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Forum: Lens Clubs 6 Days Ago  
Adaptall Mount Club (Tamron).
Posted By dms
Replies: 3,479
Views: 537,092
The Takumar 35mm f/2 and f/3.5 rectangular metal hood, with a step down (58 --> 49 mm) adapter, can be fitted to the 13A, and some photo tape used to fill in the light gaps. Just takes some care to get it threaded on. Works fine on a cropped (APS-C) sensor.

I have not tried it, but I am speculating that the 24 mm f/3.5 takumar rectangular hood, used with a 58mm filter ring (with glass removed),** may work on this lens and FF sensor. (Something I should try--except it is such a pain to get the hood properly on--so I hate to remove what I now have.)
____
** As I recall it is a clamp on hood construction (like the 28mm f/3.5 takumar hood), hence the need for the filter ring.
Forum: Digital Processing, Software, and Printing 10-09-2017, 06:00 PM  
Best all in one Photo Printer?
Posted By dms
Replies: 12
Views: 480
-- As you have a scanner/don't need an all in one, you would likely do better today with a larger dedicated printer, except that it is another machine and it takes up quite a bit of space.
-- Based on my favourable experience using the Epson Claria inks, I would choose the Epson model 1430 if I wanted to print larger, and (as I mentioned earlier) I really like the idea of buying larger paper (both 13" x 19" and 17" x22") and cutting it to desired size (the 1430 is said to support custom sizes).
-- Again, as I mentioned earlier, If you intend to use it a lot/long time I suggest getting the "Printer Potty."
Forum: Digital Processing, Software, and Printing 10-09-2017, 08:20 AM  
Best all in one Photo Printer?
Posted By dms
Replies: 12
Views: 480
I use a Epson 6 Claria inks all in one printer (RX-595 purchased refurbished about 8 years), which still works great. I use the copying, scanning and printing features. Recently I attached the "printer potty" to it.
-- It sits for 1-2 months sometimes between prints and has never clogged.
-- Epson's luster, glossy and matte paper results look great.**
-- Matte results are indistinguishable from the large Epson roll printers (never compared others).
-- RX-595 has flexibility of custom paper sizes (I routinely print 8.25" x 18.75"), but it takes paper from top rear, and not a tray. That feature may no longer be available.
_____
**I probably should mention that I use photoshop and let it, and not the printer, handle the colors.
Forum: Pentax DSLR Discussion 09-23-2017, 07:28 PM  
SR and monopod?
Posted By dms
Replies: 19
Views: 964
I would think testing at greater shutter speed would be interesting--as regards SR on or off. At 1/2 second the motion is large enough (on the monopod) that it should overwhelm any SR feedback effects. As a guess, I think something in the area of 1/15s and 1/60s, and a long FL lens (to see the effects at the faster speeds) would be such a test.
Forum: Pentax Q 09-19-2017, 07:21 PM  
Any adaptable lenses make the Q truly pocketable?
Posted By dms
Replies: 8
Views: 440
A collapsable mount (by Pentax) like on the Rollei 35S may be possible/would have been nice, but as it is the Pentax 01, 03, and 04 are the smallest, and that is why I have them (lens on camera body fits in men's sports jacket pocket).
Forum: General Talk 09-17-2017, 02:23 PM  
Looking for new vehicle
Posted By dms
Replies: 17
Views: 699
For snow nothing beats real winter tires on all 4 wheels. I like General Tire's Arctic and have 4 mounted on my winter wheels. That is from what I read (my driving being two wheel drive) more important than front wheel vs all wheel drive.
Forum: Pentax DSLR Discussion 09-17-2017, 11:38 AM  
SR and monopod?
Posted By dms
Replies: 19
Views: 964
There is likely a problem when the camera is connected to any rather stiff restraint. I believe the following describes the scenario. The camera tries to correct for very minor motion and then the camera being held in a stiff restraint reacts (vibrates due to internal motion, mirror, shutter, and the SR itself, as well as the stiff restraint) and the SR tries to correct for the correction--it is a feedback loop that can rapidly grow in size.

When held in our hand, they are soft enough that the small/rapid motion is absorbed by the soft flesh, and anyway the small/rapid motion is much smaller in amplitude than the slower actual (gross) camera motion--which the SR detects and corrects for.

