p_mui

December 1, 2012

Hello all!

Took some readings with a t 0.1 meter (Broncolor FCC) and here are the results. Quite interesting. 2400 pack, Prohead, single tube. These are good numbers to use a guidelines in case you're doing any sort of fast moving photography with the packs. The numbers that Profoto provides do not have any type of t. numbers attached to their specs, so it could be either t.5 or t.99 for all we know. Take the Profoto literature numbers with a huge iceberg sized grain of salt. Enjoy.

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September 2, 2012

Bron makes an adapter to use Profoto heads to Bron Paras. Works great!

As for the Bron para, it's a 24 segment, fully focusable. Profoto has less segments (20) and looks a bit more "coarse" in highlight reflections. Also the focus isn't as refined as the Bron para, that is, the profoto has two different focus rod lengths. Profoto is a continuous rail.

September 2, 2012

Cathy - Broncolor Scoro S will do 50 shots per second at low power levels. Recharge time is on the order of 0.02 seconds, much faster than the Profoto 8 pack. Profoto 8 is rated for 20 shots per second and has a longer recycling time. Hope the shoot went well!

October 25, 2010

Times certainly have changed since the last response of this thread. The Traveler is no longer produced and there appears to be no direct replacement in the lineup. In 1998/99, a telescope company by the name of Takahashi introduced the 4 inch f/5 double fluorite refractor. 530mm at f/5 or 850mm at f/8 with the ExtendQ 1.6x optic. The color correction is nothing short of astounding for an optic as "fast" as f/5. Plus the sharpness, contrast and resolution are also top notch. I routinely photograph nature photography with this telescope and it has proven to be an optical wonder. A quick internet search on the traveler will produce some results for astrophotography, but the takahashi FSQ (N and ED) have become the standard for serious astro imagers.

Probably THE most color correct telescope on the market, refractor wise, would be the TOA series from Takahashi. If I remember correctly, it's a cooke triplet that has double ED glass.

Using a mirror optic presents it's own set of problems. For one thing, you get a HUGE loss of contrast due to the aluminum coating. If you examine the aluminum coating, you will find that the metal itself (or any coated metal) has a columnar like structure which will cause plenty of light scatter. It's the nature of the beast and no amount of "flocking" or baffles, etc will help in this regard. A high end refractor with the equivalent aperture area will always outperform a mirror optic. True, a mirror optic will be essentially "color correct" and free of chromatic aberration, but they definitely have their own set of cons to the list. Another thing to consider - the corrector plate on many mirror optic hybrids (SCT/Schmidt Cassegrain, schmidt cameras, maksutov cassegrains, etc) will introduce chromatic aberration due to the fact that it's a piece of glass doing some, but not all of the correction.

I've had quite a few chances to shoot with the new Canon 800 IS lens and I've been severely disappointed with it's optical quality when compared to a high end telescope. Lack of contrast, lack of resolution, etc. The only thing good about it is the autofocus, the lighter weight of the optic (when compared to my 15 pounded fully loaded takahashi FSQ106N) the image stabilization and the aperture control. Optically speaking, Canon has ALOT to improve, despite what the famous Canon bird photographer says. But then he doesn't shoot with a high end Takahashi, Astro Physics or TEC telescope in the field. I definitely do.

Put it this way. Let's say you went from consumer glass to a high end telephoto lens, say an "ED" or "L" series glass. Quite a bit of difference. Huge. Now take that same difference and then some more when going over from a L glass (or ED if you're shooting the other system) to the highly corrected telescope. It's quite shocking and definitely shows up when printing 8x10. Lots of microdetails.

A factor to consider is that the high end telescopes are made with extreme precision. Companies like Tak, TEC and AP will take each batch of glass and measure out the melt data for the production run. The melt data for each type of glass or even crystal (pure fluorite) is quite critical. After the melt data is considered and plugged into their optical formula, the grinding and polishing (figuring) of each element takes place. Mind you, this isn't the high speed polishing/grinding that Canon, Nikon, Leica, Zeiss will use. They can blast out parts in 20 minutes or less with plenty of zonal errors. With the t-scope guys, it takes many hours, even DAYS to get the figure of the lens where they want it.

