Speed Booster vs. Lens Turbo -- with the same lenses

Started Jul 12, 2013 | Discussions thread
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ProfHankD Veteran Member • Posts: 5,724
Speed Booster vs. Lens Turbo -- with the same lenses

I own an FD Lens Turbo (LT) and have access to a Canon EF Speed Booster (SB). Both can take M42 lenses using appropriate adapters (chipped for the EF), which I also have. So, I spent a day doing quite a few formal & informal comparison tests using my NEX-7 with the exact same lens on either SB or LT. Here's a quick summary of my (preliminary) findings:

  • Both SB & LT are very usable as intended with most lenses, even wide open.
  • Both SB & LT are well made. LT doesn't have a tripod foot. As I noted in a different post, the FD LT did require some FL/FDn lenses to have their aperture stop-down pin/tab shaved to fit... but this seems to be caused by the complete lack of standardization of the length of the pin/tab, and shaving the exceptionally long ones appears to be a harmless fix.
  • The difference between the SB's 0.71X and LT's 0.726X is surprisingly noticeable, and might actually be significant to the designs, if not significant in most photo-taking circumstances.
  • Both the SB & LT give good sharpness, but they are different. More often than not, the LT resolves slightly finer detail, but the SB gives slightly higher microcontrast, but it varies.
  • The LT is known to suffer a central "blue spot" (sensor reflection) under certain circumstances. However, it's very dependent on which lens is being used -- as is the amount of flare seen. The Canon FDn 35mm f/2 is particularly bad, but none of the M42 lenses tested made either problem apparent.
  • The SB shows unacceptably dark corners and edges with the Canon EF 70-200mm f/2.8 L. Vignetting was fairly strong using the Vivitar Series 1 70-210mm f/3.5 (version 1) on either SB or LT. However, even the strong corner shading with the Vivitar was not particularly obtrusive, and the other M42 lenses were all ok on both the SB and LT.

The lenses I tested were:

  • 12mm f/8 Spiratone fisheye
  • 24mm f/2.8 Spiratone
  • 35mm f/2 SMC Takumar
  • 50mm f/1.4 SMC Takumar
  • 55mm f/1.4 Mamiya/Sekor
  • 100mm f/4 SMC Takumar
  • 135mm f/1.8 Spiratone
  • 70-210mm f/3.5 Vivitar Series 1
  • 300mm f/5.6 Spiratone Mirror Lens

I consider all of the above to be capable of good image quality, except the 12mm, which has the very sever CA that most fisheyes share. As a resolution test, I printed multiple small test targets and shot them from a fixed position with all the lenses. Cropping to the central target at native resolution, the left side of each image shown here is using the SB, right is LT. For example, the 24mm f/2.8 at f/2.8 gives:

24mm f/2.8 Spiratone on SB (left), LT (right)

The 35mm f/2 at f/2 gives:

35mm f/2 SMC Takumar on SB (left), LT (right)

The 50mm f/1.4 wide open gives:

50mm f/1.4 SMC Takumar on SB (left), LT (right)

Surprisingly, all the above lenses were usable wide open on both the SB and LT, although the 12mm's massive CA would have to be corrected (as always). Except for the  300mm mirror, all lenses showed good peaking in the EVF in magnified view; most even show peaking in the maximum magnification view.

Here's a couple of similar shots with the 100mm, SB & LT:

100mm f/4 SMC Takumar on SB

100mm f/4 Takumar on LT

Here's a couple with the Vivitar zoom in macro mode:

Vivitar Series 1 70-210mm f/3.5 on SB

Vivitar Series 1 70-210mm f/3.5 on LT

So, overall, both the SB and LT are darned useful.

 ProfHankD's gear list:ProfHankD's gear list
Canon PowerShot A640 Canon PowerShot A720 IS Canon PowerShot S70 Canon PowerShot G1 Canon PowerShot G5 +27 more
Sony Alpha NEX-7
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