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And another thing!! This lens has a pretty singular purpose...you can use it for others, but it is really THE portrait lens to have. In that respect, if you can't afford it, renting is a very viable option, if you know your dates for rental(or photo shoot, photo op) in advance.
And for those that can'tafford or aren't willing to spend the money on the Sigma, you can get the Bower 85mm f/1.4 manual focus lens new for about $350. Ken Rockwell has a nice review on the Vivtar version, which is just a re-branded version ofthis lens.
John.
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Originally Posted by Keith B
I've been thinking more on this, and I guess I have the opposite opinion (maybe not diametrically opposed, but opposite in principle). When I buy a microscope at work, I need to justify the purchase for business purposes, and if I need the $130,000 Zeiss scope, I need to justify why that is required instead of the $90,000 Nikon or Olympus equivalents.
I would assume the same would be true of a professional photographer buying a new lens - a cost/benefit analysis for the purchase of the 85mm f/1.2L, especially compared to something like the 85mm f/1.8. Now, it might become apparent from such an analysis that the revenues returned from the investment would justify the expense, but it might not. On the other hand, someone for whom photography is a hobby just has to answer two simple questions: 1) can I afford it?, and 2) will shooting with enhance the enjoyment of my hobby?
Just my 2¢. (Or 186,900¢, as the case may be...)
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Originally Posted by neuroanatomist
I would have thought that you are only buying more cost-effective equipment than you'd want because it's not your money. You need to have the purchase approved and justify the expense. While any self-employed photogs buy their own equipment and also use that equipment for their hobby photography. I guess I could see a staff photographer purchasing with your concerns in mind. I don't think the government is questioning anyone's small business $2000 lens write-offs as being of unnecessarily high in quality.
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Originally Posted by neuroanatomist
Yeah, I agree. If you're doing it just for fun, who cares how much it costs, as long as you can afford it. If you're doing it to make money, you want to be sure you will get a return on your investment.
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Originally Posted by neuroanatomist
Uh, $130,000 for an optical microscope? I didn't know they were that much. You could get a lot of fun toys for that, you know.
Its certainly been an interesting post this one. Since i posted this ive had my paws on a 50mm 1.4 which does the job. And ive decided that since i love the shots from my 1DS 3 much more than my 7D as i find the shots less noisy, less grainy and they have an "x" factor, im saving for the 85mm 1.2, Ive had a look at another one and was tempted to swap it for my wife but she wouldnt play ball.
I think i want it for the creamy backgrounds, the low light ability and myL disease i cannot cure. And im no pro but as in recent posts, it makes my hobby better and i can afford it. Except ive just finished university which my job made me do. 7 years study for 40 dollars a week more and i find the same guys doing the same job just up the road from me doing %50 less work are getting a massive pay increase of over 10,000 a year. And what did i say to my boss? 'Do you know how many lens's i could buy with that'. My boss didnt understand my logic. I feel you guys will. Sorry to rant.
Mick
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Originally Posted by Jon Ruyle
LOL, yeah, I know. Basic scopes, no - the one I have at home was only a couple of thousand. But high end optical microscopes, yes. Some of the planar apochromatic lenses run over $10K just for one objective. Add in fluorescence capability, motorization for automated image acquisition, etc., and it adds up.
The camera runs ~$15K - and get this, it's got a 1.5 megapixel CCD sensor (6.5 µm pixels). Sounds overpriced, but it's 'gimmicked' to go up to 13.5 megapixels in a rather neat way. You probably know that because of the microlenses over each pixel and the gaps between the pixels themselves, there's an effective 'sweet spot' in the center of each pixel. The CCD is piezo-driven, and can move in subpixel increments to compile an image from either a 2x2 (for 6 megapixels) or a 3x3 (13.5 megapixels) array, moving that sweet spot around to increase resolution. It also moves in full-pixel increments, so each pixel gets a separate exposure through the Bayer filter, mimicking a 3 CCD system by eliminating the interpolation. Of course, I'm not a victim of the 'megapixel myth' and that's especially true for microscope objectives - the most optical resolution one can deliver is about 150 Lp/mm, meaning 5 megapixels is all that's required to capture the optical resolution. That's actually with low power lenses (1.25x, 2.5x) - the high power lenses (100x oil immersion) can have all of their optical resolving power adequately captured even by VGA resolution.
