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Hasselblad 24mm (or 25mm) f2.5V and 135mm f2.5V

TechTalk

Well-known member
So how much coma is too much? There are finally some stars visible, and that left side is showing its oddities. I mean, the first day's shots didn't magically get better - I just found that for what I usually do, it didn't matter. Now I don't do astro, but the reviews of this lens's aberration-free wide open imaging had me curious. What will show up at night?...
I haven't read any reviews which assert aberration-free wide open imaging with the XCD 25V, but the reviews which suggest coma is minimized and well controlled with some astigmatism present appear to be accurate from the images I've seen so far. The astrophotography website Lonely Speck has a guide to lens aberrations and their appearance in night sky photography which I've linked below for those interested.

www.lonelyspeck.com/A Practical Guide to Lens Aberrations and the Lonely Speck Aberration Test
 

TechTalk

Well-known member
...I do wonder what the story is behind H switching from Nittoh to whoever makes the V lenses.
I haven't seen any evidence that lens manufacturing is contracted to another source, though it's certainly possible. I've seen assertions that's the case, but that's all. I expect Hasselblad chooses to work with whatever contractors they believe can and will accomplish their design goals.

The rumors could be correct, but I've seen many online assertions accepted widely as facts which later proved to be incorrect. As an example, many people have written over the years (and still do) that Fuji manufactured the XPan lens series when it was actually Nittoh which manufactured the XPan lenses sold by both Fuji and Hasselblad. It was a logical assumption to make and often repeated, but incorrect.

My hunch is that the Nittoh lenses are going to become quite sought after in the future…)
Perhaps, but the future is never easy to predict. My hunch is people will continue to buy whichever XCD, XCD–P, or XCD–V Series lens offers the right combination of focal length, speed, and features for their needs. Regardless of which company Hasselblad chooses to contract for optical manufacturing, they're ultimately all Hasselblad lenses and each model has its own set of features and specifications to meet individual requirements.
 

isteveb

New member
Thank you, I read that aberration guide (didn't you post a link to it elsewhere? It is great.). I think the star image I posted recently in this thread shows both astigmatism and coma, but more coma than other samples of this lens show. It's also much worse on the left side than on the right.

Indeed, I was being hyperbolic about "aberration-free". It's a bad habit of mine.
I'd be interested to see a few pictures posted using a star tracker with CFV100 or the X2D with this lens. That will remove the variability of the potential star trails starting on a long exposure.
 

TechTalk

Well-known member
I'd be interested to see a few pictures posted using a star tracker with CFV100 or the X2D with this lens. That will remove the variability of the potential star trails starting on a long exposure.
A simple calculator for estimating the number of pixels covered by star trails for a specific combination of focal length, sensor size, pixel pitch, exposure time, and declination as well as additional useful information can also be found at the Lonely Speck website.

https://www.lonelyspeck.com/Advanced Astrophotography Shutter Time Calculator
 
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