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Messages - jrista

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1261
Lenses / Re: question about 600mm lenses
« on: February 09, 2014, 03:03:55 PM »
Canon doesn't produce a 600 f/5.6 because they already produce a 600 f/4.

sure, but the important point is not if canon produces such a lens.
im also happy if tamron or sigma would make one.

thought i guess for 2300-2500 euro a 600mm f5.6 from canon would still sell very well. :) (i would buy one ).
and don´t steal away 600mm f4 customers.
the 600mm f4 is so far out of reach for most amateurs.

i just mentioned canon in this context because Random Orbits mentioned kit lenses and that most DSLR buyers only have one lens.

Just to make sure the point is clear...a $2500 600mm f/5.6 lens probably wouldn't offer the same level of IQ as a 150-600 f/6.3 lens. If you had the option...a 600/5.6 prime that was a bit softer with more CA, or a 150-600/6.3 that was sharper with less CA, and the latter was cheaper...which would you choose? You would choose teh 150-600/6.3. As the objective lens gets larger, it becomes exponentially more difficult to correct for optical aberrations. I've already seen the CA in the 150-600mm lens. Don shared a wonderful photo taken with it, and it was very sharp...but it definitely had more CA than even the 100-400mm canon lens. If your ok with less quality for a 600 prime, then more power to you...but I just don't think any lens manufacturer will do that. That's WHY manufacturers like Tamron opt for the narrower max aperture.

1262
Lenses / Re: question about 600mm lenses
« on: February 09, 2014, 02:24:51 PM »
Most people with SLRs don't get another lens to complement/replace the kit lens. 


sorry but if this argumentation would hold it´s water then any lens beside a kit lens makes no sense for canon. ;)
and canon would not have sold... how many... 90 million EF lenses?

Actually, I know quite a few people who own DSLRs. They only use the 18-55. Canon can sell 90 million EF lenses because pros and serious hobbyists (of which there are many millions) will usually buy dozens of lenses. For all the photographers who don't buy new lenses, there is another photographer who buys many. Canon only needs 9 million customers worldwide to buy 10 lenses each to reach 90 million lenses sold. They have far more customers than that in total...

but it doesn´t change a thing on the fact that his kind of argumentation can not be the reason why canon is not producing a 600mm f5.6.

Canon doesn't produce a 600 f/5.6 because they already produce a 600 f/4. The cost to produce a quality 600/5.6 that is actually worth the money would put it out of range of most customers (i.e. it has to be BETTER than a 150-600 f/5-6.3 in pretty much every respect). The R&D cost to design the lens would require a certain minimum sales ratio per year in order to recoup those R&D costs and make the lens profitable in a reasonable time period. Given the fact that neither Canon, nor any other manufacturer, has produced a 600/5.6 lens is a very strong indication that the cost of the lens would indeed put it into a cost bracket where sales would be very low, thus turning the R&D cost into a very long term liability...and from a business standpoint, long-term liabilities on low-volume products are particularly bad. Better to make an even more expensive product, the 600/4, that would get similar low volume at twice the cost. You reduce your R&D recoup times by half. Not to mention the fact that the EF 600 f/4 L series lens line has a very strong following (just look at the lens banks for the Olympics...there are shelves full of Canon very fast (f/2.8 and f/4) supertele lenses, and maybe a shelf or two for other lenses, so Canon is bound to sell a lot of the 600 f/4 lenses anyway (a hell of a lot more than a 600/5.6, as the people who are willing to shell out many thousands of dollars for such a lens demand that the aperture be as fast as possible as well.)

1263
Reviews / Re: Why the DxO bashing?
« on: February 09, 2014, 02:16:56 PM »
Jon, thanks for that info on the 6D. It explains a lot ! No doubt it's in the instruction manual  :-[

Isn't CR wonderful  ;D

This might be helpful:

http://cpn.canon-europe.com/content/education/infobank/exposure_settings/iFCL_metering.do

1264
Third Party Manufacturers / Re: Here is what Earth looks like from Mars
« on: February 09, 2014, 02:15:03 PM »
The really cool thing about viewing Earth from Mars is that Earth is inward of the solar system, rather than outward. It would exhibit phases like Venus does when viewed from Earth, as it orbits around the sun. So you would have New Earth phase, Waxing Earth Crescent, Waxing Earth Half, Waxing Earth Gibbous, Full Earth (largely obscured by the sun, only visible as it enters and leaves this phase, and then only moments after the sun has set on Mars), Waning Earth Gibbous, Waning Earth Half, Waning Earth Crescent.

