66 replies to this topic

[Shubham]

Shubham,

Thank you very much for your kind words, I appreciate them. I ended up buying the Sony 300mm f2.8 GM in Japan and the Vixen VSD90SS+0,71xReducer as well. I plan to compare them side-by side as soon as the necessary adapters ship. The goal will be to see how the sony lens with the staradventurer mount compares to the Vixen and Skywatcher 100i Mount at similar focal lenghts, I'll be glad to share the results.

 

Would be waiting for the comparison, Peter! Sometime in future my dream portable astro kit would be a Sigma 14mm & 24mm f1.4 & the upcoming Sony 50-150mm f2 on a Polarie U. And down the road a Sony 400mm f2.8 on an RST135E wouldn’t hurt!

[JohnH]

For a number of years on my film camera and for my very early digital, I had a Tamron 300 2.8. Well it certainly was a long telephoto with fast aperture, I was a little disappointed with it being a bit of color noise on images especially at the edge. My newer Canon 200 1.8 suffers from that too but to a much lesser extent due to a much better design

[PeterWar]

Here's a photo taken with the 300mm GM lens at f3.2 of the Owl Nebula, M108 and Merak that I believe will be interesting to our discusson:

 

I slightly stopped down the lens so that I don't see the reverse lighthouse effect on Merak that's annoying to me in petzval designs and in my 300mm lenses. The effective aperture on this photo is about 93mm. I'm using an A7RIIIA camera for this photo (I just bought it, couldn't resist having a sony sensor with twice the pixel count of the 2400MC for half the price). I've used the Staradventurer 2i mount for this photo.

 

I haven't done any BlurXterminator nor NoiseXterminator when sampling the tiny objects of this photo, would you say I'm pixel sampling limited, seeing limited or apperture limited?

You may find the original stacked with APP here.

Edited by PeterWar, 02 May 2025 - 05:59 AM.

[mattbarber]

You might be a little pixel-sampling limited, but only slightly.  I'm reasonably certain Sony's 50/1.2 GM and 135 GM lenses are out-resolving the 60MP sensor (3.76 micron) pixels on my A7R IV, and I suspect the 300/2.8 is about as sharp as those lenses (I do not have the 300), but other than getting an 'astro cam' (with even smaller pixels, and a mono sensor so not limited by the Bayer filters) and adapting it to the 300 GM, I doubt there's any way to do much better.  I could be wrong.  This image is kind of amazing for lack of noise with no BXT used - well done!

 

One thing I might suggest, if you haven't tried it:  2x drizzle, when stacking, might help bring out a little more detail.  (drizzle, then downsize back to original)  It's something I read here on CN, and it does work on some images.  I think the galaxy in this image, and maybe also the Owl, would benefit.

Edited by mattbarber, 02 May 2025 - 08:27 AM.

[PeterWar]

You might be a little pixel-sampling limited, but only slightly.  I'm reasonably certain Sony's 50/1.2 GM and 135 GM lenses are out-resolving the 60MP sensor (3.76 micron) pixels on my A7R IV, and I suspect the 300/2.8 is about as sharp as those lenses (I do not have the 300), but other than getting an 'astro cam' (with even smaller pixels, and a mono sensor so not limited by the Bayer filters) and adapting it to the 300 GM, I doubt there's any way to do much better.  I could be wrong.  This image is kind of amazing for lack of noise with no BXT used - well done!

 

One thing I might suggest, if you haven't tried it:  2x drizzle, when stacking, might help bring out a little more detail.  (drizzle, then downsize back to original)  It's something I read here on CN, and it does work on some images.  I think the galaxy in this image, and maybe also the Owl, would benefit.

Thanks a lot for the feedback, I'll try drizzle. I use no dithering (yet another thing to NOT worry about), I let the PEC of the mount do the "dithering" for me, this was done stacking 100 frames of 30 seconds. In retrospect I should have done 20s instead of 30s as I had to trow away 40% of the subs due to gusts of wind, I've now used Loctite 273 to secure the 3/8" screw on the staradventurer mount to prevent it from moving when wind blows.

Edited by PeterWar, 02 May 2025 - 08:40 AM.

[saemark30]

I use the Nikkor 300mm F2.8 IF-ED AI  lens Nikon's previous model. Good wide open but vignettes full frame, better at F4.

 

How do you sum up the images, what software?

I can avg out the frames no problem, but no added detail.

Edited by saemark30, 04 May 2025 - 12:55 PM.

