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Forum: Pentax Q 05-28-2020, 11:32 PM  
HDR, or Not Quite as Bright as the Average Bear
Posted By DeadJohn
Replies: 6
Views: 659
The differences are in how much HDR (high dynamic range) processing gets applied at high-contrast edges. HDR Auto applies a low amount, HDR 1 a bit more, and HDR 2 way too much.


Look at the white wall visible through the hole in that black thing (just above image center). Notice how the 2nd and 3rd image show halos against the white wall. Some people like strong HDR effects because it gives the illusion of shaprness, but I feel it looks overprocessed and cartoon-like.


IMO, do additional tests of no HDR vs HDR Auto to see what you prefer. Some good high contrast HDR test cases include outdoor scenes with bright clouds plus some deep shade on the ground, and indoor photos that show some sunlight through a window.
Forum: Photographic Industry and Professionals 05-21-2020, 07:02 AM  
Olympus announce retreat from S. Korean market
Posted By DeadJohn
Replies: 22
Views: 1,063
I don't "resent" competition to the brands I use, but I do feel that some camera companies have to go away in order for the others to remain in business. The camera market has shrunk because of smartphones.
Forum: General Photography 03-06-2020, 11:34 AM  
Tamron 10 - 24mm vs Pentax 15 - 30 F2.8
Posted By DeadJohn
Replies: 5
Views: 518
I did a comparison of the Pentax 15-30 to Tamron 10-24 (plus DA 15, Samyang 14) a few years ago. The 10-24 is the 1st image below, the 15-30 is second. All 4 lenses can be seen in larger sizes at Wide Angle Lens Test | Flickr.

For real estate purposes, the glare from lights looks better with the 15-30 than the 10-24. I think it's a small enough difference that it won't make a difference to your clients.


Tamron 10-24 at 15mm by jvsperoni, on Flickr

Pentax DFA 15-30 at 15mm by jvsperoni, on Flickr
Forum: Pentax K-1 02-05-2020, 02:11 PM  
K-1 & Burst Rates
Posted By DeadJohn
Replies: 17
Views: 1,207
The added noise at higher ISO might increase the JPG size, because noise can look like fake detail that can't be compressed as much. As an exercise, take a picture of something like a black t-shirt (noise is more visible on dark objects) at extremes of 100 ISO and 6400 ISO to see how file sizes differ.



Lower resolution uses less memory, so can be written to the card in less time.



1:1 mp count and file size is smaller than FF, larger than crop.
Forum: Repairs and Warranty Service 01-29-2020, 12:06 AM  
Sigma (Bigma) 50-500 Lens service needed
Posted By DeadJohn
Replies: 3
Views: 514
I can recommend Sigma's service center (Ronkonkoma NY, contact info can be found in the prior link provided by boriscleto). My experience with them went perfectly. Most importantly, they fixed the lens correctly, but they also got the little things right such as promptly replying to messages.

Note that my case was covered under warranty so I can't comment on their pricing, and it's only a single data point.
Forum: Troubleshooting and Beginner Help 01-24-2020, 11:05 AM  
Same ISO, f-stop, shutter speed but different exposures?
Posted By DeadJohn
Replies: 29
Views: 1,496
The camera keeps the lens wide open to gather as much light as possible during autofocus and to give you a bright viewfinder. The camera light meter measures while wide open then estimates how much light will come through at whatever aperture you are set at. The aperture closes as the shutter fires. A photo at f2.8 needs no aperture movement, a photo at f5.6 will have some aperture movement, and a photo at f22 will have a lot of aperture movement from the wide open state.

*If* the lens aperture is moving too slowly, the shutter will fire when the aperture is still moving somewhere between wide open and the actual aperture setting you selected. You'll probably notice it more as you stop down more. Taken to an extreme, a completely broken non-moving aperture won't have any effect f2.8, will be a little overexposed at 3.5, and will be all-white at f/22.

Faster shutter speeds help make a slow aperture more noticeable, since the shutter might open, expose, and close before the aperture had a chance to get into the correct stopped down position.
Forum: Pentax SLR Lens Discussion 01-23-2020, 10:27 AM  
FA 43mm, K 50/1.2, A 50/1.2 - which would you choose?
Posted By DeadJohn
Replies: 41
Views: 2,058
I would pick the FA 43. I like having the option of autofocus and I don't take many photos with a very thin depth of field. Those f1.2 lenses become more tempting if you want to practice thin DOF. I've seen good thin DOF photos by others but it's not my preference.

