Crop-Factor?

Discussion in 'My Astrophotos' started by ROBERT T SCHAEFER JR, Aug 16, 2018.

  1. ROBERT T SCHAEFER JR

    ROBERT T SCHAEFER JR Cyanogen Customer

    Joined:
    May 13, 2018
    Messages:
    303
    Do you think that there is a chance...that... when taking 'astrophotos' with a camera like a Canon EOS T7i being they tell you
    it has a 'crop-factor sensor' of ' 1.6 ' ...like the idea is it is magnifying an image to a higher magnification than a Canon EOS 6D 35mm 'sensor' ?
    In the case of the 35mm 'sensor' like 'clarkvision.com' says it is imaging at an ISO100 and all cameras do the same thing !...so what is the magic that is
    with a 'crop-factor sensor' of any size 'crop-factor' that it has a magic magnifying ability..?.. ? .. maybe a special lens on the 'crop-factor sensor' ..?.. or
    maybe there is a special formula after the 'sensor' is read and a magnifying presentation happens when the image is put into a computer .
    With the NGC6210 and NGC7048 for example.. I think the formula they use is like with my Telescope at 1200mmFL at 'Prime Focus' ...so with a 35mm
    camera you divide 1200 by 50 and you get about 24 which means it is seeing at about 24xpower magnification.... but if using a 'crop-factor sensor' of ' 1.6 '
    you then multiply the 24xpower magnification by 1.6 and you assume you have about 38xpower magnification. ...But... does this really exist with the
    '?crop-factor sensors' ' assumed magic ability to see things closer than a 35mm 'sensor' does ?... Or is a formula inside a 'crop-factor' camera like an ISO
    conversion really only falsely magnify and image to imitate a 35mm 'sensor' in a computer ? .. They could put a formula in a 'crop-factor' camera to say it is
    really a 35mm 'sensor' that is cut to a small size and has internal codes that can't be read by anyone and maybe it's a myth that the 'crop-factor sensor' sees
    with extra ability by bringing an 'object' closer ... but in actuality it might be seeing the same as a 35mm 'sensor' but the 35mm 'sensor' doesn't cause the image
    to greatly magnify in a computer . So with a TeleVue 2.5XPowerMate into a 2XPowerMate with my Telescope would be 1200mm x4.5=5400mmFL for a
    35mm 'sensor' and ' 5400 divided by 50 = 108xpower magnification ' .. but then with a 'crop-factor sensor' of ' 1.6 ' you then multiply ' 108xpower x 1.6 = 172.8 ' ,
    this magnification theory might be wriong..like a peanut is... a wriong . In reality a 'crop-factor' might only be seeing what a 35mm 'sensor' is seeing but it's a
    small size and the image in the laptop would be too but the formula they might use shows the image larger and some statistics in the conversion might also be
    fooling "PinPoint Astrometry" also and thinks there is a higher magnification ...where "Pinpoint Astrometry" formulas assume the camera is a 35mm 'sensor' .
    With NGC6210 I assume with the formula for the 'crop-factor sensor' of the Canon EOS Rebel T7i and it's ' 1.6 ' theory that I am see an 'object' a about
    188xpower magnification due to "PinPoint Astrometry" thinking there is a high magnification of 5900mmFL when the image is 'solved' and it usually works
    for all images like this but I do have to use the Bin3 and then Bin3 again to get the 'solve' . If I used the Canon EOS 6D instead then it should 'solve' at a
    lesser mmF/L ...which also could be the actual 'crop-factor sensor's ' reality also but then it's converted to a different theory .
    I used the Canon EOS 6D with a TeleVue 4XPowerMate into a 2XPowerMate and when the image' 'solved' with "PinPoint Astrometry" then using the
    formula of 1200mmF/L divided by 50 ..but it would be 7200mmF/L ...but due to the two PowerMates together the mmF/L was more and the image was
    'solved' to be 190xpower magnification...?????>>>> I will try that again with the Canon EOS 6D on NGC6210 and M57 and NGC7048 and see if the 'objects'
    actually look closer that the Canon EOS Rebel T7i images using a little less power of the PowerMate combinations . mnmnmn
    If you had a Canon EOS 6D 35mm image into MaximDL Pro at 'Prime Focus' and also a Canon EOS T7i at 'Prime Focus' of the same 'object' ..like
    the M42 with the Trapezium in the 'center' it might look magnified closer in the Rebel T7i image ..but if you made the 'pixel size' of the Rebel T7i 6.5microns instead
    of it's 3.72micron pixels it will become smaller ...but it might resemble the actual size of the 'object' as it's magnification... of the Canon EOS 6D 35mm image .x

