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Thread: It's a Long Shot

  1. #1
    FrankMi's Avatar
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    It's a Long Shot

    I would love to get a great detailed picture of the moon like we see in Mark's Practice for lunar eclipse but there is no way I can afford the glass necessary to get that close and sharp so I got to asking myself 'what if I used a high MP sensor and a less expensive long lens'. Could I get a better rendition of the moon than my D3100 and 55-300mm DX lens I currently use?

    For this subject, image sharpness would be more important than anything else so what would I gain over my current setup, if anything, by using a Nikon S9100 with a 1/2.3 sensor, which is incredibly small BUT has 12MP, and it's 450mm (full frame equivalent) lens? At less than $200, I could possibly fit that into my limited budget.

    Personal bias aside, what are the practical differences?

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    Re: It's a Long Shot

    Is the 55-300mm DX lens actually a 82.5-450mm full frame equivalent?

    If so then the Nikon's 14.2 Mega pixels is better than the 12 MP of the compact at the same 450mm length.

    However this is based on the assumption that the sensor and lens are equally able to resolve detail. No lens/sensor combination is perfect so if one lens/sensor has more ability to resolve detail it may swing the balance more than the straight mega pixel comparison. You cannot know this without actually testing the compact (or finding a site that has resolution test results).

    An interesting post though. It has got me thinking about the formulas to compare the achievable resolution of a subject at a set size given different cameras. Perhaps someone can post up the answer.

    May something like (units in parentheses):

    Quality (Line pairs) = Image Size (pixel) * Resolution (Line pairs/cm) / Sensor Density (pixel/cm).
    Quality (Line pairs) = Image Size on Sensor (cm) * Resolution (Line pairs/cm)

    So if the captured image is larger, the lens resolution is better or the camera sensor density is greater then the quality (amount of information) increases.

    Alex

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    Re: It's a Long Shot

    Quote Originally Posted by herbert View Post
    Is the 55-300mm DX lens actually a 82.5-450mm full frame equivalent?
    Hi Alex. As I understand it, if it were an FX lens on the Nikon D3100 DX sized sensor, then that would be the case. But as this is a DX lens, I'm thinking that it is already converted to the full frame equivalent.

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    Re: It's a Long Shot

    Not when I searched for it online. You still have to include the crop factor.

    Alex

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    Re: It's a Long Shot

    Quote Originally Posted by FrankMi View Post
    Hi Alex. As I understand it, if it were an FX lens on the Nikon D3100 DX sized sensor, then that would be the case. But as this is a DX lens, I'm thinking that it is already converted to the full frame equivalent.
    Don't know about other brands, but for nikon all lenses are the FX focal length. So you allways will need to multiply by 1.5 when you have a cropped sensor.

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    Re: It's a Long Shot

    Afaik, all lenses for SLRs are marked with their true focal length (range, in case of a zoom lens)... The focal length does NOT change between a crop sensor and full-frame sensor, the field of view does (the angle covered by the lens).

    (Think about it: if the focal length would change between cropped and full frame sensors, focusing distances would change as well... In case of a macro lens at 1:1, the working distance would change depending on your camera body... Anyone here using both full-frame and cropped sensor bodies in parallel?)

    To get back to OP's question:
    when talking in terms of 35-mm equivalent focal lengths, the sensor size is taken out of the equation as far as field of view is concerned (by definition), so the longer equivalent focal length would have the advantage, all other factors being equal (see Herbert's answer). However, at the same number of MP, the smaller sensor will have smaller photo-sites, and will thus be more sensitive to noise, especially at higher ISO settings.

    Also, what size of final image are you aiming at? As has been said before, in most cases we have more than enough pixels (esp. for on-screen use), so a less noisy, larger sensor might outperform the smaller, noisier sensor in the final image, even though the latter gives a larger image of the moon (larger as in, covering more pixels).

    Finally, the S9100 has no RAW mode apparently, but I'm not sure how serious that is for this application.

    Remco

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    Re: It's a Long Shot

    Thanks everyone for the feedback. I think a couple of clarifications may help the analysis. I am using the Nikon Coolpix 9100 with it's features as an example so other options to get telephoto images may make more sense in the $200-300 price range. From what I've read, the basic 55-300mm is not likely to do very well with a teleconverter so I am looking for other options. As I rarely do prints, the final image only needs to be suitable for monitor viewing. I don't intend to use a P&S for the bulk of my photography, that's what I use the DSLR for. If, in one case, I can get a reasonably useable telephoto image and in the other, no usable image at all, then it may well be worth the sacrifice of the additional control features and RAW image capability.

