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Which 4"refractor for mainly astrophotography?

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#1 Leebert

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Posted 17 May 2013 - 02:57 PM

I am considering a 4" or so refractor to set up an imaging rig on an HEQ5 Pro with a William Optics 66SD for a guide scope. I have had a look around and have a list of OTAs that look like they might suit the task.
They are...
Altair Wave Series 102mm F7 Super ED Triplet APO (102/715);
TS PHOTOLIN'E 102mm f/5,2 Flatfield Super APO telescope;
APM 107/700 F6.5 Super ED Triplet APO w 3" APM focuser;
William Optics FLT 98 APO Triplet;
Skywatcher Esprit ED 100 PRO 5-element.

These vary from about £1400 to £2300.

My budget is around £1700 but could increase for the right OTA (and flattener/reducer if required).

I only want to buy once and am prepared to wait. I am a relative newbie where Astrophotography and refractors are concerned. Looking at the short list, i have a few concerns from looking around the internet...
Altair - a bit slow at f7 and no dedicated reducer yet?
TS 102 - not found any reviews etc on them?
WO - Recent quality / build issues concern me.
Esprit 100 - Really stretches my budget and they don't seem to be in stock anywhere.

I would be interested in peoples thoughts on these or any other scopes...

Many thanks,
Lee

#2 CounterWeight

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Posted 18 May 2013 - 12:12 AM

Something small ~80mm and fast (f/6) with a flattener would be my recommendation. The 'quads' IMO are outstnding for imaging as you don't need to fudge with spacer rings / backdistances required for flatteners, and resulting long imaging trane hanging on the focuser. Just attach camera or CCD, focus, and start collecting photons. E-Z. If there is one of those that has a (dedicated?) reducer to take it below f/6 into the f/5 or faster (and has a great focuser) that too would be a great option. In my link below you'll see images from various scope/flattener / reducer combinations to get an idea what the field / resolution is like using an 8300 chip for reference.

#3 Leebert

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Posted 18 May 2013 - 01:06 AM

I had initially discounted the 80mm OTAs as they seem to me to be a bit close to the 66 I already have - hence looking at around 4". Similarly, I don't want to go much larger due to the capacity of the HEQ5 and the capacity of my wallet :)
Thanks for the link - some fantastic images there. It gives me a good idea of the FOV available with the different combinations with a chip size that is similar to mine.
Regards,
Lee

#4 Varun_India

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Posted 18 May 2013 - 01:18 AM

I also have an HEQ5 pro & similarly looking for a 4" refractor for astrophotography.
My budget is around $1500 & I had shortlisted "Explore Scientific 102mm f/7 Triplet Apo in Carbon fiber" which retails for $1499. Being carbon fiber this scope is really light & would be a good match for HEQ5.
Have you considered this scope, reviews seem good.
I am yet to purchase this refractor so can't give u any reviews.

#5 chaoscosmos

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Posted 18 May 2013 - 01:36 AM

NP-101, TV101...... either one or the other come up used fairly regularly.

#6 PhilCo126

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Posted 18 May 2013 - 03:48 AM

Good choice: TS PHOTOLIN'E 102mm f/5,2 Flatfield Super APO telescope;

#7 FTLAUDSKY

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Posted 20 May 2013 - 06:09 PM

I have a FLT98 and love it. Optics are amazing!! I did have to adjust the tension on the focuser, but works great now. I believe WO has one for sale. The FLT98 and the super rare 158 lens were made in Russia. Top notch clarity in my opinion. I bought mine used and I happy with the price I paid. I saw on another site they have a R&P focuser coming out with new ones. If you have the opportunity to pick a used one up don't hesitate. There are tons of scopes in the 4" APO category. Since your in Europe look at the APM/Altair scopes. Have no experience with them, but they seem like a good deal.

#8 wolfman_4_ever

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Posted 20 May 2013 - 06:39 PM

TV101is. flatner already built in.

#9 TimN

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Posted 20 May 2013 - 08:13 PM

I have a SkyWatcher 120mm ED on an HEQ5 Pro that I use for imaging. Its f7.5 but I also have an .85x focal reducer. I've been very pleased with the setup.

#10 timmbottoni

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Posted 20 May 2013 - 10:15 PM

If you would consider the WO GTF102, I can tell you that you will be very pleased for AP work. I am starting to write a full review now, and I am amazed at the optics on mine.

Timm

#11 Panotaker

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Posted 21 May 2013 - 08:28 AM

I would go for a used NP-101. The IS version is nice, but thousands of photos have been taken through the regular NP-101. They come up for sale all the time for about half the price of a new one, and like must stuff from Televue, they last forever.

#12 snommisbor

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Posted 21 May 2013 - 10:22 AM

+1 on the NP-101 or even a TV-101, the version before the NP. I had the TV 101 and it was great. I actually sold it for more than I paid. They are the best deal out there on the used market. I actually dont understand why they depreciate so much from a new price but they do. So I would go the used route and never look back then when you move up you can sell again and probably not lose much if any on resale. Pretty much a risk free purchase.

#13 chaoscosmos

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Posted 21 May 2013 - 10:31 AM

I got a used TV101 for $1700 and the objective lens is pristine. Got lucky on that one. Love it.






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