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Canon 400mm f2.8 is 2

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#1 aorion314

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Posted 25 May 2019 - 11:13 PM

aorion314 here, well the lens will arrive on Wednesday, it will be used with a Canon 5d mark 3 and a 60da cameras. To any CN'rs who may have any insight, comments, suggestions with regards to use of this lens with said cameras, please respond to this post. Additionally anybody with thoughts as to the worth of the pop-in polarizer, will do some moon shots, however the price at $229 seems a little steep, any other producers out there for the same type polarizer. Respectfully submitted. PS to moderator please move to a more appropriate section if you believe it would be better suited/viewed than current forum as feedback to post needed for any knowledge I might gain.


Edited by aorion314, 25 May 2019 - 11:14 PM.


#2 Jim Waters

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Posted 26 May 2019 - 12:07 AM

What's the exact model of this lens?  It is the DO Lens?



#3 aorion314

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Posted 26 May 2019 - 12:42 AM

aorion314 here, since I have not received said lens, I went to B&H and looked at canon label in photos no DO that I could see, full label 400mm F/2.8 l is ii USM,  specs 16 elements in 12 groups so probably not as photos show a red ring not green, cost was 8k.



#4 Jim Waters

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Posted 26 May 2019 - 12:48 AM

OK.  Good that's its not the DO lens.  I rented the DO lens last year and bright stars had a tendency to bloat.

 

Do not shoot wide open with the f/2.8 lens. Stop it down 1 or 2 stops.



#5 Samir Kharusi

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Posted 26 May 2019 - 08:01 AM

This lens has MTF curves that are as good as they can get, wide open. I would expect it to beat almost any OTA under a few thousand $ at f2.8 on a star field:

mtf.jpg

I would definitely first use it wide open. The only concern is that, with a very shallow depth of focus, any temperature drift might be an issue. But all these Canon tele primes work well with one-click autofocus on a bright star or planet (center spot only). Just slew to a planet every 15 minutes or so and autofocus if the night temperature is dropping. As for filters, keep in mind that this is an IS lens, using 52mm filters internally. Nevertheless I found my 600mm f4 worked very well with standard 2" astro filters, 48mm threads with the IS switched off for astro. You need a 52-48mm adapter ring and you need to thin down the filter rings on your astro filters (most of them have rather chunky/macho rings for some reason). Thereafter it's simple to use standard astro LPS/CLS whatever filters or even narrowband. Autoguiding should not be required on any decent mount. At f2.8 you need subs only one minute long and for narrowband you need 3 minute subs even at very dark sites. Enjoy! Should be an awesome imaging OTA, but make sure you focus it properly and keep it in focus. After trying numerous methods I found that the most reliable method to focus Canon tele primes was actually the simplest; center spot autofocus on the brightest star up or one of the planets.

 

OK.  Good that's its not the DO lens.  I rented the DO lens last year and bright stars had a tendency to bloat.

 

Do not shoot wide open with the f/2.8 lens. Stop it down 1 or 2 stops.

I would get the lens checked if closing down was actually necessary. Rather kills the whole point since the 400mm f5.6 is a fraction of the price and that can certainly be used wide open, and is better than a Televue imaging scope in a head to head comparo.


Edited by Samir Kharusi, 26 May 2019 - 08:05 AM.


#6 the Elf

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Posted 28 May 2019 - 09:20 AM

You are probably better of with a small flat field APO. I got my 65/420 quadruplet for 700Eur new. In the US they are labled AT65EDQ and no longer sold. Try to get a used one. Some people report lots of trouble, others do not. I'd ask for photos first. I'd call my copy outstanding compared to any camera lens. The flattener is included, connect the camera and go. See my website for examples. It is not as fast as the lenses, that's true. On the other hand a slower scope is forgiving regarding focus and sensor tilt.



#7 Jim Waters

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Posted 28 May 2019 - 10:17 AM

You are probably better of with a small flat field APO. I got my 65/420 quadruplet for 700Eur new. In the US they are labled AT65EDQ and no longer sold. Try to get a used one. Some people report lots of trouble, others do not. I'd ask for photos first. I'd call my copy outstanding compared to any camera lens. 

The quality for this lens is very hit-or-miss and the light cone is too small.



#8 the Elf

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Posted 28 May 2019 - 11:44 AM

 

the light cone is too small

I'm using it with an APS-C sensor with an off axis guider. The light cone is large enough for this sensor size and the 60Da is an APS-S. I can't tell if it fits FF.



