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With 2 teleconverters would an f5.6 lens be f16?
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PostPosted: Wed Aug 17, 2022 10:08 pm    Post subject: Reply with quote
Ultrapix wrote:
I only was answering to the opener's request, a front teleconverter + a rear one; the first does not change the F, just a little the T value. I didn't say that the quality is good or not, but I have to say that my Raynox (not a cheap one, its pricelist was over 300 euros, and it fits 5 elements) is not bad at all with the right lenses


Have you tried it with telephoto lenses? For 300 euros you can pick up a decent 400mm 5.6 lens...


PostPosted: Wed Aug 17, 2022 10:08 pm    Post subject: Reply with quote
Ultrapix wrote:
I only was answering to the opener's request, a front teleconverter + a rear one; the first does not change the F, just a little the T value. I didn't say that the quality is good or not, but I have to say that my Raynox (not a cheap one, its pricelist was over 300 euros, and it fits 5 elements) is not bad at all with the right lenses


Have you tried it with telephoto lenses? For 300 euros you can pick up a decent 400mm 5.6 lens...


PostPosted: Thu Aug 18, 2022 6:49 am    Post subject: Reply with quote
kymarto wrote:
Ultrapix wrote:
I only was answering to the opener's request, a front teleconverter + a rear one; the first does not change the F, just a little the T value. I didn't say that the quality is good or not, but I have to say that my Raynox (not a cheap one, its pricelist was over 300 euros, and it fits 5 elements) is not bad at all with the right lenses


Have you tried it with telephoto lenses? For 300 euros you can pick up a decent 400mm 5.6 lens...


I first got this as a small token of appreciation from a salesman friend, who told me to pick something from his stall at a market, and I took this because I was curious. Its best use in my opinion is not to "create" very long focal lengths, but to multiply x 2.2 short bright telephotos; for example it rendered very well on the Zuiko 75 1.8 M43, generating an equivalent of 330 mm F:1.8 (compared to 35 mm), and it was a combination I exploited a lot in the theatre (professionally) when I used the M43 for its silent shooting, before equally silent full frames came along. It also works very well with the Canon EF 100mm 1:2 that I still use on the EOS R, and the result is a totally exploitable 220mm. The limitations are a visible chromatic aberration, which the sw can only partially correct, and a strong lengthening of the minimum focusing distance. As far as sharpness is concerned, however, it performs absolutely decently. Another advantage is that it does not interfere in any way with the various camera automatisms when present. At longer focal lengths, on the other hand, the entrance pupil becomes proportionally insufficient, leading to brightness loss and vignetting; if it weren't for the fact that its weight (despite being very light) could stress the lens mechanism, it performs very well with my Lumix FZ 1000, turning the 400 mm (equivalent) into an almost 900 mm.
All in all it is a toy that can be useful in some situations, the important thing is to pay little for it (currently new it stands at 180 I have seen, but it is still too much IMHO).


PostPosted: Thu Aug 18, 2022 10:08 am    Post subject: Reply with quote
As I said earlier, dedicated OEM front tele/wide converters (i.e. those that have been designed specifically for one particular lens/camera) can perform quite well; they can take account of the residual imaging errors of the main lens and compensate in the converter to some extent. The results can be quite good then. Even adding an additional OEM rear 2x TC can then still result in usable images.

Having said that, the dedicated front wide/tele converters are usually designed for use with a specific non-interchangeable lens compact camera, which makes addition of a rear 2x TC impossible anyway...


The generic ones (especially the combined reversible wide/tele converters) are not that great in general but fortunate specific converter+lens combinations may perhaps be found.


PostPosted: Thu Aug 18, 2022 10:52 am    Post subject: Reply with quote
http://raynox.co.jp/english/dcr/dcr2025pro/index.htm


PostPosted: Thu Aug 18, 2022 1:00 pm    Post subject: Reply with quote
visualopsins wrote:
http://raynox.co.jp/english/dcr/dcr2025pro/index.htm


Thanks!

Just published a quick and dirt test on my older Raynox 2020: http://forum.mflenses.com/viewtopic,p,1567372.html#1567372
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