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My Lens Turbo :)
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PostPosted: Tue Mar 31, 2015 8:29 am    Post subject: Reply with quote
I'm still mad, as I invented the idea decades ago, but no optical company wanted to make it,
even Zeiss said, "not doable" until Dr Caldwell had the idea and made his product and now it
has been copied many times and thousands sold... Crying or Very sad Wink

Last edited by kds315* on Tue Mar 31, 2015 7:37 pm; edited 2 times in total


PostPosted: Tue Mar 31, 2015 8:33 am    Post subject: Reply with quote
kds315* wrote:
I'm still mad, as I invented the idea decades ago, but no optical company wanted to make it,
even Zeiss said, "not doable" until Dr Caldwell had the idea and made his product and now it
has been copied many times and thousands sold... Crying or Very sad Wink

Are you sure you invented the idea but no the others? Wink


PostPosted: Tue Mar 31, 2015 10:38 am    Post subject: Reply with quote
calvin83 wrote:
kds315* wrote:
I'm still mad, as I invented the idea decades ago, but no optical company wanted to make it,
even Zeiss said, "not doable" until Dr Caldwell had the idea and made his product and now it
has been copied many times and thousands sold... Crying or Very sad Wink

Are you sure you invented the idea but no the others? Wink


Spring 2003 it was, when I discussed that with companies Wink

Let me quote one letter (w/o naming the company):

Dear Dr. Schmitt

After exhaustive efforts to try and find a solution to fit your specification we have finally had to come to the conclusion that there is no practicable solution to the problem. The combination of requirements for field angle, back focus and reduction ratio do not appear to have a practicable solution and theoretical solutions would be uncorrectable and would not fit the camera throat diameter due to high over telecentricity.

Basically, the problem stems from the Prime lens. At this point there would be two choices which would enable a solution to be achieved.

1) Some form of redesign of the Prime Lens would need to be contemplated to achieve the result you require. This may not involve a complete redesign of the optical system. In some of our own lenses (zoom systems) we have been able to change the image size by designing a new rear section only to provide the final characteristics required whilst leaving the front of the system unchanged. As we have no knowledge of the system you are using I am afraid that we are unable to comment further on this option.

2) A complete redesign of the prime lens. At first this might seem completely impractical, but with the qty per year that you were discussing it actually may be a cost effective solution. A benefit would be a purpose made lens for the application with no requirement for a reducer lens or indeed any additional lenses. This is certainly the route that I would suggest taking.

I am sorry that we were not able to provide the solution originally required. Should you wish to discuss this problem further or wish to explore either of the two suggested ways forward please do not hesitate to contact me.

I have attached the optical drawings produced by our designer for your interest.

Kind regards


PostPosted: Sat Apr 04, 2015 8:10 pm    Post subject: Reply with quote
When you have an idea like that you have to do something... I thought that the idea is from focal reducers for telescopes... Smile


PostPosted: Sun Apr 05, 2015 4:42 am    Post subject: Reply with quote
Great pictures, love them!

Can you tell me more about the Lens Turbo? How do you like it?
I didn't do my homework about the Lens Turbo yet, so not sure how does it work: for instance, what about the mounting? Does it come with a E Mount too so I can stack my other adapters on top of it? Or it comes only as Canon, Nikon and so forth?
Also, how does it compare to a FF? Do you think it can be a good alternative for someone who wants to stick to the crop sensor but get some of the advantages of FF when it's needed?


PostPosted: Sun Apr 05, 2015 7:11 am    Post subject: Reply with quote
cgustav wrote:
Great pictures, love them!

Can you tell me more about the Lens Turbo? How do you like it?
I didn't do my homework about the Lens Turbo yet, so not sure how does it work: for instance, what about the mounting? Does it come with a E Mount too so I can stack my other adapters on top of it? Or it comes only as Canon, Nikon and so forth?
Also, how does it compare to a FF? Do you think it can be a good alternative for someone who wants to stick to the crop sensor but get some of the advantages of FF when it's needed?

Well I like it a lot, I already wrote in this thread a lot of thoughts about it.
About the mounts - it only can be used for lenses with longer working distance(SLR/DSLR lenses).
Here take a look on those reviews to see how it performs.
http://www.verybiglobo.com/metabones-speed-booster-ultra-review-part-ii-canon-ef-501-2-l/
It is a nice cheap compromise FF Smile


PostPosted: Sun Apr 05, 2015 7:42 am    Post subject: Reply with quote
simbon4o wrote:

Well I like it a lot, I already wrote in this thread a lot of thoughts about it.


Ha! I guess I looked mainly at the pictures Smile

simbon4o wrote:

About the mounts - it only can be used for lenses with longer working distance(SLR/DSLR lenses).
Here take a look on those reviews to see how it performs.
http://www.verybiglobo.com/metabones-speed-booster-ultra-review-part-ii-canon-ef-501-2-l/
It is a nice cheap compromise FF Smile


Thanks for the link!


PostPosted: Sun Apr 05, 2015 8:08 am    Post subject: Reply with quote
Yes, nice looking model you have there. I should practice more on our models. (we have three cats) That way they'll be good for something.

When I see a Lens Turbo (or equiv) being used, first thing I do is look at edge/corner sharpness. It seems to be doing an excellent job. I'm thinking very seriously about getting one for my FD lenses and my NEX 7.


PostPosted: Fri May 29, 2015 6:53 pm    Post subject: Reply with quote
Some new samples Smile

Nikkor AF-S 35 1.8 DX on Nex6 TurboII
DSC01811 by Simeon Kolev, on Flickr

Bokina on Nex6 TurboII
DSC05473-Edit by Simeon Kolev, on Flickr

Canon FDn 85 1.2L on Nex6 TurboII
DSC04883 by Simeon Kolev, on Flickr

Porst 55 1.2 on Nex6 TurboII
DSC00866-copy by Simeon Kolev, on Flickr


PostPosted: Fri May 29, 2015 10:15 pm    Post subject: Reply with quote
cgustav wrote:
Great pictures, love them!

Can you tell me more about the Lens Turbo? How do you like it?
I didn't do my homework about the Lens Turbo yet, so not sure how does it work: for instance, what about the mounting? Does it come with a E Mount too so I can stack my other adapters on top of it? Or it comes only as Canon, Nikon and so forth?
Also, how does it compare to a FF? Do you think it can be a good alternative for someone who wants to stick to the crop sensor but get some of the advantages of FF when it's needed?


It is ideal if you want to stick to the crop sensor as you get (almost) the same coverage as you would on full frame. I bought a Mk1 for my NEX when they went sub 100GBP. The Lens Turbo has the camera fitting on the back end and the lens fitting on the front. No other adaptors needed. I bought a Minolta fitting as the majority of my lenses are SR bayonet. I have an M42 adaptor so i can use my 17mm and my 28mm Lithagon. Think carefully about which system you go for. Canon FD may be good as you can adapt M42, Nikon and possibly others.


PostPosted: Sat May 30, 2015 4:25 am    Post subject: Reply with quote
This gadget appears to work surprisingly well. I was paying attention to corner/edge sharpness on the above photos that had well defined ones and I can't see much of any falloff toward the edges and corners.

Tell me, which 17mm do you have? And how does it work on your NEX with the Lens Turbo? I tell ya, just using adapters on my NEX for my Vivitar/Tokina 17 and my Tamron 17, I was less than impressed with the results. The sensor was just not able to handle the way those lenses bend light. So I'm wondering obviously if the LT was able to help out in that regard.
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