Whenever you high speed grind a lens, it generates plenty of heat. More than enough to distort the figure of the lens. But most of the time, the camera manufacturers will do this to meet production numbers. Many thousands of rpms vs a few hundred rpms of the t-scope optic.

Camera lens manufacturers will NOT have the time to measure out the melt data of each specific glass, but instead, rely on the "slop" or tolerance of the air spaced design. With a camera brand telephoto lens, most people aren't really looking for that last bit of contrast, or sharpness or saturation. Also note that camera lens makers will not give you the wavefront error or even a measurement of how good the lens is. One of the measurements is called Strehl Ratio.

A perfect optic will have a 1.00 strehl ratio. When a lens is pointed at a true point source (star or simulated star) it will have the ideal Airy disc with very little energy in the second ring. High contrast, high sharpness, all the good stuff. Now with an optic that has low strehl ratio, you will get a significant amount of smeared details, lowered contrast, etc. A link to an optical test (with strehl ratio) is listed below.

http://www.astro-physics.com/products/accessories/software/atmos/atmosfringe.htm

About the ONLY lens that I know of that advertised "diffraction limited" optics were the Leica R series telephotos. Diffraction limited means 0.8 out of 1.0, which is respectable for an optic. Not the best, but at least they're advertising. With the other brands, they won't list it. I wouldn't be surprised if the new Canon 800 lens had a strehl of .3 or lower. Takahashi and AP as well as TEC have strehl ratios of .95 (for the Tak FSQ ED and N) and .99 for the AP, TEC and TOA triplets. Truly remarkable.

Something that isn't well known about optics - you can either have the color correction (for the melt data, if it's designed correctly) or the focal length. In other words, if you get a different batch that has different melt data, you can have one or the other, not both. So if it's a 500mm optic (or thereabouts), you can keep the perfect 500mm focal length or you can vary the focal length to achieve the color correction you want. There is no free lunch.

High end telescopes will NOT play "second fiddle" to ANY commercially made camera manufacturer (or even lens manufacturer) optic out there, at least not in terms of ultimate optical quality. Times have changed!

Astro Physics now has an 8+ year waiting list.

For more info on nature photography with telescopes, you can check out my article in Nature Photographer, Winter issue, 2009. The article is labeled "ultra high resolution optics".

October 14, 2010

They definitely existed. The 4 inch f/12 version was produced a short time by Nikon. Being f/12, it wasn't a short tube in the least, nor was it using any advanced glass or mating glass that Astro Physics, TEC and Takahashi use today. You can find many telescopes in the 4 inch diameter ranging from f/5 (takahashi FSQ106N / ED) to f/8 (Astro Physics AP102). Below is a link of the Nikon f/12 model with pics.

http://www.astromart.com/classifieds/details.asp?classified_id=666037

June 1, 2010

Nice pics. That's actually the beginning portion of opening the lens completely up. I would suspect the boards first and foremost. You might have to get at each one of the elements and clean them up due to the water damage.

May 24, 2010

Emmett -

Also if you're trying to dry out the lens, nothing works better than some packs of desicant silica gel. Make sure they're brand new fresh packs. Just put the lens in a ziplock bag, add some desicant gel and squeeze out all the air in the bag, then seal shut. Much more effective than the "rice" trick.

About the only water damaged piece that I have not been able to recover was a friends Canon 5D body. But that was in a flooded basement with plenty of iron oxide in the water. It died a horrible death.

May 24, 2010

Emmett -

More than likely the lens elements can be saved if they're cleaned and dismantled. Otherwise there might be some acids and other nasties in the stream which may eat at the coatings.

As for the electronics, that's a different story. I have yet to see a USM ring motor go bad physically. The electronics which drive the USM, that's a different story. Same with the EMD.

Internal mechanics should also be good such as the focus cams and zoom cams. Canon builds them quite robustly.

Send it off to Canon. Get an estimate on the repair. I've had to repair my 70-200 2.8L since it was dropped from someone borrowing it. Had to take the entire thing apart so I'm quite familiar how they're put together. And yes, I got mine working fully. They're not too hard to work on if you know what you're doing.

