22 replies to this topic

[lurking_grue]

I'm looking to get into AP but I already have some (older) DSLR equipment.  I have a DSLR camera, but I'm really considering using the lenses with a more modern AP camera to start out.  Yes.  I am cheap.

 

How would something like a Nikon 300MM F4 compare to, say a 60MM F6 or F5 entry-level doublet for this kind of work?  AP forum might be a better place to ask but I'd like to hear from the refractor side of it.  Lenses have been around forever, but refractors have seen wave after wave of recent changes (Quads, Quints, lower-cost and decent-quality triplets, etc).  Thanks as always.

[Tapio]

What Nikon 300mm F4 is it? Does it have ED lens?

Many camera lenses are good in daylight shoots but perform poorly with stars.

Here's one older thread of similar question:
https://www.cloudyni...mm-f4-or-scope/

 

One thing which is also covered in that thread is guiding.

You are going to need it with 300mm fl if you want to get longer exposures.

And with a telescope it's easier to do than with camera optics.

Same with focusing, especially if you ever move to astro camera (and filters).

[Kitfox]

It is quite frustrating how you can spend thousands of dollars on a fast telephoto lens and it just truly stink in comparison to a simple, 3 (or even two) element astronomical scope when imaging a field of stars.

 

Big camera lenses have to make tons of compromises to make cameras work in a variety of uses:

 

-irises with irregular edges, even wide open

-the ability to focus from near to far

-a flat field from near to far

-color-free performance to match the sensor of that day's sensitivity

-balance and weight concerns

-ability to focus without changing the balance and weight

-create a package that does all of this at a price point (some have 8 or more elements)

-heaven forbid, it may even have to ZOOM?

 

Making a scope that can be optimized for correction at infinity focus only and has just 4 to 6 surfaces and doing it well is a whole different goal.  And all we need.

 

That said, there is some awfully fine work done with sir's and mirrorless cameras and modern software!

Edited by Kitfox, 31 March 2025 - 06:33 PM.

[triplemon]

Well, those telephoto lenses are optimized for a flat, evenly sharp enough views at faster apertures. Historically, very unlike telescopes.

 

The latest crop of sextuplets or more shoots for the exact same thing. Unsurprisingly at similar cost and using quite similar optical construction. So the gap is now quite small.

 

The only thing that is optimized differently for a telephoto is that those have a shorter physical length, "waste money" on electric aperture control and maybe image stabilization. As many folks use electric focus control, aka autofocus on their scopes as well.

 

So, yes - if you have a good telephoto lens, its performing very close to those telescopes. In particular if you use it with a larger sensor that doesn't have insanely small pixels.

Edited by triplemon, 31 March 2025 - 06:38 PM.

[ntph]

You can find lots of examples of images taken with camera lenses using DSLRs or cooled cameras with simple searches on AstroBin and other places, even here. The biggest drawback I can think of from my own experience is the lack of automated focusing with a lens in its native state. Good glass and modern software tools like BlurXterminator go together hand in glove. My Canon 100-400 EF lens does very nicely coupled with a cooled OSC camera I think. You can see some of my images in my A-bin gallery with a variety of focal lengths. I am resisting buying a premium short-to-midrange focal length dedicated astrorefractor--for now. Not because I am cheap, but because what I have I can happily live with--for now.  

 

How cheap? barn-door tracking? no tracking at all? The mount, the mount and the mount is where to put your money you're going to hear time and again for good reason. Also what are you using to control all of this stuff? Everything from a simple intervalometer to ASIAir to laptops and minicomputers running a zoo of software can give good results in knowledgeable hands. 

 

If you haven't made contact with a local astronomy group who have some experienced members to give you some first-hand looks at what all of this entails, then get your hands on this book. It is comprehensive enough for even the most experienced and deep-pocketed hobbyist. You will learn more there than here. 

Edited by ntph, 31 March 2025 - 06:31 PM.

[Mike W]

Comet Hyukatake over Yale Obs with a pentax K1000, 400 film on a simple barn door mount.

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[Tulsa]

Never hurts to give it a shot and see what you think.  Wide field is nice with DSLR camera and lens.  If you enjoy AP then I think you’ll quickly move to a refractor and a dedicated AP camera.  Outside our atmosphere, I only use my camera and lens for solar with a 16 stop ND filter.  I prefer that to a my scope with a solar filter.  

[lurking_grue]

The lens is an ED version, diagrams I find show 2 ED elements of 10 overall in the design.

 

About being cheap - the scope has to be short enough to be inexpensive.  Fast enough to tolerate less-than-perfect mount tracking.  It also has to be long enough to have some kind of reasonable image scale with one of the newer, less-expensive cameras.  Ideally, it has to be simple enough as not to be maddening in use.  It's helpful if the image isn't disappointing (except as I may make it). 

 

Unicorn?

