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Forum: Pentax K-S1 & K-S2 1 Hour Ago  
Pentax K-S2 or Canon 70/80D? Worried about aperture problem
Posted By dms
Replies: 4
Views: 61
I think the statistics for failure of the aperture on the KS2 are an unknown--unless you work for Ricoh--and they would not say what they know. If you are concerned I would suggest you also include a used K-5,K-5IIs, or one of the K-3 versions in your thinking. They have no identified problems. BTW I actually plan to replace my K-20D with the K-S2, but I have and use 4 Pentax DSLRs (K20D, K-x, and two K-5), so failure of one is not a big deal. With only one camera it is more problematic.
Forum: Pentax SLR Lens Discussion 3 Days Ago  
Filters
Posted By dms
Replies: 7
Views: 546
PL filter adds two layers of glass, and this affects the focus. The thicker the glass, and the longer the FL, the larger the focus shift. Did you refocus after installing the filter? The example you give seems extreme.

But, in any case, adding filter reduces resolution and increases flare. And adding a PL filter also reduces the highlights caused by sunlight reflecting of surfaces (especially wet surfaces like wet leaves,** ocean waves, etc.), which deadens the image (no sparkle).

My view is unless I see a specific (real) need for a filter, I don't use one.

_____
** Correction: actually wet leaves often look better w/ PL, as the colors are more saturated. But definitely water surfaces/waves, and the like, lose sunlight's sparkle with PL.
Forum: Lens Clubs 3 Days Ago  
Fisheye Fever Club -- Flaunt your fisheye photos!
Posted By dms
Replies: 3,148
Views: 563,161
Sharpened, however, the image is quite detailed across the frame, and the lack of flare is impressive.
Forum: Troubleshooting and Beginner Help 01-09-2019, 08:02 PM  
Sunsets
Posted By dms
Replies: 10
Views: 472
I would spot meter the clear sky near to but not at the sun, and pay attention to the back lit areas and whether you want them to have detail (which may be impossible), or be dark shapes.

Remember where you metered and then review the results--to provide feedback for the next time. From experience you will find setting the e.v. compensation handy. Matrix or center weighted metering is not able to handle a sunset/sunrise well.

And usually try and use the lowest iso to give the broadest dynamic range. If you are not using raw, either you should, or have it as a file for later use, so a killer shot can get the best pp.

A filter should not give exposure problems, but it will do no good, and certainly will give more (and possibly significant) flare.
Forum: Pentax SLR Lens Discussion 01-03-2019, 04:40 PM  
I need help picking a Vivitar lens!
Posted By dms
Replies: 19
Views: 753
Your correct, I had a senior moment. The VS1 version is not an A lanes, and not the one I had.
Forum: Pentax SLR Lens Discussion 01-03-2019, 01:35 PM  
I need help picking a Vivitar lens!
Posted By dms
Replies: 19
Views: 753
The 24-48mm SP is a very good lens. And I find the FL range very fine on FF and APSC. I often take it when I want a single lens for travel/street shooting. The only problem is fitting a hood to it--if it comes w/ the rare hood--it would be a real find. BTW with a PKA adapter it operates as any A lens.W/o hood you can use a step down and the Takumar rectangular 28mm f/3.5 hood, and fill in the gaps w/ tape. But not then for FF.
Forum: Pentax SLR Lens Discussion 01-02-2019, 11:13 PM  
Pentax Bellows and Slide Duplicator What am I doing wrong?
Posted By dms
Replies: 31
Views: 1,091
If this was true, and the slide curvature and lens curvature were opposite then the tolerance would be even worse. Since you cannot (as a simple practical matter) characterize the film and lens curvature, the best you can do is minimize the error by taking a lens that is flat field, anything else is almost certain to be worse. Of course there is a statistical chance it may be better, but that's like saying a TC optics may improve the primary lens resolution (that the TC is attached to)--it is possible but it never happens, unless by careful design (as the correction lenses added to the Hubble telescope).
Forum: Pentax SLR Lens Discussion 01-02-2019, 09:47 PM  
Pentax Bellows and Slide Duplicator What am I doing wrong?
Posted By dms
Replies: 31
Views: 1,091
It looks like you took the picture with the lens wide open? There is some halo around the bright shirt that suggests it. And this would explain the out of focus peripheral areas as the slide is not flat. Also was there a hot light source near the film that would cause it to buckle? Anyway suggest you try lens at/about f/8, or maybe even f/11 (some loss due to diffraction is not so bad, and anyway you want to figure out what is happening. Once you sort things out a macro lens at about f/5.6 is likely ideal.)**

If flatness is still a problem you can take the film out of the slide holder and sandwich it between two thin glass slides, and there is a oil that can be applied to obtain optimum results. If you do this--glass and oil you likely need to do a search on best approach. There was an extended article on this in the magazine "camera techniques" well title may not be this but it is something like this.