February 21, 2010

Takahashi FSQ106N modified petzval. 530mm at f/5. Used for serious astronomy imaging and handles the torturous astrophotography realm with virtually ZERO CA and pinpoint out to the edge of it's 100mm+ image circle. On an average day, it will still crank out over an 88mm image circle, virtually zero distortion. It was meant to cover 4x5 inch film with some vignetting, or even the large 4x4 inch sensor from Dalsa with the adapters (set for 100mm+). Add on the 1.6x ExtenQ and it becomes a 850mm at f/8 optic.

Astro Physics 130EDT telescope. 1040mm at f/8. Needs a field flattener, but is an awesome optic. 65mm image circle.

Astro Physics 155EDFS telescope. 1080mm at f/7. Also needs a flattener, but the increase in resolution is around 40% over the 130.

Every single optic that I've tried that was commercially (camera mfg) made, whether it be Zeiss, Canon, Nikon, etc would usually FAIL when it came to either the CA test or the flat field test. Shot wide open or even two stops down, you could see the field distortion, but not with the high end astro optics when photographing a star field such as the one in Sagittarius.

And they make QUITE a difference in terrestrial photography. I shoot nature and also indoor gymnastics with the FSQ106N. Manual focus only. Needs quite a bit of skill and patience to work with, but well worth it.

December 24, 2009

Arthur,

Yes, the new FSQ106ED is based off the ED glass, FPL53 if I recall correctly. The older scope, the FSQ106N uses 2 crystalline fluorite elements. On high magnification viewing, or for that matter, any viewing, the fluorite model shows a bit more contrast due to the lack of scatter.

Canon has it's own subsidiary company, Optron, which grows the fluorite crystals. Nikon probably won't go to fluorite since they're marketing ED glass heavily, and also fluorite crystals are much harder to work with. When a figure is being put on the fluorite, it's soft enough to "bound" and "rebound" as well as contract and expand due to friction of the polishing material. ED glass is much easier to work with in this aspect.

I've looked through Zeiss and Leica spotting scopes and have been disappointed with their level of color correction. A very sensitive test is to put the view onto a tree branch a few hundred feet away. If it's an overcast (mostly white) background, you'll see a purple fringe outlining the tree branch. I'll look through the 85T FL when I get a chance. What worries me is that there are quite a few optical elements in the chain, something that will definitely rob the contrast, saturation, etc. Thanks for the link!

Kelly - agreed on your observations. Better materials, with increased precision in manufacturing and detail work will make for a much better end result!

One thing about the air spaced design, it's more tolerant of batch / melt data shifts, but it will still affect the end result. It gives the camera manufacturers a bit of slop to the glass, but not too much.

As the melt data changes, you can either have the solid color correction, or keep the same focal length. NOT both. So, if they're designing a 600mm optic, they can keep the 600mm focal length, but the color correction will differ from the batch. Vice versa also - keep the same critical level of color correction, but the focal length will change from batches. In many cases, they'll keep the same focal length. Just way too much work into producing master test plates for each different batch of glass for the entire lens. Big "fudge" factor, especially if you consider some of the 17+ element designs.

December 19, 2009

It should work out fine. A "medium format" lens is just basically a lens with a larger light cone to cover the area of a 6x6, 6x7, etc. But I'd be willing to bet that the Zeiss on the D3x would produce some amazing images.

The Takahashi that I was talking about covers almost the complete area of a 4x5 inch plate. So it can be considered a large format lens.

December 16, 2009

What was the cost of the Zeiss superachromat lens?

And I'm not surprised that the "you know who" guys would like the lens. Infrared surveilance would be quite ideal with it. Not meant for the ultimate in image quality mind you, but it would definitely get the job done, especially in the IR range!

What doesn't make sense is that the overall resolving power isn't that great, at least not in terms of raw aperture. A 62.5mm front diameter lens (350mm / f/5.6) can only resolve a certain amount of detail. Roughly 2 arc seconds. A 4 inch diameter (~101mm) will resolve about 1 arc second of detail. Larger the diameter, more resolving power, all things being equal.

December 16, 2009

The wiki article mentions "fluorite glasses". This is ED glass. True fluorite elements with no glass components are called crystalline fluorite.

From the spec sheet, Zeiss did a GOOD job for color correction, AND they took into consideration the melt data for each batch. If the color chart holds true, they originally designed it for 550nm as a center point, which is what many telescope makers go for. Why the 550nm mark? Because it represents the green color, the color where the human eye is the most sensitive.

