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Forum: Pentax Camera and Field Accessories 07-26-2018, 10:57 AM  
LIM's SAH-BE52N1 52mm metal hood - anyone use one?
Posted By nater
Replies: 4
Views: 600
Thanks for mentioning that - I was using a sightly too narrow and long metal hood and cap on the lens already, and while those Sensei Pro hoods look like a good option I ended up going with this SIOTI one for a bit less that comes with a cap (and a little cleaning cloth) for $9:
Forum: Pentax SLR Lens Discussion 06-25-2012, 04:15 PM  
looking for teleconverter to match the Tamron SP AF 70-200mm f/2.8
Posted By nater
Replies: 23
Views: 12,521
Saying, "it does not allow the AF motor to disengage" is an ambiguous statement because there are two motors and two sets of gears you could be referring to - the micro-motor and gears in the lens, and the camera body AF motor and gears.

I have the Tamrom 70-200mm f/2.8 AF lens as well as three Pz-AF teleconverters, so I can describe what's going on from first-hand experience.

On Pentax AF camera bodies, the MF/AF switch is both electronic (telling the camera what mode you are shooting in) as well as mechanical. MF physically retracts the screw drive into the body, AF extends it out, something visible if you move the switch while looking at the mount with no lens on it. When the switch is in MF mode on a Pentax body, nothing can move the gears or AF motor in the body.

On an AF lens like the Tamron, the AF/MF clutch is a simple mechanical clutch. All it does is connect or disconnect the focus grip part of the lens from the internal focus part of the lens. Nothing stops you from having the camera body in AF mode and putting the lens clutch in MF, resulting in the camera driving not just the internal focus lens parts but the outer focus grip as well, slowing AF due to increased mass and risking a negative impact on the AF drive system should you grab the focus grip and 'fight' or counteract any of the AF action. With the lens focus clutch in MF, any physical force imparted to the grip is translated to the AF drive shaft, connected or not. With a body in MF, and the focus clutch in MF on the Tamron lens, the lens will spin it's AF screw drive merrily but it will not be connected to the body because the body has retracted its end of the screw drive.

Now, let's introduce an AF teleconverter. It has a screw drive extension. That extension doesn't retract or extend, it's fixed. So if a lens like the Tamron still moves it's screw drive in MF mode, then you have a screw drive extension shaft in the teleconverter that will also move, even if it's not connected to the screw drive coming out the camera body.

That is the the source of the 'drag' you'll feel in that Tamron lens (and many other lenses) when using them with an AF teleconverter - the extra effort in spinning the little screw drive shaft in the teleconverter. Now in my experience, I only find it mildly annoying, but that's because I don't really try to use my Tamron 70-200mm f/2.8 lens AF lens in MF that often at all. The lens has a very short focus throw because it was designed to be very fast in AF, so MF is just an afterthought at best. It's probably the last lens I would go to if I wanted to MF.

I have a hard time seeing how having the lens in MF mode and Pentax body in MF mode with an AF teleconverter between them could cause any harm though. The extra effort required to spin the the screw drive shaft in the teleconverter isn't that significant in my experience. It makes me wonder if the Tamron support people know what they're talking about. More likely I think that since the teleconverter is a discontinued part, they're just throwing out a 'safe' answer because they don't know or don't want to take the time to give a thorough answer and understand the situation.

This does bring me to another point I think I've made before and bears repeating - MF/AF switches on Pentax lenses can be implemented better than they typically are in most third-party lenses. Let's take the Pentax FA 100 f/2.8 Macro lens as a counterpoint. When you rotate the focus mode dial on the side of that lens to MF, it physically disengages the screw drive inside the lens. There is no need to move the switch on the body of a Pentax camera with the FA100 lens from AF to MF to use that lens in MF, you just need to move the dial on the lens. That is the right way to do an AF-MF switch on a lens, and though its not quite as elegant as the quick-shift focus system found on some Pentax lenses and some recent Sigma HSM lenses like the 85mm, I think reviews should acknowledge that a manual clutch in a non-SDM/HSM lens can and ideally should disengage (or retract) the screw drive of a lens in the lens body. It's unfortunate more lenses don't work like the FA100 in that regard.