Even cooler than Venus...with a powerful enough telescope, you could probably see the Moon's phases as well...what a sight that would be: Waxing Earth Crescent with a Waning Moon Half. :D
That would be an epic view ... one married guy from Qatar got selected to go on a one way journey to Mars, so maybe he'll get to see "Waning Earth Gibbous, Waning Earth Half, Waning Earth Crescent" etc

That would be one crazy trip. Maybe someone will bring along a 28" PlaneWave CDK and an ASA DDM160 mount for "Earth Observing". :P

I don't think it's going to happen, though. The sheer cost of such a trip is so astronomical, not even the world's most popular reality TV show could maintain the funding for it. It would become the single most expensive project the world has ever seen, and I don't think anyone can truly survive on Mars. Not permanently. Honestly, I think when the time comes, if they really do try, it'll end up being a disaster. There are SO many things that could go wrong, not the least of which is food and water supply problems, but also technical issues and personnel issues. Even assuming they try to maintain a supply chain of food and water deliveries, that just means the cost never ends, and they would always need funding.

The key problem with the Mars One mission is the masses of people who would be required to fund it by continually watching the reality show will eventually get bored. Even if the show maintained a core viewership that would never leave, they would never represent the tens of millions of sustained viewers necessary to extract the kind of advertising revenue necessary to sustain the mission.

There is also the inevitable TRUE realization of what these people are signing up for means...a ONE WAY trip to Mars. People think that's amazing right now...but there is no rescue plan, there is no return ship, there is no return period. It is a PERMANENT LIFE CHANGE, on a scale no one on Earth has experienced before. Psychologists can't gauge the effect of that on people, even if they try. That will have to sink in on multiple levels before people finally get it, and when they do, I'd say as much as half the people who sign up for a one way trip to Mars end up snapping once they are stuck there for a LONG year of MASSIVE hardship and the ever-present long-term threat of danger, going ape-S___ crazy, when they realize they are literally marooned on another planet with no hope of return...or at least, no hope unless the Mars One mission ends up building a rescue vessel (which would take years, so all these crazy people just keep on the crazy that whole time...you know what crazy people do to space missions...we've all seen the consequences of THAT via hollywood for enough years).  :o

Mars One...exciting idea...bad idea. Anyway...
Maybe a bunch of hot nud3 ch!cks, and some "Big Brother" style in-house fights/arguments, drama etc, might keep the reality show going for a few decades ;D ... I wouldn't mind contributing towards the first part ;D ;D

Yeah...lol...thats where I thought this conversation was going! :P

I suspect a bunch of hot nude chicks in a big brother style escapade is probably the best way to get everyone killed. At some point your going to get a couple of jersey shore-esque guidos going at it over the chick with big tits, and next thing you know an airlock pops open because the fools are fighting in it....derp, there goes the Mars One mission! Oh, gee, and we got to see a bunch of people bleeding from their eyes while they all died a horrifying death...on live TV...over a pair of tits....  :-\

1265
Lenses / Re: question about 600mm lenses
« on: February 09, 2014, 02:11:53 PM »
Most people with SLRs don't get another lens to complement/replace the kit lens. 


sorry but if this argumentation would hold it´s water then any lens beside a kit lens makes no sense for canon. ;)
and canon would not have sold... how many... 90 million EF lenses?

Actually, I know quite a few people who own DSLRs. They only use the 18-55. Canon can sell 90 million EF lenses because pros and serious hobbyists (of which there are many millions) will usually buy dozens of lenses. For all the photographers who don't buy new lenses, there is another photographer who buys many. Canon only needs 9 million customers worldwide to buy 10 lenses each to reach 90 million lenses sold. They have far more customers than that in total...

people are buying a 85mm f1.2 for 1900 euro, so why not a 600mm f5.6 for 2100 euro?

