This is a test of the modified 900mm Tokina f/11 lens to look at depth of field and optical quality.

We're looking at a steel ruler at an oblique angle, about 9 feet away. Lines are etched every millimeter.

Depth of field is tiny...no more than 2mm.

This image is contrast boosted, but no unsharp masking has been applied.

Fairly happy with the optical quality for a catadioptric (combination of mirrors and lenses) supertelephoto at 900mm focal length.

#photography
#TokinaLens
#900mm
#MacroPhotography
#OpticalTesting

Star test of the modified Tokina 900mm f/11 lens shows lots of bad atmospheric seeing, and probably no signs of pinched optics that result in astigmatism.

I'll say my modification was successful, and I now have a useable supertelephoto lens.

However, at 900mm focal length the atmosphere must be quite calm if you want to take sharp images of distant objects. (If you do macro work, looking through far less air, you can get sharper results.)

This is a follow up to this post:
https://universeodon.com/@KrajciTom/109911126015692565

Compared to the original performance of the lens in cold temperatures, this is a tremendous improvement. (Tonight's test was in 34F air.)

#photography
#astrophotography
#astrodon
#TokinaLens
#optics

Waxing gibbous moon shortly before sunset.

This is an informal test of a modified Tokina 900mm f/11 lens. No gross problems detected.

Star testing at night will be the severe test.

#photography
#astrophotography
#astrodon
#TokinaLens

Daytime testing of a 900mm supertelephoto lens is pointless unless the object is very close.

Looking at objects far away, such as this mountain peak, while the sun's heat is strong...is pointless with such a long focal length.

I will test again just before sunset, then again (on the moon) after sunset, and yet again on a bright star.

#photography
#videography
#TokinaLens
#Tokina

I bought a telephoto lens recently.

https://tokinalens.com/product/sz_900mmpro_reflex_f11_mf_cf/

I found that optical quality appeared to be good...at least for indoor tests.

Then I took it outdoors, where temperatures are cool in the winter months. Image quality suffered...horribly.

See image captions.

In cold temperatures the lens appeared to be giving images with lots of astigmatism.

(to be continued)

#photography
#TokinaLens
#LensRepair
#BadDesign
#DesignFlaw
#astigmatism
#MirrorSupport

I am learning to become comfortable with this somewhat untethered and unknowing state. 
#35mm #35mmfilm #thedaily35mm #fujifilm #fujifilm200 #nikon #nikonfe #nikoncamera #filmphotography #analogfilm #200mmlens #tokinalens #zoomlens #shotonfilm #grainisgood #industry

Ship & Bird

#35mm #35mmfilm #thedaily35mm #fujifilm #fujifilm200 #nikon #nikonfe #nikoncamera #filmphotography #analogfilm #200mmlens #tokinalens #zoomlens #shotonfilm #grainisgood #industry #sugarboat #seagull