#9 Marco1968

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Posted 29 May 2019 - 02:40 PM

Greetings,

 

the EF lenses from Canon are designed for their Full Frame cameras, so yes the EF 400 2.8 IS II will fully illuminate a FF sensor.

 

Some light falloff (vignetting in photographers' wording) may be visible on images taken at full aperture but will be easily and completely corrected using flats.

 

Being a Canon photographer myself and owning several EF lenses (still not the EF 400 2.8 though) I am pretty sure the lens performances will be impressive.

 

For those CNers who understand MTF graphs, please look at the following ones, the first for the Canon 400 2.8 IS II and the second for the Vixen VSD 100 3.6 astrograph.

 

The Canon MTF graph is as perfect as it gets, with contrast transfer performance extremely high, constant along the aperture (horizontal axis shows the distance in mm ftom the image center) and independent from the spatial frequency that must be resolved.

 

In turn, the VSD performance drops a bit away from the image center and also when resolving higher frequencies.

 

This means extremely well control of chromatic aberration and a very flat field.

 

Definitely use it wide open, it will be a crime to stop down such a fine lens!

 

Enjoy the Cannon!

 

Marco

 



#10 Marco1968

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Posted 29 May 2019 - 02:42 PM

Canon 400 2.8 IS II 

 

 

Attached Thumbnails

  • 20190529_212036.jpg


#11 Marco1968

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Posted 29 May 2019 - 02:42 PM

Vixen VSD 100

 

 

Attached Thumbnails

  • 20190529_212246.png


#12 the Elf

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Posted 30 May 2019 - 07:19 AM

Hmmm, don't get me wrong. Thanks for this info, but you should tell us what the different lines are, which color, what the dotted on is and what pattern was used for the test. I'd also like to point everyone to the x-axis length, the Canon graph ends at 20, the Vixen shows the result up to more than 30. Nontheless, the Canon is a very good lens for Astro. If you have ever taken astro images with a telescope and a focuser you know that this cannot be compared with a camera lens. When attaching the lens to a DSLR there is no backfocus left for an off axis guider and/or a filter wheel or drawer. Filters must be applied in front of the lens and astronomical filters are not available at any diameter. Mounting a lens flex free with a guide scope is some mechanical efford as this image shows. So the optical performance is only one part of the story.

 

Tak_low.JPG

 

The rings, screws, rails, adaptors etc, can easily add 100-200$/Eur to the setup. The smaller lenses like this end 1960s Takumar have a front lens small enough for 2'' astro filters as you can see in the image. Putting the DSLR onto the mount with a dovtail unter the camera is not very clever. You want to rotate the image for the best FOV. That is why rings are better even when not guiding. A downside of my setup is that I have to loosen the crews to correct focus. A telescope is easier to handle and some even come with a camera rotator. When using a slip in nose piece rotating is also very easy.

Long story short: there is more to be taken into consideration when deciding lens vs. telescope.


Edited by the Elf, 30 May 2019 - 07:23 AM.


#13 garret

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Posted 30 May 2019 - 02:32 PM

MTF charts should be explained like this: link:  https://www.lensrent...-and-schneider/

Image collage below is found in the link.

Unfortunately they can not test telephoto lenses on OLAF.

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  • MTF.jpg

Edited by garret, 31 May 2019 - 12:54 PM.


#14 dawziecat

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Posted 31 May 2019 - 11:49 AM

I owned the Canon EF600mm f/4.0 IS lens for many years. I did also have the drop-in polarizer but never used it.

Why? My targets were birds and the exposure penalty of the polarizer was simply too great. I could not afford the lower shutter speeds it too oft necessitated. So, I sold it, virtually unused!

I am a polarizer freak, BTW in that I love the polarized look as much as many others hate it. But, for telephotography? Nope. Not even me. 

 

I used it, and the EF300mm f/2.8 for some AP as well. The 600 produced radially squashed star images that I was never happy with. It still produced some nice astrophotos, mind you, but star shapes were a tad "weird." The 300 produced fine star shapes. These lenses are designed for wide-open shooting. It should neither be necessary, nor particularly productive to stop them down. 

The weakness of using these lenses for AP, IMO, is the inability to guide them well. Flexure was ever a problem, no matter how much steel and iron I employed in mounting them! And autofocus requires heroics I was not willing to engage in. 

 

The "problems" with using them for AP has nothing to do with their optical excellence but I gave up on them and resorted to "conventional" astro OTAs. I have long-since sold off the 600. I'll admit to missing it, but not for AP. I still own the 300. It is a superb lens that lacks the downside the size and mass of the 600 entail. 




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