But lets take a closer look. The AP graph that I posted earlier, http://www.astro-physics.com/products/telescopes/160edf/160colorcurve3.jpg , has THREE crossings from 400nm to 700nm. ALL of which are visual to the eye. Now if we take a look at the wiki definition of "superachromat", http://en.wikipedia.org/wiki/Superachromat , you'll see that it only has TWO crossings from 400nm to 700nm, with respect to the focal plane. Now if you're using a camera that has sensitivity out to 1000nm (infrared), then the Zeiss lens will fit the bill. But in terms of just attaching a standard digital back (phase one, leaf, etc) then it's very very overkill.

So why did Zeiss go with "superachromat"? My guess is that there are only two crossings from 400nm to 700nm. APO chromat says THREE crossings, from 400nm to 700nm, if memory serves me correctly.

In terms of color correction alone, it may be possibly be the best corrected commercially available camera lens out there. I'd actually like to see one of these lenses perform under a critical star test and get some strehl numbers, wavefront numbers, etc from it. I'm just tossing a number out there, but it's possibly better than .80 strehl, a number difficult to obtain with camera lens manufacturers. The only other one that claims "diffraction limited" would be Leica in SOME RARE cases. A "1.00" strehl means a perfect optic in figure, with all of the energy concentrated into the airy disk on a point source. The Takahashi FSQ106N typically gets an average of 0.95 or better, which is extraordinary in terms of a 4 element design. The TEC and AP telescopes usually get .99 on the average. Canon, and I'm just tossing out a number out there, would probably get a 0.40 or lower due to the amount of aberrations depicted on the links in previous postings. Yes, I realize that the postings were for the 300 and 400 lenses, but the distortions would be scaled up in the 800 lens. Trying to correct for 18 elements in the 800 f/5.6 lens is an extremely difficult task. Even if they took all the tricks from the t-scope manufacturers, I doubt that the strehl would get above the 0.8 mark, simply due to the amount of elements. Compounded errors with more elements.

The higher the strehl ratio number, the higher the contrast and intensity there is when rendering point sources. Rendering point sources isn't easy - it's actually one of THE toughest things to render for a lens. ALL the flaws come out, especially in multi element designs. Don't expect a Canon 800 f/5.6L EF IS to have "perfect" color correction, or for that matter, halfway close to perfect rendering of an image. It does QUITE poorly on microcontrast and other ultra fine details, something which a high end ultra precision optic would THRIVE in. The poor photons are just fighting with WAY too many air to glass interfaces which rob the microcontrast and other optical goodness.

If a lens can't render a point of light accurately, then it won't render an entire scene with the utmost in accuracy.

Zeiss didn't mention pitch polishing or any other types of fine tuning. To put it in perspective of how critical the figure is on a lens, a typical lens will take a few minutes to hog out and grind on a multi million dollar machine. It's then ready to be coated. A lens from Takahashi or AP or TEC will take several hours to several DAYS, PER SIDE of an element to be polished to an extreme critical accuracy. They perform the extra work since the lens will be used to magnify a point source many hundreds to many thousands of times and each imperfection of a lens will add up significantly, something not really expected of a camera lens.

Now just for grins and giggles - here are some strehl charts for a typical optics set. Note the roughness in the figure and the zoning errors. I would also expect this of many commercially made lenses. Note that this is considered "diffraction limited", about a .80 strehl ratio.

http://geogdata.csun.edu/~voltaire/roland/sct.html

Now lets take a look at this other one. Note that the optics is EXTREMELY smooth, no zoning errors. This will provide a much higher contrast and saturation than 99.9% of the optics out there!

http://geogdata.csun.edu/~voltaire/roland/130edf.html

Now if you change out the lens elements to include crystalline fluorite, the contrast and saturation will increase, mainly due to the fact that crystalline fluorite will have ZERO internal scatter. Remember that ED glass and fluorite GLASS (they're the same) has scatter and this will rob contrast and saturation.

Still, to the credit of Zeiss, they did a good job on color correction.

December 15, 2009

Arthur - thanks for the link. Quite interesting. Do you have any specs where they corrected for the colors, and at which nanometer wavelength?

I noticed that the spec sheet isn't saying which type of glass or ED they're using. Or if they're even using fluorite crystal.