    In MaximDL Pro they have a "Resize"command and the 'original' pixel size must be read from the FITS Header so if a CR2. image you will have to 'Edit' into the
    FITS Header for 'xpixels' and 'ypixels' and then 'open' the "Resize" command and change the pixels size to like ' 1.6 ' times the original pixels sizes ... which is this
    case it is a crop-factor DSLR camera that most likely needs to be resized to a smaller screen size in the 'buffer' to match a 35mm 'sensor' image magnification size so
    a comparison of both sensor sizes of the same 'object' look like they are both at the same magnication and the 'object' in each image looks the same size ..his will then
    hopefully be countering the in-controlled image {the expanse} of the crop-factor 'sensor' image when viewed in a computer . So there could be a 'myth' that most people
    believe like me that a 1.6 crop-factor 'sensor' DSLR is seeing at a more magnified view of an 'object' and 'multiplying' a 'solved' image's mmF/L first dividing by 50 and
    then 'multiplying' by 1.6 gives you a higher magnification and you believe it because the image is automatically 'magnified' and when put into "PinPoint Astrometry" to
    'solve' the image the program is being fooled with the higher magnification because it is made for 35mm 'sensor' 'solving' ...and then on top of that to 'multiply' what the
    'solved' image's F/L is for a 35mm 'sensor' theory by 1.6 for a greater magnification using the crop-factor DSLR is a probable larger mistake yet . So basically all 'sensors'
    might be actually imaging at a 35mm 'sensor' reality but crop-factor 'sensors' are just smaller .
    I once tried the Canon EOS 6D thru a 4XPowerMate into a 2XPowerMate and it 'solved' for 190xpower magnification which is probably real ....instead of what I think the
    Rebel thru a 2.5XPwrMte into a 2XPwrMte is doing and it isn't really 188xpwr .. it is probably 108xpower magnification????.

    NGC6888 was done with the Canon EOS Rebel T7i 'modified by Hutech' using a TeleVue .8XReducer/Flattener thru a Baader 7nm Hydrogen Alpha 2in. filter
    thru a 1200mm FL 152mm A+M Refractor(OfficinaStellare) and it's three CR2.s Sum stacked in MaximDL Pro after "Resize" to ' 6.0 micron pixels' .
    It the needed to be "Resize" to ' 6.58 micron pixels ' to 'solve' with the GSC Catalog and 'solved' at ' 934mmF/L ' which divided by 50 is about
    ' 19xpower magnification ' but this might be the real Reality Show ??? .

    www.clarkvision.com has a page called ' Comparing Stacking Methods' and the output 'stacked' image file must be '32-bit Float' to contain all the data or it will become chopped ,
    so he says ' Sigma Clip Average StdDev 2.45 ' is the method to use . ' Batch Process for NGC6888' with "Resize" in the commands .


    [ www.skyephotoacademy.com/blog/full-frame-vs-crop-sensors
    The first and most obvious effect of is how much of a scene they are able to capture (field of view). For any given focal length, a smaller sensor will capture a smaller area of the scene. For example, using a 50mm focal length lens on both a full frame and micro 4/3rd sensor will allow the former to capture around double the angle of view as the smaller sensor. Think of using a crop sensor as taking a photo on a full frame camera but only being able to see the central 50-80% of the image. The remaining peripheral areas are never captured by the smaller sensor. See the image above for an illustration of this.

    When we view our images (either on the camera’s screen or on a computer), those taken on a crop sensor need to be magnified to a greater degree in order to fill the screen. For this reason, crop sensor cameras appear to magnify the image compared to shots taken at the same focal length on a full frame cameras. This effect is known as the crop factor and is measured as a degree of magnification. The majority of APS-C sensors have a crop factor of ~1.6x, whereas 4/3rd cameras have a crop factor of around 2x. ]
    "Batch Process" needs .CSQ on the end
     
  2. Doug

    Doug Staff Member

    Joined:
    Sep 25, 2014
    Messages:
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    Yes "Crop Factor" is simply the ratio of the frame size to a 35 mm frame.

    This is distinct from the resolution of the sensor. You could have a 35 mm sensor that was 12 megapixel in one camera, and a smaller crop factor 1.6 sensor in another camera that was 16 megapixel. So the images from the smaller sensor would be be bigger on the computer, but would see a smaller field of view. The world would be "magnified" by the smaller pixel size.
     

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