Now regarding your quest for "another TC that is fully compatible with the lens", if you are adamant about getting manual focus on that Tamron lens without the 'drag' you don't like, while also getting some AF, your one and only option will be the Pentax-F 1.7x AF Adapter. The reason is this adapter has no AF connection to the lens at all, just to the camera body. Your lens will no longer AF, but the adapter will. You'll need to do some manual focus to get the lens close to the focus point, and then you can use the camera body AF to move the elements in the adapter to focus the rest of the way. I'm not sure that counts as the 'fully compatible' you're looking for, but that's the closest you're going to get.
Forum: Pentax Camera and Field Accessories 06-08-2015, 11:47 AM  
It's Heie's fault if I got a Sirui T-025X! (personal short review inside)
Posted By nater
Replies: 35
Views: 7,962
I'd call it entry-level because from a construction standpoint because the metal parts are forged aluminum. Mid-range to high grade in my mind means magnesium alloys and/or CNC machining from solid metal blocks rather than forging.

Keeping an upper bound on the prices of tripods in a comparison makes sense, but keeping less expensive tripods out that otherwise are a close match in terms of size and design does not make sense to me. Regarding load capacity, there is no standard for rating a tripod or head, so I consider that value a manufacturer suggestion at best and not something I'd use to limit the range of tripods in a review.

I've noticed that Dolica has a lot of entry-level, very inexpensive tripods. I assume like many companies, they are re-branding tripods made by one of the big Chinese companies (probably Ningbo Weifeng Image Equipment Group Co., Ltd). Dolica's highest end product looks ok though from what I've gathered. Odd thing is, the higher end stuff seems harder to come by. There was also that brief period of time where Dolica acted as a reseller of Nest (the highest end product from Weifeng), and in fact is still selling a couple of alloy models at low prices (likely they moved all the carbon fiber Nest product already). The Nest product appeared to be higher end the top of the line Dolica. The Camera Cottage in Billings, Montana is the only place in the USA actively reselling Nest product right now, but it has good distribution in the UK and Australia as far as I know.

I think it's more complicated than "you get what you pay for". All indications are that the Field Optics Research Schonfeld KF6615T carbon fiber tripod, which sells for $199 from the Field Optics Research website or $149 from B&H, is the same tripod as the AmazonBasics 52-inch carbon fiber travel tripod, which sells for $79 with ball head. In some cases there isn't much correlation between price and value. That's why I read reviews and research things before I buy.

A more accurate statement could be, "Don't have high expectations for something you haven't paid much for relative to other products on the market unless you have research or data to back up those expectations."

My interest in this thread has to do with being able to extract good information to relay to people I know to help them make decisions, and additionally to help me make a purchase decision for a second tripod since my primary tripod, while terrific, is not very portable. I can see how portable might be nice, but I need to determine my thresholds for functional tradeoffs based on facts, not conjecture.

I'd agree based on Promaster's older tripods, but I'm not sure where they stand with these newer ones.

I don't doubt that your Sirui vibrates less than your Dolica if you say it does, but there are a lot of potential factors that go into vibration, such as the overall design and construction of a tripod, the diameters of the tubing, the type and design of the metal parts, etc. I have seen lots of speculation and contrary experiences based on materials. I've seen multiple people claim that a magnesium alloy tripod from a particular manufacturer is less vibration prone than a carbon fiber variant of the same model. Perhaps a well designed and well built metal alloy tripod could outperform an inferior designed and built carbon fiber tripod. Perhaps there are design features that work better in a tripod with carbon fiber vs. alloys and vice versa, so if a manufacturer simply swaps out one material for another without redesigning, they could be making an inferior product for the sake a bullet point feature on a box and a way to charge more. The best tripod review would in my opinion make mention of the materials used but then objectively test tripods to see how they actually perform and provide the data from those tests, rather than imply performance based on materials or construction, or just relay subjective impressions.
Forum: Pentax Camera and Field Accessories 06-08-2015, 08:18 PM  
It's Heie's fault if I got a Sirui T-025X! (personal short review inside)
Posted By nater
Replies: 35
Views: 7,962
Hi Heie! Thanks for your review, it's definitely one of the better ones out there.

Those are manufacturer specs, and as I've mentioned they can't be trusted. I mean look at the games makers play, here's Cullman's Nanomax 200T CB 5.1 with it's 2kg weight rating:

and then on that same page they link to a review from the famous photographer Nicolas Beaumont where he says:

"Even if the Nanomax 200T is not certified for more the 2kg I often worked with heavy gear on it, for exemple on the great wall near Beijing; it was loaded with the 1D Mk IV and 70-200 f/2,8 L; even like that it was stable !"