About the most overkill lens (in terms of color correction) that I've seen would be from Coastal Optics, their 60mm focal length, f/4 model. They can, for an additional charge, provide a color correction and lab test for the optic. Mind you, this is just in terms of color correction.

I already know what my optical friends would say. They'd look at the lens quite critically and say "eh". What they're concerned about is not just color correction alone. They're worried about strehl ratio, contrast, what the lens is corrected and designed to in nanometer wavelength, melt data, knife edged baffles (not the cheap reflective rings that Canon uses in their 800), amount of scatter for the entire optical formula, the works.

They don't impress easily. I showed them the AP and they remarked "not bad". Showed them the Tak (FSQ106N) - they were actually smiling. From their reaction, you'd think they they knew the designer of the lens... ;)

Would be intersting to find out how well corrected the Zeiss lens is!

December 13, 2009

Arthur - the Zeiss telescopes during the early 1990s were exceptional pieces. In terms of color correction, I would say that they edge out AP, especially the Zeiss 6 inch f/8. Now AP will say differently (Astrophysics) but they are two very fine optics. If you compare the TOA Takahashi series now to the AP or even the Zeiss from back then, the TOA has better color correction due to two things. The first being that the TOA is air spaced and allows several more degrees of freedom in design than an oil spaced optic. Both the AP160 and the TOA130/150 are air spaced, which explains their extreme level of color correction. The second is that the Takahashi utilizes TWO elements in a three element design that have fluorite or fluorite mixtures in them. In other words, fluorite crystal up front, mating glass in center, ED glass at the back. NO other telescope company will do this as of this writing.

Unfortunately, Zeiss produced very very few batches of their telescopes. The accessories that they use were quite proprietary, even for attaching an eyepiece. Zeiss , according to one of the telescope companies, did a "massive sour grapes exit" and didn't know how to manage their telescope lineup. Zeiss only made enough scopes from the one single batch of glass that they had and probably didn't realize the practical and lengthy process it takes to make a ultra precision optic.

The 6 inch f/8 model that I'm talking about now sells for mid 20 thousand dollars to low 30 thousand. Highly collectible item, but not too practical in photographic usage.

Bradley- I'm not surprised that Zeiss uses a fluorite element for their UV lens. ED glass has issues with UV since ED has a glass component. Fluorite corrects down to 360nm to 380nm when properly implemented with a well chosen mating glass.

There's MUCH more to color correction than just saying "ED" or "fluorite". It depends on the spacing (air or oil?), the level of ED glass being used, the level of mating glass being used, the figure of the lens, etc etc. To this date, there is NO lens that offers "perfect" color correction with ultra high contrast, saturation, etc.

Don't even get me started on mirror based optics. They have their own set of problems. Loss of contrast, huge amount of light scatter, etc. Yes, even the famed Hubble (which so many people seem to use as a "reference") has these same problems. Lots of photoshop helps out Hubble images!

December 13, 2009

Many of you may have heard the terms "SD, UD, ED" and so forth from camera lens manufacturers. Simply put, they are just different grades of ED glass. SD might be equivalent to FPL52 or FPL53. UD may be FPL51. Technically and composition wise, they are all ED glass.

The only source that I know of for crystalline fluorite is Optron, a wholly owned subsidiary of Canon. Now does this mean it's a "canon" lens? Not technically if you're looking for the "L" lenses packaging. But yes, Canon does own the company that produces the crystalline fluorite. If I recall correctly, they also make a fair amount of the ED glass there - you have to get the fluorite from somewhere.

For an optical formula stating that they have fluorite or ED is no guarantee on the level of color correction. They can use FPL53 or even a fluorite crystal in the formula, but if it's not properly compensated for with the proper mating glass, then the color correction will be horrible. Even the term "APO" is misleading. Is it truly color correct from 400nm to 700nm? Is it a single, two or three crossing design relative to the zero mark?