Edited by lurking_grue, 31 March 2025 - 06:56 PM.

[Tony Cifani]

I'm looking to get into AP but I already have some (older) DSLR equipment.  I have a DSLR camera, but I'm really considering using the lenses with a more modern AP camera to start out.  Yes.  I am cheap.

 

How would something like a Nikon 300MM F4 compare to, say a 60MM F6 or F5 entry-level doublet for this kind of work?  AP forum might be a better place to ask but I'd like to hear from the refractor side of it.  Lenses have been around forever, but refractors have seen wave after wave of recent changes (Quads, Quints, lower-cost and decent-quality triplets, etc).  Thanks as always.

Optically speaking, the Nikon 300mm F/4 has a lot more glass inside than a doublet with many elements in many groups. So more air to glass surfaces, which may not matter so much for AP. An entry level doublet would have two lenses in one group and at F/5 or F/6 you'll see a lot of chromatic aberration. I would think your Nikon lens would outperform a fast entry level achromatic refractor when it comes to AP.

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[RichA]

I'm looking to get into AP but I already have some (older) DSLR equipment.  I have a DSLR camera, but I'm really considering using the lenses with a more modern AP camera to start out.  Yes.  I am cheap.

 

How would something like a Nikon 300MM F4 compare to, say a 60MM F6 or F5 entry-level doublet for this kind of work?  AP forum might be a better place to ask but I'd like to hear from the refractor side of it.  Lenses have been around forever, but refractors have seen wave after wave of recent changes (Quads, Quints, lower-cost and decent-quality triplets, etc).  Thanks as always.

The 300mm f4 is a good lens provided it is an ED version.  AP or manual.  Plus, you can buy them used FAR less expensively than even the cheapest ED telescope and field-flattener generally.  You'll only have to stop it down 1-stop to f5.6 to get good field correction.  But for $200, experimenting is not expensive at all.

 

https://www.ebay.com...:Bk9SR_jynOu9ZQ

Edited by RichA, 31 March 2025 - 07:17 PM.

[lurking_grue]

Sadly just discovered - there's apparently no way to control my lens aperture except through the camera.  It's got an aperture ring, but it doesn't move.  Sounds like a mid-production mod or something strange.  W/E - I have my answer - thanks to the group as always.  Like Nikons everywhere it's at F22 so no good.

Edited by lurking_grue, 31 March 2025 - 08:08 PM.

[Tapio]

Sadly just discovered - there's apparently no way to control my lens aperture except through the camera. It's got an aperture ring, but it doesn't move. Sounds like a mid-production mod or something strange. W/E - I have my answer - thanks to the group as always. Like Nikons everywhere it's at F22 so no good.

I've read that you could adjust aperture by using DSLR and taking lens out when still powered.
Don't know if it works with all brands/models.

[hfjacinto]

I've imaged using both a DSLR and a Telescope.

 

In reality you can do it with both, with the telescope being better optimized for imaging.

 

The biggest issue with imaging is not the lens/telescope its the guiding.

 

So once you have guiding down you then need to go to the next step.

 

And that is the image quality. Most Camera lens are optimized for terrestrial images and for F8. That means that at full aperture (F1 -Fx) they will most likely show pincushion on terrestrial images but stars will look like seagulls. Hence why most people end up going to astro cameras and flatners and high end mounts. 

 

The average APers doesn't start like this, but they most end up like the below.

 

 

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[Erik Bakker]

For wide, flat fields and bigger comets I use a Nikon Micro Nikkor ED AF 200mm f/4 with wonderful results. Pinsharp stars with great contrast and color saturation. It makes a great combo with my Nikon D4 and Df DSLR’s.

 

The Nikon 300mm f/4 ED is a very nice lens in it’s different incarnations and worth a try on your Nikon DSLR.

[RichA]

I've imaged using both a DSLR and a Telescope.

 

In reality you can do it with both, with the telescope being better optimized for imaging.

 

The biggest issue with imaging is not the lens/telescope its the guiding.

 

So once you have guiding down you then need to go to the next step.

 

And that is the image quality. Most Camera lens are optimized for terrestrial images and for F8. That means that at full aperture (F1 -Fx) they will most likely show pincushion on terrestrial images but stars will look like seagulls. Hence why most people end up going to astro cameras and flatners and high end mounts. 

 

The average APers doesn't start like this, but they most end up like the below.

Only very cheap or old lenses are optimized for f8 these days.  Good lenses shoot perfectly one stop down from wide.  Inexpensive aspherical elements made  that possible.

[hfjacinto]

Only very cheap or old lenses are optimized for f8 these days.  Good lenses shoot perfectly one stop down from wide.  Inexpensive aspherical elements made  that possible.

