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alan687

Telephoto Vs Telescope

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Hi

I have the Canon EF 'cheap' version though it's a long time since I used it for AP.  I recall it was 'ok' but not comparable to a scope. I was thinking maybe the Sigma version would be better - about twice the price, but still.

Thanks

Louise

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I'm finding them useful in video astronomy - I have a "pentax thread" (to C-thread) adapter, which I use with few (late Dad's) manual lenses from the 70s in the range 24-135mm. I gave up aspirations in real photography, before(!) the advent of automatic lenses, but interested in acquiring a few more (faster) focal lengths. Quality is commensurate with VA. ;)

Uhm, with "auto" lenses, the iris (focus?) is electronically controlled, right? lol. But is the default iris setting open or closed? Or must one check this, on an ad-hoc basis? I didn't know modern lenses went past infinity... All of mine stop thankfully! Looking forward to "deep" imaging the Hyades (Pleiades) shortly... Neatly framed with 1/2" Watec chip at 35mm (135mm).  :)

Edited by Macavity

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The iris is the aperture, both this and the focus can be auto controlled or set to manual. Whether the aperture is open or closed depends on the settings but my lens the aperture must be closed to attach it to the camera.

Sent from my iPad using Tapatalk

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Nearly 1000 views and 53 comments, i didn't expect this from a simple question, what an awesome response.

Ive been using my 250mm lens for normal photography, tried it for AP but at 55mm you can only take a sub 6 second exposure without a tracking mount so at 250mm it would need a very short exposure and that is not very useful.

Anyone have any advice on teleconverters, ive found i need more reach for wildlife photography but a canon 2x teleconverter is £320, i could buy a new lens for that amount.

Is there any alternative to get more reach without spending silly amounts of money?

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Nearly 1000 views and 53 comments, i didn't expect this from a simple question, what an awesome response.

Ive been using my 250mm lens for normal photography, tried it for AP but at 55mm you can only take a sub 6 second exposure without a tracking mount so at 250mm it would need a very short exposure and that is not very useful.

Anyone have any advice on teleconverters, ive found i need more reach for wildlife photography but a canon 2x teleconverter is £320, i could buy a new lens for that amount.

Is there any alternative to get more reach without spending silly amounts of money?

Nearly 1000 views and 53 comments, i didn't expect this from a simple question, what an awesome response.

Ive been using my 250mm lens for normal photography, tried it for AP but at 55mm you can only take a sub 6 second exposure without a tracking mount so at 250mm it would need a very short exposure and that is not very useful.

Anyone have any advice on teleconverters, ive found i need more reach for wildlife photography but a canon 2x teleconverter is £320, i could buy a new lens for that amount.

Is there any alternative to get more reach without spending silly amounts of money?

Nearly 1000 views and 53 comments, i didn't expect this from a simple question, what an awesome response.

Ive been using my 250mm lens for normal photography, tried it for AP but at 55mm you can only take a sub 6 second exposure without a tracking mount so at 250mm it would need a very short exposure and that is not very useful.

Anyone have any advice on teleconverters, ive found i need more reach for wildlife photography but a canon 2x teleconverter is £320, i could buy a new lens for that amount.

Is there any alternative to get more reach without spending silly amounts of money?

Why not buy a used prime 400mm? I bagged a Tokina 400mm f/5.6 in very nice condition for 65 BP delivered. Auction sites are loaded with tele converters around 20BP.--Jack

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Anyone have any advice on teleconverters, ive found i need more reach for wildlife photography but a canon 2x teleconverter is £320, i could buy a new lens for that amount.

Is there any alternative to get more reach without spending silly amounts of money?

The Canon EF 2x iii is expensive, but there's a reason for that, it's bloomin' good!  Coupled with a decent telephoto lens it will focus quickly (albeit slower than without it in place), it'll autofocus with a f/2.8 or faster lens (or with an f/4 lens on a 1 or 5 series body), and image quality will only be slightly inferior to a lens with the same native focal length.  Using it with a less expensive telephoto lens, particularly those with apertures slower than f/4 won't be a particularly enjoyable experience though.  The extended nosepiece on the EF 2x iii also prevents it being used with all but a select few lenses, so do check the Canon website for compatibility before investing.

I've tried a cheap 2x T/C in the past and results were extremely poor and I'd avoid them like the plague.  Having said that the Kenko Pro 300 DGX is fairly well reviewed, but at around £150 it's not exactly cheap, but is compatible with more lenses than Canon's version.  Overall I think the options for a manual-focus long prime lens is probably going to offer the best bang/buck ratio.