Anyway, enough shop talk - it's the weekend!
Happy Father's Day to you, Jon - enjoy the time with your family!
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Originally Posted by neuroanatomist
Totally ...I knew that! [*-)]
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Originally Posted by neuroanatomist
Ok, so this is reallythe only part Iunderstood....Have a great Father's Day guys!! [:D]
Denise
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Originally Posted by ddt0725
Sorry for being dense, but... how can one part of a pixel be "sweeter" than another? Are you saying light transmission is better in some spots than others?
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Originally Posted by ddt0725
Wild. I can't understand, though- if you're going to do three exposures, why not just change filters (instead of having them built in)?
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Originally Posted by ddt0725
Quite so. And if you're photographing still objects, sensitivity probably isn't that important either. In light of the fact that the laws of physics severely limit resolution at high maginfication, I've often wondered why super expensive optics are necessary. Sure, you want good contrast (probably paramount with microscopes) and low CA. But the glass is so *small* :)
Actually, though $10K is a lot for a tiny objective, that price does not surprise me. Very nice Zeiss 1.25" telescope eyepieces cost about $500 each (and they are *very* nice).
Okay, sorry for going so OT. Lemmie just say that if I wanted an 85mm lens faster than my f/1.8, I'd get the canon f/1.2 [:)]
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Originally Posted by ddt0725
Thanks, Denise, and likewise John. I spent all afternoon in the hot tub. We ate bbq, drank beer, and had homemade peach pie for desert. I hope everyone had as nice a day yesterday as I did :)
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Originally Posted by Jon Ruyle
Nope - just that not all of the pixel actually collects light, although I didn't explain it very well. The photodiode (which detects the light) occupies only about 40% of the area of the pixel. The microlenses on Canon's sensors are one approach to solve that problem - as illustrated on the left below. The newer gapless microlenses are more effective, since nearly all of the light covering each pixel area is focused on the photodiode (right, from Canon's 1DIV info). Zeiss' approach is to raster the sensor around, instead. Obviously, you need really fast exposures - or a completely immobile subject - to make that work. Fixed specimens don't move much...
http://www.digitalbirdphotography.com/microlens.jpg http://www.usa.canon.com/uploadedima...icrolenses.jpg
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Originally Posted by Jon Ruyle
That's how some microscope cameras work, either with a filter wheel in front of the camera or one in front of the light source. I suppose the advantage here is choice - if you want to take a faster picture, you can choose to take a single exposure and interpolate for color with the Bayer mask.
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Originally Posted by Jon Ruyle
It's small, yes. But recall that in photography, macro lenses suffer from an apparent reduction in maximum aperture with close-focusing distance. Because of that sort of effect, microscope objectives need to have significant light-gathering capability - that's what you're paying for. The relevant lens spec is called numerical aperture (NA), and although it's different than f-number, the two can be approximately related as f-number = 1/(2NA), for air lenses. So, my 20x/0.75NA objective would be equivalent to f/0.67. Air actually limits the NA to <1 (the index of refraction for air), which is why high-power objectives use oil between the lens and the slide (index of refraction of immersion oil is ~1.56, meaning higher NA and thus greater possible resolution). The NA of a good (=expensive) oil immersion lens is 1.4, which translates to approximately f/0.55 once the correction for the index of refraction is applied. Even though the amount of glass is tiny (since the focal length is so short - 0.19mm working distance), the high NA and the associated difficulty of construction and high degree of precision required are presumably what translate to cost. Also, the actual glass is different - the glass used camera lenses doesn't transmit UV wavelengths all that well, and transmits IR even less well. For fluorescence, microscope objectives need to transmit UV and IR as well as visible light. Of course, it could just be that Zeiss is making one heck of a profit. [:P]
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Originally Posted by Jon Ruyle
Sure did, and I hope all the other dads out there did as well!