Comparing 2 lenses - any feedback or thoughts?

Hardware
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All;

I shoot with a Hasselblad X2d 100C and I love to shoot milky way / night photography as well as classic landscape photography.

I have the XCD 4/21 lens now, and I get some good shots with it. I like the wide angle but I am less excited about the minimum aperture - f4

I am considering an upgrade to one of the following, I like the wide angle of the zoom but maybe the fixed lens is worth it for the minimum aperture:
Zoom - minimum aperture 3.2
XCD 3,2-4,5/20-35E

Fixed, not as wide but a minimum aperture of 2.5
XCD 2,5/25V

Thanks in advance for any feedback

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For anyone interested, here are the lenses: 25mm and the zoom.

From my understanding, you’ll want the widest aperture you can get for milkyway photography. I see a lot of people using a full frame equivalent of 24mm for this kind of astro, so it seems like 25mm would be the better choice in this situation.

Can you rent both and test them out? For the price of either of those, that’d seem like a good idea :eyes:

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Good Idea, I’ll check that out

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actually… the milky way does not move as fast as you think … there are apps like photopills (paid but really good) which can calculate for you based on sensor size/FOV/aperture what exposure time you get and if you still have dot stars or slight trails.

so i quickly ran the numbers for 2 lenses with the NPF rule applied.

25 f/2.5 3.89s for dot stars and 7.79s for the slight star tails
21 f/4 5.80s for dot stars and 11.59s for the slight star trails.

so you see with the 21mm lens you can actually expose for longer.

HTH

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But since he has f4 versus f2.5 he still loses some light. Shouldn’t it take twice as long at f4 versus f2.5?

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but the wider lens gives more time before the stars start to get trails.

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Thanks everyone, I had not considered checking times in photo pills, I’ll stick with the 21 f/4 lens for now and look to upgrade to the XCD 3,2-4,5/20-35E at some point.

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If you are in (or visiting) a dark-sky location, you might want to look at getting a star-tracker mount. Not exactly cheap, but probably less than a new lens. You could then take quite long exposures and use any aperature you want.

(It’s isn’t what you would want, however, if you also wish to capture the horizon or features on the ground…)

One example:
iOptron tracker

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The tracker you linked is $359 USD. Have you looked at the price of hasselblad lenses? Its like a drop in the bladkit!

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One degree every four minutes - and it’s the earth that is moving, not the Milky Way.

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depending on your frame of reference, either/both are moving and rotating :wink:

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