Re: Build a Super Telephoto Lenses w/o Using a Camera Lens
In reply to l_d_allan,
Jun 7, 2014
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l_d_allan wrote:
Ching-Kuang Shene wrote:
OK. Can we have a super telephoto lens without using a camera lens? Of course, we cannot. Therefore, there has to be a lens in front of the camera but it is not an expensive camera lens.
Fascinating. Thanks for sharing. Tempting to try. I'm scratching my head on what the "BOM ... bill of materials" would be for a Canon DSLR.
BOM? If you mean how much you are going to pay, it is a rather cheap project. There are some cheap Canon compatible bellows on eBay between $20 and $30. Very cheap extension tube sets below $10.00 are also available on eBay. For this setup, the most expensive element is perhaps a Canon 500D close-up lens. The problem is if Canon made something like the Nikon K-2 ring.
It seems like this might be a great parent / child joint project for a school science project, if the parent had LOTS of macro equipment at hand without too much out-of-pocket expense. There's lots of math involved, plus plenty of Optics / Physics. Mechanical engineering? Engineering Econ?
It is not really a difficult project. Some years ago, I tried to simulate what a 1839 daguerreotype camera can do, I used a Nikon #4T +2.9D with 52mm thread and yielded very good results. So, I thought I may be able to do little better with a latger diameter Canon close-up lens. Pentax made a close-up lens of diopter less than 1 (i.e., focal length larger than 1000mm). I hope I could collect enough number of cheap extension tubes that can extend longer than 1000mm.
BTW: the photos used to illustrate are Very, Very Helpful. Are you a technical writer? It would be great if more forum posts provided illustrations as good (and there is certainly room for improvement by "the guy in the mirror" ... my bad).
No, I am not a technical writer. I am a professor.
However, my understanding is that DPR does discourage more than some reasonable number of embedded images. Your images of the camera itself certainly would seem to justify an exception, but perhaps the extensive examples could be in a gallery?
I don't know about this. I kept adding images until I was blocked.
CK
Differences between 2-element close-up lens and 1-element lens
In reply to Ching-Kuang Shene,
Jun 7, 2014
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As mentioned in my post, one should use an achromat close-up (i.e., 2-element doublet) lens for this setup. Here is an example. The first image below was taken with a Canon 500D close-up lens and the second used a cheap +2 diopter single element close-up lens. The fifferences are so obvious.
CK
Nice ethereal effect for when you want it.
In reply to Ching-Kuang Shene,
Jun 7, 2014
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Ching-Kuang Shene wrote:
As mentioned in my post, one should use an achromat close-up (i.e., 2-element doublet) lens for this setup. Here is an example. The first image below was taken with a Canon 500D close-up lens and the second used a cheap +2 diopter single element close-up lens. The fifferences are so obvious.
CK