So, no I would not use the SR when using a monopod, or anyway not w/o testing it first--it may depend on the construction of the monopod (or tripod), and thus what kinds of vibrations are set up.
Forum: Pentax SLR Lens Discussion 09-04-2017, 09:53 AM  
Full Frame Wide Angle Lens List--20mm and Under
Posted By dms
Replies: 82
Views: 2,953
I presume you are excluding fisheye lenses's, but:

-- On reduced sensor camera the FF fisheye defished (w/ Fisheye Hemi) is better IMO than non-fisheye--and significantly wider. I would assume the same is true using them on FF camera.

-- FF (viable) Fisheye's by Pentax include the Takumar 17mm f/4 and PK-A 16 mm f/2.8.** [I have the latter and use it extensively as my wide angle lens w/ Fisheye Hemi.]
_____
** and the zoom already mentioned above.
Forum: Troubleshooting and Beginner Help 08-21-2017, 05:03 PM  
Bright sun, underexposed pics. Where did I get the settings wrong?
Posted By dms
Replies: 38
Views: 1,310
Full daylight is tough to meter with reflected light. Often a good method when there is clear patch of blue sky--is to spot meter that.

---------- Post added 08-21-17 at 05:08 PM ----------


If the scene is balanced with roughly 50% bright and 50% dark (or large areas of a midtone)--the meter gets the correct exposure. But when it is mostly bright, the meter will underexpose. Ditto if the scene is mostly dark, the meter will overexpose. As I said reflected light reading is tough for the camera to "guess" what the scene is. Matrix metering may help--but the best is that you learn a bit about exposure (old school stuff).
Forum: General Photography 08-14-2017, 06:14 PM  
Do you still use a hand held light meter when shooting with a Pentax DSLR?
Posted By dms
Replies: 15
Views: 599
-- Yes, an incident light meter, or the equivalent (one's own ability to recognize the required exposure, as common outdoors during daylight). This is completely different than reflected light method used by camera, and more reliable for most scenarios.
-- You learn to recognize lighting that is tough for camera to do in auto, and then use the incident meter. BTW the sun pretty high over head is such an example--where it is simple to use the incident meter (if it has the usual integrating dome), or guess the exposure--but much less reliable for the camera using reflected light. Also a scene with very unbalanced sky/earth, mostly dark or light tones, etc.
-- And it is important/useful as:
1. You may not have a chance to get another shot.
2. Checking the taken image uses battery up, may be tough in sunlight, and takes time/interferes with your work flow.
3. Bracketing shots suffers from above limitations, and is not elegant/best left for the rare situations where it is really useful.

Of course those who use B&W film, spot meter, zone system, etc. have their methods and no need for my discussion, and rightly will say it is too simple/does not apply. But for most photographers using digital or color negative film, I think a middle ground as I describe above is very useful/can give significantly greater percentage of keepers.
Forum: Pentax SLR Lens Discussion 08-14-2017, 11:53 AM  
Question about Depth-of-field & focal length relation
Posted By dms
Replies: 23
Views: 1,144
Perhaps more simply--DOF varies with f stop and magnification.
So different FL lenses at different distances have same DOF if:
-- the same object in focus is the same size (same magnification)
-- and the same f stop
-- and you print/view result at the same magnification (same size/same crop)
Forum: General Photography 08-08-2017, 07:55 PM  
Poll: What's your endgame for pictures?
Posted By dms
Replies: 16
Views: 807
Print!
I don't want to show an image until it is printed and mounted on a matte board.
Handling the print, while studying it, is important IMO.
Forum: Repairs and Warranty Service 08-01-2017, 05:19 PM  
Suggestions For Repairs To A Tokina
Posted By dms
Replies: 4
Views: 352
I had this lens twice: both the original f/2.6~2.8 and the second f/2.8 version, and each one had problems focusing/zooming. In each case it happened shortly after purchasing (from KEH) and in both cases they (KEH) said it could not be fixed, and they refunded my money.