[PeterWar]

I use the Nikkor 300mm F2.8 IF-AI  lens Nikon's previous model. Good wide open but vignettes full frame, better at F4.

 

How do you sum up the images, what software?

I can avg out the frames no problem, but no added detail.

I was using WBPP in Pixinsight up until last month, but I'm realising APP is slightly better and more convenient for OSC astro when stacking.

[xonefs]

Here's a photo taken with the 300mm GM lens at f3.2 of the Owl Nebula, M108 and Merak that I believe will be interesting to our discusson:

 

I slightly stopped down the lens so that I don't see the reverse lighthouse effect on Merak that's annoying to me in petzval designs and in my 300mm lenses. The effective aperture on this photo is about 93mm. I'm using an A7RIIIA camera for this photo (I just bought it, couldn't resist having a sony sensor with twice the pixel count of the 2400MC for half the price). I've used the Staradventurer 2i mount for this photo.

 

I haven't done any BlurXterminator nor NoiseXterminator when sampling the tiny objects of this photo, would you say I'm pixel sampling limited, seeing limited or apperture limited?

You may find the original stacked with APP here.

Does it do that to bright stars when the lens isn't stopped down?

 

I was considering a 300 GM but that looks annoying

[PeterWar]

Does it do that to bright stars when the lens isn't stopped down?

 

I was considering a 300 GM but that looks annoying

Yes it does, it's the only downside I've seen, it's similar to the artifact present at Takahashi FSQ telescopes.


I think we could correct that, in teory, by placing a round filter that slightly stops down the lens 2mm or so but haven't seen anything comercialy avaliable. It only does that on very bright stars though.

[Shubham]

Yes it does, it's the only downside I've seen, it's similar to the artifact present at Takahashi FSQ telescopes.


I think we could correct that, in teory, by placing a round filter that slightly stops down the lens 2mm or so but haven't seen anything comercialy avaliable. It only does that on very bright stars though.

Honestly, I’m one of those who isn’t really bothered by it but I’m super interested to see an example @f2.8.

[xonefs]

Yes it does, it's the only downside I've seen, it's similar to the artifact present at Takahashi FSQ telescopes.


I think we could correct that, in teory, by placing a round filter that slightly stops down the lens 2mm or so but haven't seen anything comercialy avaliable. It only does that on very bright stars though.

Is it across the whole field or only stars towards the edge?

 

I was thinking about renting one for a Namibia trip

[PeterWar]

Is it across the whole field or only stars towards the edge?

 

I was thinking about renting one for a Namibia trip

Just at 2/3 of the edge, sharp towards the center, this lens would have no trouble recreating the quality of my pleiades photo, it's the only optical flaw I've been able to spot and only applies towards the edges, it's a GREAT lens and I suspect every bit as sharp as my VSD90SS but I'll require more testing to verify this claim.

 

EDIT: An image is worth more than 1000 words, please have a look at this raw, I think it's representative of the lens quality

Edited by PeterWar, 05 May 2025 - 04:49 PM.

[Eric63]

Another reason for shooting with fast lenses is one’s situation.  I live in a high rise condo and I can shoot from 0 to 180 degrees south, therefore I have a a decent number of targets.  Unfortunately I only have a 2.5 hour window before I lose my target due to the balcony above me. Using fast lenses means that I can make the most of those 2.5 hours (2.5 hours at f2.8 is almost 8 hours at F5).  Yes I could setup downstairs on the property grounds, but I much prefer sitting in the confort of my condo (especially during the winter). I do travel to dark sites now and then, but 80% of my imaging is done at home.  

 

I have both an Ha modified DSLR and an ASI533mm pro and I focus mostly on narrowband (due to the light pollution). I used to image unguided but I now guide for the dithering and for longer narrowband subs. So fast lenses allow me to make the best of a so so situation. I know my limitations and choose my targets accordingly. I use a Samyang 135mm F2, Canon 200mm F2.8 and a Canon 300mm F4.  Post processing is my friend and I am very happy with my results, so I guess that’s what counts. Now, If I still had my house in the suburbs, you bet that I would have a nice scope on a beefy mount 

 

Eric

Edited by Eric63, 08 May 2025 - 09:40 PM.

[xonefs]

Just at 2/3 of the edge, sharp towards the center, this lens would have no trouble recreating the quality of my pleiades photo, it's the only optical flaw I've been able to spot and only applies towards the edges, it's a GREAT lens and I suspect every bit as sharp as my VSD90SS but I'll require more testing to verify this claim.

