Used Nikon 300mm ED f2.8 or new WO ZS 61

[Icesheet]

I'm continuing on my path of no money and no sense in the pursuit of my relatively new hobby and would like some opinion on the above.

I have various camera lenses covering the 17-100mm range and a refractor at 500mm. I feel like I'm missing something at the 2-300mm range (maybe you can convince me I don't need anything here and save me some money!)

I liked the look of the William Optics Zenithstar and there is some good reviews on it. Then I noticed a second hand Nikon 300m f2.8 going for not much more. It has a tiny bit of fungus but nothing that affects the image quality I'm told.

So what would you do? Assuming I can shoot wide open with the Nikon does the f2.8 over f5.6 make a difference here? Are the optical qualities going to be that much of a difference? Anything else to consider that I haven't thought of?

 

Cheers

 

Chris

[alexbb]

You'll most probably need to slow the lens down at least one stop in order to reduce the CA when imaging broadband light. A native F/4 should be a lot cheaper. Narrowband could work with the F/2.8 lens wide opened.

On another note, being an old lens, you might get some unpleasant surprises. Lenses inside might be slightly decolimated and I'm afraid F/2.8 won't show any mercy.

Best would be if you could test before spending

[kendg]

Just to add a bit more confusion, there is also a new Stellarvue 60 f5.5 refractor. 

Just trying to make your choice more difficult 

[SteveNickolls]

Hi Chris,

Thanks for your post. Don't know the mount etc. you are using but have assumed your mount carries your telescope ok for imaging. I'd suggest enjoying what you have for now and save up for the future. This will give you time to make a decision based on a lot of thought and advice. There's lots on the Internet to delve into and it's all free.

A lens with mound in it doesn't sound good.

Here's a site with advice on using lenses for astro-photography you might want to visit-http://www.astropix.com/html/i_astrop/lenses.html

This next site has a lot of reviews which may help you if you decide to go the route of camera lenses-https://www.lenstip.com/lenses_reviews.html

Have fun deciding.

Cheers,
Steve

[Icesheet]

Thanks for the replies as always ?

 

1 hour ago, moise212 said:

You'll most probably need to slow the lens down at least one stop in order to reduce the CA when imaging broadband light. A native F/4 should be a lot cheaper. 

Thanks for the advice. This is something I have wondered about. Say I had to stop down to f4 with it to improve CA and sharpness would I not need to go down two stops on the f4 to achieve a similar result? All else being equal that is.

 

1 hour ago, kendg said:

Just to add a bit more confusion, there is also a new Stellarvue 60 f5.5 refractor. 

Just trying to make your choice more difficult 

I'll look into this too. More options is not a bad thing!

 

 

[Icesheet]

59 minutes ago, SteveNickolls said:

Hi Chris,

Thanks for your post. Don't know the mount etc. you are using but have assumed your mount carries your telescope ok for imaging. I'd suggest enjoying what you have for now and save up for the future. This will give you time to make a decision based on a lot of thought and advice. There's lots on the Internet to delve into and it's all free.

A lens with mound in it doesn't sound good.

Here's a site with advice on using lenses for astro-photography you might want to visit-http://www.astropix.com/html/i_astrop/lenses.html

This next site has a lot of reviews which may help you if you decide to go the route of camera lenses-https://www.lenstip.com/lenses_reviews.html

Have fun deciding.

Cheers,
Steve

Thanks Steve, it's probably wise advice regarding using what I have. Actually my telescope may not be suitable for my mount (Star Adventurer) but when I get the proper attachments I will try!

[SteveNickolls]

1 hour ago, Icesheet said:

Actually my telescope may not be suitable for my mount (Star Adventurer) but when I get the proper attachments I will try!

Hi again Chris,

I also have the Star Adventurer (SA) mount and from what I have gathered across the Internet your 500mm telescope is likely too long and too heavy for the mount to return decent tracking. Some have successfully used auto guiding with a telescope like the WO Zenithstar 61 (360mm). Most use lenses on their SA mount to good effect. I'd suggest looking at the carious threads on SGL with the SA as the subject to see what exposures others have achieved with various lenses. This is a recent thread where folks have placed images and equipment details you might want to see-

I'd go back to suggesting just using your existing lenses on your SA and enjoying what you learn from it.

Good luck.

Steve

[Icesheet]

Hi Steve,

Im already well involved in that thread ?

 

The combined weight of camera, telescope and guide scope is 3.5kg so I think it will be the FL that would be the issue. I've seen images with 400mm so there's no harm in trying I guess.

 

And yes, I will put my lenses to good use! ??

Thanks again

 

Chris

[alexbb]

2 hours ago, Icesheet said:

Thanks for the advice. This is something I have wondered about. Say I had to stop down to f4 with it to improve CA and sharpness would I not need to go down two stops on the f4 to achieve a similar result? All else being equal that is.

2 stops down on the F4? That's F/8. 

It really depends on the optics. My Canon 300 F4 L would perform quite well wide open in terms of CA, but the IS has some random free movement. Sometimes the whole image is in focus, other times one corner is too in focus, the opposite too out.

I could recommend the Canon 300 F4 L if it the optics would stay perfectly aligned. I believe the Borg 71 uses more or less the same optics. Perhaps the Nikon equivalent is not far.

Still, best would be if you could test one.