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Canon 300mm f4 FD Lens - First Light

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#1 John Rogers

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Posted 25 August 2019 - 09:59 PM

I am pleased with my first attempt using a Canon 300mm f4 FD lens.  I converted it so that it achieves infinity focus on an EOS using Ed Mika's conversion kit:  https://edmika.com/

 

My use of telephotos lenses over the years have been mostly disappointing, since they always suffered from coma at full aperture.  However, I was stunned when I saw the results of this lens on a crop-sensor Canon 450D camera - pinpoint stars across the entire field!

 

The image was the result of 80, 30 second subs at ISO1600, stacked with DeepSkyStacker 4.2.2 Beta 1.  Post processing was performed in Photoshop.

 

I am going to have fun with this $75 lens!

 

20190923_M31_300mm_Canon_FD_f4_Small.jpg

 

 

 

 

 

 


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#2 Xeroid

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Posted 25 August 2019 - 10:15 PM

...and here I thought you were using one of those $3,000 Canon beast! lol.gif

 

Great shot!!


Edited by Xeroid, 25 August 2019 - 10:16 PM.


#3 stargazer60

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Posted 25 August 2019 - 10:24 PM

Very nice image, especially using a telephoto lens. Look forward to seeing more of your work. bow.gif 



#4 scottmm2012

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Posted 26 August 2019 - 06:02 AM

Very nice, I have a 135mm FD waiting in the wings for one of Jakub's conversion kits.



#5 Alen K

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Posted 26 August 2019 - 08:21 AM

Nice. Is there much in the way of CA from that lens? Which specific 300mm f/4 is it, btw? I see several varieties on this page. In any case, I had no idea FD lenses could be converted to EOS. Good to know. 



#6 John Rogers

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Posted 26 August 2019 - 10:53 AM

Thanks for the feedback.

 

I didn't realize the number of different lenses out there either.  I don't believe mine is the "L" variant.

 

Canon_300mm_FD.jpg

 

It does suffer somewhat from chromatic aberration as seen in the second image that is a crop of the top section of the photo, before any post processing.  However, I believe that the crop sensor reduces the adverse effects.  This lens will never compete with the modern glass that is available.  It is great lens just to have fun with.  I am still working on the color version of the image.  I have a lot to learn!

 

 

20190923_M31_Stack_Raw_Top_Crop.jpg

 

 

 



#7 Alen K

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Posted 26 August 2019 - 11:24 AM

Yeah, probably not an L model. I see both lateral CA (differential image magnification) and longitudinal/axial CA (differential focusing). Lateral is easy to correct in software; longitudinal not so much. In theory, one could tighten the focus on the blue and red using deconvolution but in practise I don't think that works so well (I have experimented but not explored the possibility completely). Perhaps a star-size reduction algorithm on the red and blue channels (only) would be effective but depending on the algorithm you might still get donuts (which might be fixable with yet another technique).

 

There are a couple things that might help when you actually image as opposed to after-the-fact. One is to use a Hoya UV(0) filter, or really any filter that cuts off steeply below 390nm or 400nm. Smaller wavelength cut-offs like 370nm do almost nothing and somewhat longer wavelength cut-offs start to cut into the visual violet and even blue (but may be worth it nevertheless). The other is to defocus very slightly away from infinity (assuming you have a hard stop there), which will reduce star bloat on blue and red in exchange for defocusing and enlarging star diameters in the green channel a bit. 


Edited by Alen K, 26 August 2019 - 11:26 AM.


#8 John Rogers

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Posted 26 August 2019 - 11:41 AM

Thanks for your analysis Alen.  I do have a lot to learn if I should become serious with imaging.

 

A quick search of eBay resulted in the marking that identifies the L model.  Mine is not that one.

 

I was thinking about the filters.  I can screw one on the end of the lens, use a drop-in filter or use one of the clip-ins.  I need to research the advantages before I decide.  I live in a dark rural area, so light pollution is not a real factor for me.

 

Most of my previous astrophoto experience dates back to 40+ years ago.  I only recently started to dabble with used equipment that I have found on eBay that can be had for very reasonable prices.  The whole world of electronic imaging fascinates me, especially compared to working with emulsions back then.



#9 Alen K

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Posted 26 August 2019 - 12:26 PM

I was quite interested to see your OP because I just bought and tested this weekend a broadly similar lens: an SMC Takumar 300mm f/4. I used a Hoya UV(0) filter on it but tested it without too. The filter cured the blue bloat but not the red (I focused at infinity). So I am on a quest for the best way to reduce red bloat after the fact. I want to get images at least as good as I have done already (example) with an SMC Pentax-M 200mm f/4, which also suffers from CA (although not quite as much!). Of course, I'm really hoping for even better images because of the 50% increase in focal length, otherwise there is little point in using the 300mm lens.

 

Re film AP, been there, done that, bought the t-shirt. I was enthused with what I could do back then (many examples in my CN photo gallery) but digital is so superior it isn't funny. I'm not dissing film, it's just a fact. 


Edited by Alen K, 26 August 2019 - 12:28 PM.

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#10 John Rogers

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Posted 30 August 2019 - 11:27 AM

Thanks Alen.  I learned a lot about my lens and filters the last few days.  Apparently, there are no standard filter threads on the front.  My model has threads that are larger than 77mm, but appears to be there to retain the lens.  Later lenses have no threads at all.  I also learned that the drop-in filters are no longer produced.  The lens came with a "REGULAR 1x" filter, that I assume came with the lens from the factory.  I have not been able to determine anything about the transmission characteristics of this filter.  Canon also sold a "UV 1x", but again I have not been able to learn anything about its characteristics.  Perhaps a knowledgeable person here would know.