2.89kg clocks in at exceeding the "max" weight by almost 50%.

Some tripod makers are reasonably intelligent and actually list different weight ratings based on the angle, so for instance 3 Legged Thing has this in the specs of the EVO3 Punks Rick Carbon Fiber Tripod System:

23° - 20kg / 44lb
55° - 15kg / 33lb
80° - 10kg / 22lb

Not that I have the time or money right now, but to do it right I should probably launch a website and do a good series of comparative reviews. It's what I want to do.

The laser beam isn't a bad idea, but I prefer what Mark Banas does in his reviews: "With the legs fully extended and the center column lowered, our vibration analyzer (an iPad on a 3 lb (1.36kg) aluminum block) was mounted to the ball head with a long lens plate. A large solenoid valve with a plastic hammer was then used as a consistent source of vibration (a knock to the bottom of one leg). The resulting graph of all three accelerometers shows both the resistance of the tripod and head to the initial shock, as well as the rate of decay for residual vibration within the tripod."

The laser pointer test was from what I can tell a controlled setting with a single lens. While I like Mark Banas' test, it could be further improved upon. Ideally we'd have a picture of how a tripod does on a variety of surfaces in different leg length configurations at different temperatures with different lenses at different center of gravity orientations experiencing different vibrations (i.e. I might be out on an overpass with vehicle traffic causing vibrations in the road, how will the tripod cope? I might be near a large waterfall with the vibrations of falling water shaking the ground, how will those be absorbed? I might be on a windy hilltop, how much will the tripod flex, vibrate, and transmit that to the camera?) Obviously a review can't test every scenario, but some reasonable subset should be determined and tested.

The lack of failure cases actually made it harder for me to determine just how good the Sirui T-025X is.

"We"? I don't pretend to speak for anyone but myself. Are there other people out there like me? Sure. How many? I have no idea. But yeah I love long, detailed reviews with lots of data. Also ideally the comparison tables in a review would be dynamic and allow the reader to select multiple criteria, assign weights to them, and then generate unique and specific results for that reader. I think it's largely a mistake that so many sites task reviewers with creating static reviews that have a combination of implied and/or explicit criteria and then reaching a single conclusion (perhaps with a few variations).

Let me be clear - your review was good. Most reviews of photo equipment are terrible. But there is room and opportunity for reviews to be great.

Right, I haven't provided examples, so let me do that.

A great SD card market review:

On MicroSD Problems

A combination of using acid to dissolve the plastic casing, reveal the insides, and then use low level tools to reveal the card ID information, combined with good information about what companies actually make the flash and the controllers and how the market works, makes this great.

Pretty much any power supply review from

Andyson N700 700W Titanium Review

but also take note of the "Death of a Gutless Wonder" series:

Death of a Gutless Wonder V: Uncool to the Max Review

Why it's great is because it reviews the packaging, marketing, claims, aesthetics, physical design, fit and finish, extras, determines the true manufacturers of the parts and components, does cold bench tests and uses a $10,000 piece of testing equipment to hot box test and simulate a range of possible load scenarios, provide the collected data and oscilloscope graphs for the results, performs a teardown and analysis of the construction. Then the "Death of a Gutless Wonder" series provides that terrific counter-point to the excellent manufacturer-supplied power supplies by going out into the real world, buying something retail, cheap, off the shelf, testing it and seeing when it lets the magic smoke out.

The closest I've seen to this in the photo review world is S.C.V. Photography Ideas, with their reviews like this that have a tripod teardown in them:

S.C.V. Photography Ideas: Nest NT-6294CT Carbon Fiber Traveler Tripod Review

I think it's great, I'd love to see more of it in the photo world.

Any of John Siracusa's reviews over on Ars Technica, like his Yosemite review:

OS X 10.10 Yosemite: The Ars Technica Review | Ars Technica

25 pages that I really enjoy reading.