You assume a 600/5.6 would only cost $2200. As I mentioned in my previous post...if one aims to maintain the same level of IQ, that means tightening tolerances, and that's where costs rapidly start to rise. A 600/5.6 could easily cost $4000, and a 600/5.6 that is optically superior enough to warrant that level of cost could easily skyrocket to around $7000. Once you get above the $2500 price point, you really have to justify the cost to a customer. You also greatly reduce your pool of potential customers who can actually afford such cost, meaning the lens has to be that much better. A $2200 estimate is the rock bottom estimate possible...and such a lens probably wouldn't be as good as the 150-600/6.3.

Over that $2500 price point, and you enter a wholly different market, which dictates an entirely different approach, and changes the name of the game. Your asking customers to spend many thousands of dollars, and they will expect a return for every single penny they spend. Your in a cost bracket now where people would probably rather spend more for 600/4 than not. Whether its $5000, $7000 or $12000, gaining a third of a stop additional light isn't really enough...even if the optical quality is great. There has to be more for that kind of expenditure. (I speak from experience, as I am one of those customers...I own the EF 600mm f/4 L II, I bought it brand new with cash...and the aperture is really necessary to justify that kind of cost.)

there are enough birders and wildlife shooters out there.
maybe not as much as shallow depth of field portrait shooter.... but still enough i think.

There are certainly lots of them. But not necessarily that many of them willing to spend more than a couple grand. If your in the 7D/100-400mm lens bracket, then your in the cost-savings bracket, not the "I'll spend the dough if you give me the closest thing to perfection money can buy" bracket.

1266
Reviews / Re: Why the DxO bashing?
« on: February 09, 2014, 01:57:06 PM »
actually DXO marks is a great site and they do all right.
for that we should respect them.
however , the way they rank all sensors is plain silly.
they put too much weight on base ISO DR, so some people do not like their site(not all of us can or do use a tripod all the time).
 that all said , most of their sensor measurements are correct maybe except lowlight sports part of their scoring.
 
I have both the 6D and the D800E(the A7R too) and even resampling the D800E files to 12mp , it is still not as clean as the 6D file.
But they obviously rate the D800E better for lowlight sports(I do not know what they mean by sports, though).
other than that most of their sensor quality assessments are correct , and I have to respect their hard work.

That is exactly the problem with DXO though. They have some measurements, but their scores are actually primarily based on weighted extrapolations derived from measures, not the measures themselves. The low-light sports "rating" is based on a mathematic extrapolation, not actual measurements of the D800's noise.

What you've said about resampled D800E files, and how they are still noisier than the 6D, is something I've stated for a while (I've poked around with some D800 files, and experienced the same thing relative to 5D III files.) I even mentioned as much in an earlier post of mine in this thread. It's one thing to use mathematics to extrapolate how much noise might exist in a downsampled image, and another thing to actually measure the noise in the downsampled image. DXO only extrapolates, they don't measure, so their results aren't real world, they are purely theoretical.

There is always a gap between theory and reality, though...we all know that.

1267
Lenses / Re: question about 600mm lenses
« on: February 09, 2014, 01:50:02 PM »
Actually, it isn't the diameter that matters, it is the total volume of glass. Assuming the thickness of the front element (and, all the other entrance-pupil elements...remember, there are elements before and after the diaphragm) don't really change, then it is the area you have to look at. If you only factor in the diameter, the difference is 107/95, which is ~12%. However if you factor in the area, that is ((107/2)^2ϖ) / ((95/2)^2ϖ), or 8992/7088, which is 27%. The front element is going to have to be thicker as well, so we are talking about at least a 30% increase in cost just for the front element. The quality of the glass would need to be higher as well, in order to produce similar quality to a smaller element, that also increases cost. The subsequent entrance pupil elements, or at least the few closest to the front element, would also need to be larger. That further increases cost, as each of those would be anywhere from 20-30% more expensive than their f/6.3 counterparts. In order to maintain midframe, edge, and corner performance, one would have to deal with the increase in optical aberrations that a larger front element brings to the table...the overall complexity of the lens design would have to increase (and mind you, were just aiming to maintain IQ parity with the 150-600 f/6.3 lens, not a 600mm f/4 lens.)

