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dyfiastro

Which Canon lenses

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hi everyone
I am in the process of switching camera systems so looking to buy a number of lenses (switch from fuji back to canon).
What lenses are you using / can recommend for astrophotography?

I intend getting something like the 14mm samyang for widefield astrolandscapes but looking at other options instead of using a small scope for when out for a few nights in the van.
Currenty looking to find a few lenses that can do double duty to save spending extra on a small scope as well. I am currently thinking along the lines of a 70-200L, 135 f/2 etc...
The camera will be an EOS R so only EF mount lenses (or possibly adapted)


Any thoughts and input would be great.

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Samyang 135mm is very popular on here, even cheaper are some of the old M42 thread lenses. Soligor I think is one that comes to mind.

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35 minutes ago, MarkAR said:

Samyang 135mm is very popular on here, even cheaper are some of the old M42 thread lenses. Soligor I think is one that comes to mind.

I had forgot about the samyang 135mm. that is another to add to the possible list, thanks.

 

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Posted (edited)

I’ve recently been experimenting with the EF 50mm f1.8 STM. Very fast and great for ultrawide field. I am using it on a 400D which is a crop sensor of course and get the equivalent field of view of a focal length of 81 mm as seen on a full frame camera. On your R it will still be the intended field of view.

I have been focusing it with a home made Y mask. I tried making a Bahtinov mask for 50mm but the slots are so close together for that it was impossible for me to make - hence the Y. In practice focus is that close to infinity it is really easy to set on this lens.

Edited by TerryMcK

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1 hour ago, TerryMcK said:

.....crop sensor of course and get a focal length of 81 mm.

Don't get "traditional" family photography mixed with astronomical imaging....crop factor doesn't exist! A 50mm fl lens is always a 50mm fl lens.

We're only interested in three things - pixel size, pixel array and effective focal length (or effective focal ratio)

 

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Posted (edited)

I meant you get the field of view as seen with an 81 mm focal length lens when using a 50mm FL lens on a crop sensor DSLR so changed the previous post too for clarity 😃

https://photo.stackexchange.com/questions/38899/why-do-full-frame-lenses-and-crop-body-lenses-exhibit-the-same-crop-factor-when

Edited by TerryMcK

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Sorry.....

No crop factor in Astronomical imaging....

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11 hours ago, dyfiastro said:


I intend getting something like the 14mm samyang for widefield astrolandscapes but looking at other options instead of using a small scope for when out for a few nights in the van.
Currenty looking to find a few lenses that can do double duty to save spending extra on a small scope as well. I am currently thinking along the lines of a 70-200L, 135 f/2 etc...
The camera will be an EOS R so only EF mount lenses (or possibly adapted)


Any thoughts and input would be great.

Have you considered the Sigma 18-35mm F1.8 as an alternative to the Samyang? I've used one for a few years now - very sharp, very fast and gives a bit of flexibility in focal length, albeit not as wide as the Samyang.

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The new Sigma ART lenses are superb, at a price though. If you go Sigma it's worth getting the dock to fine tune auto focus.

If you just want a lens for astro work then no need for auto focus. Irix lenses might be worth looking at as well.

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If you can afford it there is the Samyang XP range, there an 85mm F1.2 in the collection.

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Thanks everyone

I already have my main obsy setup so at present trying to look at lenses that will do double duty if possible.
I have always been a fan of samyang lenses. the new sigma ART range do look great and seem to be getting raving reviews for traditional photography.

I did look at the Sigma 18-35mm F1.8 but is a crop body only lens, not designed for full frame which is a real shame.

I have the body and a tamron 90mm macro coming tomorrow and making a list of possible glass going forward.

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On 22/05/2020 at 05:49, TerryMcK said:

I’ve recently been experimenting with the EF 50mm f1.8 STM. Very fast and great for ultrawide field. I am using it on a 400D which is a crop sensor of course and get the equivalent field of view of a focal length of 81 mm as seen on a full frame camera. On your R it will still be the intended field of view.

I have been focusing it with a home made Y mask. I tried making a Bahtinov mask for 50mm but the slots are so close together for that it was impossible for me to make - hence the Y. In practice focus is that close to infinity it is really easy to set on this lens.

I've got the nifty fifty lens. What aperture do you stop it down to ?

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Posted (edited)

I personally think the Canon 70-200 /f2.8 and /f4 are superb lenses for astro. Nice wide apertures on both, especially the 2.8 and decent focal length with crop for widefield shots. The sweet spot for me would be 400mm at /f2.8... but that lens is expensive!

Edited by smr
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The Canon 200mm f2.8 is reasonable, nice field of view for larger objects like M31, M44 & M45. There is some distortion of bright stars towards the edge of the frame, but nothing that can't be fixed in post processing.

James

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If you're thinking of a 14mm samyang I'd look at the 24 first..

The 135mm is a classic 

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1 hour ago, smr said:

I've got the nifty fifty lens. What aperture do you stop it down to ?

I went to f2.5 when I was experimenting the other night. I found f1.8 a little too much but was getting good focus. Nice to have a little in reserve.

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1 minute ago, TerryMcK said:

I went to f2.5 when I was experimenting the other night. I found f1.8 a little too much but was getting good focus. Nice to have a little in reserve.

I think you have to stop it down a bit to avoid too much chromatic abberation ?

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Not sure at the moment. I had a go at an asterism and just roughly pointed it at Ursa Major - I ended up getting the 4 large stars that make up the "pan" with Dubhe as the main one - there were 600 more in the shot according to DSS so it makes navigation of the subs challenging! If I had turned the camera through 90 I feel I could have fit in the plough in its entirety. The centre of the FOV looked good as did the right side. I noticed something going on in the left side that didn't look quite right. The stars in general seemed as round points of light but in parts of the left side one or two looked oval. Of course they may well have been double stars but it was a first off experiment without much care. I will be using the 50mm to do a bit of ultra wide field in the winter and am thinking of a Star Tracker to go mobile with.

I wasn't aware of any chromatic aberration but will have a look at the subs closely on its next outing. 

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Thanks everyone for the comments and suggestions.

I have pulled trigger on a number of lenses that should be here over the next week.
Amongst them are the following that I feel will get a fair amount of dark sky time

Samyang 14mm f/2.8
Samyang 20mm f/1.8
Canon 70-200 f/4

I also have a 17-40 and 24-105 f/4 coming which is mainly for daytime shooting but may well see how they perform piggybacked on my mount at some point.
The unknown at present is the tamron 90mm macro, time will tell.

Will try and get some images up once I get chance.

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