    If it makes sense, I would use the 9100 at 18X in situations where the 5.5X of my 55-300mm lens simply doesn't have the reach for subjects like shooting the moon or distant wildlife and birds and where the 9100 (or something similar) is in my pocket and the D3100 is not readily available.

    As there is a siginificant cost difference between the 9100 and a lens that has 3+ times the zoom of my 300mm, I am trying to determine the difference in image quality between the 9100's 18x zoom verses the same image cropped out of what I can take with the 300 DX lens on the D3100.

    For example, let's say I shoot a clock tower face a half-mile away with both cameras at max zoom. Which one will have the better image? I could just reluctantly buy the camera and test the results but I would think that there would be effective methods to make the determination in advance, particularly if there are factors I haven't considered that come into play.

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    Re: It's a Long Shot

    Quote Originally Posted by FrankMi View Post
    ...
    If it makes sense, I would use the 9100 at 18X in situations where the 5.5X of my 55-300mm lens simply doesn't have the reach for subjects like shooting the moon or distant wildlife and birds and where the 9100 (or something similar) is in my pocket and the D3100 is not readily available.
    ...
    Be careful not to confuse zoom range (ratio between longest and shortest focal length of a zoom) with magnification relative to a standard lens.
    Your 18x zoom range covers the ratio between widest and narrowest angle (shortest and longest focal length), but at least part of that range is in the wide-angle area. The 5.5x range on the 55-300mm otoh, is all in the tele range.
    I didn't notice before, but is that 55-300mm the actual focal length or the 35mm equivalent, by the way?

    Anyway, even though the zoom range on the P&S is 18x, for 5.5 on the SLR, your final image is NOT going to be ~3x bigger on your P&S (ratio between zoom ranges), but only 1.5x (ratio between focal lengths). Even better, iirc, the Nikon D3100 is a cropped sensor camera, with a crop factor of 1.6(?)? So that 55-300mm might well be equivalent to an 88-480mm zoom. That would give the advantage to the SLR/telezoom combination.

  9. #9
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    Re: It's a Long Shot

    Quote Originally Posted by FrankMi View Post
    I would love to get a great detailed picture of the moon like we see in Mark's Practice for lunar eclipse but there is no way I can afford the glass necessary to get that close and sharp so I got to asking myself 'what if I used a high MP sensor and a less expensive long lens'. Could I get a better rendition of the moon than my D3100 and 55-300mm DX lens I currently use?
    For this subject, image sharpness would be more important than anything else so what would I gain over my current setup, if anything, by using a Nikon S9100 with a 1/2.3 sensor, which is incredibly small BUT has 12MP, and it's 450mm (full frame equivalent) lens? At less than $200, I could possibly fit that into my limited budget.
    Personal bias aside, what are the practical differences?
    Hi Frank,

    While I can't speak to the technical aspects of one lens vs another, I feel the
    need to interject a couple other factors that go into getting a Moon pic of that clarity.

    IMO, your 300mm (450mm to us Nikon crop sensor users) and D3100 mounted
    on a very stable tripod *should* be able to capture that level of clarity. His shot
    was at 800mm, and you'll have half of that, but still more than enough to really
    get some nice sharply defined craters and definition on the mountain ridges.

    The critical key to all of that is having "seeing conditions" that are good enough
    to allow that level of sharpness. It doesn't matter what lens your using, if the
    sky/seeing conditions aren't just right taking a shot that sharp is pretty much
    a practical impossibility.

    Seeing conditions are effected by numerous factors, and there are several different
    scales to chose from in determining the quality of the atmosphere. Just having a
    clear sky (no clouds) is not enough, as the interference caused by local ambient light,
    humidity and even the flow of the jetstream have a major affect on the overall
    seeing conditions.

    Your best bet would be to check the "Clear Sky Chart", as it tracks observing conditions
    throughout the country: http://cleardarksky.com//csk/index.html#chart_list

    I would also suggest finding a location where there is "dark sky", and where the light
    pollution is virtually non-existent. To get a shot that clear you want to take advantage
    of every benefit to shooting in the best skies possible. You can check out the local dark
    sky conditions using the Dark Sky Finder, and find the best area around your home.

    Reducing the amount of total atmosphere you are shooting through can be a
    big help also, so try and take the image when the Moon is high in the sky, as then
    you are shooting through less of Earth's atmosphere.

