DT Lens that can still be used "partially" on full frame

[tankm]

Generally DT lens is meant for APS-C sensor only. With the rumor of almost FF sensor on the upcoming alpha dslr, some of this lens will most likely will be not usable anymore, or maybe not.

Had tried mounting and looking through the view finder of the FF film camera.
1. Tamron - SP AF 11-18 F4.5-5.6 Di II LD Aspherical IF - Usable on FF from around 14mm onwards. @14mm it's still much wider than the APS-C at 11mm. Quality wise, no idea yet. The KM 11-18 version most likely will be the same.

2. Tamron - SP AF 17-50 F2.8 XR Di II LD Aspherical. Not usable at all on FF, vignetting throughout the range.

3. Sigma - 18-125 F3.5-5.6 DC. Not usable at all on FF, vignetting throughout the range.

4. Peleng 8mm Fisheye M42 mount. On the APS-C there is vignetting, on the FF it's worst.

Anyone else with other DT lens and who can try it on FF, do post your result here.

[zcf]

Originally Posted by tankm Generally DT lens is meant for APS-C sensor only. With the rumor of almost FF sensor on the upcoming alpha dslr, some of this lens will most likely will be not usable anymore, or maybe not. Had tried mounting and looking through the view finder of the FF film camera. 1. Tamron - SP AF 11-18 F4.5-5.6 Di II LD Aspherical IF - Usable on FF from around 14mm onwards. @14mm it's still much wider than the APS-C at 11mm. Quality wise, no idea yet. The KM 11-18 version most likely will be the same. 2. Tamron - SP AF 17-50 F2.8 XR Di II LD Aspherical. Not usable at all on FF, vignetting throughout the range. 3. Sigma - 18-125 F3.5-5.6 DC. Not usable at all on FF, vignetting throughout the range. 4. Peleng 8mm Fisheye M42 mount. On the APS-C there is vignetting, on the FF it's worst. Anyone else with other DT lens and who can try it on FF, do post your result here.

Bro, need to take into account that most viewfinder only cover 90~95% of the view, so at 14mm show no hard vignetting doesn't mean output will be without vignetting, probably 14.5or 15mm is a safer bet.

Sigma 10-20mm no longer show hard vignetting at 13mm on Dynax 5, but safer bet is also 14 or 15mm.

Minolta 18-70mm Kit lens probably 22mm

Sigma 18-200mm also have vignetting throughout the range.

All DT lens show obvious vignetting through out the range, wonder stop down will help or not?

[rOnGrEn]

"Minolta 18-70mm Kit lens probably 22mm" ... hmmz if really 22.. still ok mah!!

bro tankm.. could you kindly mount the kit lens on your film cam and see how "usable" it is? anything below 28mm I will be happy...

if not..thinking of getting the tamron 28-300 ... hmmz... dunno should or not..

[tankm]

Yes, most FF viewfinder is around 90~95% of view, but the new alpha sensor supposedly is not totally FF either, around 1.2x~1.3x.

The kit lens is interesting, usable around 22mm onwards.

My film camera don't have DOF preview, hence no idea if stop down helps.

Originally Posted by zcf Bro, need to take into account that most viewfinder only cover 90~95% of the view, so at 14mm show no hard vignetting doesn't mean output will be without vignetting, probably 14.5or 15mm is a safer bet. Sigma 10-20mm no longer show hard vignetting at 13mm on Dynax 5, but safer bet is also 14 or 15mm. Minolta 18-70mm Kit lens probably 22mm Sigma 18-200mm also have vignetting throughout the range. All DT lens show obvious vignetting through out the range, wonder stop down will help or not?

[PsychoV]

I'm guessing stopping down will worsen the vignetting since the smaller aperture reduces the size of image formed on sensor.

[Agetan]

Hi...

Generally it is safe to assume 1.5x Focal length on DT lens to be the focal length that won't have the vignetting on KM lenses.

The 18-70 is fine from 27mm onward. After all this lens is 27-105 type for APS-C.

I look through the VF of Dynax 9 (which have 100% coverage) and 27mm you just missed the vignetting.

Stop down the lens won't help much for this type of vignetting nor worsen it. because this is not a flaw in lens design but this is the image coverage from a lens.

Regards,

Hart

[tankm]

No more kit lens to try sorry ... sold it off with my previous KM5D.

28 x 1.3 = 36.4
24 x 1.3 = 31.2

Just wait for SONY announcement to confirm the new sensor details will be better.

Originally Posted by rOnGrEn "Minolta 18-70mm Kit lens probably 22mm" ... hmmz if really 22.. still ok mah!! bro tankm.. could you kindly mount the kit lens on your film cam and see how "usable" it is? anything below 28mm I will be happy...

[tankm]

If you have seen some lens review where they indicate slight vignetting when the lens is wide open, the vignetting is reduced or eliminated when the lens is stop down by 1 to 2 stops. I think zcf is thinking about the same idea as well.

Originally Posted by PsychoV I'm guessing stopping down will worsen the vignetting since the smaller aperture reduces the size of image formed on sensor.

[tankm]

Found something interesting....both Tamron - SP AF 17-50 F2.8 and Sigma 18-125 F3.5-5.6 when used together with a 1.4x TC now no longer vignette on the FF. With the 1.4x TC of course the range coverage is back to almost the APS-C range, and the TC will slow down the lens by 1-stop and of course some image degradation.

[radedward]

Just to clarify a little.

If I'm not mistaken, the Peleng is not really a DT lens but a FF Circular Fisheye lens, which means that the image will be a circle bordered by a black frame.

The vignetting of a circular fisheye is completely intentional on FF.