DIY Image Flip Optical Prism Ideas

skategriggs

skategriggs

New member
So Im always looking for ways to build a image flipping module and i've been wondering whether an optic prism could be used to flip the image. So i did some research and found some interesting stuff. And it looks like there are several prisms out there that can easily rotate the image, even some in a more space saving way that appears to be a better method than the bulky flip modules that letus, brevis and other 35mm adapter companies use.

So anyway here is what I have found, and Im wondering if any of you know whether this could actually work.

Dove Prisms:
These prisms will rotate the image straight through and it looks like you could place them right behind the ground glass where empty spacing is usually located on DIY adapters.
Dove-prism.png

I found a company that builds these with a face up to 40mm which would be ideal to cover the area of a 35mm screen, correct?
What do you guys think of this? could it work?

Pechan Prism:
Same function as the Dove prism, just a different design. I also found this being sold with a face size of 40-50mm, again I think this would be ideal. Its also said that the Pechan Prism has a wider field of view than the Dove Prism.
What do you think?
Schmidt-pechan-prism.png


Porro-abbe Prism:
Same function, and again available in large dimensions. Seems like this one could be a little more bulky and harder to incorporate into a 35mm adapter system, but im not sure.
What do you think?
Porro-abbe-prism.png



So what do you guys think? Any knowledge on these prisms and whether it could work? Which one would be the lightest, most compact, and provide best image if it could indeed work?

Thanks for the help! I hope to nail this issue, but arn't we all? haha, and Im sure im not the only one who has investigated this, so sorry if this is a double post, but help me out if you can!
 
Postmaster said:
The dove prism does only flip horizontal so you still have to flip vertical in post.

Frank
Click to expand...

Really? Ive read that the Dove actually flips vertically. I dont think any of these flip horizontally, but they all flip vertically from what ive researched, I mean just look at the diagram of the dove, it even shows it flipping vertically, or is that incorrect?

EDIT: it actually appears that the Pechan and Porro-Abbe Prisms do flip both horizontally and vertically, but the Dove is only Vertically, is this correct?
 
Ok after a little more research it seems the Pechan Prism is the best type because its the most compact, its often used in binoculars. Although I found that you need a Schmidt-Pechan prism which is basically the same design as a Pechan Prism, but its in fact a merge between the Pechan and Schmidt Prism. In the image I provided above, is actually an image of a Schmidt-Pechan Prism, I guess the website I got it from didn't label it correctly, but its an accurate picture of a Schmidt-Pechan.

I actually found that the Schmidt Prism alone is used in SLR camera in order to flip the image horizontally. Of course a SLR camera doesn't use a full Schmidt-Pechan Prism because the mirror inside an SLR is used for that function.

But in order to conserve space and keep the optics compacted into one straight cylinder, a Schmidt-Pechan Prism is ideal. Thats why they use them in Binoculars!

So I think with a larger version of this Prism that will fit the dimensions of the 35mm ground glass, this prism could essentially be the PERFECT alternative to dropping $500.00 on a letus, brevis, SGpro, ect. flip module.

But I don't know, maybe im missing something and this actually wont work...
What do you guys think?
 
Here is a great explanation on how the Schmidt-Pechan Prism works.

___________________________________


schmidt-pechan-prism.png

The Schmidt-Pechan prism consists of two glass prisms separated by an air-gap. The second, Schmidt, prism both reverts and inverts the image but in doing so deviates the path by 45°. The first prism corrects for this delivering a beam at 45° into the Schmidt prism. The design of the first prism is such that the entrance beam and exit beam are coaxial i.e. the Schmidt-Pechan prism does not deviate the beam if centered on the optical axis.

The lower Pechan prism uses one total internal reflection followed by a reflection from a mirrored surface to direct the beam into the second Schmidt prism so the orientation of the image is not changed.

The upper prism inverts the image by three total internal reflections in the vertical plane through the roof ridge. The "roof" section of the Schmidt prism flips (reverts) the image laterally with two total internal reflections in the horizontal plane from the roof surface: once on each side of the roof. This latter pair of reflections can be considered as one reflection in the vertical plane. Both inversion and reversion together cause a 180° rotation of the image. The image's quality, focal length, size and distortion is not changed or affected.


SOURCE: http://www.absoluteastronomy.com/topics/Schmidt-Pechan_prism
 
skategriggs said:
But in order to conserve space and keep the optics compacted into one straight cylinder, a Schmidt-Pechan Prism is ideal. Thats why they use them in Binoculars!

So I think with a larger version of this Prism that will fit the dimensions of the 35mm ground glass, this prism could essentially be the PERFECT alternative to dropping $500.00 on a letus, brevis, SGpro, ect. flip module.

But I don't know, maybe im missing something and this actually wont work...
What do you guys think?
Click to expand...

Have you seen any prices for these prisms?
I remember a while ago i tried looking into the possibilities of making a flip module out of surface mirrors, I even made some CAD plans.
I looked into prisms but they seemed too expensive.
 
I'm interested in this too. I have a Go35 Pro (I don't think they are being made anymore). It's fantastic, and static and I'd like to find a way to make it flip the image before it enters the camera. I have a flip monitor but would rather use my CRT production monitor instead of any LCD screen, among other reasons.

Your ideas are a good place to start. I'll see what I can find too.

Check these out:
http://www.anchoroptics.com/catalog/product.cfm?id=359
http://www.edmundoptics.com/onlinecatalog/displayproduct.cfm?productID=2430

Couldn't one jack the prisms out of these things?
http://www.bhphotovideo.com/c/search?Ns=p_PRICE_2|0&ci=3396&N=4294541733
 
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