Of course maybe I was very unlucky--but it may also suggest the lens is problematic mechanically.
Forum: Pentax Camera and Field Accessories 07-29-2017, 09:20 AM  
Looking for good Polarizing Filters
Posted By dms
Replies: 11
Views: 676
A suggestion: snow scenes often benefit from reflected light (contre-jour), as do water scenes. As otherwise the snow/water has a dead look to it. So don't automatically use the PL for it.

Also a very wide angle FOV will have the sky showing varying intensity of blue. On balance you may be best not using the PL.
Forum: Pentax SLR Lens Discussion 07-17-2017, 02:14 PM  
Which 35mm lens? (DA 35/2.4, FA 35/2, DA 35/2.8 Macro)
Posted By dms
Replies: 49
Views: 2,189
The DA 35mm f/2.4 lacks a distance scale, which makes:
-- zone focusing inconvenient
-- cannot set focus if too dark to use AF or see well
These are very serious defects in a lens IMO. You never know when they will "bite you."
Forum: Photo Critique 07-05-2017, 02:29 AM  
Abstract how to control morning burn?
Posted By dms
Replies: 9
Views: 832
Since you (presumably) want to capture the look with the sun low on the horizon--the light will be much more yellow-orange than daylight--and doing a white balance correction would partially negate this. It would tend to make it look like it should in normal daylight. I would think adjusting the WB to daylight (5500K) would be a starting point and then adjust the temperature and tint till it looks like what you think looks best. (But you already posted a version that likely did that.)
Forum: Pentax Q 06-07-2017, 10:10 AM  
New 04 (Toy-wide) lens - any tips?
Posted By dms
Replies: 5
Views: 895
Looking down on the lens, from the normal shooting position, as follow:
-- 04 lens, the 2nd mark, moving left to right
-- 03 lens (I misspoke) it is on the first smaller mark, moving left to right

I found it is rather sensitive (too much so) to the mark/position. I simply took successive photo's at slight difference in lens setting and then refined the setting and repeated it (of a mid-distance scene, about 7 feet away as I recall). I imagine there may be manufacturing tolerance associated variation between similar lenses. (Although my second 04 lens was in proper focus at the same 2nd mark, as my first.)

When done I taped the lens to fix the position--which is convenient (I would say needed), unless significant usage is in close (few feet or less) distances.**
_____
** Using DOFMaster Calculator and the original Q, hyperfocal distance is about 4 feet for the 04 lens (and about 1.5 feet for the 03 lens)--although my usage (oddly!) suggest these are too optimistic.
Forum: Pentax Q 06-06-2017, 05:21 PM  
New 04 (Toy-wide) lens - any tips?
Posted By dms
Replies: 5
Views: 895
I assume it was my post about the (DIY) taped on 30.5 mm filter ring.

My usual lens on the Q is the #4 toy wide, or the #3 (the fish eye). The Q w/ either of these (or the #1), and an optical finder, actually fits in my shirt breast pocket and the results are quite nice. With both the #3 and #4 I have it focused to (taped in place) the 2nd major mark--and there it is fine for reasonably close to infinity. I easily print about 8'x11" with the #4 lens, and if I only could have one lens for the Q, it would be the #4.

BTW although the #2 is a fine lens--w/ a good FOV range and fast--but it is the only one (of the 1,2,3,4) I don't use--since (for me) the Q is all about size and ability to carry it in a jacket or shirt pocket, or in my book bag.
Forum: Troubleshooting and Beginner Help 06-05-2017, 10:10 PM  
So I got a camera, now what?
Posted By dms
Replies: 34
Views: 1,801
It was mentioned earlier, but you may have missed it. A large Giotto Rocket Air Blower. You don't want to touch the sensor if you can help it. Almost always (and maybe/hopefully always) it is all you need.
Forum: Pentax K-1 05-31-2017, 09:45 AM  
Dance recital = death or glory! :p
Posted By dms
Replies: 10
Views: 756
As you have done this you likely have worked out a method. But as I do this a lot maybe my experience may help. I generally (now) use the number 2).
1) spot meter the brightest area and use something like + 3 ev
2) use the lens aperture ring and camera in M mode, and by eye adjust f/stop. e.g., start at f/4, and if it (lighting) looks bright go to f/5.6 (or f/8), and dark go to f/2.8. This method obviously is very fast.