Hopefully this gives you some idea of where I'm coming from.
Forum: Pentax Camera and Field Accessories 06-05-2015, 09:23 PM  
It's Heie's fault if I got a Sirui T-025X! (personal short review inside)
Posted By nater
Replies: 35
Views: 7,962
So I've had some friends ask my advice on tripods recently. I came back to this thread, and the Sirui T-025x review on Pentaxforums (among other sources), and did my own tripod research as well. The T-025x does seem good overall, it's carved itself out a niche for itself above the questionable entry-level carbon fiber stuff, and below the bigger name brand carbon fiber things, putting some quality features into the very small travel tripod category. I was perplexed by a few things in the review however. I noticed the comparison table is chopped off on the right on page 10:

Sirui T-025x Travel Tripod Review - Value and Competition | Reviews

Also, I think the table is missing what would be some interesting competitors, and has at least one model which isn't really a competitor - the MeFoto RoadTrip is a bigger tripod that folds to 15.4", and the model listed is the aluminum RoadTrip, not even the carbon fiber model (which would be the one reason to include the MeFoto RoadTrip in the table IMO). The MeFoto Backpacker on the other hand folds down to the same 12.6" and is closer in weight to the Sirui. While the BackPacker is only available in aluminum, it is $150, which from all the reviews I've read indicate it's a quality tripod in it's class and a good value:

MeFOTO BackPacker Travel Tripod Kits - Choose Your Color!

Meanwhile, coming in at even less ($109) yet having similar specs is the Davis & Sanford TR553-P228 by Tiffen:


An then there's the $80 carbon fiber AmazonBasics 52-inch "Travel Tripod", which from what I've been able to gather doesn't have very good built quality (not surprising): : AmazonBasics 52-Inch Carbon Fiber Travel Tripod : Camera Tripods : Camera & Photo

And there's the ($70 on Amazon at the time of this writing) Dolica TX570B150DS "Traveler 57" Tripod with Ball Head and Integrated Monopod" again in the same size and similar weight class, but again with (unsurprisingly) concerns about build quality:

TX570B150DS Reversible Traveler 57" Tripod with Ball Head and Integrated Monopod ? DOLICA

The consensus seems to be that while the Dolica has a quick release plate similar to Arca-Swiss, it's not quite compatible.

However the one that's really caught my eye is the Promaster XC522:[name]=Promaster-XC522-Professio...ds][0]=1095138

It has good specs (though the only list the weight of the legs, not legs + head), good cost ($140), and the reports I've read from people who bought it are positive. It has an integrated monopod. I verified with Promaster today that the quick release plate is Arca-Swiss compatible.

By that same token, it's also worth looking at the Sirui T-005X, which is basically the $136 aluminum version of the T-025X from what I can tell, yet it has nearly the same weight as the carbon fiber version, which would be a good opportunity to test exactly what carbon fiber brings (i.e. how much more does carbon fiber actually dampen vibrations, allow tighter leg clamping and thus support more weight compared to aluminum, etc.)

There are also other things that I am curious about which weren't covered in the review, like the ease of access and quality of after-sale product support, which I think impacts value. It's nice that Sirui has a 6 year warranty, but if actually getting service and support turns out to be an ordeal or drawn out process, it's not worth much to me.
Forum: Pentax Price Watch 04-18-2015, 09:17 PM  
Lowepro Flipside 400 AW direct from China ?
Posted By nater
Replies: 21
Views: 8,465
I'm not sure I quite understand the question... but here's a recap of what's happened in the US over the last century:

1. Most goods sold in the US used to be made here in the US. Also internationally, the US used to be dominant in some areas, like the textile industry in the 1800s and the tool and die industry up until the 1960s.
2. Mergers and acquisitions, trade agreements, cheaper labor overseas, improving technology overseas, and inexpensive international shipping all contributed to an erosion of domestically produced goods and the original companies and jobs that were responsible for them.
3. Goods sold in the US are mostly now typically made in China, Taiwan, Malaysia, Vietnam, India, Mexico, and a few other places. Basically wherever labor is least expensive and a certain quality level can be achieved (as determined by the typically multi-national parent company).

In the US, certain shipping agreements have been made, such as "ePacket" for Chinese sellers selling goods on eBay to the US market, which gives them preferential shipping pricing and a direct link into the USPS from China:

USPS Gives eBay China Sellers Competitive Advantage

The economics of shipping goods from around the world cheaply rely on massive container ships which burn "bunker fuel", the lowest grade, bottom of the barrel petroleum left over from the refining process. Bunker fuel is solid at room temperature, so the container ships have additional means of heating the bunker fuel up so that it becomes liquid and can then be burned. Burning bunker fuel produces a lot of pollution, but since there are no environmental laws for international waters for the type of fuel burned, there are no legal repercussions, however at port cities where the container ships dock have very high rates of asthma, lung cancer, and other respiratory problems (that includes ports in the US).