It isn't the 12% difference in cost between a 95mm and a 107mm diameter front element. It is more like a 75-100% difference in cost between an element of 27% larger area, greater thickness, accompanied by secondary internal elements pre-diaphragm that ALSO increase in size by a similar margin, as well as increased design complexities. Ironically, that still doesn't take it outside the realm of affordability relative to a 600mm f/4 lens. The price could double, and it would still only be $2200...but there would indeed be a hefty relative increase in cost.

well i .. and as i guess most here... know that.
so when i say it needs more glass i don´t speak about area or radius, i speak (of course) about volume. ;)

but still, twice the price should be possible. even after your more detailed calculation. ;)

and why would a fixed focal lenght 600mm be more complicated then a zoom going all the way to 600mm? i would guess a zoom needs more elements and of course more moving elements.

Quote
the overall complexity of the lens design would have to increase

so the question remains... why is nobody doing it?  :)

First, I was directly responding to Don's comment about the difference merely being 95mm vs. 107mm.

As for cost, though, I think people underestimate what it really takes to increase the size of the aperture, and maintain the same level of quality. The larger each lens element gets, the more difficult it becomes to correct for optical aberrations. It isn't just making a bigger element. It is making a bigger element more perfectly. It means tightening tolerances.

It's really the tightening of tolerance where the increase in cost comes from. It's an asymptotic relationship with perfection...you can never really attain perfection...its unobtainable...however as you get closer and closer, as the gap between what you aim to achieve and perfection closes, cost begins to increase dramatically. I honestly don't know exactly where a 600mm f/5.6 falls on that asymptotic curve of perfection. Given that no one has tried to make a 600/5.6 yet, I have to suspect that it falls into a cost bracket wherein it would be difficult to recoup R&D costs in a reasonable time frame. I say $2200, based on a rather clinical mathematical extrapolation. I am no optical engineer, and it is entirely possible that to really make a 600mm f/5.6 lens that had the same optical quality as a cheaper 150-600mm f/5-6.3, the cost would fall a whole bracket higher...$4500-$7000. However, for that cost bracket, the optical quality should be quite a bit HIGHER than a 150-600mm f/5-6.3 zoom...so instead of falling around $4500 in price, it ends up closer to $7000 in price, because were pushing farther and farther up that curve towards perfection, where tolerances must be tighter and tighter.

I suspect there isn't a 600 f/5.6 yet because it just isn't cost effective, and that it is more lucrative to build a 600mm f/4 lens, as the ratio of sales is probably very similar, yet you get so much more for the f/4 version.

1268
Animal Kingdom / Re: Show your Bird Portraits
« on: February 09, 2014, 01:38:49 PM »
Thanks again jrista and I think you're right.  I'm trying things but not the best judge of the final result.

Certainly! Don't stop trying. That's how you learn.

You might want to pick up Michael Freeman's books on photography...they will give you an EXCELLENT core basis for the general photographic stables: Exposure, Composition, Tone & Color.

You should also pick up Art Morris' book The Art of Bird Photography (the older book, not the newer CD ebook). ABP is an excellent book, especially the chapter on exposure. You'll learn more from Art than I could ever possibly teach you. I strive to be as good as him some day, but I figure I'll be about his age before I am, and I could never compare to the teacher he is.

A while back I was debating a friend who generally knows more than me, having gotten into DSLRs fairly seriously some years back.  He tends to be very particular about things.

Here's what we didn't agree on, as he tried to push me towards producing a photo of wildlife that reproduces as closely as possible what the eye had seen.  This was in the context of shooting a bison that was almost black to the eye with snow everywhere.  I said that if I was shooting a brown bear in the bush and it was dull, I'd wan't a picture of a "brown" bear if possible, not a dark blob.  This seemed to register with him a little but I think both of us are a little unsure about how to view such things.  Any comments jrista or anyone else?

Photography is an art. Art is a matter of personal style. Your in the experimental phase, so right now, the best advice is to keep experimenting, play with exposure, try silhouettes, try exposing so you see the brown bear as a brown bear, etc.

Some people aim to produce "clinical" photographic results...they only care about the technical perfection. To be perfectly honest, I've always found such photography to be bland and artless. There is rarely any feeling in photos created clinically...to perfectly and exactly reproduce just what the physical eye saw, ignoring what the minds eye saw. I think involving aspects of both is important...its the ratio of the mix that really boils down to personal style. You sound much more like a minds eye kind of guy to me...you want to share what you feel you saw as much as what you actually saw (maybe more.) I wouldn't ignore that!

