Which lens stays sharp when closed?

For a long exposure project I need something which performs well with the aperture closed down.

Anything that's particularly good? Hopefully the 90mm TS/E?

uOpt wrote in post #17244741
For a long exposure project I need something which performs well with the aperture closed down.

Anything that's particularly good? Hopefully the 90mm TS/E?

TSE 17mm TSE 24mm both work good at long exposures, what are you photo graphing?

I have done long exposures with both TSE lens, if you want my to I can see if I can find some of the picks.
Farmer

uOpt wrote in post #17244741
For a long exposure project I need something which performs well with the aperture closed down.

Anything that's particularly good? Hopefully the 90mm TS/E?

Why not use an ND filter instead? While I am sure some lenses are sharper than others stopped down, they all look far less sharp than at their best apertures. It's a pretty big difference. (BTW, I assume when you say "closed down" you mean down to their minimum apertures which tend to be < f/20 for most lenses.)

None of them.

Lens softness when closed down is almost totally down to diffraction and that depends on just three things - the wavelength of the light (can't do much about that), the laws of physics (can't do anything about them) and the size of the hole you're squeezing the light through (which we can change - hoorah).

Unfortunately you want to change the size of the hole by making it smaller - and the smaller the hole the worse the diffraction. It doesn't matter what lens you use, what sort of glass it uses, whether it bends the light using glass, fluorite, Diffractive Optics, gravitational lensing or something yet to be invented - the smaller the hole the more blurry the image.

Use an ND - that's what they're made to do.

Use ND filter instead of stopping down.

I wouldnt get a TS lens for that job if you dont need it. Expecially if youre doing really long exposures during daytime (for example, IR). Because all TS lenses leak light some amount, it might be such a tiny amount that it wont be even possible to see it in the images however if it moves, it does leak light because there is gap in the middle of the lens. Atleast Samyang 24mm is know to leak light because its Tilt-Shift lens, Canon TS Ive never had a problem, but they will leak light if your exposure is long enough, however that should be really long exposure.

Photo123abc wrote in post #17246033
Use ND filter instead of stopping down.

I wouldnt get a TS lens for that job if you dont need it. Expecially if youre doing really long exposures during daytime (for example, IR). [COLOR="Red"]Because all TS lenses leak [/COLOR]light some amount, it might be such a tiny amount that it wont be even possible to see it in the images however if it moves, it does leak light because there is gap in the middle of the lens. Atleast Samyang 24mm is know to leak light because its Tilt-Shift lens, Canon TS Ive never had a problem, but they will leak light if your exposure is long enough, however that should be really long exposure.

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One sentence you say all TSE lenses leak light so don't buy a TSE lens for that job.

Couple sentences later you say you haven't had problems with the canon TSE lenses leaking light in.


I will have to agree with you I have never had a problem with my canon TSE's leaking light..............
And I haven't bought other then canon TS lenses, so I really don't know if they leak or not but I am willing to believe you that some non canon TSE lenses leak light.

I do not agree with you that all gaps leak light...............
I have a machine shop and making two surfaces light tight would be a walk in the park.

farmer

uOpt wrote in post #17244741
For a long exposure project I need something which performs well with the aperture closed down.

Anything that's particularly good? Hopefully the 90mm TS/E?

Heya,

Stop down to F8, F11, F16 at the most. Then apply an ND filter with the stopping power of your needs to meet the exposure time for whatever project. It's not worth buying glass just to stop down past F22. It's better to just use whatever glass you want, and use a high quality ND filter.

Very best,

I would have liked the wide DOF as well but I guess you guys are right.

I don't need a ND filter, it's all my light anyway.

Use ND filters on a TSE lens at f8, you can tilt a tiny bit and have your scene sharp, all of it. Do not use a TSE lens you have to stop down to f16(on a full frame body) or more, then not all of your scene will be in focus and that which is will be softened by diffraction.

Photo123abc wrote in post #17246033
Use ND filter instead of stopping down.

I wouldnt get a TS lens for that job if you dont need it. Expecially if youre doing really long exposures during daytime (for example, IR). Because all TS lenses leak light some amount, it might be such a tiny amount that it wont be even possible to see it in the images however if it moves, it does leak light because there is gap in the middle of the lens. Atleast Samyang 24mm is know to leak light because its Tilt-Shift lens, Canon TS Ive never had a problem, but they will leak light if your exposure is long enough, however that should be really long exposure.

When you say "At least Samyang 24mm is know to leak light because its Tilt-Shift lens" can I ask where you got that information? I HAVE a Sammy 24mm TS, have done quite long exposures with it while using significant tilt and/or shift, and never came across any evidence of a leak in the images.

But I agree, the ND filter is the way the OP should go, as there is no getting around diffraction (although my 1D3, since sold, with it's big pixels, was observably less affected than my EOS M with it's smaller ones).

Maxdave