There has been fostered a culture of apathy in the United States where the general populace has become complacent purchasing inexpensive goods at cheap prices, while domestic goods production has been moved overseas. There is a feedback loop in place where eliminating well-paying domestic jobs has eroded the middle class, incomes and buying ability of a significant portion of the US population has increased the appetite for cheap goods, which has accelerated the problem. It's unclear to me what the pain point will be when most people will be unhappy enough with the lack of a middle class and quality jobs for general unrest to occur.

And back to your question, the typical US consumer isn't paying a lot of attention to where goods are coming from, just how inexpensive they are. If Poland produced less expensive goods, US consumers would buy them, but a large portion of this situation is chicken-and-egg, where the pre-existing sheer volume of goods production in China and other places is already high enough to simplify production, agreements, assure shipping volumes and keep prices down (though the rising standard of living in China along with increasing domestic unrest at the levels of pollution there are making it more expensive to make goods in China, which has and will lead to goods production being moved elsewhere).
Forum: Pentax Price Watch 04-06-2015, 01:57 PM  
Lowepro Flipside 400 AW direct from China ?
Posted By nater
Replies: 21
Views: 8,465
I found out the hard way that Lowepro bags and lens cases are being cloned by Chinese maker(s). I confronted an ebay seller after receiving one, and they claimed they didn't know it wasn't genuine. I let Lowepro know as well. While it wasn't bad per se, comparing it side by side to genuine Lowepro showed the overall quality was lower, stitching/ design was slightly different, padding wasn't as dense/rigid, and it had a slight smell to it (like lower-grade plastics/nylon can).
Forum: Pentax SLR Lens Discussion 06-10-2014, 08:05 PM  
43mm 1.9 protrusion
Posted By nater
Replies: 11
Views: 1,328
Keep in mind you can use the DA 40 hood on the FA 43 when you use it on an APS-C body. I use an aftermarket DA 40 hood on mine, works great.
Forum: Pentax Price Watch 05-29-2014, 11:14 AM  
Rokinon 8mm f/3.5 HD Fisheye Lens with Hood - $199
Posted By nater
Replies: 39
Views: 6,529
I recommend reading the first part of this guide:

Shooting manual lenses on Pentax DSLRs «
Forum: Pentax SLR Lens Discussion 01-17-2014, 10:12 PM  
Which 120-400 Zoom???
Posted By nater
Replies: 11
Views: 1,152
If you're on a budget and don't mind looking around for an older zoom lens, check out Sigma 135-400mm. There's two editions, an earlier one with a smooth finish, and a later one with a crinkle finish and a zoom lock. If you don't mind the lack of a zoom lock, the earlier one can often be had for a very reasonable price. I used to have a Tokina 80-400mm, which was excellent at 80mm and ok at 400mm. The Sigma 135-400mm strengths are more at the longer end on the other hand, with excellent 300mm and good 400mm. Chromatic aberrations are more controlled at the longer end than the shorter end, too. Size is not bad, about the same as my Tamron 70-200mm f/2.8 (when the Sigma isn't zoomed out).
Forum: Pentax SLR Lens Discussion 08-28-2012, 05:30 PM  
Which pentax lens give the best 3D effect?
Posted By nater
Replies: 17
Views: 5,230
Shouldn't the Pentax Stereo Adapter win this one? ;-)
Forum: Pentax SLR Lens Discussion 08-24-2012, 07:00 PM  
Do I Really Need Tamron 70-200mm f2.8 Lens?
Posted By nater
Replies: 27
Views: 4,443
There's also the (now out of production) Tokina AT-X 80-400mm f/4.5-5.6 AF, one of the most compact lenses in it's class. Version 1 has no lens tripod mount, version 2 does (though it is small enough to be hand-holdable either way).
Forum: Pentax SLR Lens Discussion 07-06-2012, 08:47 PM  
Mount type
Posted By nater
Replies: 2
Views: 765
Forum: Pentax SLR Lens Discussion 03-02-2011, 10:27 AM  
Samyang 35mm f1.4 now Available
Posted By nater
Replies: 228
Views: 70,366
I think the problem with AF is one of R&D costs and the fact that some (all?) camera makers have proprietary AF algorithms, in many cases protected by patents. For instance, here's the situation with Canon EF:

