An idea of telephoto lens for wildlife picture shooting

[szkorotko]

Hi, it might not be the best place to post this thread so please be lenient

I have an idea of telephoto adapter for smartphones. Everyone carries a smartphone in a pocket so why not use it for wildlife photography? The only missing piece is a reasonably narrow FOV, which will give large magnification. So I came up with an idea of developing one because I couldn't find any good quality telephoto adapter on the market. There are many telephoto adapters, but actually, all of them are rubbish.

The idea itself is very simple, I just designed the optical system based on the telescope design (quite fast F/5 telescope). You can compare my solution to a mirror lens, below are renders of the design:

The main pros of this solution are:
- small size and weight
- very good image quality (this is Schmidt-Cassegrain telescope)
- easy and repetitive mounting solution (not visible)

The whole setup you can mount on the tripod (still I am thinking how to solve it) and shoot wildlife from a decent distance. As you can see on the renders the picture shooting is very ergonomic, because the telephoto adapter is mounted sideways. This means that when you are taking pictures of an object in front of you, then you do not have to put a smartphone in front of your eyes just to see what is on the display (I hope you can visualize this ).

What do you think about such solution? Would that be a good idea to proceed with a prototype? What do you think is important in wildlife photography from equipment perspective? Any answers would be much appreciated.

Best regards,
Simon

 

[goooner]

Do you have any sample fotos taken with your lens?

 

[szkorotko]

Well, no because it is still not manufactured. I need to know if there is a potential market for such solutions But I have some renders from optical software, where I have designed the optical system. You can check the renders here: Magnifico.tech on Twitter (the second one is an image simulation showing image quality of available adapters on the market).

 

[jaomul]

Will it focus fast enough to be useful.

 

[szkorotko]

The focus is on this adapter manual, which means that you need to rely mostly on your skills.

 

[FotosbyMike]

Will Smart Phone cameras focus close enough to be able to focus on the mirror inside the lens? Then trying to hand hold this at the focal length is going to be tough.

Cool idea, nice CAD work but not sure it's for me.

 

[szkorotko]

No, it is not possible to focus on the inside mirrors From simulations it seems that the closest focusing plane would be about 5-6 meters away from the lens.

 

[480sparky]

Will Smart Phone cameras focus close enough to be able to focus on the mirror inside the lens? ..............

You don't focus on the mirror. You focus on the subject.

 

[KmH]

f/5 is quite fast for a catadioptric lens, and being that fast the lens won't give as much magnification as a slower (longer focal length) lens.
The field curvature at a focal ratio of f/5 will be quite noticeable.
Meade and Celestron Schmidt-Cassegrain telescopes have a system focal ratio of f/10 that results from using an f/2 primary mirror and an f/20 corrector mirror.
The corrector plate and the secondary mirror for a Schmidt-Cassegrain are some what complicated to make.

The greater the 'reach' the steadier the mobile device would have to be mounted.

Simpler, and cheaper to make is the Maksutov negative meniscus lens corrector used for a Maksutov-Cassegrain. At f/5 chromatic aberration may be an issue.
Schematic image of Maksutov-Cassegrain. Use license: CC BY-SA 3.0 Author: Halfblue at the English language Wikipedia

 

[szkorotko]

f/5 is quite fast for a catadioptric lens, and being that fast the lens won't give as much magnification as a slower (longer focal length) lens.
The field curvature at a focal ratio of f/5 will be quite noticeable.

Yes, that is true, but we do not want to compromise on image quality and size. This is our first priority, it must be high quality and compact. Modern smartphones cameras have very large resolution sensors (usually 12 MPx). It will drive the cost up, but with large volume production, there are manufacturing technologies that can reduce this cost significantly.

Here you can see my telephoto adapter system layout:

Actually, the biggest challenge was to design reasonably small "eyepiece" which will project an image from the telescope into wide FOV smartphone camera lens

 

[FotosbyMike]

You don't focus on the mirror. You focus on the subject.

How is the smart phone camera going to focus first, then the lenses will focus on the subject.

 

[tirediron]

Moved to an appropriate forum.

 

[480sparky]

You don't focus on the mirror. You focus on the subject.

How is the smart phone camera going to focus first, then the lenses will focus on the subject.

The image is not on the mirror. There's nothing on the mirror to focus on. The AF will focus on the subject, the same as if the mirror wasn't part of the optical path.

 

[waday]

Well, no because it is still not manufactured. I need to know if there is a potential market for such solutions But I have some renders from optical software, where I have designed the optical system. You can check the renders here: Magnifico.tech on Twitter (the second one is an image simulation showing image quality of available adapters on the market).

I looked at your Tweet. Aren't they BOTH image simulations?

Also, shouldn't you try image simulations of the same subject? You're using two different images to compare to one another, which doesn't give an accurate depiction of image quality between your hypothetical lens to actual manufactured lenses.

What are you expecting costs to be?

 

[szkorotko]

I looked at your Tweet. Aren't they BOTH image simulations?

Yes, they are both simulations, I did such comparison simulations earlier. Hopefully, our real design will be close to simulations:

and this is what you can get from telephotos available on the market:

Actually, you can search for the image quality of this kind of telephoto adapters on YouTube. Here you can find real > example <

I am still not sure about the pricing since I don't have yet detailed costs estimation for volume production. I expect that optical and mechanical components will cost total roughly 60-90 USD.