Find your personal style. It won't happen overnight. It'll require time and dedicated effort, trialing various approaches and figuring out which ones best represent what you saw AND felt to your viewers. I may have a lot of advice to give (and I honestly thank you for listening, even if you don't take my advice!), but I am still exploring and discovering my own personal style. I've been photographing birds for two years now. I have a better sense of what my own personal style is, but I haven't really perfected the technique that will allow me to achieve that style every time I point the lens and press the shutter button.

Also, don't forget that post-processing is just as much a critical part of the process as what you do in camera. The camera is a clinical device...it will expose the world according to the technical specifications of its design, and the mechanical and electronic settings you give it. You have some control over those personal style aspects in-camera from the standpoint of composition and scene layout...but I think the bulk of personal style is brought out in the way you process. (I think it's always been this way as well...even in the days of film, critical photographers spent untold hours in their darkrooms playing with chemical baths, dodging, burning, perfecting transfer processes, etc.) Color, tone, contrast, crop, vignetting, etc. are all elements of style. Use them to your advantage.

1269
Reviews / Re: Why the DxO bashing?
« on: February 09, 2014, 01:24:11 PM »

Unfortunately, the same metering module put on the 6d is more erratic,

+1; you're not the only person to find that; I'm finding the matrix metering (pattern) almost 'erratic' too. It's as if it's trying to be too clever in certain lighting conditions. It also seems to react to blue by underexposing but I believe it doesn't have colour metering.

Certainly the matrix on the 5D behaved differently to the mkii which behaved differently to the 6D. I would recommend trying average metering mode - where there is nothing in the metering icon box. This is actually centre weighted, and should be more predictable but not 'intelligent'.

Keep in mind that Canon's iFCL metering is highlight-weighted. The 6D, and for that matter the 7D (the first camera to get iFCL) will change the metered exposure as highlights change. Even if the highlights are only point highlights (say specular sparkle off a car or off water) that will affect metering. The camera is trying to preserve those highlights. For some people, that's a godsend. For others, it results in what they call erratic behavior.

For me, since I rarely shoot at anything below ISO 800, the changes in highlight tonality don't really matter much...I'm almost always lifting darker midtones a couple stops anyway, and at ISO 800+ there really isn't any banding noise to be a problem. If you shoot at lower ISO settings, then you might want to increase EC a bit, because specular highlights are bound to be blown regardless, and they really don't matter all that much.

The 5D II behaved differently because it had a monochrome metering sensor that was not highlight weighted. The 7D was the first with iFCL, which stands for Focus, Color, Luminance metering. Technically speaking, anything with iFCL (which includes the 7D, 6D, 5D III, and some of the newer Rebels) are actually a LOT more intelligent than the 5D II meter. Once you learn why the meter behaves the way it does, it should help you to work with it, rather than against it.

1270
Reviews / Re: Why the DxO bashing?
« on: February 09, 2014, 01:18:45 PM »
In the film days the reason we bought spot meters was specifically not to take one reading, but to take various reading from around the scene to get a range and average, or to take a reading from a grey card, again from the different illumination within the scene.

Thanks for the information, I'm really not experienced with spot metering as the eval metering on the 60d is very good and with a bit of experience I was always able to guess a good ec.

Unfortunately, the same metering module put on the 6d is more erratic, and that's why I have to think about other means of getting a correct exposure - which is difficult when in a hurry, that's why I'm happy about as much dynamic range as I can grab, for example the +1/3-1/2 stops added by Magic Lantern.

I have always used Canon's spot meter mode when doing landscape photography. I follow the same basic methodology that Sporgon outlined. I meter, with the cameras built-in meter, to determine the true dynamic range of the scene, by metering the brightest highlights (usually not the sun, but say clouds or sky near the sun) and the deepest shadows, then computing the difference in EV. I may also meter some midtone areas to know where they fall within that range. Knowing the actual dynamic range of the scene is helpful for landscapes, as it tells you exactly how much GND filtration you need. If the scene is 12 stops, I'll use a 1-stop GND. If it's 16 stops, I'll use a 1- and a 3-stop GND filter. If it's 20 stops, I'll use the 2, 3, and 4 stop GND filters...and will usually mix hard and soft grad in some fashion.

