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Langstrum
Joined: 16 Feb 2014
Posts: 351
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 Posted: Thu Oct 16, 2014 9:19 am Post subject: Will we get a faster lens by using focal reducer? |
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Langstrum wrote:
No and yes. I will explain below.
I know this has been discussed many times but I just want to show here my experience and my point of view.
The bad points of using a focal reducer on crop mirrorless camera:
- Quality degradation: it depends on which lens you use, but in general, the difference in sharpness is not very obvious, you need to see the 100% crop to figure it out. If you use a high quality lens, that's not a big issue.
- Vignette: it also depends on the lens, sometimes I see it, sometimes I don't, but it appears with the majority of lenses I tested.
- Noise: you will have more noise, but at low ISO like 100 - 400, it's not obvious.
The good points:
- Definitely the biggest advantage of focal reducer is you will get a wider frame, which is comparable to full frame camera (about 0.72X)
- You will get more light and a bit increase in the average contrast
- The last point: whether it actually benefits you 1-2 extra stops? I will say No if I compare the two images shooting from the same distance. DOF is the same, the image becomes wider. But I will say Yes if I use the focal reducer and come closer to the object to get the same frame as I shoot without the focal reducer. The closer, the DOF is thinner, and comparing the images, it's like you get about 1 to 1.5 stops.
Here is my test with NEX 6 using CZJ Tessar 50/2.8 (Exaktar mount) at f2.8
The first shot I used the Yongnuo adapter for EF - NEX (after mounting the lens on Exaktar - EF adapter)
The second shot, I changed the adapter to Rosxen focal reducer, using same shooting condition, but I moved the camera forward until I got the similar frame as the first shot.
Overall, you can see the second one is brighter, has more contrast, no vignette and thinner DOF!
100% crop to show you the degradation to image quality: sharpness is reduced and you can see glowing edges, while the noise is almost the same
So, you will either get wider frame or more shallow DOF, not both 
_________________
Camera: Sony A7 mark III, A6300
AF Lenses:
Canon EF 50/1.8; EF 200/2.8 L, EF 200/1.8 L, EF 300/4 L Sony E mount SEL 50/1.8 OSS, SEL 16/2.8 Fuji X mount XF 35/1.4 R
MF Lenses: Peleng MC 8/3.5, 17/2.8 Samyang 14/T3.1, 35/T1.5, TS 24/3.5 ED, 85/T1.5, Polar 85/1.4 Auto Revuenon 28/2.8; MC 50/1.4 Vega11U 50/2.8 Carl Zeiss Tessar 50/2.8 (exakta mount) Auto Chinon 50/1.9 Zenitar ME1 50/1.7 Sears Auto Sears 55/1.4; Sears 135/2.8 Auto Yashinon DX 50/1.4; Tomioka 50/1.2 SMC Pentax 50/1.7; 50/1.4 Canon FD 50/1.4 S.S.C; 55/1.2 S.S.C; FD 50/1.2 L; FD 85/1.2 L; 85/1.2 S.S.C Aspherical; FD 80-200/4 L 300/2.8 S.S.C Fluorite FD 300/2.8 L FD 200/1.8 LCosina-S 50/1.2 Helios Helios 44 Chrome f/22, 44-2, 44-3, 44M-4, 44M-7 (58/2), Helios-40 85/1.5 Jupiter Jupiter-9 85/2; Jupiter-37A 135/3.5; Jupiter-21M 200/4 Nikon Ai 105/2.5 Tairs-3S 300/4.5
Voigtlander 15/4.5 Aspherical; Ultron 35/1.7
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LucisPictor
Joined: 26 Feb 2007
Posts: 17633
Location: Oberhessen, Germany / Maidstone ('95-'96)
Expire: 2013-12-03
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| Posted: Fri Oct 17, 2014 12:41 pm Post subject: |
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LucisPictor wrote:
Compare here: http://retrocameracs.wordpress.com/2014/08/17/das-pentazhong-nocticon/
(in German, though)
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Langstrum
Joined: 16 Feb 2014
Posts: 351
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| Posted: Fri Oct 17, 2014 2:43 pm Post subject: |
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Langstrum wrote:
The Google translation is amazingly good with German! I don't know if it's correct but the sentences did made sense to me. So the author's approach is a bit different from mine, he used two lenses with different focal lengths to compare . As far as I observed, the difference in quality is also not that much, very similar with what I got with Rosxen's focal reducer.
Thank you very much, it's nice to read this comparison.