Probably one of the most color correct optics come from Takahashi. The reason is simple - there is lots of color correction going on and they are using a fluorite element in front, mating glass in center and the rear element is FPL53 if I remember correctly.

http://images.google.com/imgres?imgurl=http://www.grandeye.com.hk/tak/new/toa130_chart2.jpg&imgrefurl=http://www.grandeye.com.hk/tak/new/tsa130_fct250.htm&usg=__ThQiBpzfv7FkCC-w_yUhTL394ik=&h=500&w=309&sz=15&hl=en&start=18&um=1&tbnid=wzRjfkKDXbm-cM:&tbnh=130&tbnw=80&prev=/images%3Fq%3Dtoa130%2Bcolor%2Bcorrection%26hl%3Den%26safe%3Doff%26um%3D1

Probably the next best color corrected optic that I've seen would be from Astro Physics. Their 160EDF. Note the 3 crossings to the zero plane. Many so called "APO" lenses are lucky to have 1 or 2 crossings on the zero plane. If you've noticed the previous graph, the Takahashi resides mostly on the zero plane - near absolute perfect color correction.

http://www.astro-physics.com/products/telescopes/160edf/160colorcurve3.jpg

John - the Lexus owner that uses the optic went for it since it provided the best color correction, contrast, saturation and sharpness out of any optic that he's tested. That includes the Canon 800mm f/5.6L EF IS, 600mm f/4L EF IS, 500 f/4L EF IS, 300 2.8L EF IS. Canon received a very long letter on how to redesign and improve their optics after a long field test of the 800mm 5.6L EF IS. They definitely have a flaring issue and this can be resolved by using a different type of baffle rather than the reflective rings and inadequate flocking methods currently implemented. He's very much a huge fan of Canon, Nikon, Leica, Hasselblad, and Mamiya. But the proof is in the pudding and the results.

http://photography-on-the.net/forum/showthread.php?t=534639&page=3

The first picture of the cormorant is with the 800. Fresh from the factory and microfocus calibrated. Gitzo CF1325 for the tripod - a very stable mounting. If you look at the image you'll see that there is a muddy look to it. It's not from focusing - it's from poor flare control.

The next picture down is with the Takahashi FSQ106N, a 530mm f/5 telescope. Canon has NOTHING on one of these telescopes, optical quality wise. Two of the four elements are crystalline fluorite, the other two are the mating glass. The specialized extender was used to make the focal length 850mm at f/8. Extender itself has 5 elements, none fluorite though.

"cwphoto" later admitted that he did see quite a bit of flaring and took further conversation off the board. He also later admitted that for his use an intents, he really needs the AF and the IS, but in terms of optical quality, he agrees about the flaring issues and the lack of contrast due to the flaring.

As for "color correction" in Canon lenses?

http://www.astropix.com/HTML/I_ASTROP/EQ_TESTS/C300MM.HTM

http://www.astropix.com/HTML/I_ASTROP/EQ_TESTS/C400MM.HTM

And in Nikon lenses with ED glass?

http://www.astropix.com/HTML/I_ASTROP/EQ_TESTS/N400MM.HTM

NOT SO GOOD. At least not for critical astro work or for anyone demanding the finest in optical quality.

Remember that camera lenses are mass produced. Batches WILL differ. You can purchase the same type of FPL53 with the "melt data" and have it measure differently on the optical bench. Each batch differs. I've had camera companies that will say "our process is consistent", which to me, means absolutely nothing if they do not account for the melt data of each glass type being used. Camera companies really can't do this since it's a HUGE added expense. You would have to make master test plates for each batch and type of glass. HUGELY expensive, but the telescope people have to do this since they realize that it will greatly affect color correction. Most of the camera people aren't going to blow up their prints to 13x19, 24x36 or even 30x40. With a precision optic (telescope - high end) you can still extract the most undistorted images out of them. With the production lenses (Canon/Nikon/Leica/Zeiss, etc) you will see chromatic aberration and other nasty distortions.

Further information can also be found in Nature Photographer, winter 2008 issue. There's an article there called "high resolution optics".

As for the Lexus owner, you're talking to him. Feel free to ask away on any questions relating to the ED vs Fluorite. I'm also working with many people involved in the optical field. The military/classified optics are fun. :)

December 12, 2009

An excerpt from an optical master - Yuri from Telescope Engineering Company. He utilizes fluorite in his designs as well as ED glass in his slightly cheaper scopes. Mind you, FPL53, FPL52 and FPL51 are considered types of ED glass. ED glass is simply glass mixed with fluorite. Advantages of ED are that it's more durable due to the glass component. Disadvantages is that there is less color correction when compared to crystalline fluorite.

More on this to follow. But first, a quote from Yuri...