"Third-party lenses compatible with EOS electronics are manufactured by Sigma, Tamron, Tokina, and Carl Zeiss. The manufacturers of these lenses have reverse engineered the electronics of the EF lens mount. The use of these lenses is not supported by Canon. Sometimes compatibility problems arise, as no third party has access to Canon's specifications for camera-body communication. These compatibility issues mostly occur when using a newer body with an older third-party lens. Over time, most of these issues have been resolved by the major third-party brands. Nevertheless, it is not accurate to call these lenses EF mount, as that term is reserved by Canon for its own lenses exclusively"

I've come across lots of talk in other forums on the internet about people having to send their Canon Sigma lenses back in to Sigma, more so in years past, to have them re-chipped for compatibility fixes with the latest Canon bodies. (I think it's those third-party lens reverse engineered AF protocol compatibility issues which has to some extent led a lot of review sites to try to include a review of a given lens's AF capability.)

I think it's also fascinating that for Sigma's SA mount bodies, when they chose their AF protocol, they chose to use the reverse-engineered Canon EF mount signaling and protocol, rather than come up with their own... while perhaps just a cost-cutting measure, I also imagine having to create a body that speaks the protocol perhaps helped Sigma to improve the implementation in their lenses as well by understanding it as a system better.

I get the impression Nikon's AF protocol is similar, and has to be reverse engineered. On top of that, Nikon doesn't put screw-drive AF motors in their low-end bodies which means anyone buying a low-end Nikon body only gets AF if they buy a lens with an in-lens AF motor. (Note that all Canon EF mount lenses have to have in-lens motors, and there is no such thing as an in-body motor for Canon since their mount does away with any mechanical motor connection completely.)

Even when the intellectual property is no longer covered by patents because they've expired, I don't think Nikon/Canon/etc. give out documentation to their AF systems to third parties, so if you are a third party lens maker and want to make AF lenses, it is not a trivial thing to do for many reasons... and if you do try, you need to have a repair network in place so that you can potentially take lenses back in the future for re-chipping if/when new bodies come out that don't work well with existing lenses.

Think about what Samyang has to deal with just in regards to making manual lenses:

1. Different register (flange) distances
2. Different bayonet mount diameters
3. Different bayonet lug designs

Their Pentax lenses have the advantage of auto-aperture, which fortunately for Samyang is pretty simple to implement in KA mount. Now if Samyang wanted to develop an AF lens and sell it for as many mounts as they currently sell their manual focus lenses, they'd have to:

1. Reverse engineer the Canon AF system, develop a compatible in-lens motor
2. Reverse engineer the Nikon AF system, develop a compatible in-lens motor if you want to target the low-end Nikon bodies as well as the mid/high-end bodies
3. Reverse engineer the Minolta/Sony AF system
4. Reverse engineer the Pentax AF system

Those four steps require a lot of R&D, especially if you're starting from scratch and have no help from any of the camera body makers, which I assume is where Samyang would be starting from. They'd probably need someone to come in with a lot of money and be willing to invest in the long-term with the company to make something like that happen, and I imagine it would take a lot of resources and personnel to pull off, and would make their lenses more expensive, likely having to go head-to-head with Sigma and Tamron... at that point, why would someone buy a Samyang lens (or whatever re-brand) over a Sigma or Tamron? There are already people who shy away from long-established third-party brands like Sigma and Tamron over first-party like Pentax, and if Samyang can't seriously undercut Sigma and Tamron on price or consistently coming out with unique or better products, I don't see them making market headway.

Right now Samyang is in a pretty good position - they're making solid products in a price segment that doesn't have a lot of competitors. I'd call it the modern value manual focus lens category. Voigtlander (Cosina) is above them, but no longer makes their lenses in Pentax mount, Zeiss is yet further above them and similar situation, and with the rising popularity of Pentax cameras the used market has seen supply dry up and prices rise to the point where new lenses from Samyang are not just competitive but in many cases better values.