_________________
Camera: Sony A7 mark III, A6300
AF Lenses:
Canon EF 50/1.8; EF 200/2.8 L, EF 200/1.8 L, EF 300/4 L Sony E mount SEL 50/1.8 OSS, SEL 16/2.8 Fuji X mount XF 35/1.4 R
MF Lenses: Peleng MC 8/3.5, 17/2.8 Samyang 14/T3.1, 35/T1.5, TS 24/3.5 ED, 85/T1.5, Polar 85/1.4 Auto Revuenon 28/2.8; MC 50/1.4 Vega11U 50/2.8 Carl Zeiss Tessar 50/2.8 (exakta mount) Auto Chinon 50/1.9 Zenitar ME1 50/1.7 Sears Auto Sears 55/1.4; Sears 135/2.8 Auto Yashinon DX 50/1.4; Tomioka 50/1.2 SMC Pentax 50/1.7; 50/1.4 Canon FD 50/1.4 S.S.C; 55/1.2 S.S.C; FD 50/1.2 L; FD 85/1.2 L; 85/1.2 S.S.C Aspherical; FD 80-200/4 L 300/2.8 S.S.C Fluorite FD 300/2.8 L FD 200/1.8 LCosina-S 50/1.2 Helios Helios 44 Chrome f/22, 44-2, 44-3, 44M-4, 44M-7 (58/2), Helios-40 85/1.5 Jupiter Jupiter-9 85/2; Jupiter-37A 135/3.5; Jupiter-21M 200/4 Nikon Ai 105/2.5 Tairs-3S 300/4.5
Voigtlander 15/4.5 Aspherical; Ultron 35/1.7
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LucisPictor
Joined: 26 Feb 2007
Posts: 17633
Location: Oberhessen, Germany / Maidstone ('95-'96)
Expire: 2013-12-03
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| Posted: Fri Oct 17, 2014 7:26 pm Post subject: |
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LucisPictor wrote:
| Langstrum wrote: |
The Google translation is amazingly good with German! I don't know if it's correct but the sentences did made sense to me. So the author's approach is a bit different from mine, he used two lenses with different focal lengths to compare . As far as I observed, the difference in quality is also not that much, very similar with what I got with Rosxen's focal reducer.
Thank you very much, it's nice to read this comparison. |
Yes, a 35mm and a 50mm on a lens turbo are used, so effectively a pretty similar focal lenght (= a "normal lens").
And as a result, the 50mm/lens turbo combo is - set at f/1.4 - much "faster" (and with thinner DoF) than the 1.4/35 at f/1.4.
(While the quality of the 1.4/35 is considerably better.)
BTW, the author is me. 
_________________
Personal forum activity on pause every now and again (due to job obligations)!
Carsten, former Moderator
Things ON SALE
Carsten = "KAPCTEH" = "Karusutenu" | T-shirt?.........................My photos from Emilia: http://www.schouler.net/emilia/emilia2011.html
My gear: http://retrocameracs.wordpress.com/ausrustung/
Old list: http://forum.mflenses.com/viewtopic.php?t=65 (Not up-to-date, sorry!) | http://www.lucispictor.de | http://www.alensaweek.wordpress.com |
http://www.retrocamera.de |
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Langstrum
Joined: 16 Feb 2014
Posts: 351
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| Posted: Fri Oct 17, 2014 11:39 pm Post subject: |
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Langstrum wrote:
| LucisPictor wrote: |
| Langstrum wrote: |
The Google translation is amazingly good with German! I don't know if it's correct but the sentences did made sense to me. So the author's approach is a bit different from mine, he used two lenses with different focal lengths to compare . As far as I observed, the difference in quality is also not that much, very similar with what I got with Rosxen's focal reducer.
Thank you very much, it's nice to read this comparison. |
Yes, a 35mm and a 50mm on a lens turbo are used, so effectively a pretty similar focal lenght (= a "normal lens").
And as a result, the 50mm/lens turbo combo is - set at f/1.4 - much "faster" (and with thinner DoF) than the 1.4/35 at f/1.4.
(While the quality of the 1.4/35 is considerably better.)
BTW, the author is me. |
Wow, that's great ! I had a feeling that I read that article before, and now I'm pretty sure that I did it, you must posted it in a thread before.
I wonder why they didn't make a focal reducer for full frame mirrorless cameras yet. It sounds very attractive.
_________________
Camera: Sony A7 mark III, A6300
AF Lenses:
Canon EF 50/1.8; EF 200/2.8 L, EF 200/1.8 L, EF 300/4 L Sony E mount SEL 50/1.8 OSS, SEL 16/2.8 Fuji X mount XF 35/1.4 R
MF Lenses: Peleng MC 8/3.5, 17/2.8 Samyang 14/T3.1, 35/T1.5, TS 24/3.5 ED, 85/T1.5, Polar 85/1.4 Auto Revuenon 28/2.8; MC 50/1.4 Vega11U 50/2.8 Carl Zeiss Tessar 50/2.8 (exakta mount) Auto Chinon 50/1.9 Zenitar ME1 50/1.7 Sears Auto Sears 55/1.4; Sears 135/2.8 Auto Yashinon DX 50/1.4; Tomioka 50/1.2 SMC Pentax 50/1.7; 50/1.4 Canon FD 50/1.4 S.S.C; 55/1.2 S.S.C; FD 50/1.2 L; FD 85/1.2 L; 85/1.2 S.S.C Aspherical; FD 80-200/4 L 300/2.8 S.S.C Fluorite FD 300/2.8 L FD 200/1.8 LCosina-S 50/1.2 Helios Helios 44 Chrome f/22, 44-2, 44-3, 44M-4, 44M-7 (58/2), Helios-40 85/1.5 Jupiter Jupiter-9 85/2; Jupiter-37A 135/3.5; Jupiter-21M 200/4 Nikon Ai 105/2.5 Tairs-3S 300/4.5
Voigtlander 15/4.5 Aspherical; Ultron 35/1.7
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peterqd
Joined: 28 Feb 2007
Posts: 7448
Location: near High Wycombe, UK
Expire: 2014-01-04
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| Posted: Sat Oct 18, 2014 2:50 am Post subject: |
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peterqd wrote:
| LucisPictor wrote: |
| BTW, the author is me. |
Who else could it be with an XE-1 in a lime green case? 