    Stellarium - Superb, in-depth (and FREE) Celestial program. With this you can not only
    determine exactly when the Moon will be at apex, but also have the complete celestial
    view showing exactly where the stars, nebulas (yes, you can capture some of the
    nebulas with that lens also), planets, etc. are located. A superb program, and it's free..

    If you like a bit of a challenge, try capturing a shot of an Irridium Flare from an overflying
    satellite or the ISS: http://www.heavens-above.com/. That site has time/date/coordinate
    information covering the following 7 days for every satellite overfly and irridium flare.

    I've seen some incredibly good Moon pics that came from someone using a
    DSLR prime focus mounted to a low-end 80mm scope. If you've got good glass
    you can get sharp Moon pics, so get lots of practice, and when the skies get
    purrrrrfect you'll be ready to rock-n-roll.

    Shooting when the terminator line is crossing certain Lunar features will also
    enhance the contrast of the images, and avoid shooting full Moons when possible.
    Without the "terminator line" the contrast in the craters and valleys is not nearly
    as good. I was out 2 nights ago and took a number of interesting Moon shots,
    and even at ISO 100 and f/5.6 there were times when the Moon was so bright I
    had to go up to a 1/2500th/s exposure. Unfortunately, there was a thin fog in the
    atmosphere that prohibited getting a real sharp image, but I was quite satisfied
    given the conditions.

    Through my astronomy site I've come to know many of the best planetary and
    lunar photographers from around the globe, and every one of them will tell you that
    having excellent seeing conditions is the #1 key to getting superb images.

    Hope this helps, and most of all, have fun doing it...

    Mike
    Last edited by Dizzy; 12th January 2012 at 07:57 AM.

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    Re: It's a Long Shot

    Hi Remco, the 35mm FFE is 82.5-450mm as pointed out by Alex. As you say, I need to pay more attention to the field of view but I don't understand how to use that to make a comparison between camera/lens combinations. I'll try to clarify a bit more shortly. Thanks!

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    Re: It's a Long Shot

    Hi Mike! You have posted some great reference material on how to get great shots of the moon. I'll be spending some time to review that throughly!

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    Re: It's a Long Shot

    Thanks everyone for all the help and yes, I am still trying to sort out in my mind a number of factors that I’m not sure a have a good handle on as yet.

    For example:

    My Sony DSC-H1 has a 12X zoom, 6-72mm or 36-432 mm full frame equivalent lens.

    My D3100 with 55-300mm lens has a 5.5X zoom, 82.5-450mm full frame equivalent lens.

    When I look through the viewfinder on each, I get a significantly closer view in the Sony even though the full frame equivalent is 18mm smaller than the Nikon! I can’t seem make a heads or tails comparison by using just the real or full frame equivalent lens sizes. How can we compare the results of these two combinations on a max zoom image?

    I realize that the Nikon has a 14.2 MP sensor and the Sony has only 5 MP, but with each image at full size on my monitor I don’t see any real difference, except for the size of the subject in the image.

    As my goal is to get more telephoto reach without have to spend $5-20K on a long lens, I looked at the Nikon S9100 with a much longer zoom than my Sony DSC-H1 (and physically pocket-able, which the Sony is not).

    To compare the three camera/lens, I would love to be able to say I can take a subject at max zoom on three different camera/lens combinations and determine the MP used by each. This is assuming that I’m not considering other factors that affect resolution for the moment and simply consider the pixel count.

    The specs on the Nikon S9100 give an 18X zoom, 4.5-81mm (25-450mm full frame equivalent) lens. The S9100 has a much smaller physical size sensor, but at 12MP, almost as many MP as the D3100. When I looked at the S9100 in the store it had a phenomenal zoom capability – way beyond the 300mm on my D3100. Would this be a good option for taking longer reach telephoto images? If so, is there a way to measure the difference between the options?

    Sorry for rambling but I’m not sure how to express what I am asking in succinct terms.

    My gut feel is that I’m missing a key piece of understanding that would allow me to mathematically or logically compare the three and determine if getting the S9100 or something similar would be a wise investment.

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    Re: It's a Long Shot

    Hi Frank,

    The zoom factor does not matter. Only the maximum zoom. If it is 5x or 12x but with 450mm at the top end, the 450mm is all that matters.

    Your Sony has an electronic viewfinder. I wonder if you are seeing the combined effect of optical zoom and digital zoom through the viewfinder. Then it will look bigger than the Nikon.

    Can you take a photo of the moon with both cameras, do a 100% square crop around the moon and post them up here. Then people will get an idea of the resolution you are seeing.