I see you already have an FA 50/1.7 in your signature. How does that lens limit your photography? Pick whichever of the 3 lenses fills the void.
Forum: Troubleshooting and Beginner Help 01-22-2020, 01:56 PM  
Same ISO, f-stop, shutter speed but different exposures?
Posted By DeadJohn
Replies: 29
Views: 1,496
My vote is for aperture issue. The more you stop down, the more the aperture needs to move, and if it hasn't closed all the way before the shutter fires you'll get overexposure.

It might be the lens or the camera. Do you get the problem with different lenses? Test with a different lens and stop all the way down to f/22 or f/32 to maximize the chance of the problem occurring.


Your EXIF says DFA 100 WR macro. I had an aperture issue with that same lens. It took 3 tries for Precision Camera to fix it because they weren't paying attention to the note I included with the lens.
Forum: Pentax SLR Lens Discussion 01-16-2020, 10:23 AM  
It's Pentax week on DPReview
Posted By DeadJohn
Replies: 64
Views: 4,002
How do you propose the cherry-picking be done?

Reviewers generally don't have the time nor budget to buy 10 random copies of a lens and test them all.

Reviewers should not contact manufacturers to request a copy for review. It would let unethical companies cheat. They could sell customers lenses with low quality parts, while substituting higher quality parts before sending it for review.
Forum: Photographic Industry and Professionals 01-08-2020, 03:50 PM  
What to expect from Ricoh/Pentax in 2020
Posted By DeadJohn
Replies: 32
Views: 2,262
I have low expectations. Nothing indicates 2020 will be different than prior years. I think the next lens on the roadmap is DFA 85, so maybe we'll see that, and one surprise lens that wasn't on the roadmap (like an HD update).


A new "flagship" APS-C is overdue. The K-3ii was discontinued 23 months ago. If we see a new camera I wonder whether it will be partly obsolete on arrival because of an extended design timeframe. (I think that happened with the K-1; it was released with USB 2 even though other Pentax models already had USB 3.)
Forum: Troubleshooting and Beginner Help 01-07-2020, 11:42 AM  
A way to measure batteries or chargers?
Posted By DeadJohn
Replies: 32
Views: 1,382
I suggest recording a movie because that's a relatively fast battery drainer, and doesn't wear out the mechanical shutter like taking thousands of still photos. Set the camera to the lowest resolution video mode so you don't fill the card too soon. If the first movie reaches the hard limit for one file (25 minutes?), start a new movie and add up the total time.


You could rig up a battery tester with a resistor or light bulb. Start with a fully charged battery, connect your test rig, measure how long it takes to discharge the battery. There's a risk of shorting the battery and ruining it if you do things wrong.
Forum: Pentax DSLR Discussion 01-07-2020, 11:31 AM  
Embarking on an experiment (K3 II vs. GR III)
Posted By DeadJohn
Replies: 23
Views: 1,569
You are doing an interesting experiment.

My own tastes led me to picking the GR for street photography. It's small enough for me to keep on my belt or in my hand when I go for a lunchtime walk in lower Manhattan. The 18mm lens (28 "equivalent") is wide enough to "shoot from the hip" and gives enough depth of field for manual pre-focus. TAv mode is especially useful; fast shutter speed to freeze walking subjects, stopped down a bit for depth of field, and let the camera pick ISO with the varying light levels of urban canyons.


Any Pentax DSLR can handle that technical part but can't match the size of the GR. The GR can come along on every commute, and is nearly invisible when using it. People react to a DSLR but generally ignore the GR. The GR also happens to be small enough to sneak past places that don't allow cameras; even if I don't want to take photos, I don't want to risk having a DSLR stolen from an unsecure coat check.
Forum: General Photography 01-07-2020, 10:50 AM  
When To Throw Out Old SD Cards?
Posted By DeadJohn
Replies: 27
Views: 1,006
It's absurd to armor-all your cards and throw them away because the plastic is too old. Don't mistreat the cards and the plastic body will last. The plastic body of an SD card is exposed to very little stress. The card is usually protected inside a camera, card slot, storage wallet, etc. It doesn't get bent. It's not in direct sunlight. It's not exposed to much ozone.