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LucisPictor
Joined: 26 Feb 2007
Posts: 17633
Location: Oberhessen, Germany / Maidstone ('95-'96)
Expire: 2013-12-03
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| Posted: Sun Oct 19, 2014 7:57 am Post subject: |
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LucisPictor wrote:
| peterqd wrote: |
| LucisPictor wrote: |
| BTW, the author is me. |
Who else could it be with an XE-1 in a lime green case? |
LOL
Peter, that is "apple green".
_________________
Personal forum activity on pause every now and again (due to job obligations)!
Carsten, former Moderator
Things ON SALE
Carsten = "KAPCTEH" = "Karusutenu" | T-shirt?.........................My photos from Emilia: http://www.schouler.net/emilia/emilia2011.html
My gear: http://retrocameracs.wordpress.com/ausrustung/
Old list: http://forum.mflenses.com/viewtopic.php?t=65 (Not up-to-date, sorry!) | http://www.lucispictor.de | http://www.alensaweek.wordpress.com |
http://www.retrocamera.de |
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LucisPictor
Joined: 26 Feb 2007
Posts: 17633
Location: Oberhessen, Germany / Maidstone ('95-'96)
Expire: 2013-12-03
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| Posted: Sun Oct 19, 2014 7:59 am Post subject: |
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LucisPictor wrote:
| Langstrum wrote: |
I wonder why they didn't make a focal reducer for full frame mirrorless cameras yet. It sounds very attractive. |
The answer is pretty easy: such an FLR would only be usable with medium format lenses.
The lens that is used on an FLR needs to cover a wider image circle than the sensor size.
_________________
Personal forum activity on pause every now and again (due to job obligations)!
Carsten, former Moderator
Things ON SALE
Carsten = "KAPCTEH" = "Karusutenu" | T-shirt?.........................My photos from Emilia: http://www.schouler.net/emilia/emilia2011.html
My gear: http://retrocameracs.wordpress.com/ausrustung/
Old list: http://forum.mflenses.com/viewtopic.php?t=65 (Not up-to-date, sorry!) | http://www.lucispictor.de | http://www.alensaweek.wordpress.com |
http://www.retrocamera.de |
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philslizzy
Joined: 07 Aug 2012
Posts: 4744
Location: Cheshire, England
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| Posted: Sun Oct 19, 2014 12:03 pm Post subject: |
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philslizzy wrote:
I have one and I'm pretty satisfied with it. I'm not bothered about the extra light, but that extra light allows me to stop down 2 stops (effectively only one) and that makes a world of difference to the sharpness.
It was designed to give a wider view, thats how I use it.
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dickb
Joined: 04 Apr 2008
Posts: 821
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| Posted: Sun Oct 19, 2014 3:53 pm Post subject: Re: Will we get a faster lens by using focal reducer? |
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dickb wrote:
| Langstrum wrote: |
Will we get a faster lens by using focal reducer?
No and yes. I will explain below.
So, you will either get wider frame or more shallow DOF, not both |
I may be a bit picky about language but the answer is still just yes and not no.
Lens speed is normally defined as the f/stop or the relative aperture: the focal length divided by the entrance pupil (or effective aperture). A focal reducer reduces the focal length while the effective aperture stays the same (or is reduced less than the focal length), so the relative aperture is larger.
With a focal reducer you get a faster lens with a shorter focal length, just as with a teleconverter you get a slower lens with a longer focal length. Whether the faster lens with the shorter focal length gives you the results you are looking for is another and interesting question. So your tests are informative but your statement is a little misleading. |
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ZoneV
Joined: 09 Nov 2009
Posts: 1632
Location: Germany
Expire: 2011-12-02
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| Posted: Mon Oct 20, 2014 4:17 am Post subject: |
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ZoneV wrote:
| LucisPictor wrote: |
| Langstrum wrote: |
I wonder why they didn't make a focal reducer for full frame mirrorless cameras yet. It sounds very attractive. |
The answer is pretty easy: such an FLR would only be usable with medium format lenses.
The lens that is used on an FLR needs to cover a wider image circle than the sensor size. |
Some longer lenses have a bigger usable image circle too. For example the Canon FD 400mm/2.8L and 300mm/2.8L work on medium format 6x6 too. I have made a special "adapter" for this, but my Kiev 60 needs film transport re-adjustment. I have to test my second Kiev 60, thought I have done this on one of my cameras.
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