You Know That They Say About Guys With Big Lenses?

[Tony Lovell] and [dkpeterborough] built a sizable camera lens using optics from a flight simulator projector. What they ended up with is a 900mm lens that can make a beautiful photo of the moon, or capture distant landscapes in great detail. The body of the lens was designed in CAD and sent off for fabrication out of aluminum, as seen above. The concentric baffles help to prevent lens flare but it can’t be used in its bare-aluminum condition. The internals were coated using a stippling finish that leaves a sandy texture. That was covered with matte black barbecue paint, doing a great job of preventing optical interference, and the outside received a glossy white coat. Finished weight: 59 pounds, but once you see the pictures you’ll agree it’s worth lugging the bulky instrument around to grab that killer shot.

[via Make]

35 thoughts on “You Know That They Say About Guys With Big Lenses?

  1. XD its a great DIY lens
    it does show distortion and probably has a ton of CA but for half the price of a 900mm pro lens so good job XD

    if you like big lenses check out the Sigma 200-500mm F2.8 APO EX DG

  2. @medix
    for sports photography i use the sigma 300-800 (on my D300s its more of an 500-1100 ish and thats the body i use most with it)
    it works great but the more you zoom the longer the exposure … the 2.8 across 500-800 would be godlike but wayyy beyond my budget

  3. I’m guessing that like the “projector lens telescopes” of the past this one will suffer a bit in that the lens was not made to focus at infinity.

    That said, I’d do the same exact thing if I had such a chunk of precisely ground glass. Also, regarding the suggestion to go buy an Orion dob, that’s a newt. Great for DSO’s. Not so great for other stuff due to coma and diffraction from the secondary. And they’d still need to shell out the dough to mount the DSLR.

  4. Tons of CA, hence the pictures converted to B/W :-)
    Great hack but there is almost no practical use, It would be very difficult to sell these photos for example due to all that CA.

  5. Yeah, I’m gonna go with the “He should have used a telescope.” I have an 8″ Dobsonia I got for $329 and the moon is much clearer and more impressive than that picture.

    Unforunately, Orion didn’t design the Dob for mounting a camera (they tell me the focal length is wrong. I may try anyway), but they also sell Optical Tube Assemblies that size that *can* use a camera for around $400 I think, which is how much this guy spent. The telescopes have excellent optical clarity – much better than what we’re seeing here.

  6. @Concino
    he mounted it to a medium format film body, the photos aren’t -converted- to black and white.

    It’s an interesting build, though in the posts they hit upon why extreme focal lengths are difficult and of somewhat limited utility: atmospherics making for hazy (or worse, half hazy and half clear) photos. The size certainly rules out wildlife photography…

    I’m also curious what happens to out-of-focus highlights with a lens design like this, using (as I interpreted the writing) more or less completely circular apertures.

    Definitely a neat project, though.

  7. @jeditalian Because the moon is grey?

    Sometimes it’s lit up orange through the atmosphere, but that atmospheric filtering likely also adds distortion to the image, so it might not make for good pictures. Also, the moon is grey much more often.

  8. jeditalian
    because thats the color of the moon XD
    sure it can have red/blue tints depending on how much atmosphere is in the way (doper shift effect) but its naturally black and white XD

  9. @jeditalian
    have you ever look up to see the moon
    than you can see that the moon is BLACK WHITE
    even a 9 years old now this but the moon refleckt licht do to this the color can be from red to yellow 1 tip whats more discovery than you can get smarter

  10. You’re missing the point, this was designed for medium format and large format cameras, the area projected by that lens is much larger than the 6x7cm image format in the Pentax film camera he was using. Using a smaller telescope won’t help because it won’t project the image circle needed for the formats they are using.

    He posted a reply to some of the “poo-poo” comments on the bottom of the thread. Copied here for the lazy.

    “There have been some comments on another forum about this lens which seem to ‘poo poo’ the project and say that anyone can attach a telescope to a camera and obtain similar results. However, those denigrators are missing the point that this lens has a much wider aperture than any budget priced refracting telescope and that it was primarily designed for medium and large format film photography … as distinct from 35mm film and digital . And someone else suggested that using a catadioptric lens would be much easier. Perhaps they have overlooked that mirror lenses of this aperture would be prohibitively expensive and that they would be limited to one aperture and also result in the distracting ‘doughnuts’ syndrome. Unlike a cat. lens, this lens is capable of being modified for use with an iris diaphragm. Someone else suggested the images are not that sharp but they are overlooking the fact that atmospheric pollution plays havoc with ultra-long focus lenses … plus the fact that the images are compressed before posting.”

  11. @Daniel: He seems to be blaming the image quality on the atmosphere and not the lens. While this is a contributing factor, it is not the main cause.

    Format is not relatively important. With this setup, you’re going to get fairly similar results all across the board. Aperture is a big factor, but what is the actual f number of the lens? (I haven’t had time to look into this). If it is anywhere near f/2.8 then I could see *some* advantage, but focal lengths such as this can easily be accomplished for nearly the same price using a readily available reflex lens. You’ll have a much smaller aperture (around f/8 – f/10: not really a problem with high ISO) but the quality will be much improved.

  12. @Daniel
    a proper digiscope will work with full frame (as you call it 35mm) formats at apertures as high as 1.4 if you have a proper telescope
    my $500 mirror telescope is a good 1600mm and i get F2.8 with it
    i have a nikon scouting scope (for shooting) and i get F5 with it
    and i would get much clearer images with a telescope because the optics would generally have an ED coating and aspherical lenses
    or you can just get a cheep mirror scope and it covers all of this (but blurred beams of light look like doughnuts)

  13. FWIW: For photography, a lens of a given f/# ordinarily will outperform a Newtonian reflector of the same f/# unless the desired field is extremely small. The lower the f/# the more this applies. At about f/6 and lower, coma is quite apparent at the edge of the field of a paraboloidal mirror.

    A catadioptric–Schmidt-Cass or Maksutov–can be superior to a Newt reflector but that’s largely because of the larger f/#.

    Of course, a larger mirror will give a brighter image than a smaller lens. It all depends on what you want to do with it.

  14. The main issue that he will have with the moon is the amount of light the moon chucks out and the speed its moving in the sky, will need a very quick shutter speed and probably a ‘moon’ filter of some description.

    Either that or get it onto a real German EQ telescope mount, manual or motorised and track the moon properly, maybe even look at some deep sky objects like nebulae and globular clusters :)

  15. The point here being he “built” this, yes, you can buy better. But this is not the Buy a Day website. Hacked. Plus I don’t think he did it to get on this site, he did it for his own pleasure.

  16. @Greycode

    Eh, yeah, but what he built was a 60 lb lens that doesn’t appear to provide any advantages (even cost) over commercially available telescope options.

    We normally hack stuff to save money, or do something better. Doing neither is just silly.

    And he says this is for medium format, but I still don’t see the advantage over using 35mm and a telescope if the quality is going to be that poor! Higher resolution blurry images are still blurry images.

  17. Here’s what you can do with a real telescope and a £40 webcam:

    It’s a schmidtt-cassegrain, 150mm aperture, F10, webcam was a philips SPC900NC.

    There is a technique called stacking, where you take many images and layer the best ones together to draw out subtle information.

    A webcam is used because it runs quite fast at 25fps, you take a few thousand frames and then do the stacking process. This has the added bonus of allowing you to filter out images that are poor quality due to the atmospherics or what is more commonly known as ‘seeing’.

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