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anton_v.

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Posts posted by anton_v.

    Save Medium Format - why not a 10 MP back for $3000?

    in Medium Format

    Posted

    Correction, from my calculation it follows that for the sensor A times larger than 35mm it will cost A/Exp{-(A-1)*x} more expensive compared to 35mm sized sensor, where is the average number of defects rendering sensor unusable per 35mm-sized area of the wafer. Suppose that A=2 (sensor is 2x size of 35mm frame), and the yield of 35mm sized sensors is 50%. Thus the cost of 2x35mm sized sensor will be 2/0.5 = 4x times.

    Save Medium Format - why not a 10 MP back for $3000?

    in Medium Format

    Posted

    Ok, I think how to do cost analysis.

     

    Suppose the defect that renders a given 35mm sensor unusable occurs with average intensity of x times per 35mm sized sensor. Since the defects occur uniformly on a wafer, the number of defects per given area has Poisson distribution with intensity x. Thus, for a given sensor to be usable, it should have no defects. That happens with probability of Exp{-x} (from Poisson distribution). The price of the 35mm sensor is obviously defined as (Price of a 35mm-sized area of the wafer)/(Probability it has no defects)=y/Exp{-x}, where y is the price of the 35mm-sized area of the wafer.

     

    Suppose now you want to find out the price of the sensor that is a times bigger than 35mm-sized sensor. Its price will be given similar to the formula above by (Price of a a*35mm-sized area of the wafer)/(Probability it has no defects) = (a*y)/Exp{-a*x}.

     

    Thus, the sensor that is a times bigger than 35mm will be a/Exp{-a} times more expensive, which is for a=2 14x times the price of the 35mm sensor!!!

     

    The calculation may be different given different thresholds on the amount of bad pixels on the sensor. Can anyone tell what is the standard for sensor rejection?

    RAW B&W on Canon 5D

    in Mirrorless Digital Cameras

    Posted

    I was shooting in Yosemite last month and met this photographer who

    said she was shooting in b&w raw mode on her Canon 5D. I can't stop

    thinking of what advantage the raw b&w provides over shooting color

    raw and then converting to b&w. It seems as it would give you the same

    result as just converting to b&w. Am I missing something?

    Tripod: AT 6703 Professional Tripod by DynaTran

    in Accessories

    Posted

    Trilok, the choice of the tripod depends on the equipment you are using and the conditions it will be used under. What's the focal length/shutter speed will be common with this tripod? Will you be hiking? Is the weight an issue for you?

     

    Bogen 3021 is known as one of the most versatile ones. For my MF system, I use Gitzo 1325 CF tripod since weight is an issue where I go. But it's awfully expensive as any CF (carbon-fiber) tripod.

    Tripod: AT 6703 Professional Tripod by DynaTran

    in Accessories

    Posted

    Don't get fooled by this "deal". Amnova is not a good brand of gear. They will use "professional" everywhere just to attract the customers and customer reviews are most likely spoofed. Go to b&h or adorama and look at bogen, gitzo and slick tripods. Tripod is not a piece of gear where quality may be compromised.

    Is Super the same as Super Multi Coated?

    in Medium Format

    Posted

    Not only the lenses look and constructed differently, but later models have better coating which went i believe 1-3-7 layers from Super Takumar to Super Multi Coated Takumar to SMC Pentax. I'm about to get the results from my side-by-side comparison of 2 135mm versions of 135mm macro: Super Multi Coated Takumar and SMC Pentax. From my earlier observations Super Multi Coated Takumar version of 135mm has very low contrast rendering which makes it not very useful for nature/landscapes, but very nice for skin/flesh tones. Will let you know how the comparison goes.

     

    Anton

    Has anyone bought from ADORAMA?

    in Accessories

    Posted

    I buy lots of new stuff from Adorama. I've always been happy and they never tried to sell me extras. Only time they called me was to ask for address verification. However, I purchased a used lense once from them and was VERY dissappointed with the rating. I neve buy used from them again. KEH is the best place for used equipment. Their ratings are very, very, very conservative.

     

    Anton

    Used drum scanner or Imacon Flextight?

    in The Digital Darkroom: Process, Technique & Printing

    Posted

    Andrew, I have Minolta Multi Pro and I cannot report any unsharp scans with the glass holder. Here is one of my recent scans. It is a scan of Fuji Provia 100 6x7 size. I have scanned it at 3200 DPI without sharpening, ICE, etc, just plain scan with some color correction. I want to underline that there was NO sharpening applied. Below is the fullframe scan downsized for you to see the 3 selected areas:

     

    <p><img border="0" src="http://www.cmb.usc.edu/people/valouev/sharp_test/big.jpg"></p>

     

    Further are 3 selected areas at 100% of original size (no downsizing, no sharpening applied):

     

     

    <p><img border="0" src="http://www.cmb.usc.edu/people/valouev/sharp_test/crop1.jpg"></p>

     

    <p><img border="0" src="http://www.cmb.usc.edu/people/valouev/sharp_test/crop2.jpg"></p>

     

    <p><img border="0" src="http://www.cmb.usc.edu/people/valouev/sharp_test/crop3.jpg"></p>

     

    Would you say I am having sharpness problems (the scan is done with glass holder 16x multisampling)?

     

    Anton.

    Used drum scanner or Imacon Flextight?

    in The Digital Darkroom: Process, Technique & Printing

    Posted

    I just can't see how the glass carrier doesn't hold film flat on your Minolta. Are you sure your unit is not faulty. Given what you have told us there is a good chance you will be upset with the quality of drum scans. Perhaps you need to move to MF or LF to get better scans. These days the only reason to have a drum scanner is to scan really dense slides. Anything beyond 4800 dpi on 35mm is unattainable with film. The film (not the lense!) is the resolution limiter in MF. I have tested performance of some of my MF Pentax 67 lenses. Given a high quality high resolution lupe, I can see CONSIDERABLY more detail on ground glass then on the image captured on 67 astia slide. And this is when I use heavy Gitzo CF tripod, etc to minimize any vibration.

     

    Get a LF camera and get some good pictures instead.

     

    Anton.

    binocular suggestion

    in Nature

    Posted

    For general purpose and birdwatching I would suggest Pentax 8x42 DCF HR II. Amazingly sharp, light and high quality. $209 @ adorama (add to the cart first). I compaired several and they are on par with zeiss and swarowski that are 3x-4x times more expensive. Pentax never stops impressing me.

     

    This model will work well for handholding. If you need something stronger, you will need to mount it on the tripod.

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