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The Canon EF 2x iii is expensive, but there's a reason for that, it's bloomin' good!  Coupled with a decent telephoto lens it will focus quickly (albeit slower than without it in place), it'll autofocus with a f/2.8 or faster lens (or with an f/4 lens on a 1 or 5 series body), and image quality will only be slightly inferior to a lens with the same native focal length.  Using it with a less expensive telephoto lens, particularly those with apertures slower than f/4 won't be a particularly enjoyable experience though.  The extended nosepiece on the EF 2x iii also prevents it being used with all but a select few lenses, so do check the Canon website for compatibility before investing.

I've tried a cheap 2x T/C in the past and results were extremely poor and I'd avoid them like the plague.  Having said that the Kenko Pro 300 DGX is fairly well reviewed, but at around £150 it's not exactly cheap, but is compatible with more lenses than Canon's version.  Overall I think the options for a manual-focus long prime lens is probably going to offer the best bang/buck ratio.

For the money that i would need to spend on a teleconverter i think getting a used prime would be the best solution, is it difficult to locate your target in a prime? i know its hard to even find things at 250mm so how do you do it with a 400 prime, with my 55-250 i usually locate the object at 100mm then zoom to 250

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I have tried a few of Canon's highest regarded L Lenses for Astro Work. None of them can compare to a telescope. As I think was mentioned earlier in the thread, there are just too many compromises in camera lens to make it a jack of all trades whereas a telescope has but one function.

Cheers

Stuart

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I have tried a few of Canon's highest regarded L Lenses for Astro Work. None of them can compare to a telescope. As I think was mentioned earlier in the thread, there are just too many compromises in camera lens to make it a jack of all trades whereas a telescope has but one function.

Cheers

Stuart

Depends on what telescope. If the cost is equal then the dedicated telescope will be much, much better for astro work. However most of the long primes will easily outperform an achro and can hold up well against non-premium apos as well. Additionally they are "free" if you have already got one and you get much more use out of them if you use them during the daytime as well...

I wouldn't recommend getting a premium "L" lens purely for astro work. But if you are into birding for instance I would highly recommend a Canon 400mm f/5.6 L lens for astro work on those rare clear nights and birding/bird-in-flight photography during the daytime.

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Depends on what telescope. If the cost is equal then the dedicated telescope will be much, much better for astro work. However most of the long primes will easily outperform an achro and can hold up well against non-premium apos as well. Additionally they are "free" if you have already got one and you get much more use out of them if you use them during the daytime as well...

I wouldn't recommend getting a premium "L" lens purely for astro work. But if you are into birding for instance I would highly recommend a Canon 400mm f/5.6 L lens for astro work on those rare clear nights and birding/bird-in-flight photography during the daytime.

Sorry, I should have excluded achros.

In my own experience then every apo I've owned would outperform a lens on the stars.

As you say, if you have one anyway...

But if both are available to you I doubt you will select the camera lens.

Cheers

Stuart

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I dont think the choice is allways that simple camera lenses are usually much faster than the scope equivalent if in fact there is one so its not exacly a fair comparison maybe judging them at the same F ratio would be better  it is also very difficult/impossible to get hold of a scope that is sub 250mm.

I wonder why there isnt a 200mm FL scope at F4 that could work with a full frame sensor i would certainly be very interested (the borg 60ED gets close).

Alan

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I have got my eye on the Borg 67 f3.8 at 255mm.........now where do I find the best part of 1300 quid. :grin:

Two Canon EF 200mm L f2.8 cost best part of a grand.

Astrophotography....... :rolleyes:

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I have got my eye on the Borg 67 f3.8 at 255mm.........now where do I find the best part of 1300 quid. :grin:

Two Canon EF 200mm L f2.8 cost best part of a grand.

Astrophotography....... :rolleyes:

I agree there is so many lovely targets in the 200-300mm FL range and i do prefer to see them hanging there in space to me it gives a much better sense of scale.

Alan

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I dont think the choice is allways that simple camera lenses are usually much faster than the scope equivalent if in fact there is one so its not exacly a fair comparison maybe judging them at the same F ratio would be better  it is also very difficult/impossible to get hold of a scope that is sub 250mm.

I wonder why there isnt a 200mm FL scope at F4 that could work with a full frame sensor i would certainly be very interested (the borg 60ED gets close).

Alan

I think the problem with this is that when used "wide open" most camera lenses give their worst performances. Even £10,000 worth of Canon L glass will likely need to be stopped down to f4 or f5.6 before it gives acceptable performance on the stars. At these speeds you are right back into APO territory and the APO will be cheaper...

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I'm loving this thread. :grin:

I always look forward to the next reply as I have followed this one more than any other.