 

I have been reviewing image processing on YouTube.  I discovered that a set of Photoshop actions call "Astronomy Tools" by Noel Carboni is popular and highly regarded:  https://www.prodigit...olsActions.html.  It is reasonably priced and I downloaded a copy and used it to process this color image, using the same stack I started with for the OP photo.

 

M31_Color.jpg

 

My research so far suggests that I should try a Hoya UV(0) or Tiffen Haze 2A filter.  I am going to measure the threads on the end of the lens and 3D print an adapter for 77mm filters.

 

I am having a blast with this little 3" f4 refractor!

 

 

 



#11 Alen K

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Posted 30 August 2019 - 12:59 PM

In this thread no-one seemed to know the characteristics of your Regular 1x filter either, or of the UV 1x filter for that matter. But they do confirm it is probably 34mm in size. I did manage to find one 34mm UV(0) filter on Amazon and even after the $35 shipping on a $5 item (!) it's not overly expensive. Not all UV(0) filters have the same steep cutoff as the recent Hoya ones so it's hard to know if it would do the job but at least it's multicoated. 

 

Speaking of multicoated, the Tiffen Haze 2A is NOT. In fact, as far as I can tell it has no anti-reflection coatings at all. This means brighter stars will create flares and it creates strange artifacts even on dimmer ones. I say this confidently because I bought a 52mm one and tried it for a night's imaging. I won't say I wasted the night but nearly so. I won't be using it again. (Thankfully, I only paid about $10 for it on Amazon.) 

 

Btw, your photo is definitely better but as it is now in color, I think you need a little more of that (color). Of course, increasing the color saturation will make the CA more evident, so you could always mask the stars and increase the color only on the "nebulae." (Nebulae in quotes because there are of course actually three prominent galaxies in your image, each of which are largely composed of stars but unresolved so we treat them as extended objects.) 


Edited by Alen K, 30 August 2019 - 01:00 PM.


#12 John Rogers

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Posted 30 August 2019 - 02:06 PM

Speaking of multicoated, the Tiffen Haze 2A is NOT. In fact, as far as I can tell it has no anti-reflection coatings at all. This means brighter stars will create flares and it creates strange artifacts even on dimmer ones. I say this confidently because I bought a 52mm one and tried it for a night's imaging. I won't say I wasted the night but nearly so. I won't be using it again. (Thankfully, I only paid about $10 for it on Amazon.) 

 

Interesting.  I wonder if this one would do the trick?:  https://www.adorama....ategoryID=70147

 

I still have a lot to learn on the processing.  Experimenting is fun, but time consuming.  If I can get a basic workflow down using the Astronomy Tools, that will save even more time.



#13 Alen K

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Posted 30 August 2019 - 02:49 PM

Interesting.  I wonder if this one would do the trick?:  https://www.adorama....ategoryID=70147

I don't think it will. You can see the curve for it here. The curve you want at minimum is like the one shown here and here. (Different filters, same curve.) The Haze 2A cuts off at an even longer wavelength, chopping out a little of the visible violet as well as UV but has the reflection caveat. I don't have a source for the curve for that but rekokich has done tests (you will find the applicable thread if you search the CN forums, which I'm sure you have done already). 

 

Besides, didn't you imply you can't use a 77mm filter (which is weird for a camera lens)? 


Edited by Alen K, 30 August 2019 - 02:59 PM.


#14 John Rogers

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Posted 30 August 2019 - 04:14 PM

Thanks for links Alen.  The curves are very informative and you prevented me from making a mistake.  I will go with the UV(0).

 

The lens was not designed to use a front filter.  However, my lens does have a thread (>77mm) used to retain the lens, so I will use that to design and 3D print an adapter for 77mm filters.



#15 Alen K

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Posted 31 August 2019 - 04:08 AM

This is the UV(0) filter I bought for my 300mm lens: https://www.amazon.c...uct/B000BH5OW6/. Its one of the filters whose curve I referenced from the Lenstip tests and the kind recommended by rekokich in his tests.


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#16 Kiriakos_GR

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Posted 04 September 2019 - 05:13 AM

My Olympus C2100 UZ this using Canon lens barrel with image stabilization (gyro).

One way minimizing CA this is the use of polarizer. 

 

 



#17 Kiriakos_GR

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Posted 04 September 2019 - 05:24 AM


My research so far suggests that I should try a Hoya UV(0) or Tiffen Haze 2A filter.  I am going to measure the threads on the end of the lens and 3D print an adapter for 77mm filters.

 

I am having a blast with this little 3" f4 refractor!

Canon lens of that class does not see much of improvement from such weak filters. 

The coating of Canon lens it self this is all that you can count for, and remember that other people with out quality lens they are more unhappy than you.

There is no perfect and ideal at lenses construction, 95% success this is considered as 100% satisfaction.



#18 Alen K

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Posted 04 September 2019 - 08:49 AM

Canon lens of that class does not see much of improvement from such weak filters. The coating of Canon lens it self this is all that you can count for...

The image in post number 6 is showing blue bloat, which is caused by the lens not focusing a range of wavelengths correctly. It has nothing to do with the lens's anti-reflection coatings. Attenuating those wavelengths with a "weak" filter may help. IMO it's worth $28 and a little time to try. 


Edited by Alen K, 04 September 2019 - 08:50 AM.


#19 Kiriakos_GR

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Posted 04 September 2019 - 10:43 AM

 It has nothing to do with the lens's anti-reflection coatings. Attenuating those wavelengths with a "weak" filter may help.

There is no such thing on this planet.

UV filter aiming to assist at raising contrast by filtering light pollution caused by the sun. 




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