I've been out of landscape photography for a while now (I really need to get back into it more), but back when I did it regularly, I was actually able to fairly accurately guage the tonal range of a landscape just by looking at it (and maybe framing it by making two L-shaped corners with my hands). Being able to gauge DR just by looking at a landscape is very helpful in those situation where the lighting may only last seconds, so you can drop in the necessary filtration and get the shots, rather than have to spend many minutes metering and calculating. It doesn't have to be exact...all that really matters (at least with landscapes) is that you compress the DR to fit within the limitations of the camera (i.e. compress the histogram so it isn't riding up either edge.)

Landscapes are a bit unique in this respect, with the ability to control DR with filters. If you need more DR for other kinds of scenes, then usually the only way to get it is with more sensor DR or the use of HDR processing.

1271
Third Party Manufacturers / Re: Here is what Earth looks like from Mars
« on: February 09, 2014, 12:33:46 PM »

There is also the inevitable TRUE realization of what these people are signing up for means...a ONE WAY trip to Mars. People think that's amazing right now...but there is no rescue plan, there is no return ship, there is no return period. It is a PERMANENT LIFE CHANGE, on a scale no one on Earth has experienced before.


Can we make a recommendation for the first person to go on this trip ?  ;)

Hummm...am I supposed to take a hint from that?  :o

1272
Reviews / Re: Why the DxO bashing?
« on: February 09, 2014, 12:29:18 PM »
Here's an army of ground squirrels for ya:





There were dozens of holes, each filled with about 5 prairie dogs!

1273
Lenses / Re: question about 600mm lenses
« on: February 09, 2014, 12:11:35 PM »
i talked for 2 hours with a friend on the phone today.
he asked me if i know someone who clould be interested in his EF 100-400mm.
he bought the tamron 150-600mm and has no use for the canon 100-400mm anymore.

he told me up to 400mm the tamron is as good as the canon.
above that the resolution drops but it´s still good.
he said that he thinks for noticable better image quality there is no way then buying the EF 600mm f4.
a 400mm f2.8 +TC would not yield noticable better image quality. can´t say if that´s true (he is not a pixelpeeper looking at his images at 200% all the time).

anyway... that made me think.

when tamron is able to produce a 150-600mm zoom for around 1100 euro.... then why is no company making a really good 600mm f5.6 for lets say 2000 euro?

a fixed focal length should be cheaper to produce then a zoom right?
ok for f5.6 you need a bit more glas.... but then 2000 euro would be twice the price.

if i would buy the tamron i would buy it for the 500-600mm focal range.
that´s where i would use that lens 95% of the time.
what i really need is a supertelephoto lens with great quality at the long end.

the tamron offers good quality at 600mm.
but why is nobody making a fixed 600mm f5.6 for 2000 euro that has excellent quality?

it should be possible from production cost and profit viewpoint... not?
This is a question I have been asking for years :)

The Tamron 150-600 isn't all that bad at 600, it's great from 150-400 and merely "pretty good" at 600. If they were to design a fixed lens at 600, the optics can be optimized for that focal length and the lack of zoom mechanism makes the lens lighter, simpler, and optically superior. A 600F6.3 lens should be able to be made for less than the 150-600, but with lower sales numbers (people love zooms) some of the economies of scale are lost so I would expect the price to be about the same.

Going to a 600F5.6 would mean changing the last element from to 95mm to 107mm, not a huge change, and certainly doable for twice the price...

Actually, it isn't the diameter that matters, it is the total volume of glass. Assuming the thickness of the front element (and, all the other entrance-pupil elements...remember, there are elements before and after the diaphragm) don't really change, then it is the area you have to look at. If you only factor in the diameter, the difference is 107/95, which is ~12%. However if you factor in the area, that is ((107/2)^2ϖ) / ((95/2)^2ϖ), or 8992/7088, which is 27%. The front element is going to have to be thicker as well, so we are talking about at least a 30% increase in cost just for the front element. The quality of the glass would need to be higher as well, in order to produce similar quality to a smaller element, that also increases cost. The subsequent entrance pupil elements, or at least the few closest to the front element, would also need to be larger. That further increases cost, as each of those would be anywhere from 20-30% more expensive than their f/6.3 counterparts. In order to maintain midframe, edge, and corner performance, one would have to deal with the increase in optical aberrations that a larger front element brings to the table...the overall complexity of the lens design would have to increase (and mind you, were just aiming to maintain IQ parity with the 150-600 f/6.3 lens, not a 600mm f/4 lens.)