 

EDIT: An image is worth more than 1000 words, please have a look at this raw, I think it's representative of the lens quality

that looks great guess i need to save up

[doolsduck]

I just want to flag another great lens for astrophotography: the Nikon Nikkor 200mm f/4. Mine is nearly 50 years old and has been excellent for the bit of astrophotography I've done with it. Ken Rockwell gave it a glowing review (https://www.kenrockw...kon/200f4ai.htm), and they pop up occasionally for very reasonable prices.

I’ve only done a little deep sky work with it before taking a long break, but I’m looking forward to diving back in. Here’s a shot I took of the Moon-Venus conjunction a couple of years ago at f/8. It produced perfect diffraction spikes—something I didn’t notice at f/4, if I remember correctly. I know diffraction spikes can be polarizing, but it seems like just as many people enjoy them as those who don’t.

 

[xonefs]

That's interesting. I like some diffraction spikes on stars, but they are not great on the moon.

 

Those look good for camera lens spikes. I usually find spikes from camera lenses too distracting where 4 pointed spikes from reflectors always look good. The voigtlander APO lanthar lenses also produce really clean spikes. 

 

I had the older pre-ai version of the 200 f4 and it was nothing special for normal photography, but im guessing the ai version is different. 

Edited by xonefs, 09 May 2025 - 09:41 PM.

[Marcus1]

What is the origin of diffraction spikes in a dslr lens?

[Shubham]

What is the origin of diffraction spikes in a dslr lens?

It is caused by the opening of the iris diaphragm, made from a certain number of aperture blades, not being a perfect circle.

 

[xonefs]

which exact version of the nikon 300 f2.8 did you have? The VR or regular ED II? There are some copies of the ED II on ebay with broken autofocus for decent prices that otherwise look in good cosmetic condition, but I worry if AF isn't working what else happened to them. May chance it for $700-$800... I want a fast telephoto to bring to namibia to use on star tracker unguided. I could buy one for the price of renting a sony 300 gm. renting might be an issue if I extend to europe after and can't easily return it. 

Edited by xonefs, 10 May 2025 - 09:07 PM.

[xonefs]

I’m also tempted by the Canon EF 300 f2.8 l (non is). Version 2 is expensive but v1 is similar to the nikon not sure how it performs. I know v2 is is very good.

Drawback is focus by wire if it fails but if af works then autofocus would work better adapted for terrestrial use than a nikon.

Not sure how it compares to the nikon af s non vr

Edited by xonefs, 11 May 2025 - 07:03 AM.

[PeterWar]

which exact version of the nikon 300 f2.8 did you have? The VR or regular ED II? There are some copies of the ED II on ebay with broken autofocus for decent prices that otherwise look in good cosmetic condition, but I worry if AF isn't working what else happened to them. May chance it for $700-$800... I want a fast telephoto to bring to namibia to use on star tracker unguided. I could buy one for the price of renting a sony 300 gm. renting might be an issue if I extend to europe after and can't easily return it. 

I have the AFs NIKKOR 300mm 1:2.8 DII and it is excelent, this was the last lens without VR which for astrophoto I believe it is a big plus, it's also lighter than other Nikkor 300mm 2.8 lenses.

I believe the lens adds a certain purple tint to stars that shouldn't be there, I plan to test side-by-side this lens with my new Sony 300mm GM OSII and my Vixen VSD90SS+0.71X reducer next month when I get back from Namibia.

[xonefs]

Have you used that nikon lens on sony with an autofocus adapter for daytime use? If so which one and how did it perform?

 

I'm thinking of getting one for Namibia but would also like to use it for wildlife

[PeterWar]

I have not, I bought the new Sony 300mm f2.8+telecompressors for wildlife in Namibia as well.

I would suggest you to go to Japan, visit MapCamera in Tokio and buy the sony lens, it has great autofocus capabilities even when using the x2 telecompressor. By buying it in Japan the price difference is going to pay you the trip to Japan and will get you the necessary hardware for Namibia, it’s what I did.

[Shubham]

By buying it in Japan the price difference is going to pay you the trip to Japan and will get you the necessary hardware for Namibia, it’s what I did.

Wow. Hope much does this lens cost in Japan?

[xonefs]

Maybe cheaper than Spain but I somehow doubt it's that much better priced than US. I had a friend recently go to Japan and he said the prices weren't that much better. 

 

In any case even with 1-2k off I don't think a 300 GM is in the budget or I would get enough use to justify it. 

 

Leaning towards trying the Nikon. 

Edited by xonefs, 14 May 2025 - 07:53 PM.