35 replies to this topic

[desmc]

Thanks, Daniel.

Yes, I agree that coma and other aberrations are always present. I also agree that what counts in the end is whether one is happy with the overall aesthetic of an image and not the details of what is going on in the corners. For the particular copy I was using what disturbed me more was a strong asymmetry in the coma on a canon 800d. The lens has now been returned and I await a replacement.
I’ll report back if there is anything interesting to say - most likely the new copy will show imperfections as well, at which point I’ll stop fussing and get on with some imaging!
I’ve actually captured five hours of M81 which looks good considering it is under B4 skies - not as good as yours though.
Thanks again for your advice.

CS, Des

[Daniel Dance]

Thanks, Daniel.

Yes, I agree that coma and other aberrations are always present. I also agree that what counts in the end is whether one is happy with the overall aesthetic of an image and not the details of what is going on in the corners. For the particular copy I was using what disturbed me more was a strong asymmetry in the coma on a canon 800d. The lens has now been returned and I await a replacement.
I’ll report back if there is anything interesting to say - most likely the new copy will show imperfections as well, at which point I’ll stop fussing and get on with some imaging!
I’ve actually captured five hours of M81 which looks good considering it is under B4 skies - not as good as yours though.
Thanks again for your advice.

CS, Des

Awesome.  Look forward to seeing more of your images.

[msalganik]

So dumb question but I thought all of the ART lenses are focus-by-wire. Meaning they need power to focus because it's the internal focus motors that are translating the motion of the focus ring to actual movement of the lens elements (no physical helicoid). Is that not the case for certain lenses or do you have some way of providing power to the lens even though it's attached to a ZWO camera? 

[Daniel Dance]

So dumb question but I thought all of the ART lenses are focus-by-wire. Meaning they need power to focus because it's the internal focus motors that are translating the motion of the focus ring to actual movement of the lens elements (no physical helicoid). Is that not the case for certain lenses or do you have some way of providing power to the lens even though it's attached to a ZWO camera?

All my canon mount ART lenses can be manually focused.

Edited by Daniel Dance, 23 May 2025 - 05:28 AM.

[Daniel Dance]

Somy doesnt matter anyways. There doesnt exist an adapter between the zwo camera and a sony lens. I seen and tried some 3d printed ones but they dont really work.

[msalganik]

Sure Sony FE lenses are out of the question - the flange distance of an FE mount lens is too short to make an adapter possible with the inherent backfocus that's built in to ZWO cameras (minimum 12.5mm if I remember right). I'm a little surprised that they are still making some lenses that aren't focus by wire. Are these older ART lenses? 

[Daniel Dance]

Sure Sony FE lenses are out of the question - the flange distance of an FE mount lens is too short to make an adapter possible with the inherent backfocus that's built in to ZWO cameras (minimum 12.5mm if I remember right). I'm a little surprised that they are still making some lenses that aren't focus by wire. Are these older ART lenses?

I dont know of a single ART lens that is focus by wire. I own about 6 of them - 4 purchased in past year and they are all mechanical direct drive focus rings.

Which ART lens do you think is focus by wire?

[msalganik]

I've only had Sony FE mount ones- including 24-70 DG DN II and 105/2.8 DG DN. Fairly sure both are focus by wire

[norcalryder]

I have three of them for Sony

 

135mm DG f1.8 focuses with a helicoid.  It does not have an aperture ring.  I believe it was adapted from a DSLR and is no longer in production.  Fabulous lens with amazing bokeh 

85mm DG DN f1.4 and 35mm DG DN f1.4.  Both are focus AND aperture by wire.  They do both have an aperture ring but it does not operate off camera and it closes all the way down when the camera is turned off.

Attached Thumbnails

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Edited by norcalryder, 23 May 2025 - 05:33 PM.

[Alnitak2009]

Incredible! Great contrast and colors

 

You must have some really dark skies

Edited by Alnitak2009, 24 May 2025 - 06:37 PM.

[Daniel Dance]

Incredible! Great contrast and colors

 

You must have some really dark skies

 

Not so much.  This was captured in Bortle 4-5 skies in NJ.