"The main differences between CaF2 and FPL53 are: 1. CaF2 is availabe in sizes up to 300mm diameter, the FPL53 is limited to <160mm 2. The CaF2 has dispersion characteristic that let make faster focal ratio vs. FPL53 and still have good color correction 3. CaF2 has no scatter, all ED glasses do have, see the pictures of laser beams going through ED triplet objective and through Fluorite objective (the CaF2 is the second lens - no trace of laser beam) 4. The cost of high quality CaF2 is >3 times more than FPL53 After all the CaF2 is an ideal material to work with! Best regards, Yuri"

November 18, 2009

College level gymnastics is often better lit than the high school ones. The lowest lighting level that I've shot in was back in the mid 80s. 400 speed film, f/4 lens for a whopping 1/10th of a second. That's how dim it was.

Agree with Dan - 2.8 lenses don't help much. I'm shooting with the 200 1.8L EF and the 85 1.2L EF II lenses at ISO1600/3200.

The new mark IV should help out also in the dim high school gyms in some of the older schools. ISO 12,800 sounds quite nice!

And absolutely NO flash allowed at any gymnastics event. The photographers either like the challenge or hate it.

November 16, 2009

A minimum of 1600 asa/iso. F/2.8 lenses are considered SLOW for gymnastics, especially in some of the high school venues.

I routinely shoot at iso3200 with a 1dm3, 200 1.8L EF lens and the 85 1.2L EF II lens. With the 1dm4 coming out, I can easily see iso12,800 for the gymnastics events, especially the ones with poor lighitng.

November 15, 2009

Dan,

I wonder what would happen if they removed JUST the AA filter and left the CFA alone. More than likely you would see an increase in sharpness when compared to the original picture. Yes, the color cast will still be there from the CFA, but this can always be processed out.

November 11, 2009

Dan,

Excellent stuff! How difficult was it to remove the bayer array from the sensor? I have a 20d sitting around that may benefit from the conversion...

I once tested out a monochrome prototype of a Leaf back that had the Kodak 16801 chip. The camera itself was all aluminum, no black paint or anything. Images from it were VERY good. This was around 2003/2004.

November 9, 2009

The true bit depth can be found by the full well capacity divided by the noise. See page 8 of this document, lower right hand corner.

http://ccd.com/pdf/FullProductLine.pdf

According to the SBIG site, the full well depth for the 11000 chip is 50,000 electrons. RMS noise of 13 electrons. This will give it slightly under 12 bits of resolution. Remember that this is for the sensor itself, monochrome chip. Yes, it may be a 16 bit converter at the end of the chain, but the sensor itself is only capable of slightly less than 12 bits.

http://sbig.com/sbwhtmls/online.htm

Another interesting link from clarkvision.com - the monochrome Kodak sensors are usually only good for 12 bits. Scroll about halfway down the page.

http://www.clarkvision.com/imagedetail/digital.sensor.performance.summary/

None of the Fuji sensors are listed, but it would be interesting to find out the well depth and the noise readout in electrons. This would give a true rendition of the amount of bits that are coming out of the sensor in one shot. The record holder for sensors from Kodak is the 1001, with a huge 300,000+ well depth. That sensor is only about a megapixel, but the bit depth is slightly over 15 TRUE bits from the sensor.

June 15, 2009

Brian,

Thanks for getting back to me. The lenses that I've tried were the Canon 800 f/5.6L EF IS, Canon 300 2.8L EF (both IS and NON IS models), Canon 600 4 EF L IS, Canon 400 2.8L EF IS, Canon 200 1.8L EF, Canon 85 1.2L EF II and I models, Nikon 300 2.8 VR, Nikon 70-200 2.8 VR - the list goes on and on. While many of the people will be happy with the lenses listed above, I actually use a Takahashi FSQ106N, Takahashi FS152, Astro Physics 130EDT, Astro Physics 155EDFS and other refractors for imaging. I find that the FSQ106N has outstanding color correction and contrast when compared to the "standard" autofocus lenses currently on the market.

The Canon 800 (as well as most standard terrestrial lenses) have been a disappointment. There is quite a bit of flaring when shooting high contrast objects. For example a white Egret against a dark background. The egret will have a "bloom" to it and stopping down does not help matters any. I have tried many samples of the 800 and have been disappointed. I try the same scene with the Takahashi FSQ106N and the results are outstanding. Both of these I would set on manual focus using 10x on the Liveview option.