Manufacturing defects can cause plastic to fail prematurely. Taken to an extreme, imagine using a new card every day to avoid "old" plastic. You increase your risk of manufacturing defects over what would happen if you kept using an old but proven card.


Car dashboards are a special case because of direct sun exposure sealed inside the greenhouse of a car cabin. I have a 21 year old car with a like new dashboard because the car is often parked in a garage.
Forum: Pentax SLR Lens Discussion 01-06-2020, 11:04 AM  
Pentax - A 400mm F2.8 insanity.... advice
Posted By DeadJohn
Replies: 31
Views: 1,609
I've used SCT (and other) telescopes mostly for astrophotography.

I haven't had many opportunities for terrestrial objects through a telescope. Haze and wind become major factors when photographing something distant, especially at sea level. One lighthouse I frequently photograph becomes a blurred mess beyond 500mm focal length because of air distortion.


SCT telescopes are compact, sharp, and inexpensive when you consider their extreme focal lengths. The tradeoffs are long minimum focus distance, precise but slow focuser, and ugly donut bokeh on out of focus highlights. Those tradeoffs don't matter when photographing objects miles away since you'll be focused at near-infinity the whole time.
Forum: Pentax SLR Lens Discussion 01-05-2020, 01:42 PM  
Pentax - A 400mm F2.8 insanity.... advice
Posted By DeadJohn
Replies: 31
Views: 1,609
Sticky aperture and cracked glass on a lens for which parts are tough to find would be a dealbreaker for me. Imagine if DIY cleaning doesn't fix the aperture, you send it to KEH, and they find it needs some part that is no longer available. The glass crack looks like it's all the way through, so shouldn't expand out into the middle of the glass, but glass chips could be floating around inside contributing to the aperture issue.

I would only take the risk keeping that lens if the seller was willing to drop the price from $2600 to the $500 range. That makes it a good gamble on your part. Note that after you try cleaning the aperture, the seller can reasonably refuse to take a return, because they can't tell whether you made things worse.

_____________________________

As an alternative, consider a 6" Schmidt-Cassegrain telescope for an inexpensive 1500mm focal length f/10 lens. It will be slow manual focus but at that distance it should be relatively easy to keep in focus. Your location is "Virginia" so I assume you'll be photographing Wallops launches; those are medium size rockets and 1500mm probably won't be too much focal length. f/10 seems slow for night launches but the bright glow of rocket exhaust will be a limiting factor regardless of aperture.

If you decide to go the telescope route, I suggest ordering from High Point Scientific because of their outstanding technical support. They can help match a t-ring for your camera, a t-to-SCT or t-to-eyepiece adapter for the telescope, and a tripod adapter for your existing tripod (if heavy duty) or a new tripod. Celestron C6-A SCT | Purchase Celestron C6-A SCT Aluminum Optical Tube, Celestron Optical Tubes Online at High Point Scientific
Forum: Troubleshooting and Beginner Help 01-05-2020, 01:30 PM  
Not sharp enough pictures, blurry
Posted By DeadJohn
Replies: 29
Views: 1,455
Blurred photos can happen because of camera shake, missed focus, or a lens optical problem. While I agree with others that it's likely an adjustable focus calibration issue, I suggest starting by ruling out optical problems.


For testing the lens, focus with liveview through the rear screen because it tends to be more precise (but slower) than focusing through the viewfinder. Put the camera on a tripod (or sturdy table if you don't have a tripod). Turn on the 2-second timer to remove any blur from pressing the shutter button and to disable shake reduction. Turn on liveview. Take test photos of something roughly 10 feet away from the camera. Are the photos sharp? I think they will be.