That's not true, all my lens are either L or Tamron and every lens is sharper at F8, than 1 stop down. My F2.8 lens are nice are nice at F2.8, great at F4, slightly better at F5.6 and minimally better at F8.  The best is between F5.6 and F8 (I'm using a full frame camera) You also minimize distortion at F8 compared to F4. But being honest, I shoot at the fastest possible and clean up in post processing. 

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Edited by hfjacinto, 01 April 2025 - 12:21 PM.

[RichA]

That's not true, all my lens are either L or Tamron and every lens is sharper at F8, than 1 stop down. My F2.8 lens are nice are nice at F2.8, great at F4, slightly better at F5.6 and minimally better at F8.  The best is between F5.6 and F8 (I'm using a full frame camera) You also minimize distortion at F8 compared to F4. But being honest, I shoot at the fastest possible and clean up in post processing. 

Tamron is an also-ran lens.  Stick to manufacturers lenses.  Olympus 300mm f4 micro4/3rds lens is incredibly sharp wide open as are the Nikon Z lenses.

[hfjacinto]

 

Tamron is an also-ran lens.  Stick to manufacturers lenses.  Olympus 300mm f4 micro4/3rds lens is incredibly sharp wide open as are the Nikon Z lenses.

Your comparing 4/3 to full frame. BIG difference. I agree with the Nikon Z but if I was paying $2400 for a lens, I would expect it to perfect at the edges (and they aren't). Look at Ken Rockwell review of the lenses, almost all perform better at F4+ and on some that is 2 full stops. Comparing the lens at F1.8 to F8, you don't see spherochromatism at F8, but do see it at F1.8

 

I also disagree with your take on Tamron, they have excellent lens that you can't get in the Manufacturers lens, I don't see Canon or Nikon having a 150-600.

[mikefulb]

You might be able to stop down the lens with a simple lens ring on the end - I do this with my Canon 200mm L lens to stop it down to f/4 with a 50mm lens ring.

[n2068dd]

 

About being cheap

 

- the scope has to be short enough to be inexpensive.

 

I'd prefer 3inch ED telescopes like Vixen SD81SII. The focal length 625mm is suited for those of Ha nebula, and several large galxies.

and it is up-gladable as more wide field and fast photo lens. or it can be used as both visual and photo.

 

Fast enough to tolerate less-than-perfect mount tracking.

 

It requires very fast F2.8 400 mm class lens, or short 180mm class lens. Cat 71 WIFD is F4.9 350mm, not easy to take pinpoint stars with no guided mounts. If you'd consider lucky imaging method, it also requires Fast F4 to 6 class lens and telescopes. F7 class tend to be noisy.

 

It also has to be long enough to have some kind of reasonable image scale with one of the newer, less-expensive cameras.

 

It's better to use with APS-C class camera or 4/3 camera. If you'd hope to use with full 35mm size camera, the telescope price will be tremendusly high. and it's must to use with filter modified camera. To purchace a used modified astro camera is best way. Canon 6D or 60Da is most popular and standard.If you use 6D, crop out the fringe area of fat image with large coma and as. I don't think newer miror less camera is best way to choice, except Sigma FP or FPL.

 

Ideally, it has to be simple enough as not to be maddening in use.  It's helpful if the image isn't disappointing (except as I may make it).

 

Fitst of all, try it, fail it and recover it. Expeience is a good teacher. The images is only depends on the lens design. You can not recover. Disapointing or not? it depends on the personal boarder bar. You can't say it's enough or not on some one.

 

In my experiences, Sigma 40mm F1.4, 70mm F2.8, 135mm F1.8s are the best lense as full frame image circle with pin point stars. About for the 300mm class, Canon 100-400 F4.5LII also the best lens. Canon EF 300mm f/2.8L IS II is discontinued, though not high as EF 400mm f/2.8L IS III in used market.

 

It's better to try first with your already owned camera and lens. Experience will tell you the way to next.

Edited by n2068dd, 01 April 2025 - 08:51 PM.

[lurking_grue]

I ruled my DSLR out as 200 is high ISO for it. It is very old and very heavy. The lens 300mm I have won’t allow aperture selection except through the camera. I’m not that interested in the super wide stuff - my next lens from 300 is 85, with the same aperture stop issue.

Apertura 75Q and the new ish 60mm from our sponsor are the short list now. TY all.

[akdwivedi]

there is no rule saying you shouldn't start with what you have. some lenses are well optimized and have been reviewed in this forum. samyang/rokinon 135mm f/2, sigma 14mm widefield, canon 200mm f/2.8.. I think I saw some saying canon 300mm f/4 and nikon 300 f/4 ED.. try them and if you get hooked into AP, you can get a higher quality triplet.

[kim.davis]

Dedicated Apos would give tighter stars. One downside is its size and weight with FF/FR and backfocus requirements. So for wide angle ap, i prefer telephoto lens. It's simple and easy to carry, and I can use it for daylight photography as well.

It depends on what you want.

Edited by kim.davis, 08 April 2025 - 12:47 PM.