While I can fantasize about inexpensive autofocus Samyang lenses (and maybe they'll surprise me and pull a rabbit out of a hat someday in that regard), I have a hard time envisioning it becoming a practical reality from a business perspective.
Forum: Pentax SLR Lens Discussion 10-25-2011, 03:19 PM  
Discontinued Zeiss PK and Voigtlander
Posted By nater
Replies: 21
Views: 3,732
Depth of field and angle of view when composing are two other factors that come into play when comparing formats. It's not something easily summarized, so I recommend reading the wikipedia article on depth of field, in particular the section on DOF vs. format size.
Forum: Pentax SLR Lens Discussion 09-13-2011, 07:41 AM  
RMC Tokina 70-210mm F3.5 is the same as Tokina Vivitar Series I 70-210mm ?
Posted By nater
Replies: 11
Views: 7,894
SD is not a Tokina series, it's a technology - Super Low Dispersion:
Forum: Pentax SLR Lens Discussion 08-08-2011, 03:18 PM  
Sigma 70-200 2.8 (NON-HSM) + Sigma/Kenko/Pentax TC?
Posted By nater
Replies: 4
Views: 2,879
No question that the Kenko 1.5x TC will work with the Sigma 70-200mm non-HSM f/2.8 (I say this because the Sigma 1.4x TC works and that will protrude slightly into the lens and the Kenko does not).

Chances are the Sigma will be better quality for three reasons:

1. Sigma 1.4x is a 5 element TC (Kenko 1.5x is a 4 element)
2. Sigma 1.4x is APO (apochromatic) and should be better corrected against chromatic aberrations (Kenko is not APO)
3. Sigma 1.4x protrudes slightly into lens body (when it's possible to use TCs with this design combined with a telephoto lens the results tend to be better)

How much better will need someone who has tested both TCs with this lens to chime in...
Forum: Pentax SLR Lens Discussion 06-27-2011, 02:46 PM  
Nice comparison of CPL Filters
Posted By nater
Replies: 8
Views: 5,943
Lenstip also has a UV filters test and supplement, and there are some other filter reviews and comparisons I've come across, and some of that applies to polarizing filters as well (in terms of comparing the build quality and coatings of different brands and filter lines)...

This page has some good general tips on using polarizers, and this page has some more specific suggestions. There's also some useful info on filters (including polarizers) in this wiki.
Forum: Pentax SLR Lens Discussion 05-26-2011, 07:51 PM  
HSM or SDM mount
Posted By nater
Replies: 18
Views: 5,383
I think a decent number of SDM lenses are in circulation, however there are a few factors:

- SDM (and HSM) motors are used on higher-end lenses, and only in the last 5 years, so in the secondhand marketplace they will constitute a minority for some time to come

- Some SDM lenses have had motor failures for some fraction of people both in and out of warranty. There have been some posts about it here, however it is hard to gauge actual percentage failure rates since it is not information that Pentax has released and people who haven't had any problems don't necessarily post about it.

- For what it's worth I haven't seen any posts about Sigma HSM lenses having motor failures, however Sigma brought HSM to Pentax mount later than SDM, and in some cases has released some lenses for Pentax with screw drive that have had HSM on other camera bodies, so it's a pretty small fraction of Sigma lenses. Also I'd assume there are fewer Sigma HSM lenses sold for Pentax than there are Pentax SDM lenses sold, so the number of Sigma HSM lenses in the secondhand marketplace is an even smaller fraction.

- There has been some recent anecdotal evidence of a revised motor being used when failed SDM lenses are repaired, so it's possible that going forward SDM failures could be even more uncommon than they have been.

- Pentax recently introduced a new motor in their DA 18-135mm lens that they call DC (so a new sub-type of SDM lens)

Your K100D Super definitely does support SDM lenses, and while it was the first Pentax body to ship with SDM support out of the box, the K10D like I said supported SDM lenses with firmware update 1.30 (and the K10D did technically come out a year before, so it could be argued it was the first SDM body).

SDM has been a bit of a divisive issue on the forums, with some people saying they're avoiding SDM lenses due to the problems some have had. (I simply haven't bought any because they've been out of my price range, or because I've wanted to use a teleconverter, and old Pz-AF teleconverters aren't quite compatible in practice, even though they happen to have the requisite contacts).

I hope this info helps.
Forum: Pentax SLR Lens Discussion 05-19-2011, 03:44 PM  
Vivitar 85mm f/1.4
Posted By nater
Replies: 40
Views: 7,433
It's actually both metal and polycarbonate, the outer front (focus ring/filter threads) is where I think most of the plastic is.

It's the tightest fitting lens of all of my lenses by a good margin. Not sure what's up with that.

I wouldn't say cheap... but I wouldn't say luxurious either. Somewhere in between. In fact, I noticed that the texture pattern of the lens finish (Rokinon at least, and I assume the Vivitar is the same and they only changed the rubber grip pattern and text coloring) is an almost identical match to my K200D, and I don't think that feels cheap.