    Remember that resolution is the ability to see detail. For example alternating black and white lines. The best you can ever hope for is that your camera capture the black lines on one row of pixels and the white on the next. However if the lines are so far apart that they are 3 pixels apart on one camera and 2 pixels apart on the other then you subject does not have the detail necessary to separate the two cameras. For example if the detail is not there in the moon then you won't see any difference between the two cameras.

    This is why test charts have black and white lines that get closer and closer together. At a certain point the camera cannot see the difference. This can be used to measure the camera and lens resolution.

    If all your cameras have approximately the same focal length (450mm), then the one with higher mega pixels should win. This is assuming equal optics and pixel resolution. Under these assumptions you should be able to get a fair comparison with this formula:

    Quality = focal length x pixel density

    Approximating a square sensor you can get pixel density as the square root of the mega pixels. If you know the sensor ratio (e.g. 3/2, 4/3, etc.) use the following to get the x and y density:

    X = sqrt(MP * ratio)
    Y = sqrt(MP / ratio)

    Then you should be able to compare the quality of lots of different focal lengths with different pixel sensor densities. Make sure you compare the long edge to the long edge, e.g. X to X.

    Hope this helps.

    Alex

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    Re: It's a Long Shot

    Quote Originally Posted by herbert View Post
    I wonder if you are seeing the combined effect of optical zoom and digital zoom through the viewfinder. Can you take a photo of the moon with both cameras, do a 100% square crop around the moon and post them up here. Then people will get an idea of the resolution you are seeing.

    If all your cameras have approximately the same focal length (450mm), then the one with higher mega pixels should win. This is assuming equal optics and pixel resolution. Under these assumptions you should be able to get a fair comparison with this formula:

    Quality = focal length x pixel density

    Approximating a square sensor you can get pixel density as the square root of the mega pixels. If you know the sensor ratio (e.g. 3/2, 4/3, etc.) use the following to get the x and y density:

    X = sqrt(MP * ratio)
    Y = sqrt(MP / ratio)

    Then you should be able to compare the quality of lots of different focal lengths with different pixel sensor densities. Make sure you compare the long edge to the long edge, e.g. X to X.
    The zoom on the Sony is all optical but the lower MP sensor will likely offset the benefit of the longer range lens. My hope is that the much larger zoom on the S9100 along with the higher MP will make it worthwhile. I'll try some testing using your suggestions as soon as I can. Thanks for the help!

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    Re: It's a Long Shot

    Quote Originally Posted by FrankMi View Post
    The zoom on the Sony is all optical but the lower MP sensor will likely offset the benefit of the longer range lens. My hope is that the much larger zoom on the S9100 along with the higher MP will make it worthwhile. I'll try some testing using your suggestions as soon as I can. Thanks for the help!
    What we are trying to tell you is:

    The S9100 does not have a larger zoom than your Nikon SLR, nor more MP


    The S9100 goes farther into the wide-angle range than your SLR+telezoom, but that is covered by the 18-55mm (or thereabouts) kit lens you probably have (or have replaced...).
    Look at it this way: the P&S have fixed lenses, so want the largest zoom range crammed in the package, at the cost of some optical quality; SLRs have exchangeable lenses, so don't need to cover the whole wanted range with one lens, and thus can reach higher optical quality

  16. #16
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    Re: It's a Long Shot

    Hi Frank,

    Because this has me quite interested, I built a spreadsheet containing the camera information and my quality measure:

    Code:
    Camera   Length   Crop Factor   EFL   MP     Ratio   Pixel density   Quality
    D3100    300      1.5           450   14.2   1.5     4.6             2076.8
    DSC-H1                          432   5.1    1.33    2.6             1125.1
    DS9100                          450   12     1.33    4.0             1797.7
    1D4      800      1.3           1040  16.1   1.5     4.9             5110.8
    This assumes that Mark used his Canon 1D4 for the image and not the 5D. However it shows that there is little difference between your Nikon and the Sony DS9100, with the Nikon in front due to the higher MP count. However the shot that Mark took is 2.5 times higher in quality.

    Note that this table is based on having perfect optics. It also assumes the subject has detail to fill the pixels on the sensor. In practice, as revi pointed out, the zooms with less range and the primes will have better optical quality as fewer compromises are made in the design. You should then expect the SLR cameras to do better than these figures show.

    Private message me with your e-mail address and I can send you the spreadsheet. You can then fill in whatever cameras you care to evaluate.