_____
** A macro lens (flat field) is still best for copying, even if film is not flat. There was once a theory that an enlarger lens should not be flat field, and should have a curvature that sort of compensated for curvature of the negative, or the taking lens (don't recall which), and this was debunked long ago. It is essentially the same situation as here. Actually most symmetrical or close to symmetrical 50 mm (or close to 50 mm) relatively slow lenses (typically f/1.7 to f/2) should do pretty well if you don't have/don't buy a macro lens. (e.g., the Pentax 55mm f/1.8, 50 mm f/1.7, and 50 mm f/2, are likely pretty good--look at the lens optical layout--if about symmetrical then should be good).

---------- Post added 01-02-19 at 10:20 PM ----------

Possibly more reading than you want to invest in this, but you could read: " How to 'Scan' Film with a Camera—Well (Part 1)" and " ...Part 2)" by Ctein at The Online Photographer (Mike Johnston's blog). I did not read it, but in searching for camera technique article on the web, I found Ctein's article. (I like MIke Johnston's site BTW, it is one of three I give money to, the other two are this one [PF] and KenRockwell--as these three provide me much useful information so I return the favour.)
Forum: Troubleshooting and Beginner Help 01-02-2019, 01:26 PM  
Pentamirror
Posted By dms
Replies: 10
Views: 656
focussing screen (.com) list focussing screens for the K-r, although the price would roughly equal the cost of a used K-r.
Forum: Pentax SLR Lens Discussion 01-01-2019, 07:46 PM  
For a beginner, is the price premium of 16-85 lens over the 18-135 worth paying for
Posted By dms
Replies: 49
Views: 1,804
(The following was already written in a couple (actually several) of the posts, but maybe said a little differently.)

As you have the kit lens you likely should explore using it to see how wide you really want to go, and just forget about the lesser quality. It is one thing to see the difference in doing A vs B, but for the photo does it really make a difference, if you only saw A? This is especially true if you print at moderate size. Personally I try to avoid doing A to B comparisons (even though I am using 3 different cameras and many different lenses to shoot the same performance—I do theater photgraphy). I only want to know if what I am using is good enough, and (for me) the ergonomics/physical construction are also very, perhaps more so, important.

Once you see what FL or FL range you are usually in, you can make a more informed decision. You may even find a wider single FL lens may serve you better (and be faster, less expensive, and better IQ).
Forum: Pentax SLR Lens Discussion 12-29-2018, 02:27 AM  
Pentax-K 50mm F1.4 vs DA 50mm F1.8
Posted By dms
Replies: 26
Views: 1,180
I thought so too, that was why I rechecked my lens to see that it was set to infinity--after seeing the results on the computer. Not able to redo the photos now, or next days. But it may be my Takumar has a centering problem. (I had not used my 50mm Takumar for decades, and took it out for this comparison.) Hopefully this does not affect the conclusion as to the aberrations with strong light sources in the image.
Forum: Pentax DSLR Discussion 12-27-2018, 05:57 PM  
My K-3 died. What now?
Posted By dms
Replies: 15
Views: 806
B&H has a K-3II available used.
Forum: Pentax SLR Lens Discussion 12-27-2018, 12:58 AM  
Pentax-K 50mm F1.4 vs DA 50mm F1.8
Posted By dms
Replies: 26
Views: 1,180
Clackers suggestion would seem to be especially easy in this case as there is a region (about 3/4 way up) that is very dark across the entire image, so a crop there, and butt the two images against each other, and maybe slight blending at the crop line.

Also I looked at night images I did w/ takumar 50mm f/1.4 (which should be the same optical formulae as your K version, just not multi coated), and some with the SMC-M 50 mm f/1.7, and the 50mm f/1.7 is considerably better. Just don't have any good A vs B of the same scene--if I can get this I will post it.

Okay I was curious and did same scene with these two lenses, as follows. Except last one, they are 100% crop of left upper section, and last one is 100% crop of central section. The last one to check/verify the focus was OK--I used LV to check focus, and I looked at lens to verify it was set to infinity, but the image edge is quite a bit less sharp, hence I include a central section. The takumar is single coated, but I don't think that is the problem we are seeing (meaning about the smearing of the light with the 50mm f/1.4, not the lower resolution).

50mm f/1.7 wide open
50mm f/1.7 one click closed
50mm f/1.4 wide open
50mm f/1.4 one click closed
50mm f/1.4 wide open

BTW, (as an unrelated comment) although I saved these as medium quality jpg's, the artifacts due to the jpg compression are very obvious in the sky--while viewed as pro-photo there is none of this problem.
Forum: Pentax SLR Lens Discussion 12-24-2018, 07:00 PM  
Pentax-K 50mm F1.4 vs DA 50mm F1.8
Posted By dms
Replies: 26
Views: 1,180
Lenstip has a review of the DA 50mm f/1.8 and the comma is fairly pronounced, so likely not a good choice.
BTW they also tested the FA 50m f/1.4 so you can compare their comma results.
Forum: Troubleshooting and Beginner Help 12-24-2018, 05:41 PM  
K3II + M 200 f4 + T6-2x Math Question
Posted By dms
Replies: 6
Views: 421
Only as regards the field of view.

