-1 06-29-2016, 02:12 PM  
Kai (DigitalRev TV) reviews the K-1 - NSFW
Posted By osv
Replies: 37
Views: 3,766
lol... if i added all of the time i wasted watching his videos, my rebate request would probably be rejected :D
Forum: Pentax K-1 06-29-2016, 09:58 AM  
Kai (DigitalRev TV) reviews the K-1 - NSFW
Posted By osv
Replies: 37
Views: 3,766
10 minutes of my life that i'll never get back, lol
Forum: Pentax SLR Lens Discussion 06-29-2016, 09:42 AM  
Nothing but failures on the bay
Posted By osv
Replies: 39
Views: 2,158
i've seen that with legacy primes at 135mm and up, pretty reliable, it's the wide lenses that are problematic.

for example, i like the sigma superwide II lens, but it has a sample variation problem: 24mm lens sample variation: Three Sigma 24mm lens and three Canon FDn 24mm lenses compared

defective fa35, vs. other 35mm primes: 35mm lens comparison, second round, Minolta 35/2.8 & Pentax FA35/2, on the Sony a7R.

etc.

the key is to have a testing program, learn what to look for when buying these old lenses... clean glass and fast blades don't tell the whole story.
Forum: General Photography 06-29-2016, 09:13 AM  
Clean Lens
Posted By osv
Replies: 22
Views: 1,468
kimwipes are the current industry standard, and they are made out of 100% virgin wood fiber. Kimberly Clark Professional | 34120 - Kimtech Wipes Competition
Forum: Pentax SLR Lens Discussion 06-29-2016, 08:45 AM  
Craigslist find
Posted By osv
Replies: 21
Views: 1,748
if everything is functional, that nikon package will easily pay for the whole batch, well done.

fwiw, there are some threads about nikon glass on pentax bodies, it would interesting to see how it compares to the a50/1.4 you got.
Forum: Pentax SLR Lens Discussion 06-29-2016, 08:36 AM  
Nothing but failures on the bay
Posted By osv
Replies: 39
Views: 2,158
i've had some great experiences there also, i think the key is to identify the sellers who know how to look at lenses... sometimes they will say that the blades work, no fungus, etc... one of the oregon sellers knows camera lenses, and the prices that his store gets reflect that.

some of the sellers there don't know anything, one time i got a minolta 50/1.4 that had all of the aperture blades rusted together :confused: tore it down, cleaned it up, replaced the blades, turned out well.

when dealing with legacy glass, being able to do rudimentary disassembly and cleaning can make a huge difference.
Search took 0.02 seconds | Showing results 1 to 25 of 300

 
Forum Jump


All times are GMT -7. The time now is 12:19 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