Also as boh cameras are basically "isoless" you may want to consider leaving at iso 400 (so you can look at the LCD and not see too dark an image) and a moderate shutter speed (to not completely freeze the motion) and a moderate f-stop (where DOF is not too tight), and leave camera at these setting for all pictures. I do this often w/ my K-5 , but use above 2) with my K-20D.

As you mention fast paced--if you are close enough a wide angle lens zone focused with an optical finder is useful. I use a K-x with a 35 mm (equiv. FOV) finder and usually a 20 mm lens. (I take 4 DSLRs and cover from fisheye to telephoto.)
Forum: Pentax K-1 05-31-2017, 09:05 AM  
Dance recital = death or glory! :p
Posted By dms
Replies: 10
Views: 756
Usually the lighting is fixed with no follow spot, and if this is the case suggest setting camera to manual and taking an initial shot(s) to see/adjust the exposure.
Forum: Pentax DSLR Discussion 05-31-2017, 08:53 AM  
Aperture lever formula
Posted By dms
Replies: 3
Views: 536
Lenses used to have a very large distance between the f-stops at the full open end (fmin), becoming successively smaller towards the most closed end (fmax). Now they are generally equally spaced. For one that is equally spaced, it likely is:

percent travel = L/Lmax *100% = (log f - log fmin)/(log fmax - log fmin) * 100%

BTW my basis is: travel distance L is proportional to log of f-stop, and then I used a linear interpolation formula for L going from L=0 to L=Lmax

---------- Post added 05-31-17 at 09:29 AM ----------

If you rather not use logarithms you could number the f-stops starting with 0. E.g., if it goes from f/2.8 to f/22:
f/2.8 --> N=0, f/4 --> N=1, f/5.6 --> N=2, f/8 --> N=3, f/11 --> N=4, f/16 --> N=5, f/22 --> N=6
and replace the log f/stop by N in the equation.
Forum: General Photography 05-31-2017, 08:21 AM  
Kickstart Pinhole Pro: Professional Pinhole Lens Includes Pentax K
Posted By dms
Replies: 5
Views: 671
Internally it has a disk with holes of varying size. The center of this disk is offset, so as you turn the aperture ring, it moves a different hole under the larger center opening of the "lens" assembly. Probably similar in design to a lens with several filters built in.

So yes, on the fly, like a screw mount lens set to manual.
Forum: General Photography 05-30-2017, 08:29 PM  
Kickstart Pinhole Pro: Professional Pinhole Lens Includes Pentax K
Posted By dms
Replies: 5
Views: 671
I did a few calculations using an earlier comment in this (Kickstarter) project, and find the pinhole diameters are likely pretty well thought out**--although I should caution that I don't do pinhole photography (yet) but used a reliable (IMO) reference in the following. It was a comment I left in that project--as follows.

Using Phillip Reed's earlier comment (calculations) I obtain the following for Pentax K (easily adjusted for other cameras). Following specific numbers w/ Pentax K extension tubes, and using Blaker in “Field Photography” [1976] page 352. He quotes result from Kingslake “Lenses in Photography” [1963] as follows:
Optimum diameter [mm] = 0.032 SQRT [Focal Length (mm)]
And using Pentax K Extension Tubes (12mm, 19 mm, 26 mm) it would seem three optimal choices are as follows:

1) lens w/o extension (Focal Length = 50 mm) Optimal Pinhole D ~ 0.25 mm and ~ f/223
2) lens w/ 26 mm extension (F.L. = 76 mm) Optimal Pinhole D ~ 0.30 mm and ~ f/280
3) lens w/ 57 mm extension (F.L. = 107 mm) Optimal Pinhole D ~ 0.35 mm and ~ f/340

_____
** They are: 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.5, 0.8 mm
Forum: General Photography 05-30-2017, 07:04 PM  
Kickstart Pinhole Pro: Professional Pinhole Lens Includes Pentax K
Posted By dms
Replies: 5
Views: 671
-- There is a Canadian company making variable aperture pinhole lens (Pinhole Pro: Professional Pinhole Lens For DSLR & SLR Camera).
-- They have reached their money goal, and are making number of mounts including Pentax K. Price is about $70 for people who pledge.
-- Last 4 days of the program.
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