    Regards,

    Alex

  17. #17
    Moderator Dave Humphries's Avatar
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    Re: It's a Long Shot

    Hi Frank,

    I can understand your confusion, I'm not sure enough of my facts to clarify from theory

    I think where things are going wrong are that when you view the image 'full captured frame' on screen, the effect of different sensor sizes is lost because the screen's resolution is so low compared to the sensor.

    As has been said; the sensor's angles of view should be the same if they are both equivalent to 450mm (as they seem to be from the figures).

    The sensor MP differences will probably have a small effect on perceived magnification because to fit a 1920 x 1080 screen 'full frame', they will undergo different zoom ratios in the editor programme.

    If the 9100 doesn't do RAW, I suspect that the PP you can do to the D3100's RAW files will produce a better result than editing a jpg - except you have a lot of practice at that and dealing with jpg and sharpening artefacts.

    I think the best quality comparison method was suggested by Alex; get the two capture images on same screen in an image editor, make both 1:1 or 100% (i.e. pixel peep) views, crop both so the edges of a full moon touch the sides of a square crop. Then see what size the resultant images are in pixels.

    Now make them both the same physical size on the monitor screen and review their respective qualities, what you're after is as big and sharp an image as possible.

    Not sure if that helped

    The figures Alex just posted are what I would expect.

  18. #18

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    Re: It's a Long Shot

    Frank,

    as Dave and Remco have said the s9100 doesn't have a longer zoom. I think the problem is that people see 18x and equate this to a pair of binoculars say.

    On binoculars 10x means that the image is magnified by 10x what it would be if you were viewing with the naked. So any pair of 10x binoculars will magnify the image by the same amount. The field of view may change change a top brand like a 1500 10x pair of Zeiss/Leica/Swaro will magnify the image the same as a 99 pair of 10x bins. There are differences that persuade you to part with your dosh but magnification isn't it.

    On cameras the multiplier is a bit of misnomer, since camera A may be 18x but have a 20-360mm range whereas a CAmera B may be 18x but have 24-432mm range BOTH are 18x but one bring you much closer to the image! all it tells you is the range of the field of view NOT magnification.

    What I don't know is if you can convert an 450mm to the amount of magnification in the multiplier of a binocular. MY rule of thumb is divide it by 50 (normal naked eye...??) so your 55-300 is 9x after you allow for the dx crop!

    Also note this is only at infinity. A camera lens like the Nikon 18-200 is only rated 200mm when focusing at infinity. When focused at a close distance it probably is 18-135 - its called focus breathing. The new Nikon 70-200 lens was controversial because it was quite short when used close up.

    hope that helps

    cheers

    Pete

  19. #19
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    Re: It's a Long Shot

    Thanks to everyone that has been patient enough to help me get this through my thick head.

    Using Alex’s spreadsheet as a starting point and finding 35mm FFE calculator at http://www.digified.net/focallength/ I was able to prove to myself what had been said earlier but I blindly missed, the 18X of the S9100 doesn’t match the 55-300mm 5.5X and now I can see exactly where and how it doesn’t compare.

    D3100 at 55-300mm is FFE 82.5 – 450mm or 5.5X

    S9100 at 4.5 - 81mm is FFE 25.7 - 461.7mm or 18X

    To see the real difference, I have to include ALL Three of my D3100 lenses so I really have 11 - 16mm, 18 - 55mm and 55 - 300mm.

    Now it becomes 11 - 300mm or FFE 16.5 - 450mm or 27X when compared the same way that the zoom is calculated on the S9100!

    What was throwing me is that when I previously looked through the H1 at max optical zoom and the D3100 at 300mm, I 'thought' I could see further with the H1 even though the FFE is smaller than the 300mm. Not sure what I was smoking that day but today I went out and took some identical shots at max zoom and when I carefully compared the results, the 300mm had a slight size benefit over the H1 and a huge MP benefit.

    The S8100 has a great small size benefit being pocket-able, so it might be worth getting as a carry-everywhere camera, but it won't address my original goals of a longer reach.

    Another learning experience for which I can thank the members of CiC, again!

  20. #20

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    Re: It's a Long Shot

    Something that hasn't been mentioned is stacking of the images. Some free software like Registax can add several images together and average them out giving a better result than you can get with a single shot.

    Some things to bear in mind though.
    1) Have the camera on a tripod to get the shots as stable as possible.
    2) The software can't cope with rotation between images, so use a tripod.
    3) Take lots of shots for stacking.
    4) Play with the software for a long time until you get used to it.

    HTH

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