Then turn off liveview and repeat the test. Keep the camera on the tripod or table. Are the photos blurry? If yes, that confirms liveview autofocus is sharp while viewfinder autofocus is blurred. You need to calibrate autofocus using the camera menus. There are forum threads about the process.
Forum: General Photography 01-03-2020, 11:41 AM  
Does UV matter in digital ?
Posted By DeadJohn
Replies: 38
Views: 1,246
I think your graph shows the unfiltered pixel sensitivity, as if we were using a B&W sensor. The Bayer filter that gives us color has more green pixels than red pixels so the green to red balance of our cameras is higher than that graph suggests. Corrections welcomed.
Forum: General Photography 01-03-2020, 11:35 AM  
Does UV matter in digital ?
Posted By DeadJohn
Replies: 38
Views: 1,246
Those wideband light pollution filters are effective for astrophotography. They are unfortunately becoming less effective as LED lighting becomes more common. Here's one of many discussions on the topic How to filter "LED-poisoning"? - Equipment - Cloudy Nights

Narrowband filters do a better job blocking artificial lighting and moonlight, but they are best matched with a specialty B&W (aka monochromatic or panchromatic) sensor. Around 1/3 of the pixels on a color sensor become useless through a narrowband filter.
Forum: General Photography 01-03-2020, 11:23 AM  
Does UV matter in digital ?
Posted By DeadJohn
Replies: 38
Views: 1,246
For lessening haze, a CPL filter is more effective than a UV filter.

A little bit of dust and smudges on the front of a lens are invisible in photos. Cleaning lenses or filters too often is a common way things get damaged. I don't know about your outdoor conditions, though, and maybe your climate has a lot of sticky dust that needs frequent cleaning.
Forum: General Photography 01-02-2020, 09:38 PM  
Does UV matter in digital ?
Posted By DeadJohn
Replies: 38
Views: 1,246
No, a UV filter is not needed because digital sensors generally have very low sensitivity to UV.


You'll read many opinions on UV filters. I feel that using one when not needed adds an extra piece of (often cheap) glass, which creates more risk of flare and low contrast.

Some people insist UV filters will protect the lens from damage. I think the chance of it helping is very small. Modern glass coatings are very resistant to damage. For me, a filter for protection only makes sense when taking photos in a hazardous environment such as salt spray, sandstorms, or spray paint.


(Use a lens hood. They also offer minor protection, but improve image quality while doing so.)
Forum: Troubleshooting and Beginner Help 12-29-2019, 11:22 PM  
SD card slots - do you use RAW and JPG or only RAW?
Posted By DeadJohn
Replies: 43
Views: 1,732
I use raw (DNG format) only. I used raw+ a long time ago but eventually decided it was quicker to process a raw, instead of studying the JPG to determine whether I should process the raw.
Forum: Pentax DSLR Discussion 12-26-2019, 09:41 PM  
Every company's lens production in the last decade
Posted By DeadJohn
Replies: 29
Views: 1,569
Canon and Nikon undoubtedly have a more diverse selection of lenses than Pentax. A lot of the lenses are expensive specialty items, though, that are completely irrelevant for the vast majority of photographers. A quick check of the B&H website shows 39 Canon lenses priced over $5000 dollars. The most expensive is $70,000. I'm not in the market for such gear so it doesn't matter to me.


Use whatever system meets your needs. When your current system can no longer meet your needs, add a 2nd system, or sell what you have and do a full changeover. Changing too often gets expensive and prevents your from mastering the brand's quirks.

I picked Pentax because they were the "best" (for me). Today, as cameras have evolved, I think I could be equally happy with Nikon or Sony, but there's no pressing need for me to change from Pentax.


I do wish Pentax filled in some gaping holes in their full frame prime lens lineup. The 15-30 zoom is good but heavy. Their widest full frame prime is 31mm.
Forum: Troubleshooting and Beginner Help 12-26-2019, 09:03 PM  
GR - charging flexibility?
Posted By DeadJohn
Replies: 4
Views: 393
Within the USA? Other countries can have different electrical standards for voltage, and different plug designs, so a USA charger is not universal.
Forum: Troubleshooting and Beginner Help 12-26-2019, 09:00 PM  
GR - charging flexibility?
Posted By DeadJohn
Replies: 4
Views: 393
Higher amperage is fine. The number of amps in a charger measures the maximum it can supply, but it won't try to push extra amps into a device that doesn't want it.

Voltage must match. A large difference can overheat or otherwise damage electronics.
Forum: Photographic Technique 12-26-2019, 09:30 AM  
Street photography advice
Posted By DeadJohn
Replies: 43
Views: 4,373
I'll offer an alternative viewpoint: TAv is my preferred mode for street photography. I use a fast shutter speed to freeze subject movement, medium aperture to get some depth of field, then let the camera pick ISO.
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