I'd strongly recommend a replacement focus screen and a Pentax O-ME53 or Tenpa 1.36 magnifying eyecup. They help a lot.
Forum: Pentax SLR Lens Discussion 04-02-2011, 08:58 PM  
Samyang 35mm f1.4 now Available
Posted By nater
Replies: 228
Views: 70,366
I'm not so sure it's that simple. It's clouded by the fact that people have emotional investments in this stuff. Start off with the fact that only a minority of people here actually make money from photography, and the vast majority are hobbyist or documenting their lives through photography, that means that in a lot of cases equipment purchases fall under discretionary spending. A person wants to feel good about their discretionary spending, since it's hard to quantify it's value (i.e. it's not about expenditure/return on investment in any easily or universally quantifiable way). For some people, there is a continuing need to justify/support not just recent and current expenditures, but also past expenditures. Therefore if something comes along that's new and that could be better than something already purchased, or there's a suggestion that perhaps it's the decision making process of spending itself that should be revised, it's likely a person will defend both their past decisions and their methodology. I think that the form of this defense can sometimes be 'recommendations' to other people (especially the more forceful, hardline, or narrow).

Sometimes recommendations are just simply recommendations - I tend to trust them most when a person describes them more from their person experience and what has worked for them (which allows a reader to 'map' that experience to their own to see how well it fits) vs. saying something should work for everyone, all the time. And ideally it's an dialog, where all parties are open to revising their own perceptions and methodologies when presenting with new information or observations not previously considered.
Forum: Pentax SLR Lens Discussion 03-10-2011, 10:18 AM  
More Pentax love from Thom Hogan
Posted By nater
Replies: 18
Views: 4,720
I'm not sure if you realize, but technically it's not the government "not charging sales tax," but it's actually a situation of the national government not stipulating that state sales tax be collected at the time of sale for online sales, unless the company doing the online sales is also in the same state as the buyer, in which case it is collected at time of sale. However, the consumer is still obligated to pay use tax for their purchases in the state they live in when they file their annual taxes. (I am a resident of MA and NH has no sales tax so I am very aware of this.) Wikipedia has a good summary of this situation:

With many states in bad shape financially these days, and with internet sales only increasing year-to-year, there are obviously a lot of people in government who want to educate consumers about this situation and make it easier for people to pay the taxes due. (For more on that, read the section in the Wikipedia article under "Enforcement".)
Forum: Pentax Camera and Field Accessories 10-27-2010, 11:32 AM  
Why buy expensive tripod?
Posted By nater
Replies: 41
Views: 11,262
Here are all the links I used when choosing my tripod and head a year ago:

Tripods & Heads

Tripods 101

Dante Stella - Choosing a Ballhead
Forum: Pentax SLR Lens Discussion 07-16-2010, 09:47 AM  
Samyang lenses
Posted By nater
Replies: 38
Views: 11,826
"Non-professional" Nikon cameras require CPUs in the lenses for metered operation, so I think the Nikon versions of the Samyang lenses are as lame (or perhaps lamer, for those "non-professional" Nikon DSLR users). That's why Cosina likes to declare the Voigtländer SL Ⅱ as "CPU-enabled" manual focus, since that can be a big selling point for some Nikon users.
Forum: Pentax Camera and Field Accessories 06-22-2010, 10:36 AM  
What Head for My Tripod?
Posted By nater
Replies: 38
Views: 10,837
Well, I recently spent a bunch of time investigating tripods and ball heads. I was on a budget, so I decided to mostly ignore the weight of the tripod and ball head and instead find the best price/performance for what I wanted. I have a K200D with battery grip, and for shooting macro I have the Pentax FA 100mm lens. I read that ball head ratings are the max they can support, not the ideal amount they can support well and still be used easily, so that when buying one, you should buy a head which is rated for considerably more weight that you will actually be using it with: "Some ballheads are very smooth at a light load, but if the load approaches their ‘rated’ weight load they become rough and jerky."

I decided partway through that it could be useful to get something that had Arca-Swiss compatible quick release plates, and that really limited my options, especially in the price-conscious category, but I did find the Smith Victor BH5, and it should be arriving shortly. It's considerably heavier than either of the heads you list, but it's rated for 26lbs, has lock and drag controls, and has Arca-Swiss compatible plates.

I'm not sure you're going to find a ball head that is both light and can handle the load you want to put on it and have it work well without spending a serious amount of money.
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