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I can only really comment on the Canon 500mm f/4 L IS which I use to image with and I always shoot with it wide open. If I use my 70-200mm f/4 L IS lens I also shoot wide open but it isn't as good in the corners. Going any wider than 100mm is asking a lot of a lens and probably why there are no (or not many) wide angle astrographs out there.

The findings on Samir's page might sum it up for long focal length (500mm+) premium Canon lenses...

http://www.samirkharusi.net/televue_canon.html

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If I wanted to get both the Lagoon and Trifid in the frame, or the entire Veil I would choose a lens. If I wanted to image the Milky Way I would choose a lens. If I chose to image the North America I would choose a lens. I doubt if many have actually done 1:1 comparisons. Opinions are free.

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I think the problem with this is that when used "wide open" most camera lenses give their worst performances. Even £10,000 worth of Canon L glass will likely need to be stopped down to f4 or f5.6 before it gives acceptable performance on the stars. At these speeds you are right back into APO territory and the APO will be cheaper...

I agree, I have a Leica 75mm F2 Apo Summicron ASPH for my M cameras and this lens is as good as  it gets for a commercially available lens. At F2 is more than adequate on even a 24Mpixel full frame digital camera but for AP I am sure that it has to be stopped down to F2.8 to get rid of any residual aberrations.

A.G

Edited by lensman57

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I can only really comment on the Canon 500mm f/4 L IS which I use to image with and I always shoot with it wide open. If I use my 70-200mm f/4 L IS lens I also shoot wide open but it isn't as good in the corners. Going any wider than 100mm is asking a lot of a lens and probably why there are no (or not many) wide angle astrographs out there.

The findings on Samir's page might sum it up for long focal length (500mm+) premium Canon lenses...

http://www.samirkharusi.net/televue_canon.html

Hi Stuart,

You do amazing work with your 500 F4 L but the list price for that lens from WEX Photo is just over £7000.00. A while ago I bought a second hand Canon F2.8 L lens and at f2.8 it does have a bit of fringing, nothing excessive but it is there. I use a front mask to bring it down to f3.8 and there it seems to be fine, a good compromise between speed and performance.

Regards,

A.G

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If I wanted to get both the Lagoon and Trifid in the frame, or the entire Veil I would choose a lens. If I wanted to image the Milky Way I would choose a lens. If I chose to image the North America I would choose a lens. I doubt if many have actually done 1:1 comparisons. Opinions are free.

I have imaged the north american nebula and veil with lenses and the results are ok in a sense of showing someone what's there, but to pick through and correct all of the issues with colour offsets, star fringing etc would be a labour beyond my patience.

I have also imaged north america with a small 370mm apo triplet and the results were far more pleasing and mucheasier to correct the smaller number of residual issues.

That's just my opinion based on my experience.

Regards

Stuart

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I have one camera lens that outperforms my ED80 with star shapes right into the corners. And that's using it wide open at f/2.8, which means I pick up a huge amount of feint stuff. I had the resulting image put through CCD inspector, and whilst not quite pancake flat, it's really not far off. That was using a Sigma 150mm f/2.8 Macro lens at f/2.8. This sits nicely on my Astrotrac, which means I don't have to haul out my HEQ5 and set it up (which is not a good idea with a bad back). I plan, at some point soon, to image the Veil with the 150 @ f/2.8.

The 50mm primes are great lenses, but the star shapes are horrendous to the edges on the f/1.8 until f/4.5, and on the f/1.4 until f/3.5 (although at f/3.5 there's a lot of red CA through the middle of the image). Realistically, they both need to be at f/4.5 for best results. I've not had a chance yet to try out the little 40mm pancake lens (hopefully, the field will take after it's name :D)

I use a CLS Clip filter with my EF lenses.

I have two Kenko TC's, both a 1.4 (which I use with both the Sigma 150 and my 70-200 F/4L for normal photography) and a 2x which I use with my ED80 (on a camera tripod) for the moon and sun. 

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Hi Stuart,

You do amazing work with your 500 F4 L but the list price for that lens from WEX Photo is just over £7000.00. A while ago I bought a second hand Canon F2.8 L lens and at f2.8 it does have a bit of fringing, nothing excessive but it is there. I use a front mask to bring it down to f3.8 and there it seems to be fine, a good compromise between speed and performance.

Regards,

A.G

Don't buy new then (I didn't...)...admittedly the 2nd hand prices of the mark 1 are still high (have gone up in fact), they slumped a few years ago when the mark 2 was launched and that is when I bought mine...

It was someone else who mentioned £10k lenses that need stopping down which I don't necessarily agree with 100%.

I know someone with a Canon 500mm f/4.5 L non IS and it would be interesting to see how that performs...it cost him £1.2k 2nd hand and he gets cracking bird photos during the day as well...

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