It isn't the 12% difference in cost between a 95mm and a 107mm diameter front element. It is more like a 75-100% difference in cost between an element of 27% larger area, greater thickness, accompanied by secondary internal elements pre-diaphragm that ALSO increase in size by a similar margin, as well as increased design complexities. Ironically, that still doesn't take it outside the realm of affordability relative to a 600mm f/4 lens. The price could double, and it would still only be $2200...but there would indeed be a hefty relative increase in cost.

1274
Third Party Manufacturers / Re: Here is what Earth looks like from Mars
« on: February 09, 2014, 11:59:32 AM »
The really cool thing about viewing Earth from Mars is that Earth is inward of the solar system, rather than outward. It would exhibit phases like Venus does when viewed from Earth, as it orbits around the sun. So you would have New Earth phase, Waxing Earth Crescent, Waxing Earth Half, Waxing Earth Gibbous, Full Earth (largely obscured by the sun, only visible as it enters and leaves this phase, and then only moments after the sun has set on Mars), Waning Earth Gibbous, Waning Earth Half, Waning Earth Crescent.

Even cooler than Venus...with a powerful enough telescope, you could probably see the Moon's phases as well...what a sight that would be: Waxing Earth Crescent with a Waning Moon Half. :D
That would be an epic view ... one married guy from Qatar got selected to go on a one way journey to Mars, so maybe he'll get to see "Waning Earth Gibbous, Waning Earth Half, Waning Earth Crescent" etc

That would be one crazy trip. Maybe someone will bring along a 28" PlaneWave CDK and an ASA DDM160 mount for "Earth Observing". :P

I don't think it's going to happen, though. The sheer cost of such a trip is so astronomical, not even the world's most popular reality TV show could maintain the funding for it. It would become the single most expensive project the world has ever seen, and I don't think anyone can truly survive on Mars. Not permanently. Honestly, I think when the time comes, if they really do try, it'll end up being a disaster. There are SO many things that could go wrong, not the least of which is food and water supply problems, but also technical issues and personnel issues. Even assuming they try to maintain a supply chain of food and water deliveries, that just means the cost never ends, and they would always need funding.

The key problem with the Mars One mission is the masses of people who would be required to fund it by continually watching the reality show will eventually get bored. Even if the show maintained a core viewership that would never leave, they would never represent the tens of millions of sustained viewers necessary to extract the kind of advertising revenue necessary to sustain the mission.

There is also the inevitable TRUE realization of what these people are signing up for means...a ONE WAY trip to Mars. People think that's amazing right now...but there is no rescue plan, there is no return ship, there is no return period. It is a PERMANENT LIFE CHANGE, on a scale no one on Earth has experienced before. Psychologists can't gauge the effect of that on people, even if they try. That will have to sink in on multiple levels before people finally get it, and when they do, I'd say as much as half the people who sign up for a one way trip to Mars end up snapping once they are stuck there for a LONG year of MASSIVE hardship and the ever-present long-term threat of danger, going ape-S___ crazy, when they realize they are literally marooned on another planet with no hope of return...or at least, no hope unless the Mars One mission ends up building a rescue vessel (which would take years, so all these crazy people just keep on the crazy that whole time...you know what crazy people do to space missions...we've all seen the consequences of THAT via hollywood for enough years).  :o

Mars One...exciting idea...bad idea. Anyway...

1275
Animal Kingdom / Re: Show your Bird Portraits
« on: February 09, 2014, 11:45:51 AM »
IslanderMV, I just love that duck!

jrista, I'm guessing this doesn't really work either??

Jack

Same deal. You can see where the foreground object blurrs into the stuff behind it. That just never really works. Not in the general case anyway. Birds are highly detailed. If you did that with things that did not contain as much fine detail as birds and bark, you might be able to put OOF foreground elements to good purpose, but I am not a big fan of it for anything nature, really. The only time I've seen foreground OOF work is when the only thing from the subject plane it obscures is the birds feet and legs. I've seen this a couple times, where shorebirds sometimes have one or both feet obscured by a slight hump of sand in the foreground.

Overall, though, my personal recommendation is you keep the subject plane unobscured.

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