---------- Post added 12-24-18 at 05:43 PM ----------

As regards the f-stop, the effective f stop for exposure is two stops more closed down--so f/5.6 would become f/11.
Forum: Flashes, Lighting, and Studio 12-22-2018, 01:19 AM  
question on how to eliminate lighting reflections from the eyes.
Posted By dms
Replies: 23
Views: 779
Ansel Adams ** has a nice example in his book "Camera and Lens"--see Photo 138 on page 274 (of Foujita). He (Adams) mentions using two light fixtures and "The angle of lighting was such that there are no reflections in the glasses. [and] There are no catch-lights in the eyes (which some photographers may consider a fault)." So apparently it can be done w/o and particular additional equipment.

One of my colleges has a series of many very large portraits and I find the sameness of the catchlights to be very unnatural and rather ugly. And by extension I can see how individual portraits, all w/ a catchlight, would become problematic. In any event, whatever I or any other photographer (besides yourself) likes or does not like is of no consequence.
_____
** By the way, it may be useful to look at his Book V "Artificial-Light Photography"--I never looked at that book so I cannot say more about it.
Forum: Repairs and Warranty Service 12-13-2018, 10:34 AM  
Broken filter filter ring on DA 35mm 2.4
Posted By dms
Replies: 18
Views: 457
Or just take glass out of a 49mm filter and thread it in/glue it in place. Actually if you worry about damage to the front filter ring, mounting a filter ring w/o glass is not a bad practice to start when the lens is pristine.
Forum: Mini-Challenges, Games, and Photo Stories 12-06-2018, 10:41 AM  
Post-Processing Post Processing Challenge #279 - Winter Fog
Posted By dms
Replies: 25
Views: 884
And a cropped version.
Forum: Mini-Challenges, Games, and Photo Stories 12-06-2018, 10:27 AM  
Post-Processing Post Processing Challenge #279 - Winter Fog
Posted By dms
Replies: 25
Views: 884
Processed w/ photoshop CS6.
Forum: Pentax Medium Format 12-04-2018, 12:38 PM  
Why Medium Format?
Posted By dms
Replies: 21
Views: 1,331
It seems to me (and this is often missed--that is that it is not technical or not only so) there is a format/camera type/size/etc. that allows us to take better pictures, and it is not technical but rather what is an extension of our senses, and how we evaluate and take the image.

-- For some it is a large rather cumbersome camera that forces us to be slow and methodical.
-- For others it is a light rangefinder.
-- Similarly some use zoom, AF or primes and MF, etc.
Forum: Pentax K-1 12-03-2018, 11:14 PM  
Shooting white background artwork
Posted By dms
Replies: 7
Views: 575
If the art work is flat (2-D) and does not have mirrored areas, the (f/ stops ) range should be from 100% (white) to the blackest black (deep velvet) which is around 1%, or a range of about 7 stops (and more likely 5 to 6 stops)--any dslr should be able to handle that--even slide film could just about do it! So why would you have a need for HDR, and the like?

---------- Post added 12-03-18 at 11:27 PM ----------

I have no experience with silverpoint, but with acrylic and oil paintings (not a smooth surface) polarizing filters on the lights and the lens (that being turned to effect) allow much improved contrast/saturation. It may be worth a try.

---------- Post added 12-03-18 at 11:41 PM ----------

Interesting: doing a quick search mention is made that it is difficult to photograph (due to reflections from the metal), and it is done at very low light levels (they don't say but likely they mean diffuse light), and the white background will be gray, and thus photo's do not give a realistic representation. Presumably that is what you are finding.
Forum: Pentax SLR Lens Discussion 12-02-2018, 01:07 PM  
Angenieux enlarger lens : is it worth it?
Posted By dms
Replies: 10
Views: 559
But are you interested in a lens that may be sharp in the near field (but not macro) range?
Forum: Pentax K-5 11-22-2018, 02:24 PM  
K-5 or D300
Posted By dms
Replies: 13
Views: 681
I had the K20d w/stock focusing screen, and K-5 w/ same, and I don't recall any significant difference in focussing, but it's been many years since changing the K20D's screen (I changed the K20D to a split screen for vastly improved focusing). Also the K-7 and K-5 should be the same basic camera/same focussing screen--the sensor was the significant difference.
Forum: Pentax SLR Lens Discussion 11-18-2018, 08:17 PM  
Lens hood for SMC Pentax-M 100mm F4 Macro
Posted By dms
Replies: 21
Views: 617
Ken Rockwell has a nice review of this lens and shows the standard bayonet hood, case, etc. As I know his name brings a knee jerk reaction to some, I would add this review is very straightforward, and very complimentary of the lens.

BTW I think I would get the metal Takumar hood (49mm) labeled as for 135, 150 and 200 mm. They are widely available used and inexpensive.**
_____
** Just re-looked at Rockwell's review, and the Pentax bayonet hood is reversible--very neat.
Forum: Troubleshooting and Beginner Help 11-18-2018, 12:38 AM  
What kind of adapter is this ...
Posted By dms
Replies: 12
Views: 799
As Docrwm said, looks like an adapter to mount a reversed lens onto another lens for extreme macro. If so the both ends would be male threads.
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