On astronomy imaging, the limitations of the Canon/Nikon/Zeiss,etc lenses just becomes much more pronounced. I'm looking for pinpoint images, wide open, or even stopped down 1 stop. The Tak FSQ106N - pinpoints on a 20x30 enlargement with a STL11000, and some of the stars are still smaller than a pinpoint (literally) but are easily resolved.

Some of the astro imaging tests done by other photographers can be seen here.

http://www.astropix.com/HTML/I_ASTROP/EQ_TESTS/C300MM.HTM

http://www.astropix.com/HTML/I_ASTROP/EQ_TESTS/N400MM.HTM

As for the PV numbers, Roland at Astro Physics will always attest to his telescopes. Many of the 130/6.3 and the older 130/6 models are testing at better than .95 strehl. I have seen .995 and better from the batches, the .95 is probably the lowest number that I've seen. http://www.astro-physics.com

Color correction - I routinely use the Takahashi FSQ106N for terrestrial photography since it doesn't have the "warmish" character of the Canon lenses, nor the "cold" character of the german glass. To me, the FSQ106N is quite neutral and I've already recommended this lens to Jonathon Singer who will give it a spin with his Hasselblad 39 megapixel and 50+ megapixel backs. For those that know Jonathon, he demands absolute color fidelity without any "character" imposed. I'm very sure he'll be pleased with the Takahashi. http://www.botanicamagnifica.com/

I'm one of the few that will use a high end refractor for terrestrial photography. Nature Photographer featured my article on this - you can find it in the winter 2008 issue. It's quite possibly the FIRST international publication (non web) in a non astronomy related magazine. Other photographers are adopting to this method also mainly due to cost and better optical quality at equivalent f/ratios and f/lengths.

How much more would the lens report add to the cost?

February 11, 2009

I've shot with both systems. Nikon D3 and the 200 f/2.0 VR lens and the Canon 1D mark 3 with 200 1.8L EF and the newer 2.0 lenses. Here's what I've noticed.

The Mark 3 focuses faster, and fires off many more shots than the D3 can in the same scenario. The D3 will WAIT until the object is in focus, at times slowing down to 3 frames per second, but the keeper ratio is about the same as the Mark 3. Mark 3 feels more "fluid" and the frame rates are definitely higher.

I still feel that they have an AF problem of over and undershoot for focus. But, the results that I've seen with the D3 have about the same hit/miss ratio. Most of my indoor sports shoots are in the 90% "focused - sharp" region. Quite acceptable!

I would suggest that you handle both cameras and decide which system you like. You really can't go wrong with either. I just like the additional speed and control of the mark 3. The 200 1.8 lens doesn't hurt either!

February 11, 2009

The amount of light reaching the sensor is critical. Consider a 2.8 lens as MINIMUM. I used to shoot with 100 speed print film a couple of decades ago with an f/4 lens so this taught me alot about handholding technique as well as starting out from the bottom rung. This was when 400 speeds was considered "fast film".

Canon 135/2 seems to be quite popular among the 1.6x crowd. It's not ultra expensive and is quite portable. I've seen a couple of 70-200 f/4 lenses among the crowds and they're not freezing the action shots, even at 1600iso. 85 1.8 also seems to be quite popular.

Focus tracking is also critical. I've shot with the 5d mark 2 and the performance is, ime and imo, lacking on the full power tumbling runs. It just can't keep up. On the static shots or the slow movement shots, it works out fine. This is with the 200/2L EF IS lens and with the gymnast ending her run about 6 feet away from me.

I now routinely use a 200 1.8L EF and 85 1.2L EF II with 1D Mark 3 and 1Ds Mark 3 bodies. The ratio of keeper shots vs the 5dm2 is much higher due to the faster computing of the AF tracking with the 1 series bodies. I got away from the zooms since the prime quality was much better, visible even in 5x7 prints, but I usually go for 13x19 or larger.

Now some may ask why I go for the 1.8 vs the 2.0 200mm offerings. Simple. The 1/3rd of a stop will make or break a shot. It's that critical in some gyms, even with the ISO settings on "H" mode.

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